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Antares
Launch of an Antares 230
FunctionMedium-lift launch vehicle
Manufacturer
Country of originUnited States
Project costUS$472 million until 2012[1]
Cost per launchUS$80−85 million[2]
Size
Height
  • 110/120: 40.5 m (133 ft)[3][4]
  • 130: 41.9 m (137 ft)
  • 230/230+: 42.5 m (139 ft)[5]
Diameter3.9 m (13 ft)[6][5]
Mass
  • 100 series: 282,000–296,000 kg (622,000–653,000 lb)[4]
  • 200 series: 298,000 kg (657,000 lb)[5]
Stages2 to 3[6]
Capacity
Payload to LEO
Mass8,000 kg (18,000 lb)[7]
Associated rockets
ComparableDelta II, Atlas III, Atlas V, Falcon 9
Launch history
Status
  • 110: Retired
  • 120: Retired
  • 130: Retired
  • 230: Retired
  • 230+: Retired
  • 300: In development
Launch sitesMARS, LP-0A
Total launches18 (110: 2, 120: 2, 130: 1, 230: 5, 230+: 8)
Success(es)17 (110: 2, 120: 2, 130: 0, 230: 5, 230+: 8)
Failure1 (130)
First flight
  • 110: April 21, 2013
  • 120: January 9, 2014
  • 130: October 28, 2014
  • 230: October 17, 2016
  • 230+: November 2, 2019
  • 300: 2026 (planned)
Last flight
  • 110: September 18, 2013
  • 120: July 13, 2014
  • 130: October 28, 2014
  • 230: April 17, 2019
  • 230+: August 2, 2023
Carries passengers or cargoCygnus
First stage (Antares 100)
Empty mass18,700 kg (41,200 lb)[4]
Gross mass260,700 kg (574,700 lb)[4]
Powered by2 × NK-33 (AJ26-62)[8]
Maximum thrust3,265 kN (734,000 lbf)[8]
Specific impulseSL: 297 s (2.91 km/s)
vac: 331 s (3.25 km/s)[4]
Burn time235 seconds[4]
PropellantRP-1 / LOX[8]
First stage (Antares 200)
Empty mass20,600 kg (45,400 lb)[5]
Gross mass262,600 kg (578,900 lb)[5]
Powered by2 × RD-181[5]
Maximum thrust3,844 kN (864,000 lbf)[5]
Specific impulseSL: 311.9 s (3.06 km/s)
vac: 339.2 s (3.33 km/s)[5]
Burn time215 seconds[5]
PropellantRP-1 / LOX
First stage (Antares 300)
Powered by7 × Miranda[9]
PropellantRP-1 / LOX
Second stage – Castor 30A/B/XL
Gross mass
  • A: 14,035 kg (30,942 lb)
  • B: 13,970 kg (30,800 lb)
  • XL: 26,300 kg (58,000 lb)
Propellant mass
  • A: 12,815 kg (28,252 lb)
  • B: 12,887 kg (28,411 lb)
  • XL: 24,200 kg (53,400 lb)
Maximum thrust
  • A: 259 kN (58,200 lbf)
  • B: 293.4 kN (65,960 lbf)
  • XL: 474 kN (107,000 lbf)[10]
Burn time
  • A: 136 seconds
  • B: 127 seconds
  • XL: 156 seconds[4][5]
PropellantTP-H8299 / Al / AP[11]
[edit on Wikidata]
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Antares (/ænˈtɑːriːz/), known during early development as Taurus II, is an American expendable medium-lift launch vehicle developed by Orbital Sciences Corporation with financial support from NASA under the Commercial Orbital Transportation Services (COTS) program awarded in February 2008. It was developed alongside Orbital's automated cargo spacecraft, Cygnus, which also received COTS funding. Like other Orbital launch vehicles, Antares leveraged lower-cost, off-the-shelf parts and designs. Since 2018, the rocket has been manufactured by Northrop Grumman.

The first stage is liquid fueled, burning RP-1 (kerosene) and liquid oxygen (LOX). As Orbital had limited experience with large liquid stages, construction was subcontracted for all versions of Antares. The 100 and 200 series were built by the Ukrainian companies Pivdenne and Pivdenmash, using refurbished NK-33 engines from the Soviet N1 program on the 100 series and newly built Russian RD-181 engines on the 200 series after the loss of an Antares 130 vehicle in 2014.[12] After Russia’s 2022 invasion of Ukraine ended access to these suppliers, Northrop Grumman announced the 300 series, with a first stage developed by Firefly Aerospace based on the company's MLV rocket using composite structures and seven Miranda engines to increase payload capacity.

The second stage is a solid-fuel motor from the Castor 30 family, derived from the Castor 120 used on the Minotaur-C (the original Taurus I) and ultimately from the Peacekeeper ICBM first stage. While an optional third stage is offered, it has never been used, as the Cygnus spacecraft incorporates its own service module for orbital maneuvers.

Antares made its first flight on April 21, 2013, launching the Antares A-ONE mission from Launch Pad 0A at the Mid-Atlantic Regional Spaceport (MARS) with a Cygnus mass simulator. On September 18, 2013, it successfully launched Orb-D1, the first Cygnus mission to rendezvous with the International Space Station (ISS). After completing the two COTS demonstration flights, Antares and Cygnus were awarded two Commercial Resupply Services contracts covering 25 ISS cargo missions.

The COTS program also supported the development of SpaceX's Dragon spacecraft and Falcon 9 rocket, intended to foster a competitive commercial spaceflight industry. Unlike Falcon 9, which has secured a broad commercial launch market, Antares has been used exclusively for NASA cargo missions, with Cygnus as its sole payload.

History

[edit]

As the Space Shuttle program neared its end, NASA sought to develop new capabilities for resupplying the International Space Station (ISS). Departing from the traditional model of government-owned and operated spacecraft, the agency proposed a new approach: commercial companies would operate spacecraft, while NASA would act as a customer.

To encourage innovation, NASA offered funding through the Commercial Orbital Transportation Services (COTS) program to support the development of new spacecraft and launch vehicles. On February 19, 2008, NASA announced that it would award Orbital Sciences Corporation a COTS contract worth $171 million. Orbital was expected to invest an additional $150 million, divided between $130 million for the rocket booster and $20 million for the spacecraft.[13]

As part of the COTS program, Orbital would be expected to conduct a successful demonstration of its rocket booster and spacecraft. If both demonstration flights were successful, Orbital would be eligible for a lucrative Commercial Resupply Service contract of $1.9 billion for eight flights to the ISS.[14]

In June 2008, it was announced that the Mid-Atlantic Regional Spaceport, formerly part of the Wallops Flight Facility, in Virginia, would be the primary launch site for the rocket.[15] Launch pad 0A (LP-0A), previously used for the failed Conestoga rocket, would be modified to handle Antares.[16] Wallops allows launches which reach the International Space Station's orbit as effectively as those from Cape Canaveral, Florida, while being less crowded.[13][17] The first Antares flight launched a Cygnus mass simulator.[18]

On December 10, 2009, Alliant Techsystems Inc. (ATK) test-fired their Castor 30 motor for use on the second stage of the Antares rocket.[19] In March 2010, Orbital Sciences and Aerojet completed test firings of the AJ-26 engines.[20]

Originally designated the Taurus II, Orbital Sciences renamed the vehicle Antares, after the star of the same name,[21] on December 12, 2011.

As of April 2012, development costs were estimated at $472 million.[1]

On February 22, 2013, a hot fire test was successfully performed, the entire first stage being erected on the pad and held down while the engines fired for 29 seconds.[18]

Design

[edit]
An assembled Antares rocket in the Horizontal Integration Facility.

First stage

[edit]

The first stage of Antares burns RP-1 (kerosene) and liquid oxygen (LOX). As Orbital had little experience with large liquid stages and LOX propellant, the first stage core was designed and is manufactured in Ukraine by Pivdenne Design Office and Pivdenmash[13] and includes propellant tanks, pressurization tanks, valves, sensors, feed lines, tubing, wiring and other associated hardware.[22] Like the Zenit—also manufactured by Pivdenmash—the Antares vehicle has a diameter of 3.9 m (150 in) with a matching 3.9 m payload fairing.[6]

Antares 100 series

[edit]

The Antares 100-series first stage was powered by two Aerojet AJ26 engines. These began as Kuznetsov NK-33 engines built in the Soviet Union in the late 1960s and early 1970s, 43 of which were purchased by Aerojet in the 1990s. Twenty of these were refurbished into AJ26 engines for Antares.[23] Modifications included equipping the engines for gimballing, adding US electronics, and qualifying the engines to fire for twice as long as designed and to operate at 108% of their original thrust.[3][20] Together they produced 3,265 kilonewtons (734,000 lbf) of thrust at sea level and 3,630 kN (816,100 lbf) in vacuum.[8]

Following the catastrophic failure of an AJ26 during testing at Stennis Space Center in May 2014 and the Orb-3 launch failure in October 2014, likely caused by an engine turbopump,[24] the Antares 100-series was retired.

Antares 200 series

[edit]

Because of concerns over corrosion, aging, and the limited supply of AJ26 engines, Orbital had selected new first stage engines[20][25] to bid on a second major long-term contract for cargo resupply of the ISS. After the loss of the Antares rocket in October 2014, Orbital Sciences announced that the Russian RD-181—a modified version of the RD-191—would replace the AJ-26 on the Antares 200-series.[26][27] The first flight of the Antares 230 configuration using the RD-181 launched on October 17, 2016, carrying the Cygnus OA-5 cargo to the ISS.

The Antares 200 and 200+ first stages are powered by two RD-181 engines, which provide 440 kilonewtons (100,000 lbf) more thrust than the dual AJ26 engines used on the Antares 100. Orbital adapted the existing core stage to accommodate the increased performance in the 200 Series, allowing Antares to deliver up to 6,500 kg (14,300 lb) to low Earth orbit.[7] The surplus performance of the Antares 200-series will allow Orbital to fulfill its ISS resupply contract in only four additional flights, rather than the five that would have been required with the Antares 100-series.[28][29][30]

While the 200 series adapted the originally ordered 100 Series stages (KB Pivdenne/Pivdenmash, Zenit derived),[31] it requires under-throttling the RD-181 engines, which reduces performance.[29]

The Antares was upgraded to the Antares 230+ for the NASA Commercial Resupply Services 2 contract. NG-12, launched November 2, 2019, was the first NASA CRS-2 mission to ISS using the 230+ upgrades. The most significant upgrades were structural changes to the intertank bay (between the LOX and RP-1 tanks) and the forward bay (forward of the LOX). Additionally, the company is working on trajectory improvements via a "load-release autopilot" that will provide greater mass to orbit capability.[32]

Antares 300 series

[edit]

In August 2022, Northrop Grumman announced that it had contracted Firefly Aerospace to build the 300-series first stage. They will also be collaborating on the in-development Eclipse launch vehicle. Eclipse and the Antares 300-series will use the same composite structures, and seven Miranda engines. The 7,200 kN (1,600,000 lbf) of thrust they provide will be substantially greater than that of the previous 200-series first stage. Northrop Grumman indicated the new first stage will substantially increase the mass capability of Antares.[33][9]

The announcement occurred as a result of the 2022 Russian invasion of Ukraine, which jeopardized supply chains for the previous first stages, which had been manufactured in Ukraine and used RD-181 engines from Russia.[34]

Second stage

[edit]

The second stage is an Orbital ATK Castor 30-series solid-fuel rocket, developed as a derivative of the Castor 120 solid motor used as Minotaur-C's first stage, itself based on a LGM-118 Peacekeeper ICBM first stage.[35] The first two flights of Antares used a Castor 30A, which was replaced by the enhanced Castor 30B for subsequent flights. The Castor 30B produces 293.4 kN (65,960 lbf) average and 395.7 kN (88,960 lbf) maximum thrust, and uses electromechanical thrust vector control.[8] For increased performance, the larger Castor 30XL is available[31] and will be used on ISS resupply flights to allow Antares to carry the Enhanced Cygnus.[8][36][37]

The Castor 30XL upper stage for Antares 230+ is being optimized for the CRS-2 contract. The initial design of the Castor 30XL was conservatively built, and after gaining flight experience it was determined that the structural component of the motor case could be lightened.[32]

Third stage

[edit]

Antares offers three optional third stages: the Bi-Propellant Third Stage (BTS), a Star 48-based third stage and an Orion 38 motor. BTS is derived from Orbital's GEOStar, a spacecraft bus and uses nitrogen tetroxide and hydrazine for propellant; it is intended to precisely place payloads into their final orbits.[6] The Star 48-based stage uses a Star 48BV solid rocket motor and would be used for higher energy orbits.[6] The Orion 38 is used on the Minotaur and Pegasus rockets as an upper stage.[38]

Fairing

[edit]

The 3.9-meter (13 ft) diameter, 9.9-meter (32 ft) high fairing is manufactured by Northrop Grumman of Iuka, Mississippi, which also builds other composite structures for the vehicle, including the combined fairing adapter, dodecagon, motor cone, and interstage.[39]

Rear view of Antares

NASA Commercial Resupply Services-2 : Enhancements

[edit]

On January 14, 2016, NASA awarded three cargo contracts via CRS-2. Orbital ATK's Cygnus was one of these contracts.[40]

According to Mark Pieczynski, Orbital ATK Vice President, Flight Systems Group, "A further improved version [of Antares for CRS-2 contract] is in development which will include: Stage 1 core updates including structural reinforcements and optimization to accommodate increased loads. (Also) certain refinements to the RD-181 engines and CASTOR 30XL motor; and Payload accommodations improvements including a 'pop-top' feature incorporated in the fairing to allow late Cygnus cargo load and optimized fairing adapter structure".

Previously, it was understood that these planned upgrades from the Antares 230 series would create a vehicle known as the Antares 300 series. However, when asked specifically about Antares 300 series development, Mr. Pieczynski stated that Orbital ATK has "not determined to call the upgrades, we are working on, a 300 series. This is still TBD".[41]

In May 2018, the Antares program manager Kurt Eberly indicated that the upgrades will be referred to as Antares 230+.[32]

Use of Antares 330 for future CRS flights was confirmed in reporting from Breaking Defense in June, 2024. The 330 will used the same second stage, fairing, avionics and software as prior versions.[42]

Configurations and numbering

[edit]
Test firing of Castor 30 second stage

The first two test flights used a Castor 30A second stage. All subsequent flights will use either a Castor 30B or Castor 30XL. The rocket's configuration is indicated by a three-digit number, the first number representing the first stage, the second the type of second stage, and the third the type of third stage.[36] A + sign added as suffix (fourth position) signifies performance upgrades to the Antares 230 variant.

Number First digit Second digit Third digit
(First stage) (Second stage) (Third stage)
0 — — No third stage
1 2 × AJ26-62 Castor 30A BTS (3 × BT-4)
2 2 × RD-181 Castor 30B Star 48BV
3 7 × Miranda Castor 30XL Orion 38

Notable missions and anomalies

[edit]

Antares A-ONE

[edit]
Main article: Antares A-ONE

Originally scheduled for 2012, the first Antares launch, designated A-ONE[43] was conducted on April 21, 2013,[44] carrying the Cygnus Mass Simulator (a boilerplate Cygnus spacecraft) and four CubeSats contracted by Spaceflight Incorporated: Dove 1 for Cosmogia Incorporated (now Planet Labs) and three PhoneSat satellites—Alexander,[45] Graham and Bell for NASA.[46]

Prior to the launch, a 27-second test firing of the rocket's AJ26 engines was conducted successfully on February 22, 2013, following an attempt on February 13 which was abandoned before ignition.[18]

A-ONE used the Antares 110 configuration, with a Castor 30A second stage and no third stage. The launch took place from Pad 0A of the Mid-Atlantic Regional Spaceport on Wallops Island, Virginia. LP-0A was a former Conestoga launch complex which had only been used once before, in 1995, for the Conestoga's only orbital launch attempt.[11] Antares became the largest—and first—liquid-fuelled rocket to fly from Wallops Island, as well as the largest rocket launched by Orbital Sciences.[43]

The first attempt to launch the rocket, on April 17, 2013, was scrubbed after an umbilical detached from the rocket's second stage, and a second attempt on April 20 was scrubbed due to high altitude winds.[47] At the third attempt on April 21, the rocket lifted off at the beginning of its launch window. The launch window for all three attempts was three hours beginning at 21:00 UTC (17:00 EDT), shortening to two hours at the start of the terminal count, and ten minutes later[clarification needed] in the count.[11][48]

Cygnus CRS Orb-3

[edit]
Main article: Cygnus Orb-3
Video of Cygnus CRS Orb-3 failed launch
Pad 0A after the incident

On October 28, 2014, the attempted launch of an Antares carrying a Cygnus cargo spacecraft on the Orb-3 resupply mission failed catastrophically six seconds after liftoff from Mid-Atlantic Regional Spaceport at Wallops Flight Facility, Virginia.[49] An explosion occurred in the thrust section just as the vehicle cleared the tower, and it fell back down onto the launch pad. The range safety officer sent the destruct command just before impact.[50][51] There were no injuries.[52] Orbital Sciences reported that Launch Pad 0A "escaped significant damage",[51] though initial estimates for repairs were in the $20 million range.[53] Orbital Sciences formed an anomaly investigation board to investigate the cause of the incident. They traced it to a failure of the first stage LOX turbopump, but could not find a specific cause. However, the refurbished NK-33 engines, originally manufactured over 40 years earlier and stored for decades, were suspected as having leaks, corrosion, or manufacturing defects that had not been detected.[54] The NASA Accident Investigation Report was more direct in its failure assessment.[55] On October 6, 2015, almost one year after the accident, Pad 0A was restored to use. Total repair costs were about $15 million.[56]

Following the failure, Orbital sought to purchase launch services for its Cygnus spacecraft in order to satisfy its cargo contract with NASA,[25] and on December 9, 2014, Orbital announced that at least one, and possibly two, Cygnus flights would be launched on Atlas V rockets from Cape Canaveral Air Force Station.[57] As it happened, Cygnus OA-4 and Cygnus OA-6 were launched with an Atlas V and the Antares 230 performed its maiden flight with Cygnus OA-5 in October 2016. One further mission was launched aboard an Atlas in April 2017 (Cygnus OA-7), fulfilling Orbital's contractual obligations towards NASA. It was followed by the Antares 230 in regular service with Cygnus OA-8E in November 2017, with three further missions scheduled on their extended contract.

Launch statistics

[edit]

Rocket configurations

[edit]
  •   Antares 110
  •   Antares 120
  •   Antares 130
  •   Antares 230
  •   Antares 230+

Launch outcomes

[edit]
1
2
3
2013
'14
'15
'16
'17
'18
'19
'20
'21
'22
'23
'24
'25
'26
  •   Failure
  •   Partial failure
  •   Success
  •   Scheduled

Operator

[edit]
1
2
3
2013
'14
'15
'16
'17
'18
'19
'20
'21
'22
'23

Past launches

[edit]
Flight No. Date / time (UTC) Rocket variant Launch site Payload,
Spacecraft name 		Payload mass Orbit Operator Customer Launch
outcome
1 April 21, 2013
21:00 		Antares 110 MARS, LP-0A
— LEO Orbital Sciences Corporation NASA (COTS) Success
Antares A-ONE, Antares test flight, using a Castor 30A second stage and no third stage.[58][59]
2 September 18, 2013
14:58 		Antares 110 MARS, LP-0A Cygnus (standard)
Orb-D1
G. David Low[60] 		700 kg
(1,543 lb)[61] 		LEO (ISS) Orbital Sciences Corporation NASA (COTS) Success
Orbital Sciences COTS demonstration flight. First Antares mission with a real Cygnus capsule, first mission to rendezvous and berth with the International Space Station, second launch of Antares. The rendezvous maneuver was delayed due to a computer data link problem,[62] but the issue was resolved and berthing followed shortly thereafter.[63][64]
3 January 9, 2014
18:07 		Antares 120 MARS, LP-0A Cygnus (standard)
CRS Orb-1
C. Gordon Fullerton[60] 		1,260 kg
(2,780 lb)[65] 		LEO (ISS) Orbital Sciences Corporation NASA (CRS) Success
First Commercial Resupply Service (CRS) mission for Cygnus, and first Antares launch using the Castor 30B upper stage.[66][67]
4 July 13, 2014
16:52 		Antares 120 MARS, LP-0A Cygnus (standard)
CRS Orb-2
Janice Voss[68] 		1,494 kg
(3,293 lb)[69] 		LEO (ISS) Orbital Sciences Corporation NASA (CRS) Success
Spacecraft carried supplies for the ISS, including research equipment, crew provisions, hardware, and science experiments.[70]
5 October 28, 2014
22:22 		Antares 130 MARS, LP-0A Cygnus (standard)
CRS Orb-3
Deke Slayton[71] 		2,215 kg
(4,883 lb)[72] 		LEO (ISS) Orbital Sciences Corporation NASA (CRS) Failure
LOX turbopump failure T+6 seconds. Rocket fell back onto the pad and exploded.[55][49][52] First Antares launch to use Castor 30XL upper stage. In addition to ISS supplies, payload included a Planetary Resources Arkyd-3 satellite[73] and a NASA JPL/UT Austin CubeSat mission named RACE.[74]
6 October 17, 2016
23:45 		Antares 230 MARS, LP-0A Cygnus (enhanced)
CRS OA-5
Alan G. Poindexter[75] 		2,425 kg
(5,346 lb)[76] 		LEO (ISS) Orbital ATK NASA (CRS) Success
First launch of Enhanced Cygnus on Orbital's new Antares 230.[77][78][79][80]
7 November 12, 2017
12:19 		Antares 230 MARS, LP-0A Cygnus (enhanced)
CRS OA-8E
Gene Cernan[81] 		3,338 kg
(7,359 lb)[82] 		LEO (ISS) Orbital ATK NASA (CRS) Success
8 May 21, 2018
08:44 		Antares 230 MARS, LP-0A Cygnus (enhanced)
CRS OA-9E
J.R. Thompson[83] 		3,350 kg
(7,386 lb)[84] 		LEO (ISS) Orbital ATK NASA (CRS) Success
Spacecraft carried ISS hardware, crew supplies, and scientific payloads, including the Cold Atom Lab and the Biomolecule Extraction and Sequencing Technology experiment.[84] The Cygnus also demonstrated boosting the station's orbital velocity for the first time, by 0.06 meter per second.[85]
9 November 17, 2018
09:01 		Antares 230 MARS, LP-0A Cygnus (enhanced)
CRS NG-10
John Young 		3,416 kg
(7,531 lb) 		LEO (ISS) Northrop Grumman NASA (CRS) Success
Largest number of satellites launched on a single rocket (108). Cygnus NG-10, CHEFsat 2, Kicksat 2, 104 Sprite Chipsats (deployed from Kicksat 2), MYSAT 1.
10 April 17, 2019
20:46 		Antares 230 MARS, LP-0A Cygnus (enhanced)
CRS NG-11
Roger Chaffee[34] 		3,447 kg (7,600 lbs) LEO (ISS) Northrop Grumman NASA (CRS) Success
Launched the last mission under the Commercial Resupply Services-1 for Cygnus.[34]
11 November 2, 2019
13:59 		Antares 230+ MARS, LP-0A Cygnus (enhanced)
CRS NG-12
Alan Bean[86] 		3,728 kg (8,221 lbs) LEO (ISS) Northrop Grumman NASA (CRS) Success
Cygnus NG-12 is the first mission under the NASA Commercial Resupply Services-2 contract. NG-12 is also the first to use upgraded launcher, Antares 230+.
12 February 15, 2020
20:21 		Antares 230+ MARS, LP-0A Cygnus (enhanced)
CRS NG-13
Robert Lawrence, Jr. 		3,377 kg (7,445 lbs) LEO (ISS) Northrop Grumman NASA (CRS) Success
13 October 3, 2020
01:16 		Antares 230+ MARS, LP-0A Cygnus (enhanced)
CRS NG-14
Kalpana Chawla 		3,458 kg (7,624 lbs)[87] LEO (ISS) Northrop Grumman NASA (CRS) Success
Spacecraft carried ISS hardware, crew supplies, and scientific payloads, including a new toilet (Universal Waste Management System, UWMS), Ammonia Electrooxidation, radishes for Plant Habitat-02, drugs for targeted cancer treatments with Onco-Selectors, and a customized 360-degree camera to capture future spacewalks.[88][87]
14 February 20, 2021
17:36 		Antares 230+ MARS, LP-0A Cygnus (enhanced)
CRS NG-15
Katherine Johnson 		3,810 kg (8399 lbs)[89] LEO (ISS) Northrop Grumman NASA (CRS) Success
This mission carried over 8,000 pounds of cargo including roundworms to study muscle loss and the Spaceborne Computer 2, as well as an experiment to study the protein-based manufacturing of artificial retinas.[90]
15 August 10, 2021
22:01 		Antares 230+ MARS, LP-0A Cygnus (enhanced)
CRS NG-16
Ellison Onizuka 		3,723 kg (8210 lbs)[91] LEO (ISS) Northrop Grumman NASA (CRS) Success
16 February 19, 2022
17:40 		Antares 230+ MARS, LP-0A Cygnus (enhanced)
CRS NG-17
Piers Sellers 		3,800 kg (8,400 lb)[92] LEO (ISS) Northrop Grumman NASA (CRS) Success
17 November 7, 2022
10:32 		Antares 230+ MARS, LP-0A Cygnus (enhanced)
CRS NG-18
Sally Ride 		3,652 kg (8,051 lb)[93] LEO (ISS) Northrop Grumman NASA (CRS) Success
18 August 2, 2023
00:31 		Antares 230+ MARS, LP-0A Cygnus (enhanced)
CRS NG-19
Laurel Clark 		3,729 kg (8,221 lb)[94] LEO (ISS) Northrop Grumman NASA (CRS) Success
Final Antares 230+ launch.

Note: Cygnus CRS OA-4, the first Enhanced Cygnus mission, and Cygnus OA-6 were propelled by Atlas V 401 launch vehicles while the new Antares 230 was in its final stages of development. Cygnus CRS OA-7 was also switched to an Atlas V 401 and launched on April 18, 2017

Future launches

[edit]
Date / time (UTC) Rocket variant Launch site Payload Orbit Customer
2026[95] Antares 330 MARS, LP-0A Cygnus NG-22 (Enhanced Cygnus) LEO (ISS) NASA
First flight of the Antares 330.
2026[96] Antares 330 MARS, LP-0A Cygnus NG-25 (Cygnus XL) LEO (ISS) NASA

Launch sequence

[edit]

The following table shows a typical launch sequence of Antares-100 series rockets, such as for launching a Cygnus spacecraft on a cargo resupply mission to the International Space Station.[69] The coast phase is required because the solid-fuel upper stage has a short burn time.[97]

Mission time Event Altitude
T− 03:50:00 Launch management call to stations
T− 03:05:00 Poll to initiate liquid oxygen loading system chilldown
T− 01:30:00 Poll for readiness to initiate propellant loading
T− 00:15:00 Cygnus/payload switched to internal power
T− 00:12:00 Poll for final countdown and MES medium flow chilldown
T− 00:11:00 Transporter-Erector-Launcher (TEL) armed for rapid retract
T− 00:05:00 Antares avionics switched to internal power
T− 00:03:00 Auto-sequence start (terminal count)
T− 00:02:00 Pressurize propellant tanks
T− 00:00:00 Main engine ignition
T+ 00:00:02.1 Liftoff 0
T+ 00:03:55 Main engine cut-off (MECO) 102 km (63 mi)
T+ 00:04:01 Stage one separation 108 km (67 mi)
T+ 00:05:31 Fairing separation 168 km (104 mi)
T+ 00:05:36 Interstage separation 170 km (106 mi)
T+ 00:05:40 Stage two ignition 171 km (106 mi)
T+ 00:07:57 Stage two burnout 202 km (126 mi)
T+ 00:09:57 Payload separation 201 km (125 mi)

See also

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References

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Antares (rocket)

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Antares is an American medium-lift expendable launch vehicle developed by Orbital Sciences Corporation, now part of Northrop Grumman, to deliver up to 8,000 kilograms of payload to low Earth orbit, primarily for resupplying the International Space Station using the Cygnus spacecraft under NASA's Commercial Resupply Services program. The rocket consists of a two-stage configuration with an optional third stage, featuring a first stage powered by two Russian RD-181 liquid-fueled engines integrated into a Ukrainian-designed structural assembly from KB Yuzhnoye, and a second stage utilizing the American Castor 30XL solid-propellant motor. Launched from the Mid-Atlantic Regional Spaceport at Wallops Island, Virginia, Antares was conceived under NASA's Commercial Orbital Transportation Services initiative, with development funded by a 2006 award leading to its inaugural test flight in April 2013. The vehicle achieved operational status through successful demonstrations, completing 17 out of 18 launches, enabling the delivery of over 40 metric tons of cargo to the ISS across multiple missions from 2013 to 2023. A defining setback occurred on , 2014, during the Orb-3 mission, when the rocket exploded seconds after liftoff due to a failure in one of its refurbished Soviet-era AJ26 engines, destroying the vehicle and payload but causing no injuries. Subsequent investigations revealed manufacturing defects from the engines' origins, prompting Orbital to replace them with new RD-181 units for resumed flights in 2016. Antares exemplifies commercial spaceflight integration of international components for cost efficiency, though geopolitical tensions following Russia's 2022 invasion of disrupted engine supplies, halting launches after the final Antares 230+ mission in August 2023 and necessitating Cygnus pairings with rockets in the interim. is advancing the Antares 330 variant, incorporating domestic alternatives like Firefly Aerospace's Reaver engines to restore independent capability, underscoring the vehicle's evolution amid and reliability challenges.

Development History

Origins as Taurus II

The Taurus II launch vehicle was initially conceived by in the mid-2000s as a medium-lift expendable to fill an emerging performance gap in the U.S. commercial launch market, where existing vehicles like the and Delta II were either too large or being phased out. This design leveraged Orbital's experience with solid-propellant motors from the Taurus and families for upper stages, paired with a novel first stage incorporating a modified Ukrainian Zenit booster core powered by RD-181 engines to enable cryogenic for higher . The concept emphasized cost-effective development through commercial partnerships, including sourcing the first-stage engines and tanks from Ukrainian firms Yuzhnoye and Yuzhmash, reflecting Orbital's strategy to avoid the high costs of fully domestic cryogenic engine production at the time. In December 2008, NASA selected Orbital Sciences for its Commercial Orbital Transportation Services (COTS) program, awarding up to $170 million in milestone-based funding to demonstrate a new cargo delivery system for the International Space Station using the Taurus II rocket and the Cygnus spacecraft. This partnership formalized the vehicle's primary role in ISS resupply missions under NASA's Commercial Resupply Services (CRS) contracts, with Orbital committing matching private investment exceeding $500 million to achieve operational capability by 2012. The COTS selection prioritized the Taurus II's projected reliability target of 98% or higher, achieved through integrated management practices from Orbital's existing launch programs, and its ability to loft up to 5,500 kg to low Earth orbit in the baseline configuration. The rocket retained the Taurus II designation through initial design reviews and subscale testing until December 12, 2011, when Orbital announced its rebranding to —named after the brightest star in the constellation—to better evoke the vehicle's medium-lift capabilities and distinguish it from the company's smaller Taurus orbital . This rename occurred ahead of the first integrated test flight, scheduled from NASA's in , marking the transition from concept validation to full-scale demonstration under COTS milestones. The redesignation did not alter core technical specifications but aligned with Orbital's branding for its expanding commercial space portfolio.

Initial Flights and Early Challenges

The Antares rocket's maiden flight, designated A-ONE, occurred on April 21, 2013, from Pad 0A at the Mid-Atlantic Regional Spaceport in Virginia. This demonstration mission successfully tested the first stage, powered by two refurbished AJ-26 engines derived from Soviet-era designs, achieving a burn duration of 3 minutes and 50.5 seconds and reaching an altitude of about 107.5 kilometers, though the upper stage was not ignited for full orbital insertion. The payload consisted of a mass simulator approximating the weight of the Cygnus spacecraft, validating the rocket's structural integrity and separation systems without attempting rendezvous or docking. The first operational mission, Orb-1, launched on January 9, 2014, at 18:07 UTC using an Antares 120 configuration with an enhanced upper stage. This flight successfully delivered the Cygnus cargo spacecraft to the , marking Orbital Sciences Corporation's fulfillment of initial Commercial Resupply Services contract requirements and demonstrating end-to-end capability for uncrewed cargo delivery. The mission proceeded without anomalies, with Cygnus berthing to the ISS on January 12, 2014, after a series of proximity operations maneuvers. The third launch attempt, Orb-3, on October 28, 2014, failed 15 seconds after liftoff when the rocket lost thrust and fell back onto the pad, resulting in a catastrophic explosion that destroyed the vehicle and damaged launch infrastructure. NASA and Orbital investigations identified the root cause as an explosion in the liquid oxygen turbopump of the AJ-26 engine designated E15, likely due to a manufacturing defect or foreign object debris in the refurbished component, leading to turbine blade failure and propellant line rupture. These engines, originally produced in the 1960s for the Soviet Luna program and refurbished by Aerojet, had not undergone comprehensive modern qualification testing commensurate with their age and storage history, exposing vulnerabilities in the propulsion system's reliability. The incident grounded Antares for over two years, necessitating extensive pad repairs and a reevaluation of the first-stage propulsion architecture.

Post-Explosion Upgrades and Engine Transitions

Following the catastrophic failure of the Antares Orb-3 mission on October 28, 2014, which occurred approximately 6 seconds after liftoff due to a turbopump malfunction in one of the first-stage AJ-26 engines leading to loss of thrust and vehicle destruction, Orbital ATK conducted a thorough investigation in collaboration with NASA. The root cause was traced to a degraded bearing in the liquid oxygen turbopump of the Soviet-era NK-33-derived AJ-26 engine, highlighting reliability issues with the refurbished heritage hardware sourced from Russia via Aerojet Rocketdyne. In response, Orbital ATK opted not to pursue further modifications to the AJ-26 but instead accelerated a planned upgrade to replace both first-stage engines with two new RD-181 liquid-propellant engines procured from Russia's NPO Energomash, contracted in December 2014. The RD-181s, operating on a staged-combustion cycle with RP-1 and liquid oxygen, delivered approximately 820,000 pounds (3.65 MN) of combined sea-level thrust—over 100,000 pounds more than the prior AJ-26 pair—enhancing payload capacity to the International Space Station while addressing the failure mode through modern manufacturing and design. The upgraded Antares 230 configuration achieved its return-to-flight with the OA-5 (Cygnus CRS OA-5) mission on October 17, 2016, from Wallops Island, Virginia, successfully delivering 3,500 pounds of to after a 3-minute, 18-second first-stage burn. Concurrently, the MARS Pad 0A underwent $15 million in repairs and enhancements post-explosion, including removal of debris-contaminated soil, reconstruction of the launch mount, and upgrades to the hydraulic system for improved rocket erection and hold-down capabilities, enabling safer operations for subsequent launches. These modifications, completed by October 2015, incorporated reinforced infrastructure to withstand potential anomalies, with no major structural damage from the 2014 incident having compromised the pad's foundational elements. Subsequent geopolitical tensions, particularly following Russia's 2022 invasion of , prompted U.S. export controls and sanctions that restricted further RD-181 imports, culminating in the engines' final use on the NG-19 mission launched , 2023. To ensure continuity for Commercial Resupply Services missions, —having acquired Orbital ATK in 2018—announced in August 2022 a with to develop the Antares 330, featuring an all-U.S. first stage powered by seven liquid-propellant Miranda engines and leveraging Firefly's composite structures for reduced mass. This transition, aimed at a in mid-2025, eliminates reliance on foreign propulsion while maintaining compatibility with the existing Castor 30XL second stage, with the Miranda engines undergoing qualification testing to achieve over 5,000 pounds of thrust each in a kerolox configuration.

Acquisition by Northrop Grumman and Recent Adaptations

In September 2017, Northrop Grumman announced its agreement to acquire Orbital ATK, the entity responsible for Antares development following the 2015 merger of Orbital Sciences Corporation and Alliant Techsystems, for $9.2 billion including net debt. The deal closed on June 6, 2018, integrating Orbital ATK's space division into Northrop Grumman and rebranding it as Northrop Grumman Innovation Systems, which assumed ongoing Antares manufacturing and launch operations. This acquisition enabled Northrop Grumman to expand its space portfolio, supporting continued Commercial Resupply Services missions to the International Space Station using Antares and Cygnus spacecraft. Recent adaptations to Antares stem from supply chain vulnerabilities exposed by the 2022 , which disrupted availability of Russian RD-181 first-stage engines and Ukrainian propellant tanks. The last flight employing these components, NG-19 on August 1, 2023, marked the end of the Antares 230 configuration's reliance on foreign propulsion. In response, partnered with in August 2022 to create the Antares 330 variant, replacing the first stage with a new liquid-propellant design powered by seven Firefly Miranda engines and featuring Firefly-built composite tanks and structures for full domestic production in . The Antares 330 retains the Castor 30XL solid-propellant upper stage, incorporates upgraded MACH avionics and guidance systems, and supports a 3.9-meter fairing, yielding a low-Earth orbit payload capacity of 10,500 kg while using the same / propellants to minimize modifications. To expedite development, invested $50 million in Firefly in May 2025, targeting a in late 2025 for Cygnus resupply continuity amid evolving post-ISS requirements. This effort also underpins the derivative medium for broader commercial and applications.

Technical Specifications

Overall Architecture and Propulsion

The Antares rocket features a modular two-stage architecture designed for reliable access to low-Earth orbit, primarily supporting commercial resupply missions to the International Space Station via the Cygnus spacecraft. The core design integrates a liquid-fueled first stage for high-thrust ascent with a solid-propellant second stage for orbital insertion, allowing for payload capacities up to approximately 8,000 kg to low-Earth orbit in baseline configurations. This hybrid propulsion approach leverages the high thrust-to-weight ratio of liquid engines for liftoff and the simplicity of solid motors for upper-stage efficiency. The first stage structure draws from the Zenit launch vehicle's heritage, consisting of a for propellant tanks holding and in a 2.59:1 oxidizer-to-fuel . is provided by two gimbaled, first-stage engines clustered at the base, each capable of for steering. Early Antares 100 and 200 series variants employed refurbished AJ-26 engines—derived from Soviet-era motors manufactured in —delivering a combined sea-level of about 3.89 MN. Following the 2014 Orb-3 mission attributed to an AJ-26 malfunction, the configuration shifted to newly produced RD-181 engines sourced from Russia's , which offer similar performance with enhanced reliability through modern manufacturing; each RD-181 generates approximately 1.92 MN of vacuum using the same propellants. Geopolitical tensions, including post-2022 sanctions on Russian technology, have prompted to pursue domestic alternatives, with the forthcoming 330 planned to employ seven Miranda engines clustered for a total first-stage exceeding 7.3 MN. The second stage utilizes Northrop Grumman's Castor 30 family of solid rocket motors, which provide non-gimbaled via a fixed , supplemented by attitude control systems for trajectory adjustments. Variants include the Castor 30A (initial flights, 259 kN ), 30B (293 kN), and 30XL (474 kN average with a of 282 seconds), selected based on mission requirements; the 30XL, with its 24,866 kg propellant load, supports heavier Cygnus payloads by extending burn time to around 150 seconds. This stage's solid-fuel design minimizes complexity and ground handling risks compared to liquid alternatives, though it limits throttlability. An optional , such as the thrust-vector-controlled STAR 48BV motor, can be added beneath the for missions needing precise orbital circularization or higher energy orbits.

First Stage Configurations

The Antares rocket's first stage employs a liquid-fueled core derived from the Ukrainian Zenit launch vehicle's structure, utilizing (refined ) and liquid oxygen () propellants in all operational configurations. This cylindrical tankage assembly, manufactured by Yuzhnoye Design Bureau, measures approximately 25.6 meters in length and 3.9 meters in diameter, with a propellant load exceeding 160 metric tons. The stage features two gimbaled engines for thrust vector control, enabling pitch, yaw, and roll maneuvers during ascent. In the Antares 100 series (configurations 110, 120, and 130), the first stage was powered by two AJ-26 engines, refurbished variants of the Soviet-era NK-33 originally developed for the lunar rocket program. Each AJ-26 delivered approximately 854 kN of sea-level thrust, providing a total of about 1.7 MN for the stage, with burn times around 210 seconds. These engines, sourced from surplus inventories and modified in the United States, ignited at liftoff to accelerate the vehicle to roughly Mach 3 before separation. The configuration supported payloads up to 5,000-6,000 kg to , depending on upper stage variants. Following the Orbital-3 mission failure on October 28, 2014, attributed to a disintegration in one AJ-26 engine due to material fatigue in its refurbished components, Orbital ATK (now ) transitioned to the Antares 200 series (210, 220, 230, and 230+). This upgrade replaced the AJ-26 with two Energomash RD-181 engines, modern Russian bipropellant units derived from the RD-191 family and designed for the rocket. Each RD-181 produced about 1,920 kN of (1,583 kN at ), yielding a combined stage of approximately 3.85 MN and enabling higher payload capacities of up to 8,000 kg to in the 230+ variant through optimized tank ullage and full-throttle operation. The RD-181 configuration debuted successfully on the OA-5 mission on October 17, 2016, with subsequent flights confirming reliability until geopolitical tensions halted further engine imports after the NG-19 mission on August 1, 2023. The forthcoming Antares 300 series (notably the 330 configuration) introduces an American-sourced propulsion system to mitigate supply chain risks from foreign engines. The first stage will integrate seven Miranda engines, each a 22 kN-thrust, electrically pumped / unit qualifying under U.S. (ITAR). This cluster arrangement aims to deliver comparable total thrust to prior configurations while enhancing restart capability and reducing dependency on Russian manufacturing, with a targeted in mid-2025 or later pending qualification testing. The stage retains the Zenit-derived core but incorporates structural reinforcements and updates for compatibility.

Upper Stages and Fairing

The second stage of the Antares rocket utilizes the CASTOR 30XL solid rocket motor, which features a composite /epoxy wound motor case and a Flexseal design enabling two-axis . This motor evolved from earlier Castor family variants and has been employed in the Antares 200 series configurations following initial flights that used the Orion 38 motor. The CASTOR 30XL ignites shortly after first-stage separation, providing the delta-v required for payload insertion into , with levels supporting missions up to approximately 8,000 kg to in standard configurations. Optional third stages are available for enhanced performance in certain Antares variants. The 231 configuration incorporates an Orbit Adjust Module with monopropellant propulsion, utilizing up to four 1,200 kg spherical tanks and eight 45 lbf assemblies for multiple burns and precise adjustments. The 232 variant employs a STAR 48BV solid rocket motor with two-axis thrust vector control, drawing from a heritage of over 100 successful flights. In the 233 setup, an Orion 38 solid motor provides additional capability, benefiting from more than 75 prior missions. These upper stage options accommodate varied mission requirements beyond standard resupply profiles. The measures 3.9 meters in diameter and adopts a bi-sector to encapsulate the upper stage and , shielding them from aerodynamic and thermal loads during atmospheric ascent. Constructed with graphite-epoxy facesheets over an aluminum core, it incorporates frangible rail and ring joints for reliable separation, augmented by cold gas thrusters for deployment. The fairing includes RF-transparent properties to maintain communication links and a 610 mm by 610 mm access door for integration and late-loading operations, with a removable pop-top facilitating access prior to launch.

Guidance and Control Systems

The Antares rocket's (GNC) system is integrated into the Modular Avionics Control Hardware (MACH), a flight-proven architecture that manages power transfer, , interfaces with solid rocket boosters, and ordnance initiation across vehicle stages. The on-board flight computers within MACH execute autonomous sequencing starting at T-3 minutes, including engine start commands, health monitoring, and real-time trajectory adjustments via mission-specific software verified through . This setup enables the guidance computer to command pivots on the first-stage liquid engines (such as RD-181 variants) for initial steering and ascent control. Attitude control relies on a heritage cold gas nitrogen (RCS) for three-axis stabilization during coast phases, roll control during second- and optional third-stage burns in configurations like 232 and 233, and orientation prior to separation. vector actuators on the second (e.g., Castor 30XL motor) provide additional pointing authority, while the RCS supports post-separation collision and contamination avoidance maneuvers (CCAM). The system interfaces with ground support via Ethernet and discrete I/O for pre-launch calibration and , ensuring alignment with launch requirements. Orbit insertion performance demonstrates the GNC precision, with accuracies of ±5-25 km in the insertion and ±60-80 km in the non-insertion for the 230 series, improving to ±15 km in both for the 231 configuration; these metrics derive from six-degree-of-freedom simulations and analyses tailored to and parameters. Upgrades post-2014 Orbital-3 retained core MACH in the upper stack for subsequent flights, with enhancements focused on sensors like accelerometers and strain gauges for rather than fundamental GNC redesign. The Antares 330 maintains this heritage alongside its new first stage, preserving compatibility for low-Earth insertions up to 10,500 kg.

Operational Configurations

Antares 100, 200, and 300 Series

The Antares rocket's operational configurations follow a three-digit numbering system, with the first digit denoting the first stage variant, the second the number of solid rocket boosters (0 for none, 2 for two Castor 30 motors), and the third the fairing length (0 for 3.9 m, 1 for 4.6 m), supplemented by a letter for the upper stage type such as Castor 30XL. The 100 Series employed a first stage powered by two Aerojet AJ-26 liquid engines burning kerosene and liquid oxygen, refurbished from Soviet NK-33 hardware originally produced for the N1 lunar program. The baseline 110 configuration, lacking boosters, conducted the A-ONE demonstration flight on April 21, 2013, successfully reaching space but not orbit due to an upper stage anomaly. Subsequent 120 and 130 variants added two Castor 30A/B boosters and optional extended fairings, enabling five successful Cygnus launches from Orb-1 on January 9, 2014, to Orb-3 before the October 28, 2014, failure caused by an AJ-26 turbopump rupture. The 200 Series replaced the AJ-26 with two Energomash RD-181 engines, also kerosene-liquid oxygen fueled but derived from the family for improved thrust and a 25 percent payload increase to over the 100 Series. Primarily flown as the 230 configuration with Castor 30XL upper stage, it resumed operations with OA-5 on October 17, 2016, and completed 11 Cygnus missions through NG-19 on August 1, 2023, demonstrating reliability post-upgrades including enhanced and structural reinforcements. The series supported payloads up to approximately 8,000 kg to . The 300 Series, designated as 330, introduces a fully American first stage developed with , featuring seven Reaver-derived Miranda engines in a tap-off cycle using and for cleaner performance and reduced dependency on foreign propulsion. Retaining the Castor 30 upper stage and 3.9 m fairing, it boosts capacity to 10,500 kg to through composite materials and optimized staging. As of 2025, development continues for initial flights no earlier than mid-2025 to fulfill Commercial Resupply Services contracts, addressing sanctions on Russian engines used in prior series.
SeriesFirst Stage EnginesBoostersTypical Upper StageLEO Payload (kg)
1002 × AJ-26 (kerolox)0 or 2 Castor 30Castor 30XL~6,000
2002 × RD-181 (kerolox)2 Castor 30BCastor 30XL~8,000
3007 × Miranda (methalox)NoneCastor 3010,500

Payload Capabilities and Adaptations

The Antares rocket employs a standard 3.9-meter diameter measuring 9.9 meters in height, featuring a core structure with composite face sheets to enclose and protect during ascent. This fairing configuration supports low-Earth (LEO) insertions for payloads up to 8,000 kilograms in the Antares 230+ series, with common interfaces for electrical, mechanical, and reaction control systems across variants. Payload integration includes accommodations for electrical ground support equipment (EGSE) housed in the launch site's Launch Equipment Vault, enabling pre-launch testing and monitoring without compromising vehicle security. The optional , a solid motor such as the Castor 30 series, provides thrust vector guidance, 3-axis stabilization, and adjustable delta-V to tailor performance for diverse orbital requirements beyond baseline LEO missions. Upper stage adaptations, including motor selections matched to and demands, have enabled missions like the 2013 A-ONE demonstration flight, which carried a Cygnus simulator to verify structural and dynamic interfaces. For International Space Station (ISS) resupply, the rocket is optimized for the Cygnus spacecraft, delivering up to approximately 3,500 kilograms of cargo to the orbit while leveraging dedicated service module interfaces for propulsion and attitude control post-separation. The planned Antares 330 variant enhances adaptability with a reinforced first stage using seven Miranda engines and an upgraded upper stage, boosting LEO capacity to 10,500 kilograms and supporting broader payload envelopes through increased thrust and structural margins. These modifications address prior limitations in responsiveness to non-Cygnus payloads, such as small satellite dispensers, by standardizing fairing and stage interfaces for rideshare opportunities.

Launch Operations

Launch Sites and Infrastructure

The Antares rocket launches from Launch Pad 0A at the Mid-Atlantic Regional Spaceport (MARS), situated at NASA's Wallops Flight Facility on Wallops Island, Virginia. This facility provides an eastward over-ocean trajectory, enabling safe launches toward polar or low-inclination orbits while minimizing risks to nearby populations. Pad 0A was constructed specifically for medium-class liquid-fueled rockets like Antares, completed in 2011 by the Virginia Spaceport Authority at a cost of approximately $120 million to support Orbital ATK's (now Northrop Grumman) commercial resupply missions to the International Space Station. Infrastructure at Pad 0A includes a reinforced launch mount designed for the rocket's two-stage configuration, a water deluge system for sound suppression and fire mitigation during liftoff, and integration with for fueling and countdown operations. Adjacent facilities at Wallops encompass buildings for assembly, where the vehicle is stacked and mated with the Cygnus payload before being transported via rail to the pad for erection. Following the catastrophic failure of the Orb-3 mission on October 28, 2014, which destroyed the initial pad infrastructure, extensive repairs and upgrades were completed, including enhanced blast-resistant features, allowing resumption of launches by 2016. MARS Pad 0A supports multi-user operations, with as the primary tenant for through the Antares 330 configuration, which maintains compatibility with the existing site despite propulsion changes. Additional Wallops infrastructure, such as payload processing facilities and telemetry tracking stations, facilitates mission control and data acquisition during ascent. No alternative launch sites have been utilized for Antares operational flights, emphasizing the site's role as the dedicated infrastructure for the vehicle's 18 launches as of 2023.

Sequence and Ground Support

The Antares rocket undergoes in the Horizontal Integration Facility (HIF), designated Building X-79, at the (MARS) on , , where the core stages and are assembled prior to vertical erection on the . Payload processing occurs separately in the Payload Processing Facility (PPF), followed by mating with the rocket in the HIF. Ground support equipment includes the Transporter-Erector-Launcher (TEL), a specialized rail-mounted vehicle that transports the fully integrated rocket horizontally from the HIF to Pad 0A approximately three days prior to launch, after which it erects the vehicle to vertical position on the launch mount. Additional equipment comprises the Portable Environmental Control System (PECS) for maintaining payload thermal conditions during ground operations, electrical ground support equipment (GSE) housed in the Launch Equipment Vault (LEV) for vehicle commanding and power supply, and mechanical GSE such as cranes, dollies, and fixtures for handling components. Pad infrastructure at Pad 0A features a flame duct with water deluge system for suppressing exhaust heat, lightning protection towers, and fueling skids for liquid oxygen (LOX) and rocket propellant (RP-1), with environmental control systems ensuring stable conditions during final checks. The launch countdown, directed from the Range Control Center (RCC) with oversight from the Wallops Mission Operations Control Center (MOCC), begins with vehicle power-up and systems testing approximately six hours prior to liftoff, progressing through commodity loading (, ) and payload door closure. Stage 1 fueling commences around T-minus 90 minutes, involving loading followed by chilldown and tanking, while the Castor 30XL upper stage motors are armed. Final polls for "go" status from vehicle, range, and teams occur in the last 30 minutes, culminating in auto-sequence initiation at T-minus 3 minutes, managed by the onboard for engine health checks and ignition preparation. Ignition of the two RD-181 first-stage engines occurs approximately 3.7 seconds before liftoff (L-0), with the hold-down posts releasing at T+2 seconds upon confirmation of nominal thrust, allowing the rocket to clear the tower by T+10 seconds. Ground support during this phase includes real-time telemetry monitoring via the RCC for flight termination system (FTS) readiness and range safety, with contingency procedures for scrubs, such as those implemented in 2020 due to GSE faults requiring rocket lowering via the TEL.

Mission Record

Successful Resupply Missions

The Antares rocket has executed 17 successful launches of the Cygnus spacecraft for resupply missions to the International Space Station under NASA's Commercial Resupply Services program, achieving a 94.4% success rate across 18 attempts. These missions delivered supplies, scientific experiments, and equipment essential for ISS operations, spanning from demonstration flights to operational cargo deliveries totaling thousands of kilograms. The inaugural demonstration mission, designated Orb-D1, launched on September 18, 2013, from , enabling the first Cygnus rendezvous and berthing with the ISS on September 22. This flight validated the integrated Antares-Cygnus system, carrying student experiments and small payloads despite its test status. The first operational resupply, CRS Orb-1, occurred on January 9, 2014, with Cygnus C. Gordon Fullerton transporting 1,225 kg of pressurized cargo and 651 kg unpressurized, docking on January 12. CRS Orb-2 followed on July 13, 2014, launching Cygnus II to deliver additional crew provisions and research materials. After upgrading to the Antares 230 configuration featuring Castor 30 upper stages, resupply operations resumed with OA-5 on October 30, 2016. The program then conducted consistent successes, including OA-6 in April 2017, OA-8E on November 12, 2017, and OA-9E in May 2018, before transitioning to the NG-series numbering. Notable NG-series missions encompassed NG-10 on November 17, 2018; NG-11 in April 2019, highlighted by a nighttime launch; NG-12 in September 2019; NG-13 on February 15, 2020; NG-14 on October 2, 2020; NG-15 on February 20, 2021; NG-16 on August 10, 2021; NG-17 on February 19, 2022; NG-18 on November 7, 2022; and NG-19, the final Antares 230+ flight, on August 1, 2023. Each mission involved precise guidance to achieve low Earth orbit insertion, followed by Cygnus autonomous rendezvous, capture by the ISS robotic arm, and berthing to the Unity module's nadir port, with departures typically after 30-90 days to dispose of the spacecraft via atmospheric reentry.

Anomalies and Failures

The sole major failure in the Antares rocket's operational history occurred during the Orb-3 resupply mission on October 28, 2014, launched from Pad 0A at the Mid-Atlantic Regional Spaceport on Wallops Island, Virginia. Six seconds after liftoff, the vehicle suffered a catastrophic anomaly, with one of the two first-stage AJ-26 engines exploding, causing the rocket to lose thrust and pitch over, leading to its destruction by the range safety system before impact to minimize ground hazards. No injuries were reported, though the launch pad sustained significant damage from debris and fire, requiring extensive repairs before subsequent launches. NASA's Independent Review Team (IRT) investigation, detailed in its October 2015 report, identified the proximate cause as an explosion within the AJ-26 turbopump assembly of Engine E15, triggered by the failure of the high-pressure fuel turbopump. The team pinpointed three potential root causes: a workmanship fault in the turbine housing bearing bore misalignment, foreign object debris (FOD) consisting of titanium and silica particles present prior to testing, or material defects such as subsurface flaws in the turbine blades leading to fatigue cracking. These engines, refurbished from Soviet-era NK-33 designs by Aerojet Rocketdyne, exhibited inconsistencies between Orbital ATK's and NASA's analyses; Orbital emphasized FOD or bearing wear from manufacturing, while NASA highlighted broader turbopump vulnerabilities without a singular definitive root cause. The failure prompted Orbital ATK (now ) to retire the AJ-26 engines, replacing them with RD-181 engines sourced from for the Antares 230 configuration to mitigate recurrence risks. This transition delayed subsequent Commercial Resupply Services (CRS) missions, with approving alternative launchers like the for interim Cygnus flights while Antares infrastructure was refurbished. Pre-flight anomalies, such as umbilical dislocations or helium leaks in earlier missions, resulted in scrubs rather than in-flight failures and were addressed through ground procedures without compromising overall reliability post-Orb-3. No additional mission losses have been recorded in Antares' 11 operational launches through 2020.

Transition to Alternative Launchers

Following the catastrophic failure of the Antares Orb-3 mission on October 28, 2014, which resulted in the destruction of the and significant damage to the pad at , Orbital ATK (now ) temporarily shifted Cygnus resupply missions to the rocket to maintain schedule compliance under NASA's Commercial Resupply Services (CRS) contract. This transition enabled the OA-5 mission to launch successfully on December 6, 2015, from Station's SLC-41, delivering approximately 3,500 kg of cargo to the (ISS). A second flight, OA-7, followed on , 2017, from the same pad, carrying over 3,700 kg of supplies and marking the final such interim use before returned to service with the upgraded 230 configuration. These adaptations underscored Cygnus's launcher-agnostic design, allowing rapid integration with alternative vehicles while Antares infrastructure was repaired and the rocket upgraded with new and Castor 30XL second-stage motors. A second major transition occurred after the 2022 prompted international sanctions that halted exports of RD-181 first-stage engines from , leaving unable to procure additional units beyond its pre-existing stockpile. The final 230+ launch, NG-19 carrying the S.S. , lifted off on August 1, 2023, from Wallops Island's Pad 0A, delivering more than 3,700 kg of cargo and concluding the 200-series operations after 13 flights since 2016. To fulfill remaining CRS-2 obligations without interruption, contracted for launches, beginning with NG-20 on January 30, 2024, from Cape Canaveral's SLC-40, which transported the upgraded Cygnus XL variant with enhanced cargo capacity of up to 5,000 kg. This was followed by NG-21 on August 4, 2024, and NG-23 on September 14, 2025, both on , enabling three missions in the interim period while 330 development progresses toward a projected debut no earlier than late 2025 using American-sourced Miranda engines. These shifts highlight supply chain vulnerabilities tied to foreign-sourced components, with the RD-181 dependency—originally chosen for cost and performance—exposing geopolitical risks that U.S. policy changes post-2022 exacerbated. Northrop Grumman has secured up to four Falcon 9 slots through 2026 to bridge to domestic alternatives, preserving ISS resupply cadence amid NASA's emphasis on assured access and reduced reliance on adversarial suppliers.

Performance Analysis

Launch Outcomes and Reliability Metrics

The Antares rocket has completed 18 launches since its inaugural flight in April 2013, with 17 successes and one failure, resulting in an overall success rate of 94.4%. All missions carried Cygnus spacecraft under NASA's Commercial Resupply Services (CRS) contracts to deliver cargo to the International Space Station, with the final Antares 230+ launch occurring on August 1, 2023, for the NG-19 mission.
The single failure took place on October 28, 2014, during the CRS-3 (Orb-3) mission, when the vehicle exploded approximately 15 seconds after liftoff from . Investigation by and Orbital Sciences (now ) identified the root cause as a bearing failure in one of the first-stage AJ26 engines, leading to an explosion that destroyed the vehicle and payload; the engines, refurbished from 1960s Soviet stock, exhibited cracking and material degradation from prolonged storage. This incident grounded the Antares 100/130 series and prompted the use of rockets for interim Cygnus missions in 2015 and 2016. Subsequent upgrades in the Antares 230 and 230+ configurations addressed engine vulnerabilities by adopting new RD-181 first-stage engines (sourced from Russia's KB KhA) and enhanced , achieving 13 consecutive successes from October 2016 through August 2023 without anomalies. These flights delivered over 100 metric tons of cargo cumulatively, demonstrating improved operational reliability post-redesign. No partial successes or upper-stage failures were recorded, underscoring the vehicle's consistency in achieving orbital insertion for ISS resupply.

Comparative Efficiency and Cost Factors

The Antares rocket's launch costs under NASA's Commercial Resupply Services (CRS) program have averaged approximately $80–85 million per mission for the Antares 230 configuration, reflecting fixed-price contracts that bundle launch vehicle and Cygnus spacecraft operations. In comparison, SpaceX's Falcon 9, the primary alternative for ISS cargo delivery, operates at $62–67 million per launch for similar missions, benefiting from partial reusability of the first stage, which reduces marginal costs after initial recovery investments. This disparity contributed to NASA awarding SpaceX a larger share of CRS-2 missions, as Orbital ATK (now Northrop Grumman) proposals exceeded competitive pricing thresholds despite equivalent cargo capacities of 2,000–3,000 kg delivered to the ISS per flight. Cost per kilogram to (LEO) further highlights ' disadvantages, with estimates around $10,000–$10,600 per kg based on its 8,000 kg LEO payload capacity, versus Falcon 9's $2,900–$3,000 per kg for 22,800 kg capacity. ' higher unit economics stem from expendable architecture and dependencies, including Ukrainian Zenit-derived first-stage engines (NJ-26/RD-181) that faced and sanctions post-2014, inflating by forcing transitions to domestic alternatives like Northrop Grumman's Castor 300 solids. Falcon 9's all-liquid propulsion and iterative reusability, achieving over 300 first-stage recoveries by 2025, enable amortized cost reductions unavailable to , which lacks recovery mechanisms. Propulsive efficiency metrics underscore Antares' structural limitations: its hybrid design pairs solid rocket boosters ( ~250–260 seconds) with a upper (RD-181 ISP ~311 seconds ), yielding lower overall exhaust velocity than Falcon 9's engines (311 seconds , 348 seconds ). This results in a fraction of ~2–3% of gross liftoff mass (~370 metric tons for Antares 230), compared to Falcon 9's ~4–5% (~550 tons GLOW), prioritizing over in a medium-lift profile optimized for Wallops' coastal pads rather than intrinsic performance. Geopolitical risks, such as RD-181 sourcing from until 2022 sanctions, added ~20–30% to engine costs via requalification, eroding any initial domestic manufacturing advantages over imported alternatives like .
RocketLEO Payload (kg)Est. Launch Cost ($M)Cost/kg to LEO ($)
8,00080–8510,000–10,625
22,80062–672,720–2,939
These figures derive from manufacturer data and analyses, excluding ancillary CRS integration costs; actual mission economics for worsened post-2014 Orb-3 due to grounding and redesign expenses exceeding $100 million.

Challenges and Criticisms

Engineering and Reliability Shortcomings

The Antares rocket's engineering shortcomings were prominently exposed by the Orb-3 mission failure on October 28, 2014, when the vehicle exploded seconds after ignition on the launch pad at . The proximate cause was an explosion within one of the two AJ-26 first-stage engines, resulting from a malfunction that caused the blades to disintegrate. Orbital ATK's investigation identified a defect—a cracked originating from production in the during the engines' original Soviet-era manufacture—as the initiating factor, exacerbated by the refurbishment process. This defect led to loss of rotor radial positioning, frictional rubbing, and subsequent under operational stresses. NASA's Independent Review Team (IRT) corroborated the turbopump explosion but could not conclusively determine the root cause, citing potential contributors including inadequate design robustness in the AJ-26's hydraulic balance assembly and turbine-end bearing, foreign object debris, or a mechanically faulty bearing. The AJ-26 engines, refurbished NK-33 variants from Soviet stockpiles, exhibited vulnerabilities such as , cracking, and hardware stress from decades of storage, underscoring the risks of relying on aged components without comprehensive modern requalification. Prior to Orb-3, engine-related anomalies, including a static-fire test investigation, had already delayed launches, highlighting ongoing reliability concerns. These issues eroded confidence in the Antares system's overall reliability, with the single failure representing a 20% loss rate across its initial five launch attempts (four successes prior to Orb-3). The design's dependence on foreign-derived engines lacked the redundancy and seen in more vertically integrated systems, amplifying the impact of isolated component failures. Post-failure mitigation involved replacing the AJ-26 with newly manufactured RD-181 engines, which feature improved designs but introduced new integration challenges and required enhanced oversight for qualification testing. Despite subsequent successful launches, the Orb-3 incident revealed fundamental limitations in , refurbishment processes, and system-level robustness for a vehicle intended for recurrent resupply.

Supply Chain and Geopolitical Vulnerabilities

The Antares rocket's first stage has historically depended on foreign suppliers for critical propulsion components, exposing it to geopolitical risks. From the Antares 230+ configuration introduced in 2016, the vehicle utilized two Russian-manufactured RD-181 engines produced by , paired with a first-stage structure assembled in by Yuzhmash using Ukrainian and tankage. This arrangement stemmed from a 2015 decision by Orbital ATK (now ) to replace earlier Ukrainian-sourced AJ26 engines—rebuilt Soviet-era variants that contributed to the 2014 Orb-3 explosion—due to perceived reliability advantages of the RD-181, despite introducing dependency on Russian technology. Such reliance persisted amid post-2014 tensions but prioritized operational continuity over full domestic sourcing. Russia's full-scale invasion of Ukraine in February 2022 severely disrupted these supply chains, halting Ukrainian first-stage production at Yuzhmash and rendering Russian engine exports untenable under Western sanctions and export controls. Northrop Grumman had procured a limited stockpile of nine RD-181 engines prior to the conflict, sufficient for only a few launches, but broader component shortages compounded delays; for instance, the NG-20 Cygnus mission slipped from August to October 2022 due to supply chain constraints unrelated to engines but exacerbated by global disruptions. The NG-19 mission on August 1, 2023, marked the final Antares flight incorporating Russian and Ukrainian elements, after which Northrop retired the 230+ variant to avoid further geopolitical exposure. In response, the company provisionally shifted Cygnus resupply missions to SpaceX Falcon 9 rockets under NASA's Commercial Resupply Services-2 contract, launching NG-20 in January 2024 and subsequent flights. To mitigate long-term vulnerabilities, announced an August 2022 partnership with to develop the 330, featuring a fully U.S.-built first stage powered by Firefly's Reaver engines—medium-class engines designed to supplant the RD-181 without foreign inputs. This upgrade aims for a 2025 debut, though development delays pushed initial timelines from 2024, reflecting challenges in scaling domestic manufacturing amid persistent aerospace supply bottlenecks for composites, electronics, and propellants. Critics, including U.S. policymakers, have highlighted the original foreign dependencies as a strategic liability, arguing that earlier diversification could have averted mission gaps and underscoring broader U.S. space sector risks from over-reliance on adversarial suppliers. As of October 2025, 330 qualification remains ongoing, with no operational flights, leaving Cygnus launches contingent on third-party vehicles until certification.

Contractual and Economic Critiques

NASA's Commercial Resupply Services (CRS) contract with (later Orbital ATK, now ), valued at $1.9 billion for eight missions delivering 18.6 metric tons of cargo to the by the end of 2016, drew scrutiny for its milestone-based payment structure that front-loaded funds relative to achieved progress. By the end of 2012, had disbursed $910 million under the combined COTS and CRS agreements, including $633 million specifically for five CRS rocket systems, despite Orbital having completed no International Space Station resupply flights. The (OIG) highlighted that Orbital was positioned to receive up to 70 percent of payments for six missions prior to a successful demonstration flight, deeming portions—such as $150 million for missions scheduled in 2015—as premature and elevating 's financial risk of funding potential redesigns without verified performance. Delays in Orbital's schedule, including a 33-month postponement of the system demonstration flight to or September 2013, were not swiftly incorporated into payment adjustments, amplifying concerns over the contract's inflexibility in reflecting slippage. Following the October 28, 2014, Orb-3 failure, which destroyed the vehicle and cargo while damaging the launch pad, approved a revised return-to-flight plan in January 2015 that reduced missions to four (delivering 13 metric tons) using two launches and two modified flights. However, forewent invoking a contractual provision for a $21 million price reduction due to delays, settling instead for $2 million in nonmonetary concessions, and failed to negotiate lower per-kilogram pricing that could have yielded up to $84 million in total savings ($21 million from delays plus $65 million from adjusted rates). This approach, coupled with 's expenditure of $5 million on pad repairs despite no contractual liability for Orbital, underscored critiques that the fixed-price framework inadequately protected agency interests amid performance shortfalls. Economically, Antares-Cygnus missions under CRS-1 averaged approximately $135,000 per kilogram of delivered cargo to the , roughly 50 percent higher than the $90,000 per kilogram for SpaceX's 9-Dragon equivalent. Per-mission costs for Cygnus were estimated at around $222 million, compared to $182 million for flights, rendering Orbital's system 1.86 times more expensive on a per-flight basis when accounting for capacities and allocations. These disparities, persisting into CRS-2 despite opportunities for renegotiation, fueled arguments that 's commitment to Antares for redundancy came at a premium inefficient for taxpayer funds, particularly as alternatives demonstrated superior cost-effectiveness without comparable reliability issues. The OIG recommended enhanced contractual mechanisms, such as detailed technical assessments and pricing updates tied to verified capabilities, to mitigate such financial exposures in future agreements.

Future Prospects

Antares 330 Development

The development of the 330 variant began in response to supply chain disruptions and geopolitical risks associated with foreign-sourced engines in prior Antares configurations, aiming to establish a fully domestic propulsion system for continued Commercial Resupply Services (CRS) missions to the (ISS). initiated collaboration with in 2022 to design a new liquid-fueled first stage, replacing the heritage liquid engines previously derived from Russian and Ukrainian technology. The Antares 330 retains the upper stage assembly from the Antares 230+ model, including the Castor 30XL solid rocket motor second stage, 3.9-meter payload fairing, and upgraded MACH avionics system, while introducing a redesigned first stage powered by seven Firefly Miranda engines. Each Miranda engine operates on kerosene and liquid oxygen, delivering 230,000 pounds-force (lbf) of thrust, for a combined first-stage output of approximately 1.6 million lbf. This configuration achieves a payload capacity of 10,500 kilograms to low Earth orbit (LEO), enabling compatibility with Cygnus spacecraft for ISS cargo delivery. Key milestones include the first hot-fire test of a Miranda engine on November 28, 2023, validating the engine's performance under operational conditions. In May 2025, invested $50 million in Firefly to accelerate development of the shared first-stage technology, which also supports Firefly's medium-lift vehicle—a derivative with a upper stage but the same base booster. This investment underscores the program's focus on scalability and risk reduction through proven heritage from . As of mid-2025, the Antares 330 remains in qualification testing, with initial flight targeted to support up to three CRS missions from , , prioritizing reliability enhancements over prior variants' vulnerabilities. The design emphasizes modularity, allowing the first stage to integrate with either the Antares solid upper stage or alternative configurations for broader applications.

Integration with Ongoing CRS Contracts

Northrop Grumman, under its Commercial Resupply Services-2 (CRS-2) contract awarded by NASA in January 2016, committed to delivering cargo to the International Space Station using the Cygnus spacecraft, with Antares rockets originally designated as the primary launch vehicle for missions originating from Wallops Flight Facility in Virginia. The CRS-2 agreement provides for an initial six missions at approximately $3.1 billion total across providers, with options for additional task orders to sustain ISS resupply through at least 2025 and potential extensions. Following the 2022 grounding of Antares 230+ due to U.S. sanctions prohibiting procurement of Russian RD-181 engines amid the Russia-Ukraine war, Northrop Grumman shifted to interim launches via SpaceX Falcon 9 rockets to maintain contractual cadence, including NG-20 in late 2024, NG-21, NG-22, and NG-23 on September 14, 2025, which delivered over 11,000 pounds of cargo. The 330 configuration integrates with remaining CRS-2 task orders by serving as the successor vehicle, designed specifically to loft Cygnus payloads from Wallops and restore Northrop Grumman's independent launch autonomy under the contract. Developed in partnership with , which supplies the first-stage Reaver engines to eliminate foreign dependencies, Antares 330 offers increased performance with a 3.9-meter fairing and capability to deliver up to 10,500 kg to , enabling more efficient fulfillment of future resupply demands. Initial qualification flights are targeted for no earlier than 2026, with NG-25 as the baseline debut mission, aligning with NASA's requirement for diverse commercial providers to mitigate single-point failures in ISS logistics. This integration preserves the economic and operational benefits of the CRS-2 framework, including fixed-price task orders that incentivize cost control, while addressing prior vulnerabilities exposed by geopolitical risks; has adjusted cargo manifests across missions, such as augmenting SpaceX's CRS-32 in , to accommodate delays without disrupting station operations. Long-term, Antares 330 supports potential CRS-3 competitions by demonstrating scalable, domestically sourced hardware compatible with evolving Cygnus variants, ensuring Northrop Grumman's continued role in 's multi-provider resupply paradigm beyond ISS deorbit.

Potential Broader Applications

The upgraded Antares 330 configuration, with a projected payload capacity of up to 10,500 kilograms to low Earth orbit, positions it to support missions beyond dedicated International Space Station cargo delivery, including potential secondary payloads or adapted upper stages for dedicated orbital insertions. This enhanced lift capability stems from replacing the legacy first stage with a domestic cluster of seven Firefly Aerospace Miranda engines, enabling greater flexibility for medium-class payloads while maintaining compatibility with the established Cygnus spacecraft interface. Northrop Grumman's evolution of the architecture into the Medium Launch Vehicle (MLV), rebranded as in collaboration with , explicitly targets broader commercial viability. This vehicle, building on Antares 330's first-stage advancements, incorporates a new liquid second stage and a 5.4-meter to accommodate constellations, civil science missions, national security payloads under programs like the (NSSL), and international customers. With a target capacity of 16,300 kilograms to , aims to deliver to customer-preferred s at competitive pricing, addressing demand for proliferated low-Earth orbit architectures that require reliable, cost-effective medium-lift access. These applications leverage the Antares program's proven avionics, software, and launch infrastructure at , reducing development risks for non-NASA operators seeking alternatives to dominant providers like . However, realization depends on securing contracts amid competition; to date, Antares variants have exclusively flown Cygnus resupply missions under NASA's Commercial Resupply Services contracts, with no demonstrated commercial satellite deployments. Northrop Grumman's $50 million investment in Firefly underscores commitment to this expansion, with initial launches targeted as early as 2026 from .

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