SpaceX CRS-6

SpaceX CRS-6, also known as SpX-6, was a Commercial Resupply Service mission to the International Space Station, contracted to NASA. It was the eighth flight for SpaceX's uncrewed Dragon cargo spacecraft and the sixth SpaceX operational mission contracted to NASA under a Commercial Resupply Services contract. It was docked to the International Space Station from 17 April to 21 May 2015.

In July 2014, the launch was scheduled by NASA for February 2015, with berthing to the station occurring two days later. However, as a result of delays in the launch of the previous SpaceX CRS-5 mission, SpaceX CRS-6 launched on 14 April 2015. In late March, 2015, the launch was scheduled for 13 April 2015, but was later postponed to 14 April 2015 due to weather conditions.

A Federal Communications Commission (FCC) application submitted for temporary communication frequency authority noted the launch planning date as no earlier than 8 April 2015. The application also confirmed communication uplinks for use with the first stage of this mission as it attempted to conduct a first-ever propulsive landing on the Autonomous spaceport drone ship after staging.

NASA has contracted for the CRS-6 mission from SpaceX and therefore determines the primary payload, date/time of launch, and orbital parameters for the Dragon space capsule. The Dragon spacecraft was filled with 2,015 kg (4,442 lb) of supplies and payloads, including critical materials to directly support about 40 of the more than 250 science and research investigations that will occur during Expedition 43 and Expedition 44.

Among other items on board:

SpaceX has the primary control over manifesting, scheduling and loading secondary payloads. However, there are certain restrictions included in their contract with NASA that preclude specified hazards on the secondary payloads, and also require contract-specified probabilities of success and safety margins for any SpaceX reboosts of the secondary satellites once the Falcon 9 second stage has achieved its initial low Earth orbit (LEO).

SpaceX CRS-6 included science payloads for studying new ways to possibly counteract the microgravity-induced cell damage seen during spaceflight, the effects of microgravity on the most common cells in bones, gather new insight that could lead to treatments for osteoporosis and muscle wasting conditions, continue studies into astronaut vision changes and test a new material that could one day be used as a synthetic muscle for robotics explorers of the future. Also making the trip was a new espresso machine for space station crews.

A part of this payload includes science experiments from high schools, such as a project from Ambassador High School in Torrance, California.