Jeffrey Alan Hoffman (born November 2, 1944) is an American former NASA astronaut and currently a professor of aeronautics and astronautics at the Massachusetts Institute of Technology.

Hoffman made five flights as a Space Shuttle astronaut, including the first mission to repair the Hubble Space Telescope in 1993, when the orbiting telescope's flawed optical system was corrected. Trained as an astrophysicist, he also flew on the 1990 Spacelab Shuttle mission that featured the Astro-1 ultraviolet astronomical observatory in the Shuttle's payload bay. Over the course of his five missions he logged more than 1,211 hours and 21.5 million miles in space. He was also NASA's second Jewish astronaut, and the second Jewish man in space after Soviet cosmonaut Boris Volynov.

Hoffman was born November 2, 1944, in Brooklyn, New York, but considers Scarsdale, New York, to be his hometown. He graduated from Scarsdale High School in 1962. He received a Bachelor of Arts degree (summa cum laude) in astronomy from Amherst College in 1966, a Doctor of Philosophy in astrophysics from Harvard University in 1971, and a Master of Science degree in materials science from Rice University in 1988. Hoffman is an Eagle Scout.

Hoffman is a member of the International Academy of Astronautics, the International Astronomical Union, the American Institute of Aeronautics and Astronautics, the American Astronomical Society, the Spanish Academy of Engineering, Phi Beta Kappa, and Sigma Xi.

As of 2005^[update] he is co-director of the Massachusetts Space Grant Consortium and a professor of the Practice in the Department of Aeronautics and Astronautics at MIT.

Hoffman's original research interests were in high-energy astrophysics, specifically cosmic gamma ray and x-ray astronomy. His doctoral work at Harvard was the design, construction, testing, and flight of a balloon-borne, low-energy, gamma ray telescope.

From 1972 to 1975, during post-doctoral work at the University of Leicester in the United Kingdom, he worked on several x-ray astronomy rocket payloads. He also designed and supervised the construction and testing of the test equipment for use in an x-ray beam facility which he used to measure the scattering and reflectivity properties of x-ray concentrating mirrors. During his last year at Leicester, he was project scientist for the medium-energy x-ray experiment on the European Space Agency's EXOSAT satellite and played a leading role in the proposal and design studies for this project.

He worked in the Center for Space Research at the Massachusetts Institute of Technology (MIT) from 1975 to 1978 as project scientist in charge of the orbiting HEAO-1 A4 hard x-ray and gamma ray experiment, launched in August 1977. His involvement included pre-launch design of the data analysis system, supervising its operation post-launch, and directing the MIT team undertaking the scientific analysis of flight data being returned. He was also involved extensively in analysis of x-ray data from the SAS-3 satellite being operated by MIT. His principal research was the study of x-ray bursts, about which he authored or co-authored more than 20 papers.