[3] In 1977 Dr. Weisskopf left Columbia to become Senior X- Ray Astronomer at MSFC and AXAF (now Chandra) Project Scientist.

Before his retirement in May 2022, he was Chief Scientist for X-Ray Astronomy at MSFC, a highly prestigious civil-service Senior Scientific and Technical position – one of only a few within the Agency.

It is also noteworthy that Dr. Weisskopf obtained the funds that gave John Carlstrom and Marshall Joy their start for using interferometry to measure the Sunyaev- Zel’dovich effect, which not only supported X-ray observations of clusters of galaxies but has become a major scientific "industry" onto itself.

In 2004, together with Dr. H. Tananbaum, he received the Rossi Prize of the High Energy Astrophysics Division of the American Astronomical Society which cited "their vision, dedication, and leadership in the development, testing, and operation of the Chandra X-ray Observatory"[9] In 2006 he was awarded an honorary Dr. of Science degree by Oberlin College, Oberlin Ohio.

In 2024 he won another Bruno Rossi Prize, together with Paolo Soffitta and the IXPE team, "for their development of the Imaging X-ray Polarimetry Explorer whose novel measurements advance our understanding of particle acceleration and emission from astrophysical shocks, black holes and neutron stars.