Servicing Mission 3B was actually the fourth visit to Hubble. NASA split the original Servicing Mission 3 into two parts and conducted 3A in December of 1999. During SM3B a new science instrument will be installed: the Advanced Camera for Surveys (ACS). Several other activities were accomplished as well over a 12-day mission with 5 spacewalks.
Four astronauts trained for five scheduled spacewalks to upgrade and service the Hubble Space Telescope during the STS-109 mission in early 2002. Three veteran astronauts, John M.Grunsfeld, James H. Newman, and Richard M. Linnehan, were joined by Michael J. Massimino, who will be making his first space flight.
Scott Altman, (Cmdr., USN), a two-time shuttle veteran, commanded the STS-109 mission. He was joined on the flight deck by pilot Duane Carey, (Lt. Col., USAF), making his first space flight, and flight engineer Nancy Currie (Lt. Col, USA, Ph.D.). Currie had three previous space flights to her credit.