TY - BOOK T1 - Humans to Marsfifty years of mission planning, 1950-2000 / DA - 2001. CY - Washington, DC : AU - Portree, David S. F. VL - no. 21 VL - 2001-4521 CN - NAS 1.21: CN - TL799.M3 PB - NASA History Division, Office of Policy and Plans, NASA Headquarters, PP - Washington, DC : PY - 2001. N1 - "February 2001." N1 - Shipping list no.: 2003-0099-M. N1 - "NASA Center for AeroSpace Information (CASI), Global connection to aerospace research"--Cover. ID - 289216 KW - Space flight to Mars TI - Humans to Marsfifty years of mission planning, 1950-2000 / ER -