letcher’s order all would rely to some degree on NASA’s low-Earth orbit (LEO) Space Station. Her piloted Mars program, for example, could proceed without her permanent piloted lunar outpost, her robotic program to study Earth from space (“Mission to Planet Earth”), or her robotic Solar System exploration program (“Mission from Planet Earth”).
SAIC began to design the Ride Report’s piloted Mars program in January 1987. The company presented its final report to the NASA Headquarters Office of Exploration (nicknamed “Code Z” for its mail code) in November of that year. Fletcher had created Code Z in June 1987 and placed Ride in charge as his Acting Assistant Administrator for Exploration. By that time, Ride had announced that she would leave NASA in August. John Aaron, who replaced her as Code Z chief, made SAIC’s report the basis for Code Z’s piloted Mars and Phobos mission “Case Studies” in Fiscal Year 1988.
SAIC employed a split/sprint Mars mission design. The company credited a 1985 University of Texas/Texas A & M student design project with originating the split/sprint concept. The split/sprint mission would use a pair of spacecraft: an automated one-way cargo spacecraft launched first followed by a piloted spacecraft. Both would burn chemical propellants and rely on aerobraking.
The cargo spacecraft would follow a propellant-saving low-energy path to Mars. It would transport to Mars orbit propellants for the piloted spacecraft’s return to Earth. The piloted sprint spacecraft would leave LEO only after the cargo spacecraft was confirmed to have arrived safely in Mars orbit.
In order that its crew should be exposed to weightlessness, radiation, and isolation for as little time as possible, the piloted spacecraft would follow a roughly six-month path to Mars, would remain at the planet for only one month, and then would return to Earth in about six months. This would yield a piloted Mars mission duration of between 12 and 14 months.
In common with most other post-Challenger piloted Mars plans, the SAIC team abandoned the Space Shuttle as its primary means of launching spacecraft components and propellants to LEO. In the Shuttle’s place, it proposed a heavy-lift rocket based in part on Shuttle hardware. The new rocket would debut in 1996 with a launch capability of 36 metric tons to LEO, then would evolve by 2002 to carry 91 metric tons to LEO.
Though it featured a piloted mission of short duration – which in most cases would imply expenditure of large quantities of propellants – the split/sprint mission design offered substantial propellant savings by refueling the crew spacecraft in Mars orbit. This would in turn slash the number of costly heavy-lift rockets required to launch Mars spacecraft components and propellants to the Space Station for assembly. A sprint-type mission using a single combined round-trip crew/cargo spacecraft would, SAIC calculated, need 25 heavy-lifters, while the split/sprint design would need only 15. In addition, because the cargo and crew spacecraft would depart Earth more than a year apart, the heavy-lift launches could be spread over a longer period.
By the time the heavy-lifter attained its maximum capability, Phase I of SAIC’s three-phase Mars program would be ended and Phase II would have just begun. Phase I, spanning from 1992 through 2002, would include a series of robotic precursor missions. Mars Observer, in 1987 already an approved NASA mission, would map Mars from orbit beginning in 1993; then, in 1995, Mars Observer 2 would establish and act as radio relay for a planet-wide network of hard-landed penetrator sensor stations. Orbital mapping and the seismic/meteorological net would help scientists and engineers select landing sites for automated Mars Sample Return (MSR) and piloted Mars missions.
A pair of MSR spacecraft would depart Earth in 1996 to collect Mars surface samples and return them to high-Earth orbit (HEO) in 1999. A reusable Orbital Maneuvering Vehicle (OMV) based at the Space Station would retrieve the samples from HEO and deliver them for quarantine and initial study