oned 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 to an “isolation half-module” added to the Space Station in 1998. The samples would enable scientists to identify any hazards in Mars’s surface materials and would aid engineers in the design of spacecraft, rovers, habitats, space suits, and tools.
Phase I would also include biomedical research on board the Space Station, which would reach Permanent Manned Configuration (PMC) in 1994. Almost immediately after it achieved PMC, NASA would add a Life Science Module. A six-person crew would then conduct a Mars mission simulation on board the Station that would last for the planned piloted sprint mission duration.
If the astronauts remained healthy after the simulation, then in 1996 NASA would begin development of a Mars sprint spacecraft lacking any provision for artificial gravity (that is, no part of it would rotate to create acceleration which the crew would feel as gravity). A module for housing Mars spacecraft assembly crews would join the Station in 2002, kicking off Phase II of SAIC’s Mars program. The cargo spacecraft for the first split/sprint mission would depart LEO during the 2003 low-energy Earth-Mars transfer opportunity.
If, on the other hand, biomedical researchers determined that the simulation crew had suffered harm, then NASA would add a “variable-gravity module” to the Station in 2001. Crews would conduct simulations in the spinning module to determine the minimum level of artificial gravity required to safeguard astronaut health. Development of an artificial-gravity sprint spacecraft would not commence until after the simulations ended in 2004. If the artificial-gravity sprint spacecraft needed as much development time as its no-gravity counterpart, then the first piloted Mars mission might not leave Earth until 2013. SAIC largely ignored this possibility.
Launching parts and propellants from Earth’s surface for the 238.5-metric-ton cargo spacecraft and its single 349.6-metric-ton reusable Orbital Transfer Vehicle (OTV) would require seven heavy-lift rocket launches. The cargo spacecraft would c