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Landing on Mars: Extensive Solution and Justification
The Ion Propulsion Package (IPP), carrying scientific equipment, will begin its descent
only when both the IPP and Nuclear Propulsion Package (NPP), carrying the crew, are in Low Mars
Orbit (LMO). When the IPP initially reaches LMO, each component will precisely insert itself into
the same orbital inclination. The individual modules of the IPP will join together to form a
"super-structure" that will land on Mars as one spacecraft. Both the IPP and NPP will orbit Mars once
every 48 hours in a highly elliptical orbit with an apogee of 56,000 km and a perigee of 300 km. The
two packages must then initiate a burn to lower the apogee to an altitude of approximately 400 km before
descending to Mars.
At the start of the IPP's descent to
the Martian surface, a heat shield will be employed to ensure that the package will not burn up in the
Martian atmosphere. At an altitude of 110 km, the heat shield will jettison, uncovering a liquid
propellant rocket and landing legs. The IPP will then perform a controlled burn to slow its descent
to a suitable landing velocity. After the IPP has confirmed landing, its homing device will be activated.
This will enable the NPP to land in close proximity of the IPP lander. The descent portion of the
NPP will include the
Surface Habitat and the ascent vehicle, the Falcon. The Surface Habitat will serve as a living quarter
for the crew while on the martian surface. The Surface Habitat coupled with the Falcon will land in
a similar manner as the IPP. The NPP lander will use aerobraking to enter the Martian atmosphere. A
burn must be inititated to lower the perigee of the NPP lander into the upper extreme of the Martian
atmosphere. During every subsequent pass through the orbit's perigee, the NPP will encounter air
resistance and lose speed. Consequently, the spacecraft will not climb as high on the next pass through
the orbit's apogee.
When first entering the Martian atmosphere, the Surface Habitat and Falcon will be protected by a
combination of ablative materials (possibly Avcoat-5026-39HC) and reradiating aero brake materials
(such as reinforced carbon-carbon - RCC). At an appropriate altitude, the ablative heat shield
will be jettisoned. Descent will then be slowed by a combination of parachutes and a liquid propulsion
retro-rocket. Six landing legs, previously tucked behind the ablative heat shield, will deploy to softly
land the descent configuration on the Martian surface.
Justification:
Both landing systems are based on those used for the Lunar Lander and the Mars Polar Lander.
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Copyright © 2000 Massachusetts Institute of Technology