ALBERT

Description: This paper introduces a mission architecture called 'Mars Direct' which brings together several technologies and existing hardware into a novel mission strategy to achieve a highly capable and affordable approach to the Mars and Lunar exploratory objective of the Space Exploration Initiative (SEI). Three innovations working in concept cut the initial mass by a factor of three, greatly expand out ability to explore Mars, and eliminate the need to assemble vehicles in Earth orbit. The first innovation, a hybrid Earth/Mars propellant production process works as follows. An Earth Return Vehicle (ERV), tanks loaded with liquid hydrogen, is sent to Mars. After landing, a 100 kWe nuclear reactor is deployed which powers a propellant processor that combines onboard hydrogen with Mars' atmospheric CO2 to produce methane and water. The water is then electrolized to create oxygen and, in the process, liberates the hydrogen for further processing. Additional oxygen is gained directly by decomposition of Mars' CO2 atmosphere. This second innovation, a hybrid crew transport/habitation method, uses the same habitat for transfer to Mars as well as for the 18 month stay on the surface. The crew return via the previously launched ERV in a modest, lightweight return capsule. This reduces mission mass for two reasons. One, it eliminates the unnecessary mass of two large habitats, one in orbit and one on the surface. And two, it eliminates the need for a trans-Earth injection stage. The third innovation is a launch vehicle optimized for Earth escape. The launch vehicle is a Shuttle Derived Vehicle (SDV) consisting of two solid rocket boosters, a modified external tank, four space shuttle main engines and a large cryogenic upper stage mounted atop the external tank. This vehicle can throw 40 tonnes (40,000 kg) onto a trans-Mars trajectory, which is about the same capability as Saturn-5. Using two such launches, a four person mission can be carried out every twenty-six months with minimal impact on shared Shuttle launch facilities at Kennedy Space Center (KSC). The same launch vehicle, habitat, and upper stage of the ERV can also be used to perform Lunar missions. It is concluded that the Mars Direct architecture offers a cost effective approach to accomplishing the Lunar and Mars goals of the Space Exploration Initiative.

Description: The coherency of the conventional earth-orbital assembly/Mars orbital rendezvous is analyzed in terms of the Space Exploration Initiative (SEI) architecture and an alternate approach is given. The coherency - defined as a combination of simplicity, robustness, and cost-effectiveness - of the conventional SEI is found to be inadequate. The Mars Direct plan is described in detail and proposed as an efficient alternative for both Martian and lunar applications. In situ propellant production on the target-planet's surface is described, and candidate vehicle designs are set forth. Objectives and problems associated with a manned mission are outlined, and details regarding surface activities and support are given. Nuclear thermal rocket propulsion is determined to be an efficient way to improve mission capability, and the Mars Direct SEI architecture can integrate such technology. The Mars Direct SEI is concluded to be a more effective plan than the conventional rendezvous mission.

Description: Both the Martian and lunar forms of implementation of the Mars Direct architecture are discussed. Candidate vehicle designs are presented and the means of performing the required in situ propellant production is explained. The in situ propellant process is also shown to present very high leverage for a Mars Rover Sample Return mission flown as a scaled down precursor version of the manned Mars Direct. Methods of coping with the radiation and zero gravity problems presented by a manned Mars mission are discussed. Prime objectives for surface exploration are outlined and the need for substantial surface mobility is made clear. Combustion powered vehicles utilizing the in situ produced methane/oxygen are proposed as a means for meeting the surface mobility requirement. Nuclear thermal rocket propulsion is suggested as a means to improve mission capability.