Entry Velocities at Mars and Earth for Short Transit Times
Abstract
Propulsion systems composed of a Shuttle External Tank, appropriately modified for the purpose, with a rocket engine that is either an SSME or a NERVA could inject a gross personnel payload of 100,000 lb on a trans-Mars trajectory from Space Station Freedom with aerobraking at Mars with transit times of less that 70 days. Such transit times reflect a significant reduction from the 200- plus days generally considered. The 100,000-lb payload would include the mass of a hypothetical aerobrake for aerocapture at Mars. The entry velocities at Mars compatible with such transit times are greater that 21 km/sec, to be compared with previously stated constraints of 8.5 to 9.5 km/sec for nominal Mars entry velocity. Limits of current aerobrake technology are not well enough defined to determine the feasibility of an aerobrake to handle Mars-entry velocities for short-transit-time trajectories. Return from Mars to Earth on a mirror image of 70-days outbound trajectory (consistent with a stay time of about 12 days) would require a Mars-departure velocity increment more than twice as great as that at Earth departure and would require a correspondingly more capable propulsion system. The return propulsion system would preferably be predeployed at Mars by one or more separate minimum-energy, 0.5-to-1.1-Mlb-gross-payload cargo flights with the same outbound propulsion systems as the personnel flight, before commitment of the personnel flight. Aerobraking entry velocity at Earth after such a transit time would be about 16 km/sec, to be compared with constraints set at 12.5 to 16 km/sec.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1993
- Accession Number
- ADA272591
Entities
People
- Reinald G. Finke
Organizations
- Institute for Defense Analyses