DRM Habitat Credit - NASA

This July 1997 DRM was a subscale version of the original, with a scrub of the original payloads to reduce mass wherever possible. An integral pressure structure and heat shield was proposed for the lander, requiring the use of lighter composite structural materials. The stages would be launched without the spacecraft, meaning more launches would be required, but development of a monster heavy lift vehicle would not be needed. There would be 8 launches of a shuttle-derived vehicle with an 85 metric ton payload, consisting of three nuclear stages and three spacecraft on the first launch opportunity. At the next opportunity two more launches would put a fourth nuclear stage and the manned spacecraft in orbit. The total mass hurled toward Mars would be 303 metric tons, 75 metric tons less than the 1993 DRM.

In 1996 public interest in Mars was renewed by the reputed discovery of fossils of microscopic life forms in meteorite ALH 84001, believed to have been blasted off Mars and falling on the Antarctic Ice Cap. NASA responded by reviving its manned Mars study function. In July 1997 the office produced Human Exploration of Mars: Reference Mission of the NASA Mars Exploration Team, which revised 1993's Design Reference Mission 1.0 and was released to coincide with public interest as a result of the Pathfinder robot lander mission.

• Summary: Refine DRM 1.0 systems concepts and design; smaller class launch vehicle (80mt);source data from Borowski paper
• Propulsion: Nuclear thermal
• Braking at Mars: aerodynamic
• Mission Type: conjunction
• Split or All-Up: split
• ISRU: ISRU
• Launch Year: 2011
• Crew: 6
• Mars Surface payload-metric tons: 40
• Outbound time-days: 150
• Mars Stay Time-days: 610
• Return Time-days: 120
• Total Mission Time-days: 880
• Total Payload Required in Low Earth Orbit-metric tons: 410
• Total Propellant Required-metric tons: 140
• Propellant Fraction: 0.34
• Mass per crew-metric tons: 68
• Launch Vehicle Payload to LEO-metric tons: 75
• Number of Launches Required to Assemble Payload in Low Earth Orbit: 6
• Launch Vehicle: Magnum

• Cargo Lander Reference Version 3.  Class: Manned. Type: Mars Lander. Destination: Mars. Nation: USA. Agency: NASA.

  The second version of the NASA Cargo Lander for the design reference mission 3.0 was similar in concept to the first but mass was reduced nearly 30% by a thorough study and scrub of each element. The cargo lander would land an Earth Entry/Mars Ascent Capsule, an ascent stage, and an ISRU plant on the surface that would produce propellant for the crew's return journey from the Martian atmosphere. It had a typical mass of 66,043 kg on approach to Mars and 44,440 kg on the surface.

  Cargo Lander 1 Reference Version 3.0 Mass Summary Earth Entry/Mars Ascent Capsule: 4,829 kg Ascent stage dry mass: 4,069 kg ISRU plant: 3,941 kg Hydrogen feedstock: 5,420 kg PVA keep-alive power system: 825 kg 160 kw nuclear power plant: 11,425 kg 1.0 km power cables, PMAD: 837 kg Communication system: 320 kg Inflatable Laboratory Module: 3,100 kg 15 kwe DIPS cart: 1,500 kg Unpressurized rove: 550 kg 3 teleoperable science rovers: 1,500 kg Water storage tank: 150 kg Science equipment: 1,770 kg TOTAL CARGO MASS : 40,236 kg Vehicle Structure: 3,186 kg Terminal propulsion system: 1,018 kg TOTAL LANDED MASS : 44,440 kg Propellant : 10,985 kg Forward Aeroshell : 9,918 kg Parachutes and mechanisms: 700 kg TOTAL ENTRY MASS : 66,043 kg NTR Propulsion System: 23,400 kg TMI Propellant: 45,300 kg TOTAL INITIAL MASS: 134,743 kg

  Length: 40.30 m (132.20 ft). Mass: 134,743 kg (297,057 lb).

• Crew Lander Reference Version 3.  Class: Manned. Type: Mars Lander. Destination: Mars. Nation: USA. Agency: NASA.

  The second version of the NASA Crew Lander for the design reference mission would land the crew and a Mars surface habitat on the surface near the previously-landed cargo lander. The crew would have to use the ascent stage and return capsule of the cargo lander to get back to earth. A scrub of the estimated masses in the first design reduced the mass of the crew lander by a third, to 60,806 kg on approach to Mars and 35,145 kg on the surface.

  Crew Lander Reference Version 3.0 Mass Summary Habitat element 2: 28,505 kg Life Support System: 4,661 kg Health Care: 0 kg Crew Accommodations: 12,058 kg EVA equipment: 243 kg Comm/infomanagement: 320 kg Power: 3,249 kg Thermal: 550 kg Structure: 5,500 kg Spares: 1,924 kg Crew: 500 kg Unpressurized rover 3: 550 kg EVA consumables: 446 kg EVA suits: 940 kg TOTAL PAYLOAD MASS: 30,941 kg Vehicle structure: 3186 kg Terminal propulsion system: 1018 kg TOTAL LANDED MASS: 35,145 kg Propellant: 11,381 kg Forward Aeroshell: 13,580 kg Parachutes and mechanisms: 700 kg TOTAL ENTRY MASS: 60,806 kg NTR Propulsion System: 23,400 kg Shadow Shield: 3,200 kg TMI Propellant: 50,000 kg TOTAL INITIAL MASS: 137,406 kg

  Mass: 137,406 kg (302,928 lb).

• Griffin, Brand; Thomas, Brent; Vaughan, Diane, A Comparison of Transportation Systems for Human Missions to Mars, AIAA 2004-3834, 40th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit ,11-14 July 2004.

• Portree, David S. F., Humans to Mars: Fifty Years of Mission Planning, 1950 - 2000, NASA Monographs in Aerospace History Series, Number 21, February 2001. Excellent overview of American plans for sending men to Mars.

• NASA Report, Mars Design Reference Mission 3, . Accessed at: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19980218778_1998218778.pdf. -right click to download pdfs!

• Drake, Bret U, Editor, Reference Mission Version 3.0 - Addendum to the Human Exploration of Mars: The Reference Mission of the NASA Mars Exploration Study Team, NASA Special Publication 6107-ADD EX13-98-036 June 1998.