UMPIRE Douglas Credit - © Mark Wade

Unfavorable Manned Planetary - Interplanetary Roundtrip Expedition profiles were studied under NASA Huntsville contracts to General Dynamics and Douglas in June 1963.

The studies looked at manned Mars missions at unfavorable mission opportunities (e.g. 1975, 1977). Douglas believed a nuclear-powered spacecraft, boosted in a single launch of Bono's ROMBUS booster, could take six crew on a 460 day mission to Mars even at unfavorable opportunities.

• Summary: Nuclear thermal expedition designed for unfavorable launch opportunities.
• Propulsion: Nuclear thermal
• Braking at Mars: propulsive
• Mission Type: opposition
• Split or All-Up: all up
• ISRU: no ISRU
• Crew: 6
• Outbound time-days: 200
• Mars Stay Time-days: 30
• Return Time-days: 230
• Total Mission Time-days: 460
• Total Payload Required in Low Earth Orbit-metric tons: 450
• Mass per crew-metric tons: 75
• Launch Vehicle Payload to LEO-metric tons: 450
• Number of Launches Required to Assemble Payload in Low Earth Orbit: 1
• Launch Vehicle: ROMBUS

Crew Size: 6. Design Life: 460 days. Length: 96.00 m (314.00 ft). Basic Diameter: 18.00 m (59.00 ft). Main Engine Propellants: Nuclear/LH2.