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Athena Mars Flyby

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Status: Study 1996. Gross mass: 25,900 kg (57,000 lb). Height: 15.00 m (49.00 ft).

Unlike previous fly-by concepts, Athena would remain in the vicinity of Mars for a year while the crew remotely operated probes of the Martian surface and atmosphere. This would eliminate the round-trip radio time lag of ten to forty minutes in trying to operate such probes from the earth.

Athena would follow a low-energy earth-Mars trajectory. At Mars encounter the planet's gravity would be used to change the spacecraft's orbit to one similar to but inclined 9.5 degrees from that of Mars. The spacecraft would spend a year 'shadowing' the planet and operating four remote-controlled rovers delivered separately to the surface. At the end of that period Athena's orbit would again bring it to Mars. The flyby would send it on a slow nine month trajectory back towards earth. On approach to earth the crew would an ISS ACRV-derived re-entry vehicle to renter the earth's atmosphere. The 2.5 year mission would finish with splashdown in the ocean for recovery by the US Navy.

Athena would have a crew of two. The spacecraft and its trans-Mars injection stage would be assembled in low earth orbit using two shuttle launches and four Proton launches. The Mars probes (four rovers) would be launched separately by Delta 7925 or Molniya launch vehicles. Other possible probes would include subsonic remotely piloted drones or controlled balloons equipped with imaging systems and deployable/recoverable rovers.

The Athena spacecraft would be 5 m in diameter and 15 m long. It would be spun to generate artificial gravity, with fixed solar panels generating 5 to 10 kilowatts of power. Total mass would be 25.9 metric tons, broken down as follows:

• Habitation Structure - 4.0 metric tons
• Life support system - 2.0 metric tons
• Consumables (water, food, oxygen for 900 days) - 7.7 metric tons
• Electrical Power (5 kWe solar) - 1.0 metric ton
• Reaction Control system - 0.5 metric ton
• Communications and Information Management - 0.2 metric ton
• Science Equipment - 0.2 metric ton
• Crew - 0.2 (4) metric ton
• EVA Suits - 0.4 metric ton
• Furniture and Interior - 0.5 metric ton
• Re-entry Capsule - 4.0 metric tons
• Spares and Margin (25 percent) - 5.2 metric tons

Three mission trajectories were calculated:

• Launch April 16, 2001; Mars encounter Nov. 16, 2001 to Nov. 16, 2002; splashdown Oct. 16, 2003.
• Launch July, 20, 2003; Mars encounter July 15, 2004 to July 20, 2005; splashdown May 15, 2006.
• Launch Aug. 29, 2005; Mars encounter Oct. 1, 2006 to Aug.15, 2007; splashdown May 5, 2008.

The total estimated cost of $ 2.148 billion broke down as follows:

• Habitation development using ISS technology: $400 million
• Re-Entry Capsule, adapted from ISS ACRV: $100 million
• Four Mars Surveyor landers: $200 million
• Operations Costs: $100 million
• 2 Shuttle Launches: $600 million
• 4 Proton Launches: $280 million
• 2 Delta Launches: $110 million
• Reserves and Contingency (20%) = $358 million

Zubrin advocated Athena as an 'icebreaker' mission - a quick and cheap way to demonstrate once and for all the possibility of long-duration manned interplanetary flight. He contrasted this to NASA's 30 year Mars plan that would spend vast sums and time in an attempt to eliminate all risk and solve the problem of long-duration zero-gravity flight.

Athena Mission Summary:

• Summary: Mars flyby with manned spacecraft hovering at L1 Sun-Mars Lagrangian point for sustained operation of robotic probes on Martian surface.
• Propulsion: LOX/LH2
• Braking at Mars: propulsive
• Mission Type: Lagrangian
• Split or All-Up: all up
• ISRU: flyby
• Launch Year: 2001
• Crew: 2
• Outbound time-days: 280
• Mars Stay Time-days: 360
• Return Time-days: 270
• Total Mission Time-days: 910
• Total Payload Required in Low Earth Orbit-metric tons: 100
• Total Propellant Required-metric tons: 54
• Propellant Fraction: 0.54
• Mass per crew-metric tons: 50
• Launch Vehicle Payload to LEO-metric tons: 20
• Number of Launches Required to Assemble Payload in Low Earth Orbit: 6
• Launch Vehicle: Proton K

Unit Cost $: 500.000 million. Crew Size: 2.