SpaceX heavy and near term solar sail for manned missions to Near Earth Objects

Centauri Dreams has a published paper by Gregory Matloff who has written extensively on Interstellar Travel and solar sails. Gregory new work looks at applying the SpaceX Falcon Heavy and a 700 meter by 700 meter square solar sail.

Above – A SpaceX Dragon V2 and a larger Bigelow 330 module. 330 cubic meters versus 16 cubic meters for the BEAM module. A SpaceX BFR and BFS would be able to make interplanetary missions with Bigleow 330 modules. The BFS would already have 825 cubic meters of volume.

Matloff describes a manned mission to near earth asteroids.

The Dragon version 2 has 10 cubic meters of pressurized volume and the Bigelow Beam has 16 cubic meters of volume inside.

The Apollo command and service module had 6.2 cubic meters of volume.

The possibility of applying the Space-X Falcon-Heavy booster to human exploration of the inner solar system is discussed. A human-rated Dragon command module and an inflatable habitat module would house and support the 2-4 person crew during a ~1 year interplanetary venture. To minimize effects of galactic cosmic rays, older astronauts should conduct the mission during Solar Maximum. Crew life support is discussed as is application of a ~1-km square solar photon sail. The sail would be applied to rendezvous with the destination Near Earth Object (NEO) and to accelerate the spacecraft on its return to Earth. An on-line NASA trajectory browser has been used to examine optimized trajectories and destinations during 2025-2026. A suitable destination with well established solar-orbital parameters is Asteroid 2009 HC.

The Dragon V2 capsule appropriately modified for interplanetary application, an inflatable Bigelow space habitat similar to the one to be launched to the ISS in the near future will be used for crews habitability.

After the spacecraft is launched towards Mars, a state-of-the-art solar photon sail with a dimension of ~0.7 km will be unfurled. This will allow, as will be demonstrated, non-rocket accelerations of 1-2 km/s per month in the solar system region between Earth and Mars.

A recent comprehensive study of in-space radiation effects reveals that galactic cosmic radiation beyond LEO is reduced by a factor of ~5 above LEO, if missions are conducted during solar maximum. During solar flares and coronal plasma discharges, the crew could be protected by aligning the Dragon’s heat shield between the crew quarters and the Sun.

Human landings on Mars will not be possible using a single Dragon launch. But a host of Near Earth Objects of asteroidal and cometary origin and possibly the Martian satellites Deimos and Phobos will be open to human explorers.

A Falcon-Heavy is capable of projecting 13,200 kg on a trans-Mars trajectory. The dry mass of a Dragon V2 capsule is 4200 kg and the endurance of this spacecraft is about 2 years in space. The mass of the BEAM inflatable module is 1360 kg.

Our ECLSS mass projection is 5,000 kg, the remaining mass amounts to 2,640 kg. If 640 kg is required for scientific equipment, 2,000 kg remains to be allowed. We will assume that the sail mass is 2,000 kg.

As an example of a large solar-photon sail that could be constructed in the not very distant future, we consider a 90% reflective opaque 1-km2 sail with an areal mass density of 2 g/m2. The sail mass is 2,000 kg and the areal mass density of the spacecraft is 0.0132 kg/m2.

The sail configuration can result in a daily velocity increment of about 57 meters per second. Every month, the sail can alter the spacecraft velocity by about 1.6 km/s, if it is oriented normal to the Sun at a solar distance of 1 AU. At the orbit of Mars (1.52 AU), this sail oriented normal to the Sun can alter the spacecraft’s solar velocity each month by about 0.69 km/s.

The total force exerted on an 800 by 800 meter solar sail is about 5 newtons (1.1 lbf) at Earth’s distance from the Sun making it a low-thrust propulsion system.

Galactic cosmic radiation will increase cancer risk by 3% for a 1 year mission

Cucinotta and Durante estimate that during an interplanetary transfer, the high-Z GCR dose might be 1-2 mSv per day or 0.4-0.8 Sv per year. From Tables 1 and 2 of McKenna et al, the NASA one-year dose limits for 40-year old female and male astronauts are respectively 0.7 and 0.88 Sv. For older astronauts, the limits are higher. Dose limits for men are higher than dose limits for women.

During a 1-year interplanetary voyage, the dose limits for 40-year old astronauts may be exceeded. Exposures beyond these recommended limits may result in a 3% increased risk of fatal cancers.


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