Thursday, September 22, 2011

NASA's Next Manned Mission to an Asteroid


Now that the Space Launch System program is officially on its tracks, lets take a look at what NASA plans to do with the giant rocket. After the first couple of test flights (including a manned fly-by around the moon somewhere between 2017 and 2021), the first big objective is to send 4 astronauts to a 6 month trip to a Near Earth Object (NEO). The mission would be called 'Plymouth Rock'.

Near Earth Objects are asteroids that orbit the sun in an orbit very similar to Earth, and are relatively close to us, either slightly trailing us or preceding us. What makes them easy to reach is the fact that their speed relative to earth is very small, so the space ship that will reach it will not need large amounts of fuel to accelerate to match its speed and then decelerate when you come back to Earth. Also, those asteroids are pretty small (about a hundred feet wide), so their gravity is practically negligible. No need to spend fuel landing on it and taking off it, you can just float right next to it.

You might ask, why go to a small rock in the middle of nowhere? Well, NASA officials feel that a mission to an asteroid would be a baby step that would give us the opportunity to develop some experience in deep space travel before we venture to longer missions like a trip to Mars.

It's also a question of security. These NEO's are very close to Earth and some day we might very well discover one on a collision course with us. Exploring them will improve our understanding of their structure and composition, and we will learn how to operate around and on them. Sure, we could send robotic probes to study them, but when the day comes when we need to save our planet from a giant meteor, will you want to entrust our survival to a probe? I'd rather have some people up there making sure the job is done correctly.

Dual-Orion configuration


The spaceship used would be a Orion MPCV (Multi-Purpose Crew Vehicle) mated to a habitat module for added storage and comfort for the crew. The habitat could be a straightforward module like the ones used on the International Space Station, an inflatable module like the ones developed by Bigelow Aerospace, or a modified Orion MPCV (without seats and re-entry capability) docked nose-to-nose with the other Orion, although that latest option would be smaller and only allow room for two astronauts.

      

The mission would also include MMSEV (Multi Mission Space Exploration Vehicle), a pressurized exploration vehicle equipped with remote-manipulation arms. This vehicle could be re-used on other missions. Its design shares a common pressurized module being developed for other explorations, like the moon surface (it would then have wheels).



The whole stack would be assembled in low earth orbit (LEO) and propelled towards the Asteroid by an Earth Departure Stage (EDS). Two SLS rockets would be needed to launch it to LEO, one for the Crew, Orion, Habitat module and MMSEV, the other with the EDS.

Once there, the crew would install a network of ropes on the asteroid so that they can hang on to it while they perform their experiments.


Several asteroids are being considered as potential candidates for exploration. The first opportunity will come in 2019 when asteroid 2008 EA9 will come close enough to Earth to be within reach of a SLS/Orion spacecraft.

© Lockheed-Martin


This mission would take about 6 months, with 92 days for the way in, 5 days on the asteroid and 98 days on the way back. It would take the astronauts 12 million kilometers away from the Earth, or about 32 times the distance from the Earth to the Moon. It seems like a lot, but as a comparison, Mars is between 56 and 400 million km from the Earth (depending on the time of the year).

Here is a view of the trip as seen from the earth:
© Lockheed-Martin

















(The reason why the asteroid seems to make a loop in the sky in this graph is because it's a Geocentric coordinate system, so what we see is similar to the Retrograde Motion optical illusion).

It is not certain that the SLS will be ready for such a mission by 2019, so another asteroid, 1999 AO10 is also being considered for a 5 month trip in 2025 that would include a 14 day stay on the rock.

NASA has already started training its astronauts for such a mission in the Aquarius underwater training facility in Key Largo, Florida.

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