Wednesday, 25 March 2015

Destination Phobos?

Phobos is one of two small moons circling the planet Mars. The other is Deimos.
Phobos as photographed from the Mars Express
It is only 3,700 miles above the  surface and circles around Mars in only 11 hours 9 minutes, which is slightly less than half a Martian day (24 hours 37 minutes). As far as we know this is lower than the moon of any other planet in our solar system. As this photo shows its appearance alone is intriguing and there is reason to suppose that it could reveal secrets about the history of its parent planet, including any biological life that may have been present over its 4 billion year history. The low density of Phobos suggests that it may be partially hollow, with underground caves and rock consisting of lightly packed microfragments. Large amounts of interior ice are also probable.

The most likely theory for its formation is that it comprises debris from the surface of Mars. This would have been thrown into orbit by meteorite collisions over the probably 4 billion years since the planet was formed and during this time the debris has coalesced to form the Phobos we see today. So within the material that makes up this satellite could be a record of life on the surface of its parent planet.

Why not go there? It would be much cheaper than visiting the surface of Mars or even that of our own Moon, which is never less than 140x closer than Phobos. This is because it is so small (mean radius 6.9 miles) that it has virtually no gravity for a spacecraft’s engines to have to battle against, so only a small amount of fuel would need to be carried and the larger distance would be covered largely by coasting from the Earth’s orbit around the Sun to that of Mars after an initial boost; similarly, but in reverse, for the return mission.

In my view this should seriously be considered as a priority destination for the MPCV (multi-person crew vehicle), also known as Orion, now being developed by NASA for missions beyond earth orbit. The Moon and nearby asteroids are other targets being evaluated for manned missions before the much bigger and more expensive step of landing men on Mars is taken. Russia and the USA both have experience of prolonged micro-gravity effects on humans, which is necessary since the trip out would take about 9 months.

I think Phobos should be the next step for a manned expedition for the following reasons:

  • It would take less energy and money to get men to Phobos than to the surface of the Moon and back (as explained above).
  • Phobos’s rocks could provide evidence of past life or absence of life on the Martian surface over billions of years.
  • Underground caves would provide an ideal shelter from cosmic bombardment, a major problem for manned missions, and a logistic base for future descents to the Martian surface. 
  • Humans on Phobos could observe Mars in great detail without risking contamination of the surface with terrestrial bacteria.

This last point is important because the occurrence or non-occurrence of any form of biological life independent of Earth would be of enormous significance in assessing the nature of its origin and putting terrestrial life into a cosmic context. Since the inception of terrestrial life there have been innumerable ejections of organic debris into space due to meteorite, asteroid and comet impacts, so that some of this is likely to have found its way to other planets. However, I believe it is possible to identifiy this life asa terrestrial in origin or otherwise.

Interest in Phobos is growing. Russia attempted to send an unmanned probe there recently (November 2011) but this failed. China had experiments on board the Russian probe, called Fobos-Grunt and the USA is also interested.

To get there or anywhere else beyond  earth orbit efficiently we need to be able to launch materials, equipment and prefabricated structures into orbit more cheaply and frequently than was possible with the Space Shuttle, so that earth orbit can serve as a base. Once a vehicle is assembled there it can be launched off into deep space without having to fight hard against gravity.

 I am still mystified as to why the Skylon spaceplane, a UK design, with its revolutionary air breathing rocket engine (SABRE), is not being developed as a matter of priority. Skylon could get mass into orbit at a fraction of the cost of any other technology of which I am aware. Presumably politics is a factor since space exploration is moving towards international cooperative ventures to share costs and expertise. There is also a major trend towards private ventures and away from government-led programmes.

My view is that the universe is there to be explored, not ignored. International space exploration projects are a way of raising our horizons and cooperating instead of stewing up the biosphere and destroying ourselves spiritually and in internecine conflict.


see also Interplanetary mining

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