An illustration of the asteroid 24 Themis along with two small fragments that orbit with it. One of the small fragments is inert (as most asteroids are) and the other has a comet-like tail, produced by the sublimation of water ice from its surface. Scientists announced the first discovery of water ice on 24 Themis. Full Story. Credit: Gabriel Pérez, Servicio MultiMedia, Instituto de Astrofisica de Canarias, Tenerife, Spain
From the article...
he recent discovery of an asteroid wrapped in a layer of water ice has revived the possibility that some space rocks would be great potential pit stops – as well as destinations – for manned or robotic exploration missions.
If a space destination has water, that means astronauts traveling there could potentially use it for drinking and washing. But much more importantly, the water could be broken down into its component parts (hydrogen and oxygen) to make rocket fuel, experts say.
"Water is the main component in how you might make propellants," said Jerry Sanders, leader of in-situ resource utilization at NASA's Lunar Surface Systems Office at the Johnson Space Center in Houston. "If you're going to go repeatedly to an asteroid, then the ability to basically start setting up gas stations could be extremely beneficial.
Researchers announced last week that they had found definitive proof of frozen water, along with organic compounds, coating the surface of the large asteroid 24 Themis in the asteroid belt between Mars and Jupiter. Previously, scientists had believed that asteroids there were too close to the sun to harbor water without it evaporating away.
In addition to the practical benefit, water means that the site may potentially be habitable to life, which boosts the asteroid's scientific appeal as well. Although there's no sign yet that this or any other spot in the universe hosts extraterrestrials, the presence of water is the first thing researchers look for when scouting out where potential alien neighbors may reside.
The main challenge in extracting water from an asteroid would be dealing with the lack of gravity, Sanders said. Even places like the moon, which have 1/6 the gravity of Earth, would be easier to work on thanks to that modicum of gravitational pull toward the surface.
"Gravity helps you control where solids are and it helps you control the movement of those kind of resources in and out of your processing chamber," Sanders said. "It's not impossible to come up with ways of moving, but it's different than how we've done it up to this point."
Additionally, the spacecraft would have to find a good way to anchor securely to the surface without the help of gravity.
To find out if 24 Themis or any other asteroid is a promising spot for visiting, and initial prospecting mission is a good idea. Such a mission could take a closer look and analyze samples to determine whether there is enough water in a usable form to merit building a space gas station there.
Link: Space.com article ('Wet' Asteroid Could Be a Space Gas Station)