Posted on 02/03/2005 7:28:57 AM PST by Arkie2
Gregory Benford of the University of California, Irvine, and his brother James, who runs aerospace research firm Microwave Sciences in Lafayette, California, envisage beaming microwave energy up from Earth to boil off volatile molecules from a specially formulated paint applied to the sail. The recoil of the molecules as they streamed off the sail would give it a significant kick that would help the craft on its way. "It's a different way of thinking about propulsion," Gregory Benford says. "We leave the engine on the ground."
Solar sails are in essence nothing more than giant mirrors. Photons of light from the sun bounce off the surface, giving the sail a gentle push. It was while developing a solar sail five years ago that the brothers stumbled upon their idea for enhancing the effect.
The pair were testing a very thin carbon-mesh sail by firing microwaves at it. To their surprise, the sail experienced a force several times stronger than they expected. They eventually worked out that the heat from the microwave beam was causing carbon monoxide gas to escape from the sail's surface, and that the recoil from the emerging gas molecules was giving the sail an extra push.
In a forthcoming issue of the journal Acta Astronautica, the Benfords explain how a sail covered with a paint designed to emit gas when it is heated might propel a spacecraft to Mars in just a month. A rocket would take the craft to low-Earth orbit, 300 kilometres up. After the craft unfurls a solar sail 100 metres across, a transmitter on Earth would fire microwaves at it to heat it up. The Benfords calculate a one-hour burst of microwaves could accelerate the craft to 60 kilometres per second, faster than any interplanetary spacecraft to date.
“It's a different way of thinking about spacecraft propulsion. We leave the engine on the ground”The feat would require a 60-megawatt microwave beam with a similar diameter to the sail. It would also have to be capable of tracking the craft as it accelerated away. But this power level could not be delivered by any existing microwave transmission system. The deep-space communications network that NASA uses to communicate with Mars rovers and the Cassini probe now orbiting Saturn can only manage half a megawatt. The Benfords say the power could be ramped up in future and hope to persuade NASA to consider doing this as part of a future upgrade to the network.
A further challenge is how to formulate the evaporating paint. The ideal material would lock up large amounts of a light gas like hydrogen and only release it at very high temperature, when the high speed of the gas molecules would maximise the recoil. Ideally all the paint would boil away, leaving a micrometre-thin sail to continue the voyage to Mars.
"It's pretty cool," says Geoffrey Landis, a physicist at NASA's Glenn Research Center in Cleveland, Ohio. "There are obviously some details to be worked out here, but in a fundamental way the idea makes sense."
So.....how do they get back?
Research like this is good.
The fact is if we are to make manned interplanetary exploration possible, we need to reduce the trip time.
Keeping a crew alive, happy and sane for six months is one thing, keeping them alive, happy and sane for 26 months is another.
If we could get to Mars in a month, we could go there and return on the same Earth-Mars opposition, instead of having wait for the NEXT opposition to get home.
Bones
Solar oars.
Attention passengers - if you look out the right side cabin windows, you will see the Grand Canyon, and .... what's that ? zzzzzzzzzzzzzzzzzzzz
Moties?
"So.....how do they get back?"
Another microwave transmitter in a Mars polar orbit?
Powered by a beefy RTG perhaps?
Bones
Sounds like a job for Project Orion.
Presumably this would be used for one way robotic missions.
Not sure I'd be wanting to sit behind the sail when that 60 megawatt microwave beam comes past....
Sounds like a good way to become space junk -- medium rare.
LOL. Exactly my thought. But the idea appears to have promise for speedy and accurate delivery of equipment for an outpost well in advance of a manned mission.
That equipment could include the means for a return to earth.
I like the thought that there are people actually thinking outside the bun.
Where's the brake?
There do appear to be some minor technical issues that need to be ironed out!
Can Mars capture an object going that speed? Or do the astronauts just wave at Mars on their way out of the solar syatem?
You know, the more I think about this, the more I realized how bad of an idea it is :-)
No problem......
just crew the ship with Democrats from Congress.
"So.....how do they get back?"
And the other Question:
How do they slow down?
"60 km/sec is about 130,000 mph.
Can Mars capture an object going that speed? Or do the astronauts just wave at Mars on their way out of the solar syatem?"
I'm not sure what the plan is, but that is WAY (way!) too fast to be captured by Mars' gravity. And way to fast for aerocapture also, I would think.
There will HAVE to be a way to slow down, if they are to stop at Mars. Period.
Another microwave generator in Martian polar orbit would do the trick, as well as get them home. The could accelerate for half the journey, and decelerate the other half.
Still, I am not sure I like this idea. I'm not big on the power-from-the-ground idea... I would like to see self contained, maneuverable craft. We just need better propulsion
Bones
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