Hayabusa spacecraft apparently collects asteroid sample to return to earth

[NNadir]

Japanese space probe has become the first craft to collect samples from the surface of an asteroid, mission scientists say.

The probe, called Hayabusa - Japanese for falcon - briefly touched down on the Itokawa asteroid and fired a projectile to loosen surface material.

Scientists believe it collected the debris, but will only be sure when the craft returns to Earth in 2007.

Moon rocks have been analysed before, but asteroids could contain material

from the birth of the solar system.

http://news.bbc.co.uk/2/hi/science/nature/4467676.stm

The spacecraft has been dogged by problems, but the engineers seem to have fixed them. I'm keeping my fingers crossed for this exciting mission.

[icymist]

1. WOW! They actually got this thing to collect samples?

Is this craft returning back by the ion propulsion engine? NNadir, could you please explain how this engine works? Thank you in advance.
Icy.

[nadinbrzezinski]

2. from my notes... for a sci fi game I am writing

These drives are far more efficient than our current chemical drives. They have higher burns and higher thrust, which makes them invaluable when dealing with an enormous black ocean. Even today, making the crossing to Mars, takes over two years. An Ion Drive can potentially cut this down to nine months. By the 35th century Ion Drives are a staple of Interstellar in system drives, which are driven at the heart by a nuclear reactor that uses the plasma to create thrust. In order to get the reactions started they use antimatter pellets and lasers. Ion drives are in some ways similar in principle to the LAPPS drives that are right now theoretical. The speeds they can reach is pretty good, at

Deep Space One is the first practical Ion drive, which used Xenon gas (inert gas) as its fuel. This was released into a propulsion chamber surrounded by magnets. Then electrons were used to bombard the Xenon gas, which led to the gas ionizing, with a practical speed of close to 100,000 KHz. It did yield ten times the thrust of a chemical engine, and the delta V change was quite impressive. Ion drives are not counting on a short burst, though. They are work horses that exert continuous delta v changes, even if they are not that high. Deep Space one achieved a change of 20 KHz \ day, but over nine months the change was close to 2,000 KHz. The amount of Xenon consumed during the course of the mission was 11.5 Kg.

Deep Space one was a proof of concept mission, which made it a candidate for the Thousand Astronomical Unit (TAU) mission. In the 35th century Ion Drives are common, and in fact among the cheapest systems out there. They are common with workhorses because they are easy to handle and over the course of months, even years, they can reach relativistic speeds. Using a nuclear reactor and the magnetic bottles at the center of the drive, they can release plasma creating the Delta V necessary, at a constant acceleration.

Ion Drives are very efficient, and provide constant acceleration. They require relatively low masses of fuel to do their voodoo. They are impractical for military vessels though, because they are incapable of high Delta Vs, but are favored by Space Cruise ships

[icymist]

3. This is for a Si-fi game?

Amazing! Thank you for your explanation of this fascinating engine. I can't wait to see your game.

[nadinbrzezinski]

4. The info is based on actual real info

Deep space one is real and was the first proof of concept mission

[NNadir]

5. An ion engine works by stripping electrons off of a heavy volatile

element. In practice, most ion engines use xenon for this purpose, even though xenon requires slightly more energy to ionize than the other elements that have been tested for this purpose, rubidium, and, probably the best, cesium. (The drawback of the use of cesium and rubidium is that both elements are somewhat difficult to handle -in their metallic form, they burst into flame when exposed to air - and both are corrosive. The air is not a problem in space of course, but it is during manufacture and launch.)

In the vacuum of space, the charged ions are focused into a beam using electrical and magnetic fields and then are accelerated between electrical plates having a potential in such a way that the ion does not actually strike the plates. Because of Newton's third law, the plates are pulled toward the ions with a force equal to that with which the ions are pulled toward the electrode. In one variation, if my memory serves me well, the ions pass through the hole into space and the plates, which are attached to the space craft are accelerated in the opposite direction. Thus the entire spacecraft is accelerated forward. One can, of course, modify this basic design to use repulsive electrical forces as well.

Essentially ion propulsion engines are simply linear accelerators. One can accelerate ion propellants to much higher speeds - in theory (though not in practice yet) relativistic speeds - than one can accelerate chemical propellants. Thus one gets a much bigger bang for a given element of fuel mass. It is useful to use the heaviest possible volatile ion that one can use for these purposes that forms a singly charged ion.

This is of course as simplified explanation, but this is general idea.

Probably the most compact thrust/mass ion for these purposes is Cesium-135, a fission product that is meta-stable, in the sense that it's half life is 2,300,000 years. Cesium-133 (natural cesium) is almost as good.

[bemildred]

6. It's a long way home, may the force be with Hayabusa. nt

[icymist]

7. Japan space probe has thruster problem

TOKYO — A Japanese spacecraft that landed on an asteroid to collect surface samples for analysis has developed trouble with its thruster system, the nation's space agency said Tuesday.

The problem is the latest facing Japan's attempt to complete the world's first two-way trip to an asteroid, following earlier problems with the probe's gyroscopes and two botched practice landings.

The Hayabusa probe appeared to have touched down Saturday, just long enough to collect powder from the asteroid's surface and lift off again to return to Earth.

http://seattletimes.nwsource.com/APWires/headlines/D8E65PHO4.html

<snip>
On top of recovering samples from the asteroid Itokawa, the probe also is testing a new type of ion engine that uses an electric field to accelerate positive ions to a high velocity. It also swung by Earth for a gravity assist that propelled the probe toward Itokawa.

I hope they can get this probe home!

[Dead_Parrot]

8. I hope it gets back in one peice.

I believe the plan is for it to land in the Australian outback: After watching Genesis go splat last year, and given the problems they've had, I wouldn't like to have any money on it...

Fingers crossed here, too.

[icymist]

9. I have my fingers crossed.

Holding my breath, too.