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Next Goals For The ESA
zeux writes "With all the news we got recently from space I tried to gather some information about the next goals of the ESA (European Space Agency). Along with a space vehicle designed to carry supplies to the ISS between 2004 and 2013, they are working on the new 'Vega' launcher (2006) and still playing with the SMART-1 probe which is slowly heading to the moon testing an ion drive that is ten times more efficient than the usual chemical systems (1500 hours cumulated thrust time so far)."
If you RTFA'd, you would realize that the satelite isn't on a direct moonshot, it's spiralling out from an earth orbit, to a lunar orbit. This would be hella slow compaired to a direct shot, which should get it there in a few days at worst. The thing is traveling at 3850km/h, it's just not doing it with a direct vector to the moon, rather, a spiral.
"Victory means exit strategy, and it's important for the President to explain to us what the exit strategy is." G.W.Bush
A better link
http://www.esa.int/export/SPECIALS/Mars_Express
The ESA also has a probe named Huygens headed for Titan, the largest moon of Saturn that will land on the surface in 2005 and send back photos. Titan is the only moon in our solar system with a thick atmosphere. It is believed it may be similar to that of Earth's millions of years ago.
SMART-1 is part of the Small Missions for Advanced Research in Technology; these missions are specifically designed to develop new space-based technologies. A sister mission, due for launch in June 2007 is SMART-2 , which will be a testbed for laser ranging. The technology will eventually be put to use by LISA (Laser Interferometry Space Antenna), a proposed ESA mission intended to look for the gravitational waves predicted by Einstein's General Theory of Relativity.
The knowhow obtained from SMART-2 will also prove instrumental in developing ESA's Infra-Red Space Interferometer, known informally as Darwin. Darwin, part of ESA's Horizons 2000 programme, will consist of 6 infra-red telescopes flying in precise formation, with the aim of performing nulling interferometry of nearby solar-type stars. Darwin will be sensitive enough to detect the infra-red absorption-line signatures of water, ozone and carbon dioxide in the atmospheres terrestrial-sized planets orbiting one of these stars; these signatures, if detected together, would amount to strong evidence for extraterrestrial life.
Tubal-Cain smokes the white owl.
A little flash animation for those confused about ion drives: http://www.esa.int/export/esaSC/SEM3K81P4HD_index_ 0.html . Of course depends on mass, momentum, etc. too....
Would a colony actually *stay* in the lagrange point?
L4 and L5 are the stable Lagrange points; these are the ones in the same orbit as the moon, but leading or trailing by 1/6th of a revolution. The other points, L1-L3, are unstable: while the effective gravitational force at these points is zero, an infinitessimal displacement away from a point will lead to a force which is also directed away from the point, leading to runaway.
So, in answer to the quesiton, a colony at L4 or L5 would stay in position without further assitance. At L1-L3, it would need positioning rockets to stop it from wandering. This in fact is how SOHO (the Solar and Heliospheric Observatory) remains in its Sun-Earth L1 position (inside the Earth's orbit, on the line between Earth and Sun).
Tubal-Cain smokes the white owl.
Probably has to do with the number of available electrons to strip away.
Xenon is pretty plentiful (8 valence electrons), and compared to nitrogen (5 valence electrons), seems to have just a few more electrons available with little increase in mass, while still remaining a noble, inert gas.
IANAC
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A better better link
You said: "One word: fusion. As soon as fusion comes along, coupled with ion drives, chemical rocketry is history. Period.'
Unlikely.
There are two main designs for a fission rocket.
(1) To couple a semi-conventional PWR or BWR with an ion engine. The big downside to this is that you have to have a large secondary system to use the steam to make electricity. What this means is that you have to have a large heat sink (large radiators) and lots of moving parts. A design like the GT-MHR could simplify this, but not hugely so.
(2) Using a bladder of fuel (hydrogen, or water or whatever), you use this as coolant to a critical reactor that jets the superheated portion directly to space. The downside is that this doesn't make electricity, so you would have to divert some of the coolant (which requires construction of the additional secondary systems) or use solar panels or RTGs to electrically power the spacecraft (there will be additional power requirements due to reactor safety equipment).
There are two main designs for fusion power:
(1) Tokamak: basically shaped like a donut, a low atomic number elemental plasma is magnetically confined and heated (with I^2*R losses or X-rays) to the point where fusion occurs. The means of useful energy transfer is via neutrons emitted which hit a water tank surrounding the fusion reactor. From here its just like the secondary side of a normal fission nuclear reactor (ex 1 above).
(2) A pellet of low atomic number elements is simultaneously hit by energetic radition from all directions compressing it until fusion occurs. Heat transfer like above.
You could argue that either of these fusion reactions could operate like the fission reaction #2 above (with part of coolant directed to make electricity), but an important point is that a significant fraction of the energy released by fusion (if it ever produces more energy than is required to induce it) is required to sustain it. This requires the construction of a very large secondary system compared to that of the fission reactor (a lot more heat being transferred). Since a fission reactor will probably provide way more power than is needed anyways, there is no reason to build a much heavier fusion reactor.
Suddenly, the hairy finger of a familiar monkey tapped me on the shoulder. It was time.--G. T.
ESA has a long term exploration program called Aurora that aims to take humans to the Moon by 2020 and Mars by 2030. This was announced some time ago, well ahead of Bush's proclamation. The nearer term goals include ExoMars, a long-duration rover, and a Mars sample return mission with the ambitious launch date of 2011.
They are not ignored by "mainstream" science. Mainstream science has already determined that they don't work.
So mainstream science "ignores" them only in the sense that they also ignore reading chicken entrails to fortell the future.
For starters, this is not a drive without a reaction mass. That's what the ball is.
When the ball hits the spring the spring compresses,i.e. deforms, otherwise it wouldn't be a spring, now would it? But only some of the energy of the ball goes into compressing the spring. Some of that energy goes into driving the entire tube "backwards." When the spring expands, again, some of that energy goes into driving the ball forwards, but some into driving the tube backwards again. In the process, as you note some energy is lost as heat.
When the ball "klunks" it drives the tube forward and the ball backward and some energy is lost as heat.
There is no essential difference between the spring and the klunk with regards to energy transfer other than the difference between the energy losses, as you note, which are very small (the klunk heats the ball more than the spring does).
What you have described is an oscillator that winds down after a relatively few klunks because energy is lost at each exchange. Use your brain. Analyze what "energy is lost" means.
It means the thingy goes back and forth a few times and then stops.
Unless you add energy.
By driving a reaction mass.
i.e. the ball.
And you still need a rocket to get it "up there" 'cause it ain't gonna do squat but fall over if you set it up on end and start it going here on earth. And that rocket has to carry the fuel to get the ball going in the first place, and all the fuel to keep it going, so that it can sit there in space and wobble until the fuel runs out. A quantity of fuel that still has to equal the energy value you intend to get out of the device.
This is nothing more than an obfuscated version of the drop hammer that lifts veeeeeeeeery slowly and thenswings down against a stop suddenly.
When the hammer lifts slowly the machine moves backwards slowly. When it swings down and hits the stop it moves forwards quickly but an equal distance less the heat loss in the impact versus the heat loss in the bearings as it rises and it needs fuel to drive it. Fuel which must be lifted into space and carried by the device. About the same amount of fuel that a conventional rocket uses.
And all it does is wobble.
KFG
I would say that is the smallest "big list of all spacecraft" I have ever seen. A more comprehensive resource on spacecraft, be it manned, planetary or ordinary telcomms, is the ever-useful www.astronautix.com. Go here for a full list sorted by type of mission. (scroll down to 'planetary' for the interesting stuff).
> hasn't had much sucess lately (due to the
> Arianne and Beagle 2 fiascos)
Beagle 2 was a late "add on" to the Mars Express Mission... Beagle 2 was developed by the British. Attributing the failure of Beagle 2 to ESA is tantamount to saying there is UNIX code in Linux.
The Mars Express is SUCCESFULL, and is already returning clear stereo pictures of the Martian surface.
I am still sorry Beagle 2 failed.. but dont catogorise the whole mission a failure for ESA, just because of one part. rememebr the original mission did NOT include a lander....
Have a nice day!