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Biscay
2003-Dec-14, 07:23 PM
Some simple questions, nothing complex:

1.- Which is the closest Solar System to ours? How far away is it? And the closest Star? Are there any maps of the Milky Way?

2.- Could a Solar wind-type spacecraft orbit the sun? (in order to increase its speed) Could it carry any other kind of propulsion? Carrying several kind of propulsions means higher speeds in space?

Thanks in advance for any answer

Planetwatcher
2003-Dec-14, 10:33 PM
1.- Which is the closest Solar System to ours? How far away is it? And the closest Star? The closest star system to us is called Alpha Centauri, or sometimes Rigel Kentauris.
It can be seen in the southern hemosphere in a constalation called the Southern Cross.
Alpha Centauri is in the neighborhood of 4.25 to 4.35 light years away, or more simply 25 trillion miles.
I say neighborhood because Alpha Centauri has the virtue of being a system with 3 stars. The smallest of the 3, Alpha Centauri C is the closest to us, while the other 2 are equally distant. Alpha Centauri C is also distinct from the others in that it is also called Proxama Centauri, whereas the others are referred to as Alpha Centauri A, and B, or sometimes again Rigel Kentauris.


Are there any maps of the Milky Way?
I don't know of any of just the Milky Way, but there are different types of star charts.

2.- Could a Solar wind-type spacecraft orbit the sun? (in order to increase its speed) Yes, but not nearly enough to achieve intersteller travel.
In fact the Smart 1 spacecraft is doing just that, except it orbits Earth and has ion type engines, making larger orbits until it approaches the Moon.


Could it carry any other kind of propulsion? Yes, but that would reduce it's speed while using solar wind alone because of the bulk and mass other methods of propulsion would require. Also note that solar wind power is confined to the solar system and would not be practical for star travel.


Carrying several kind of propulsions means higher speeds in space? Yes, but again most combinations will not work well for intersteller travel.
For example, solar wind sails and ion engines would be wonderful for many missions within the solar system, but try to send it to a star, and it might just as well be Voyager 1 which will take 25,000 years or more to reach any star.

Current rocket technology will speed up solar system mission, but not make a difference in trying to reach any stars, because they are still much too slow and the fuel range severely limited.
Ion engines can run (in theory) hundreds of years without refueling, however the acceleration is too slow to be of value. Remember Smart 1 has ion engines and is going to the moon, but it will take years, where as the Saturn 5 rockets took days.

Nuclear fission technology currently uses a boiling water reactor principle in that the craft would use hydrogen as it's fuel, but pass it through a fission reactor to superheat and expand the hydrogen, which is then expelled through rocket nossels.
Much like producing electricity, water is piped through a reactor which turns it into steam which runs a turbine. We have yet to harness nuclear fission directly.

Nuclear fission with solar sails would be self defeating. The mass associated with nuclear engines is too heavy to be propelled by solar wind sails, and the sails would create too much volume drag to make the nuclear engines usefull.
Remember space is not totally empty, just very dispersed.

Solar wind sails with rockets would be fast and reliable for lunar and inner solar system missions, but too limited for anything else.

Nuclear fission with rockets would work will in the outer solar system and Kupier Belt, and perhaps to the outer parts of the Orrt Cloud, although that is really pushing it, and such journeys will take a very long time, months, and years.

Nuclear fussion is not currently usable, but projected in theory to reach a third of light speed.

Nuclear fussion ramscoop is theory only. It would use expendable tanks to reach speeds up to a third of light, then scoop the tiny amounts of intersteller hydrogen in space for fussion, and without the bulk of carrying on board fuel, could reach up to 75% of light speed.

Anti-matter annilation is Star Treks faster then light theory, but realisticly could never exceed the speed of light.
Right now it is about as achievable as nuclear fusson ramscoop.

To date, the Saturn 5 rocket is the best we have ever done.
Solar wind sails will be about 5 times faster if they work, and if the payload is very small.
Ion engines could achieve a quarter of light speed but take hundreds of years to reach such speeds, and again the payload must be very small.
Nuclear fission is a good bet in the next 20 years, for it will be about 7 times faster then the Saturn 5 rocket was.
Direct power, or thrust from nuclear fission is about 50 years away, unless we got really busy, and started right away.

All in all, your simple questions have some compicated anwsers.

DippyHippy
2003-Dec-14, 10:48 PM
I've done a bit of digging and I *think* the closest known star with planets is Gliese 876, a red dwarf in Aquarius that's 15 LY away :)

http://www.obs-hp.fr/www/nouvelles/gl876.html

Guest
2003-Dec-15, 12:13 PM
Thank you indeed for both answers! I must admit that I thought that, in space, mass was almost irrelevant. I took for granted that there was no friction or gravitational effects (relevant ones).

Thank again for the answers.

Biscay
2003-Dec-15, 12:18 PM
Me again. Forgot to login. Thanks again