Slashdot Mirror
Odyssey Arriving at Mars Tonight
moloader writes: "Odyssey will arrive at Mars on October 24, 2001, 0230 Universal Time (October 23, 7:30pm PDT/ 10:30pm EDT). As it nears its closest point to the planet over the northern hemisphere, the spacecraft will fire its 640-newton main engine for approximately 19.7 minutes to allow itself to be captured into an elliptical, or looping, orbit about 20 hours long. Go Mars!"
Should be enough for anybody
Best Slashdot Co
on the mars section of the site : If you want to be a real engineer, set your hands to work on paper models of: Pathfinder Mars Global Surveyor (pdf), and 2001 Mars Odyssey Color or Black-and-White (pdfs) spacecraft.
with these kinds of drafting techniques...
Fighting for peace is like fucking for virginity
We will know more. That's how.
Knowledge is the only thing that truly separates us from barbarism and animals.
an elliptical, or looping, orbit
All stable orbits are looping. Elliptical just means that it isn't always a uniform distance from the origin of the orbit, in this case, Mars.
http://twitter.com/onion2k
The real goal is to have the orbiter revolve around the planet every two hours. The rockets will slow the orbiter down to a 20 hour orbit - then, over a period of months, the orbiter will ease into a two hour orbit - thanks to aerobraking.
If all works well, that's what'll make this mission a success - the aerobraking technique means significantly lower fuel requirements, which makes for a lighter and thus less expensive mission.
Let's hope everything works right this time!
All orbits (about a single body) are conic sections, not necessarily ellipses. Given just barely enough energy to escape the body results in a parabolic orbit, and having excess energy results in a hyperbolic one. If the orbit is 'captured,' it has an elliptical shape.
I agree though, that 'looping' and 'elliptical' shouldnt be used as synonyms.
"Open the pod by doors, Hal" > "I'm afraid I can't do that, Dave" sudo "Open the pod bay doors, Hal" > alright
Actually, we don't, that's one of the things this probe has been sent to determine. There is an ambiguous but intriguing body of evidence that liquid water may once have flowed on Mars' surface, but what water remains is yet to be determined.
We have known for some considerable time that Mars has a very thin atmosphere composed primarily of carbon dioxide. It is less than 1% as thick as Earth's atmosphere.
Your chain of reasoning is getting increasingly tenuous.
Odyssey is an orbiter, not a lander. It will never come in contact with the planet. Even if the worst happens, like it did with Mars Climate Orbiter in 1999, the thin Martian atmosphere is still thick enough to ensure that nothing uncharred reaches the surface. All landers are thoroughly sterilized before leaving Earth.
Since space radiation presents an extreme hazard to crews of interplanetary missions, the experiment will attempt to predict anticipated radiation doses that would be experienced by future astronauts and help determine possible effects of Martian radiation on human
You have to give NASA credit for thinking far ahead. I'm not that optimistic about space exploration. We need some major breaktroughs in order to get further away from the moon.
First theres the problem with the propulsion system: we're simply not fast enough in our spaceships. In order to get anywhere we need to approach the speed of light or even exceed it (or better yet, make the whole thing about space/time irrelevant, but that is sci-fi for the time being)
Second humans are really not meant to be put in space. We need to adapt, and we need to adapt in a serious way. Most of our body is made up of this little molecule H2O, and we need lots of it to survive. Water is not easy to get in space! Food is another problem. Another is that the human bonestructure degenerates in space (it wouldn't be smart spending billions on spaceexploration just to make astronauts land on mars realizing that they have become crippled in the meantime. We can minimize the effect of zero gravity but the problem remains.
I dream of space too (wonder if all people does in a way). Just can't see how we're going to get there. What bothers me the most are that I don't find much evidence either, of breakthrough technologies that will make humans able to explore space by them self in my lifetime. Pitty really, it's just not the same wathing a robot land somewhere doing the exploration for us! (well maybe for the guy controlling the robot
Thomas S. Iversen
High Res Spectrometers
This baby has two spectrometers, one in infrared for working out the mineral composition of the surface to a resolution of 100 metres, and one in gamma rays, for working out how much hydrogen there is near the surface, and consequently how much rocket fuel they can make in different places if/when they land.
Comms satellite It acts as a relay between the surface and the Earth, so any new probes (like the twin rovers due to take off next year) wont have to carry big dishes and radios.
All this and more on the website.
Once more unto the breach, dear friends, once more, Or close the wall up with our American dead!
The Dust Storm which can dramatically change the height and density of the atmosphere, are a particular concern during aerobraking.
A great article on the whole procedure is at this link.
Krispy Cream is people
Perhaps we've deduced the source of the original post?
Easy, 400 leagues over the spot where those three rocks make a small triangle the engine should engage to point the craft down roughly four spans. A few orbits in, the thrusters will be fired to reduce the elliptical orbit by about a thousand rods.
"God is a comedian playing to an audience too afraid to laugh." -Voltaire
How is mankind any better off? In two areas: technologically and, for lack of a better word, spiritually.
Two examples should suffice to prove my point.
With regard to technology, the integrated circuit was developed for NASA, to use in satellites and spacecraft. No doubt, if the space program had not existed, the IC would have been invented some time or other; but the space program meant that we had it sooner and faster than we would have had otherwise. Big, interesting problems bring about technologies that are interesting and useful; and no problem is bigger or more interesting than space flight.
With regard to the spiritual value, think of the photograph of the Earth rising over the Moon that Anders took in Apollo 8, in 1968. Can you think of a better description of the unity of the Earth, and its relation to the cosmos? I think that photo alone was worth the billions we spent on the space program.
Recently, I viewed the movie "Apollo 13" with my two teen-aged children. It's quite a movie, for it captures the excitement - the romance, if you will - of the Apollo adventure. The hardest part was trying to explain to the kids why it was that when I was their age, we were flying men to the Moon, but nowadays we have simply given up going.
When I look around the world now, with the horror of 911, and of the Afghanistan war, and the rise of Islamo-Fascism threatening to return the world to the dark ages, we need to remember the glories of enterprises like the the exploration of space, which enriched the lives and broadened the imagination of all humankind.
First theres the problem with the propulsion system: we're simply not fast enough in our spaceships. In order to get anywhere we need to approach the speed of light or even exceed it
Getting to another star system would require near-C travel, but getting to other planets certainly doesn't. Chemical rockets can get just about anywhere in the inner solar system in a couple of years, and anywhere in the outer solar system within about five years.
Use an ion drive, and you can get just about anywhere within 1-2 years.
Sure, you won't be commuting to Mars for the weekend, but this is certainly good enough for colonization and trade. Think back to the old days of wooden ships on Earth.
Second humans are really not meant to be put in space. We need to adapt, and we need to adapt in a serious way. Most of our body is made up of this little molecule H2O, and we need lots of it to survive. Water is not easy to get in space! Food is another problem. Another is that the human bonestructure degenerates in space.
Humans aren't going to change their basic structure. We can, however, build contained environments that can support us.
Water isn't a problem. We already have water-reclamation systems that are perfectly efficient (we just don't use them because they're expensive). Your ship is air- and water-tight - you won't lose any mass to space.
If you have a big enough ship, food isn't a problem - grow it the old-fashioned way. Or stockpile a year's worth of army rations (this will take mass, but not an unmanageable amount of mass; it's just probably cheaper to grow food).
Gravity similarly isn't a problem. You can either live with bone degeneration, or you can connect two ship parts with a long cable and spin them to get a wonderful simulation of gravity and avoid all zero-g related health problems.
In summary, I don't think we need any new magical technology for in-system space travel. We have pretty much everything we need already.
All orbits are elliptical, anyway.
Actually, orbits are only elliptical around isolated, spherically symmetric objects in Newtonian gravity. Planets are neither isolated, nor spherically symmetric, and gravity is not Newtonian :-) In the real universe, planets are approximately oblate spheroids with "small" surface ripples, like mountains, valleys, etc, which result in radial variations that make individual orbits look like "wavy ellipses" (which is actually a major source of systematic error in the GPS system that needs to be regularly corrected); further, the non-Newtonian nature of gravity (read General Relativity) causes orbits, even around perfectly symmetrical objects, to not close into ellipses, but to precess with time. And there are all sorts of other effects that you need to worry about (other planets, the sun, atmospheric drag, etc. etc. etc.) that further modify the orbit of spacecraft, guaranteeing that they're orbits won't actually look anything like ellipses on all but an "average basis" over a few orbital periods.