Thorgalaeg
Deity
Well, since Earth has twice the diameter of Mars i entered the data for a meteor twice the diameter of the comet in this calculator and the result is:
So it seems not.
The thread for space cadets!
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Winner
Diverse in Unity
I read that this is one theory about how Phobos and Deimos originally formed. The other hypothesis considers them to be captured asteroids, but their orbits are way too circular and equatorial for that to be easily explained.
Phobos and Deimos might thus have formed in the aftermath of some of the giant impact, when the debris thrown into orbit first formed a ring and then coalesced into the tiny moons.
Not by much, I think.
But I should look for some sources concerning the magnitude of atmospheric change that could result from such an impact. Tens, perhaps hundreds of thousands of cubic kilometres of ice and rock would be vaporized and released into the thin Martian atmosphere. Considering how tiny it is today, it could perhaps thicken by tens of %, maybe more if it caused the ice caps to evaporate and CO2 to be released from the regolith. Mars could be sent into a "warm age", if only briefly.
I vaguely remember dropping comets on Mars was also proposed by Zubrin as a method of terraforming (then he changed his mind, because he thought the colonists actually living on the surface wouldn't like that very much).
BTW, look at how deep the transcient crater would be if it hit Earth - almost 100 km. That's all the way down into the mantle. It would leave a 500 km hole in the crust, that would probably steam and vent volcanic gasses for quite a long time.
Mars could use that
Winner
Diverse in Unity
Moon transit as seen from 50 million kilometres away by the Deep Impact probe:
Also, the Economist writes about the comet-Mars thing:
Spoiler :
Also, the Economist writes about the comet-Mars thing:
A PAIR of middle-aged tourists (see previous post) are not the only thing headed for Mars. Comet C/2013 A1 (Siding Spring) is also on its way. Discovered on January 3rd, some calculations of its orbit, according to Phil Plait, the rather good “Bad Astronomer”, have it passing 37,000km above the surface of the planet in October 2014—roughly the height at which communication satellites orbit Earth, and a remarkably close shave by cosmic standards. An official NASA website puts the most likely “close-approach” distance between the comet and Mars at something more like 100,000km.
But the minimum close-approach distance is zero. Comets do not move smoothly on their tracks like ball bearings or planets. The gases that blow off their surfaces as the sun warms them up push them hither and yon, changing their trajectories. So, though the odds are strongly against it (how strongly no one can yet say) the comet has a real if small chance of actually hitting the planet.
Which would be cool, in all sorts of ways. For a start, it should be simply spectacular. Given the unusual speed of the comet (which is moving so fast that it may well be coming from outside the solar system—cool upon cool) and the fact that it is travelling the wrong way round the sun, from a planet’s point of view, Mr Plait estimates that its impact should yield a blast equivalent to that of a billion megatons of TNT. It would be an event on the same sort of scale as the impact that drove the dinosaurs extinct 65m years ago. If it really is that big, and if the comet were to hit the side of Mars facing Earth (it seems that it might do, but it might also hit the far side), then the blast could well be visible to the naked eye, even in daylight.
It is worth pointing out that, for C2013 A1 (Siding Spring), this is the nearest thing to a direct effect on Earth that can be imagined. The recent meteor break-up over Russia, and the close pass of asteroid 2012 DA14, have reminded people that Earth, and all other planets, are vulnerable to intervention from outside. But this particular comet is not coming anywhere near Earth.
That does not mean it would not have scientists salivating. Observing such an impact, which might leave a crater hundreds of kilometres across, would be a huge scientific boon. Of the geological processes which shape the surfaces of planets, impacts are the ones that humans have had the least opportunity to observe up close. The faces of the moon, of Mars and of Mercury show the aftereffects of such impacts, but the processes by which they hollow out their craters and raise their rims and central peaks have only been witnessed in miniature. If a fair sized comet smacks into the surface of Mars, telescopes on Earth and in orbit around it will be able to see large-scale cratering in real time and remarkable detail. Telescopes orbiting Mars will do better still—but perhaps not for long. The amount of debris thrown up from the planet’s surface and into space would seem likely to make their orbits quite hazardous.
The cratering process would be interesting to geologists. Its aftermath would be fascinating to astrobiologists. There is a lot of ice frozen into the Martian crust. The heat of an enormous impact would melt a huge amount of it. If, as some believe, there are microbes living deep under the Martian surface, such a burst of warm, wet conditions over a substantial chunk of the planet would give them a brief chance to thrive at and close to the surface before the planet refroze. It’s not obvious how to observe such exciting developments, but there are surely already people at NASA and elsewhere giving thought to the matter. And they will have time. Parts of the surface and subsurface in the impact region, if there is an impact, will stay warm for decades.
In all likelihood there won’t be an impact. But even a near miss could be exciting and, for humankind’s emissaries on Mars, spectacular. The various spacecraft now orbiting Mars will get to see a fresh comet at very close quarters. There is a good chance that they will pass through the comet’s “coma”, the comparatively dense (though still remarkably thin) cloud of dust and gas that surrounds the solid nucleus. This will subject them to some risk, as indispensable planetary science blogger Emily Lakdawalla points out—the coma has some grit in it, and at 55km a second a little grit can do a lot of damage. The risks a close approach would pose to the spacecraft currently on the Martian surface, Opportunity and Curiosity, would probably be negligible, and they, too, should get some spectacular pictures to send back to Earth. As Donald Yeomans of NASA says, "unless this comet completely fizzles, it should be extraordinary as seen with Mars-based assets".
And if the comet passes close enough to the planet it may allow a natural experiment. Over the past decade there has been much discussion of the possibility that there might be methane on Mars, possibly produced by the aforementioned subterranean microbes. Various observers claim to have seen evidence for the gas, but theoretical arguments cast serious doubt on their results. One of the questions in play is how fast the Martian environment can oxidise organic compounds (such as methane) which get pumped or dumped into it. A very close encounter with a comet might result in a measurable pulse of organic matter being introduced into the upper atmosphere; its fate would be interesting to track.
At the very least, NASA and the European Space Agency, which also has a satellite around Mars, will get an unexpected close encounter with a new and intriguing comet. At most, though more than a billion dollars worth of spacecraft may be lost, scientists might get to see the creation of a giant crater and, later, to explore a defrosted tranche of Mars that will give them the best chance they could imagine of discovering life on the planet, if life there is.
More detail on the orbit of C/2013 A1 (Siding Spring) will not be available for a few months, as it is currently hidden from view by the sun. When it reappears, a great many telescopes will be trained on it, trying to work out where, exactly, it will end up. In the meantime, Don Dixon's illustration (above) depicts the sort of thing which might just possibly be in store.
warpus
Sommerswerd asked me to change this
If this thing hits, imagine the imagery they're going to be able to send back to us to stare at. So I guess if it does, we should just make the best of it and get as much data as possible to study and be amazed by.
Winner
Diverse in Unity
And lose our low-orbiting probes, hopefully after they send images. Mars Express could perhaps dodge the bullet.
I know it won't happen, but it would be so cool in so many respects it is mind-boggling. Besides, seeing what a large impact could do to a planet in real time would be a far better wake-up call than a small meteorite in Russia, I'd say.
If Mars really thawed as a result of the impact, it would perhaps stimulate exploration/and colonization, since terraforming would have been kick-started by mother Nature herself
Later, we could do the same, albeit in a less violent manner. Sending smaller icy fragments to burn up in the atmosphere instead of directly slamming the surface would accomplish almost the same without most of the damage.
hobbsyoyo
Deity
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You responded with your own unsubstantiated claim so the best we can agree to is something along the lines of 'claims without evidence can be dismissed out of hand' with respect to each other.Me?I called you on your unsubstantiated claim, and you responded with "sure dude, whatever" and other sarcastic ad hominem comments, so I'd shut up about twerps if I were you. I don't know what your problem is, but leave me out of it.
Congrats!
I reacted as such a jerk because you post to win, Winner. Multiple times now (not in this case though) we have posted things 95% in agreement with each other. What gets annoying is your constant insistence on the 'winning' the last 5% of any discussion and your extremely contemptuous posting style.
You know the truth and everyone else is stupid for thinking otherwise even if it's as silly a point as their personal movie preferences. It's obnoxious and I hit my limit with it after your face palm smilie in the asteroid soap box thread (I need to get back to that
).That was a perfect example, we were actually posting much the same thing yet you had the nerve to tell me to stop posting before I post something I regret. Do you not understand how abrasive that is?
It's not just me that you talk down to and you do it incessantly. Sometimes though it's hard to see our own faults. It took me a while to understand just how big of a troll I really am, for instance.
LamaGT
Emperor
I've been thinking about creating a game about space with 2D orbital mechanics, but I just have no idea on how to actually simulate orbits. Do I have to calculate manually all of the orbital elements, or maybe do everything with just a velocity vector? Maybe another way?
I don't really need n-body simulation, just one that wouldn't alter the orbit after a couple of periods.
I don't really need n-body simulation, just one that wouldn't alter the orbit after a couple of periods.
hobbsyoyo
Deity
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Ask me again next semester when I've taken my orbital mechanics course.
I had some friends last semester who were working on an android game that had a simple gravity simulation. It actually worked a bit like Angry Birds Space; you kind of pointed where you wanted to shoot your ship and the gravity fields would warp your course around and you had to go through a black hole/warp on the other side of the map by navigating through the gavity fields.
It was fun but it never got finished AFAIK and I'd ask the guys for you but they all moved to St. Louis and I lost touch with them.
I had some friends last semester who were working on an android game that had a simple gravity simulation. It actually worked a bit like Angry Birds Space; you kind of pointed where you wanted to shoot your ship and the gravity fields would warp your course around and you had to go through a black hole/warp on the other side of the map by navigating through the gavity fields.
It was fun but it never got finished AFAIK and I'd ask the guys for you but they all moved to St. Louis and I lost touch with them.
Borachio
Way past lunacy
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Maple wasn't too bad for that sort of thing. As I remember. I used it without much difficulty for a 3-body simulation, a few years ago.
http://www.maplesoft.com/
Still, it's kind of industrial-strength mathematics. So maybe not what you're looking for. And I can't imagine how you'd make it into a video game.
warpus
Sommerswerd asked me to change this
Maple brings back bad memories for me. The Scientific Computation class I had to use it for sucked space donkey balls.
warpus
Sommerswerd asked me to change this
On a more positive note, this website will tell you how many people are in space
If you just want the stable orbit of a light body orbiting a heavy body, without any 3-body interactions or changes in orbit, that is pretty easy: Just implement Kepler's laws.
First you define your orbits as ellipses with the heavy body in one of the focal points. The you parametrize that ellipse in polar coordinates and find that the position of the light body is determined by just one variable, the polar angle. Kepler's second and third law give you the change of that angle. So you get just one differential equation. Solve that one by brute force: Make small timesteps, calculate the change in angle, calculate the new angle and repeat. Because that way the body can never leave the predefined ellipse, the orbit can never become unstable. If for some reason your numerics get unstable, the only thing that could happen is that the body speeds up or slows down too much. If that happens, decrease the size of the timesteps. Computers are fast enough these days, that this shouldn't be a problem.
Once you got the motion in polar coordinates, you just have to make a coordinate transform into your real coordinate system.
If you need something more complicated, you could try a full gravity simulation. However that is much more tricky to implement in numerically stable and efficient way. And if you include 3-body interactions, you might get unstable orbits because they would be unstable in reality.
I'm sure this has been posted in this thread before somewhere. Let's do it again in HD!
Total Earth annihilation
Link to video.
Total Earth annihilation
Link to video.
Thorgalaeg
Deity
That must hurt... Still for Earth as planet it would be only a "reset".
Image taken by Col. Hatfield from ISS.
Image shows a full moon, I see a quarter moon out my window.
I *think* it's possible for an astronaut to see a full moon from a point in orbit while on the earth we see a different phase, but um not certain.
Any thoughts?
LamaGT
Emperor
Thorgalaeg
Deity
Looking at some profiles, it is curious how the piloting experience of the Russians is mostly based in slow heavy jets like Il-76 and Tu-134 or even slower attack planes like the Su-25. Also L-39, L-29 but this two are trainers so it would be logical. Not any Mig-31, Mig-29 or Su-27 fighter pilot as i would have expected.
PlutonianEmpire
King of the Plutonian Empire
Did you check the timestamps on that image, if any? (Not always visible visually, but it. Might be there in the metatags.)
Image taken by Col. Hatfield from ISS.
Image shows a full moon, I see a quarter moon out my window.
I *think* it's possible for an astronaut to see a full moon from a point in orbit while on the earth we see a different phase, but um not certain.
Any thoughts?
No. Thrust would put an object into a different orbit, so the predefined orbit wouldn't work anymore.
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