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Chinese Researchers Propose Asteroid Deflection Mission
wisebabo writes "Researchers in China have proposed sending a solar sail-driven probe to hit the asteroid Apophis to make sure it has no chance of going through a 'keyhole' near earth in 2029. If it goes through the keyhole, then it will hit the earth seven years later. The reason why they need to use a solar sail is because they want the very small probe (~10kg) to hit the asteroid in the opposite direction, a retrograde orbit which would otherwise require an insane amount of fuel (after being put on an escape trajectory, it would need to first cancel out the earth's orbital momentum and then basically speed up to a likewise high velocity in the opposite direction). They are doing this to hit the asteroid at a very high impact speed. While Apophis may not literally be capable of wiping us out (it 'only' weighs 46 million kilograms), it might be able to wreck our civilization."
Read on for the rest of wisebabo's thoughts.
wisebabo continues, "Rather than putting the fate of our species into the hands of an untried technology (no solar sail has yet imparted substantial delta-V to its spacecraft) may I suggest an alternative? By using Jupiter as a gravity assist, we could send a much heavier probe to hit it at comparable speeds. For example, the Juno spacecraft, recently launched to the gas giant weighs almost 8000kgs. Jupiter could sling a spacecraft around so as to completely cancel its orbital momentum (with no fuel expenditure!). Then it will fall directly towards the sun and, if guided correctly, could hit Apophis broadside. Considering it will be falling from a height of several hundred million miles, it would pack quite a wallop. Admittedly, the impact will be on the side rather than head-on, but that should be okay since all we have to do is assure that Apophis doesn't pass through the keyhole, which is only 600m wide. Don't get me wrong, I hope solar sails become widely used for the (slow, cheap) transport of cargoes in the solar system. It's just that I wouldn't base the defense of earth on them."
> (it 'only' weighs 46 million kilograms)
No it doesnâ(TM)t. Kilograms are a unit of mass, not of weight.
Don't worry. Teal'c will take care of Apophis.
Do daemons dream of electric sleep()?
Well I hear lots of organizations and governments have made plans to deflect an asteroid with a missile should one threaten to hit Earth. I think it wouldn't be a bad think to practice a little on asteroids that are passing close but not threatening us. I think we'd want to be ready for when a real danger shows up.
How out doing both? Even if one fails the other would succeed, and you'd test both technologies in a real-world setting. We're talking fairly cheap missions, relatively speaking, and they could almost be worth it just for the incidental research data if you let some of their mass be instruments and communications equipment.
Trust the Computer. The Computer is your friend.
It's basically been confirmed that it's not going to hit the Earth: http://en.wikipedia.org/wiki/99942_Apophis#History_of_impact_estimates, http://en.wikipedia.org/wiki/File:Apophis_pass_zoom.svg, but then this is China we're talking about so they probably don't believe the rest of the world's measurements.
> (it 'only' weighs 46 million kilograms)
No it doesn't. Kilograms are a unit of mass, not of weight.
Yes, this also made me very amused:
Considering it will be falling from a height of several hundred million miles ...
What're Bruce Willis and Ben Affleck up to?
http://en.wikipedia.org/wiki/99942_Apophis
2.7×10^10 kg
How difficult is it to copy paste?
I do not believe in karma. "Funny"=-6. Do good and forbid evil. Yours, Oft-Offtopic Flamebaiting Troll.
"Apophis pushed through 'keyhole' in space by solar sail. Seven year countdown begins."
and china state tv will just show clips from movies or tv shows to show this off.
There's a nearby asteroid, close to hitting us but almost guaranteed not to. If they go out and meddle with its direction, what could possibly go wrong?
Since we still don't even know that it will hit that keyhole (the last stat I saw was 1:250,000 chance), what are the chances that instead of a direct hit, we'll just make a glancing blow that ultimately nudges it through the keyhole?
This mission seems to make more sense if there's a 100% chance it will hit the keyhole, because then there's no way to make it worse, but I'd like to see some statistics on the chances of making the situation worse (or on completely missing it and doing nothing at all)
At the very least, we should plan on *two* missions... one farther away, and then if it turns out we haven't pushed it out of the way, send a modified spaceshuttle full of Texas Oil workers to drill a hole and plant a nuclear bomb in its core. Then they could make a movie about it.
So, assume that with this new trajectory it will unintentionally hit another inhabited planet in some distant future. They may discover pieces of the probe before impact and assume that it's being sent to their planet as an intentional act of war. We will then be doomed...
In my submission I actually had some more speculation:
"Then again, if you were able to very accurately control the asteroid impactor, not only could you control IF the asteroid was going to go through the keyhole but WHERE it was going to go through. Then you could determine where, on earth, the asteroid was going to eventually going to hit."
Say on an unfriendly nation (that was preferably on another continent).
But then again they didn't like my submission on how you could convert the promising pan-viral "cure" (MIT Tech review) that doesn't kill the virus directly but rather the cells it infects into a biological weapon of universal power.
By the way, the Jupiter slingshot idea has been proposed to send a probe on a (one-way) trip to the sun. A variant of this idea was used to send the Ulysses spacecraft into a sun polar orbit. It allowed them to use a Delta launch vehicle instead of a Saturn V.
I think it's interesting that in most doomsday asteroid scenarios, the US is the one to launch a mission to save the earth. Granted, part of that is because Hollywood wrote those scenarios, but generally the rest of the world doesn't think twice when watching those movies because US is the de facto leader in most things. I think this is a telling inflection point in the history of nations.
See? The end of the epoch *is* the end of life! Screw the Aztecs...
I worry that an impact, rather than moving the entire asteroid, could shatter it and make it much more likely that one small (but still potentially dangerous) part would go through the keyhole.
(T>t && O(n)--) == sqrt(666)
If it hits in '36, I'll be 86. I likely won't care one way or another. Besides, civilization as we know it will end at 21:14:07 UTC on Monday, January 18, 2038, so even if the earth doesn't get smacked, we will be in pretty serious trouble.
they will come to destroy us for putting Apophis (jigily-hi in their native language) in collision course with their civilization.
"Meanwhile, the Chinese, in order to retaliate for biological attacks by the US, detonate a huge explosion next to an asteroid (2002OA), with the aim of deflecting it into Earth orbit and threatening the world with targeted precision strikes in the future. Unfortunately, their calculations are wrong as they didn't take into account the size of the asteroid could cause a Cretaceous-Tertiary extinction event. The asteroid strikes Earth, critically damaging the planetary ecosystem. The Titan team members are presumably the last humans left alive."
http://en.wikipedia.org/wiki/Titan_(Stephen_Baxter_novel)
Why not just send Bruce Willis?
So they figured out that generalized multi-body problem, then, I guess? There are so many variables and errors in our best calculations that a mission like that is probably just as likely to doom us as it is to save us. We'd probably end up pushing it right into Los Angeles. (Wait, that could be a good thing...)
What if instead of hitting the asteroid away from the keyhole, they really want to hit it through the keyhole?
First, Apophis will not hit Earth, neither in 2029 nor in 2036.
Second, such a scheme would be incredibly dangerous. When you look at how close Apophis will pass (Apophis 2029 Pass), a mission to deflect it might just give it the little nudge it needs to hit Earth if something goes wrong. If you want to test deflecting strategies, please do it on an asteroid that is not going anywhere near Earth.
Third, the whole impactor idea is bad. There is no way to predict how an asteroid will react to an impact. It might make things worse, or more likely will have no effect. A gravity tractor is a much more subtle and effective method. It works because we can detect asteroids that pose a threat years in advance, and it allows precise control of the trajectory.
Top Gun never gets old.
It appears we have an open definition debate. Let me define it how I see it: When used with a force unit, "weighs" means "has a weight of". When used with a mass unit, it means "has a mass of" despite its etymological link to "weight".
Anything that adds to our knowledge of working with asteroids is ok by me.
... in gravity assists (which as I pointed out in my submission) could make the mission much cheaper and less risky.
Since they don't have any experience with gravity assists and (no-one) has any real experience with solar sails, I figure they just picked the one that sounded more sexy. If they actually had a long track record of deep space missions (they've only gotten to the moon whereas the U.S. is on its way to PLUTO), they wouldn't go this route. So I think the inflection point is still a ways off.
Right before they finish building this project...
"Project cancelled."
"Incan civilization completes wonder: Asteroid Defense Satellite"
Or maybe it would be more appropriate for SMAC instead of Civ...
Puting aside the debate on mass and weight, there seems to be some contradiction on the mass of Apophis.
In the post, it is 46 million kg (pretty lightweight), in the first link of the post it is 46 million tonnes and on wikipedia (http://en.wikipedia.org/wiki/99942_Apophis) it is 27 million tonnes...
How about not concerning yourself with impacting it at high speed, but simply landing on it and then activating the solar sale? Twenty-nine years of drag from that would certainly deflect it from its orbit.
If the solar sale provided enough delta-v to accelerate a ram, in less than a year, to a speed high enough to deflect the rock, it would necessarily be powerful enough to directly maneuver the rock.
Juno's mass is listed as 3625kg, or almost 8000 pounds, not almost 8 metric tons.
As for the energy obtained from "falling several hundred million miles": that would be exactly the same energy it took to get that far "up" in the first place (not saying that there's no energy to steal from Jupiter, but it's a pretty hair-brained plan, imho, not in the least because such a trajectory would probably take the better part of a decade to complete).
of the solution. The second part is expending a substantial portion of the earth's nuclear arsenal to be detonated once Apophis has passed a safe distance. We don't have much experience with solar sail deflection systems but we do know something about blowing stuff up.
That is a very bad word to use. It makes people think of a single small area that the asteroid has to pass through. when in fact its more like a "tunnel" that it would have to pass through. The asteroid could enter the tunnel in perfect center, but drift to one side not exit the tunnel in the center and still not be on path to hit us.
We can't let mankind's job of destroying itself be outsourced to illegal alien asteroids that can be payed practically nothing.
Even if it is not going to hit earth we'll at least see if this idea works should we need to REALLY do it in the future.
Good way for China to practice stuffamagig in space.
"That's the way to do it" - Punch
is not familiar with the phrase 'First, do no harm".
yeah and supposed they had a little "oops" in their practice run and deflected it the WRONG WAY?
ELOI, ELOI, LAMA SABACHTHANI!?
Yes, all the stuff I get from China is so reliable that I'd trust it not to deflect the asteroid in the wrong direction, into Earth. China's military is so accountable to reasonable, compassionate authorities that they'd never risk hurting people just to demonstrate their strength and spread around some military/industrial money. After all, the Chinese space programme has so much experience doing hard things no others have ever tried, let alone accomplished. This project couldn't possibly be just a reckless way to spend money and get foreign cooperation in boosting China's ballistic nuke/missile programmes. It must be the well-known Chinese government altruism, always looking to sacrifice other goals to protect their fellow humans' wellbeing from even the smallest risk.
--
make install -not war
A broadside trajectory sounds spectacular and does the greatest benefit, but any error at all is a miss. There's no way to fly enough sensing gear, thruster fuel, etc for a hyper-high speed, broadside intercept. There can also be unpredictable out-gassing shifting Apophis' course. Rather, going up the tailpipe matches vectors so the time of intercept can be off by a lot more.
Is it a rule, that there's an exception to every rule?
Chuck Norris will throw the probe on the asteroid and completely destroy it.
Our civilization is already wrecked.
is that China can hold the rest of the world hostage once they are able to nudge the largest WMD ever either towards or away from the Earth. ;-b
the man said --
Practice a little, not practice on little asteroids. That little oops is going to cause all seven billion of us to have a REAL BAD DAY (tm).
ELOI, ELOI, LAMA SABACHTHANI!?
Yes, like we all trust China to go out and deflect a fucking asteroid. This has **fail** written all over it in 165 languages.
An asteroid destroying civilization in 2029 or even 2036 would *greatly* simplify my retirement planning. Having to worry about small but non-zero chances of living (or probably "living") a very long time significantly increases the nest egg I need for retirement and/or the % I can spend each month.
I'm assuming you're right about the conversion error, I just plucked the 8000kg figure off the first web site that I got off Google (I'm the submitter). Still 8000 LBS. is a lot more than the Chinese probe's 10 kgs.
As far as the energy calculations go, using a (large) gravitational body to change the velocity (speed AND direction) allows the transfer of momentum (energy) from Jupiter to and from the spacecraft. By causing the spacecraft to "lose" its forward momentum relative to the sun, Jupiter can rob it of energy (and consequently Jupiter is sped up a tiny amount). However because it's lost its forward momentum, the spacecraft will now fall towards the sun in a direct line that will (hopefully) intersect the path of the asteroid.
If the asteroid was at rest relative to the sun then the spacecraft would hit it with" only" the force derived from its fall from Jupiter orbit (still quite a lot). But the asteroid is most certainly not at rest, it's a Near Earth Object and thus has an orbit roughly similar to that of the earth. Like the earth, it is traveling through space at about 66,000mph (relative to the sun). So even if the spacecraft gained no speed from its hundreds of millions of kilometers fall from Jupiter's orbit to Earth space the spacecraft would still hit it at a velocity of 66,000 mph (remember it's had all its forward momentum cancelled). Or rather the asteroid will hit the spacecraft at this speed (depending on your frame of reference). Either way, the asteroid's orbit is going to be changed. Thats why I'm sure if the retrograde Chinese 10 kg probe could knock it off course, a spacecraft the size of Juno, could do so also (assuming they hit with a similar amount of time in advance of going through the keyhole).
You are right of course about the long trajectory taking the probe out to Jupiter and then falling back. In fact the space probe I mentioned, Juno, is not even on a direct trajectory, I understand it will first loop back to use the Earth for a gravity assist. Still, this is something we could do NOW, not only does the technology exist but we could probably have Juno execute this mission NOW. If we were willing to abandon the science goals of examining Jupiter, it would be easy to reprogram Juno to sling around Jupiter and dive bomb Apophis. Juno has way more than enough fuel to carry out its mission (it is designed to go into close orbit around Jupiter, talk about a big insertion burn!) and its super radiation hardened instrumentation could survive any close approach to Jupiter. (The heavy titanium armor of course makes it into an even better impactor). Even the fact that it uses solar panels is a plus because, as it falls back towards the inner solar system it would be well supplied with power.
I am not seriously proposing redirecting this mission (I don't want to be lynched by the mission scientists!) although it may be worth looking at seeing if after the mission there is some way using its residual fuel and the Gallilean satellites for gravity assist it could escape Jupiter orbit and be sent on this solar suicide mission. (Remember it doesn't have to hit Apophis at any particular place in its orbit, a good whack from any direction, years in advance, should be enough to make Apophis miss the tiny keyhole). I just want to point out how feasible this idea is IF we deem Apophis to really be a threat. On the other hand using a solar sail seems much iffier. Not withstanding the long development times, it would probably be the first time a mission like this would be tried. Gravity assists, on the other hand have been done by NASA for DECADES starting with Pioneer 10 and 11 in the seventies. I lost track long ago of all the missions that used it/are using it. Finally, although gravity assist trajectories are inherently time consuming, any forseeable solar sail technology is likely to be even more so. Remember that accelerations are going to measured in the thousandths of a G and to get the solar sail into a retrograde orbit is going to require the spacecr