Schoolboy Corrects NASA's Math On Killer Asteroid

spiracle writes "A German schoolboy, Nico Marquardt, has revised NASA's figures for the chances that the Apophis asteroid will hit earth. Apparently if the asteroid hits a satellite in 2029, its path could be diverted enough to cause it to collide with Earth on the next orbit, in 2036. NASA had calculated the chances as 1 in 45,000 but the 13-year-old, in his science project, made it 1 in 450. NASA agreed." Update: 04/16 16:47 GMT by Z : This is not entirely accurate, it turns out — more details.

Other news stories on this

[goombah99]

NASA previously estimated the chance "Apophis" the asteroid would strike earth in 2027 was 1 in 45,000. But a german schoolboy, Nico Marquardt, pointed out that NASA overlooked the probability the asteroid would strike one of the 40,000 sattelites orbiting Earth and enter a new solar orbit intersecting Earth in 2036. A german newspaper reports that NASA now concurs the chance this will happen is about 1 in 450. If the 200 billion tonne ball of iridium and iron stikes the planet then it's literally light's out for earth: 800 foot tidal waves followed by an indefinite period of dust cloud covered darkness, not to mention metal vapor in the atmosphere. The original Slashdot discussion [slashdot.org] was in 2007 when the odds were better. At that time it was known that there was a small risk of a gravitational slingshot dropping it into the 2036 collisional orbit, however, to do so the asteroid had to pass through an improbable 400 meter wide strike zone to be properly deflected, as described in 2006 in Popular Science [popularmechanics.com] from 2006. Today's announcement of the new finding is here [physorg.com]and here [yahoo.com].

Friday the 13th

[goombah99]

By the way, it passes by the earth in 2027 on friday the 13th. If it hit's it will hit in the pacific ocean. So California may get wet. The energy content is said to be 26,000 Hiroshimas which is not that much but recent calculation suggest is more than enough to darken the earth.

Re:Where's the math?

[Anonymous Coward]

He didn't really correct NASA. He only extended their prediction: NASA predicted, correctly, that the asteroid had a 1 in 45,000 chance of hitting the earth in 2029. Nico pointed out, also correctly, apparently, that if the asteroid missed the earth but hit a satellite in 2029, then it would have a 1 in 450 chance of hitting the earth in 2036.

Re:Hang on ...

[Anonymous Coward]

Knowing how Earth moves in space, they simply had to look up which part of our planet would be facing the asteroid when it comes back.

Re:Not peer reviewed.

[goombah99]

You are right that NASA has not updated it's site since 2006. Here's what they said a while back [nasa.gov]:

The future for Apophis on Friday, April 13 of 2029 includes an approach to Earth no closer than 29,470 km (18,300 miles, or 5.6 Earth radii from the center, or 4.6 Earth-radii from the surface) over the mid-Atlantic, appearing to the naked eye as a moderately bright point of light moving rapidly across the sky. Depending on its mechanical nature, it could experience shape or spin-state alteration due to tidal forces caused by Earth's gravity field.

This is within the distance of Earth's geosynchronous satellites. However, because Apophis will pass interior to the positions of these satellites at closest approach, in a plane inclined at 40 degrees to the Earth's equator and passing outside the equatorial geosynchronous zone when crossing the equatorial plane, it does not threaten the satellites in that heavily populated region.

So what is being claimed here is not so implausible. It is going to pass within the geosynconous orbit distance.

Original article

[ulash]

Here is the original article [www.bild.de], in German, from the German newspaper. It looks like a professor helped him (Professor Spahn from Potsdam University). Bild is semi-infamous in Europe for sensationalizing stories but at least we know that the boy is real if nothing else...

Re:Not peer reviewed.

[commander_gallium]

You are right that NASA has not updated it's site since 2006.

Just to be clear, the Impact Risk Page [nasa.gov] is kept current (pretty much to the day). You'll see the link for Apophis if you scroll down a little. If the odds of impact jumped by a factor of 100, this would be one of the first places to show it.

Re:Hang on ...

[evanbd]

NASA and Marquardt agree that ... [it] will crash into the Atlantic ocean

Ah, so there's only a 1 in 450 chance of it hitting earth, but we know which ocean it will land in if it does (7 years after it hits the satellite).

Yes, actually, that's the easy part. We know very precisely when and from what direction it will be coming, the question is will it go left, right, or straight down the middle? (Metaphorically speaking... I don't know the details, for all I know we're above and to the left of the center track.)

Once you know when and what direction, you know which hemisphere. Once you account for projection distortion, that puts the odds as pretty good it lands in an area well less than half of the Earth's surface. Something the size of, say, the Atlantic Ocean.

Re:Um, was this by any chance an April Fools paper

[evanbd]

Collisions in space are actually quite predictable. The asteroid is huge and fast, so the entire satellite gets obliterated -- no random debris falling off, because odds are that the satellite is either entirely within the path or entirely outside it. Supersonic (relative to speed of sound in asteroid / satellite, not something irrelevant like Earth's atmosphere) collisions are basically completely inelastic (details more complex, but reasonably well understood).

Satellites don't vary in mass all that much. The big ones are a few tons to a few tens of tons, once you ignore the ISS. The little ones don't matter, so you ignore them.

Telescope observations can most definitely produce the many nines of precision needed for this work. It goes something like this: on day one, it's within this error bar. On day two, within that error bar. On day a few thousand, this other error bar. Individually, the error bar is large, but as they spread out, the path through every one of them gets rather precisely defined. Imagine positioning a set of 1 meter wide gates across the US -- sure, you can't measure the position of the bowling ball you rolled through them to better than 1 meter at any one point, but by the time it's gone through *all* of them, you have sub-ppm accuracy on its exact angle. Extend the scale a bit and you get the precision needed.

Calling the pocket is the easy part: if it hits, then the piece of the Earth pointed in that direction will be the Atlantic. Sure, it might strike a glancing blow and hit at the edge, but thanks to foreshortening the odds are against that.

Re:Friday the 13th

[Qiadron]

No. With my luck, I'd be right in its path and be incinerated.

I'd rather glow a delightful lime color prior to death. That'd be pretty awesome.

Re:Not Math Error

[JLF65]

They didn't forget about them. There is almost no chance a satellite will be struck. If you read the original FA, you'd see that a) the asteroid will pass inside the orbit of them, b) it will pass at a 40 degree angle to them, and c) when the satellite does reach the distance the satellites orbit at, it'll be well beyond the region the satellites are in.

The kid calculated the odds of the asteroid hitting the earth IF the asteroid hit a satellite JUST PERFECTLY. The odds of the asteroid hitting a satellite, much less just right for that to occur, are remote at best. This is just media hype to increase ratings.

Re:I want to see NASA's acknowledgement he is righ

[Nyeerrmm]

Thinking about the problem for a second, I can see how you can make some rough calculations. Generally any GEO, HEO, etc. type orbit will be fairly slow, especially compared to the hyperbolic orbit that the asteroid will be entering at (in the Earth's reference). Thus based on the range of velocities and masses you could predict a range of possible perturbations to the orbit.

Though I don't have any numbers to back it up right now, a small perturbation in the velocity can propagate forward to be a very large error after 7 years. Thats why we have so much trouble predicting whether or not it will hit us; a 10 meter error in its position or a 1 m/s error in velocity measurements translates into multiple Earth radii over a few years. So combine the small change in velocity from an impact with the gravitational slingshot from the 2029 close approach, and it may be enough to shift the keyhole.

Of course I think the article is misleading, it may be more like there's a 1/450 chance of some kind of impact that will have an unknown effect on the orbit but may shift it into an impact trajectory, or something like that. At any rate, there are still other unknowns such as the effect of solar wind that can vary the trajectory dramatically too.

Note of course that I could be completely wrong, although I do plan to attempt some simulations now, since one of my advisors classes is working on a related project.

Re:Google translation of German source

[thodi]

No need to translate it to make it hilarious:
a) The source "newspaper" is Germany's biggest tabloid - with as much knowledge on astrophysics as a kindergarten kid
b) No 13 year old German kid says "stuerben"

No, he didn't win

[hweimer]

First of all, the competition is "Jugend forscht [wikipedia.org]", which is the largest science competition in Germany. It consists of three stages: first there is a regional competition with winners advancing to the state finals. The winners of the state finals then advance to the federal finals, which is the last round. Roughly speaking, in every round one winner (or winning team) is chosen by a jury in each discipline (mathematics, physics, chemistry, ...).

It seems that the kid won the regional competition [tagesspiegel.de], but failed to advance in the state finals [jugend-forscht.de].

Re:Other news stories on this

[icebrain]

Multi-body orbit problems are highly chaotic... part of my senior design program was writing a program to simulate this asteroid's trajectory and a spacecraft observing it to refine the data, then projecting the refined data forward. Essentially, we wanted to find out how long we would need to observe said asteroid in order to get our error ellipse down to a specified level.

Turns out that even tiny velocity changes (well below 1m/s) had huge effects on the rest of the trajectory. If our spacecraft's first measurement was off in the wrong direction, our solution never converged in the time we needed it to.

Re:Other news stories on this

[anonymous_echidna]

Still, no one has scrutinized the boy's work for math errors. So don't start training Bruce Willis just yet.

Wouldn't be so sure about that; he did not do this alone. You get a lot more information in German. He had support with formulas from Professor Spahn of Potsdam University, and with calculations from Professor Landgraf from the ESA satellite Control Center. http://www.bild.de/BILD/news/2008/04/04/ich-hab-den/weltuntergang-ausgerechnet.html [www.bild.de]

Correction: Source wrong

[Peregr1n]

Sorry to burst the balloon, but apart from the one German article that was picked up by AFP, there's no source for this story. And NASA and the ESA deny ever saying that the schoolboy was right. It seems that the schoolboy's sums were wrong, and NASA's original workings are right. More info: http://www.theregister.co.uk/2008/04/16/esa_german_schoolboy_apophis_denial/ [theregister.co.uk] I'd file this under 'web hoax' or 'lazy journalists pick up on anything sensational'

The News is wrong

[phoenix_nz]

Just in case anyone still believes we'll all be killed by an asteroid in 2029 or 2036, here's an article from El Reg, claiming that the boy got it all wrong.
I guess we'll have to live with the miniscule 1 in 45,000 chance.

link to article:
http://www.theregister.co.uk/2008/04/16/esa_german_schoolboy_apophis_denial/ [theregister.co.uk]

As usual.. missing information

[ninja_assault_kitten]

"In April 2008 it was reported that 13 year-old Nico Marquardt from Potsdam, Germany had recalculated the odds as part of a science competition, and found the risk had been underestimated. Taking into account the possibility of the asteroid colliding with one or more of the estimated 40,000 artificial satellites orbiting the earth, possibly causing a shift in its orbit, increases the probability of a collision with [5] earth on its next fly-by in 2036 to 1 in 450. NASA was reported as confirming these results with the ESA[6], yet they have since apparently denied these claims, and on April 15, 2008 it was reported Nico Marquardt's calculations were incorrect." -- Wikipedia http://en.wikipedia.org/wiki/99942_Apophis/ [wikipedia.org]

Re:Other news stories on this

[Captain Nitpick]

First off... how does a 200,000,000,000 tonne asteroid (200,000,000,000,000 kg) travelling at any substantial inter-planetary speed be deflected by a satellite travelling at 3070 m/s and at most wieghing 10,000kg?

The same way sunlight can push a 270m rock around. Lest you think I am kidding, let's read what NASA has to say about that:

For example, the team found solar energy can cause between 20 and 740 km (12 and 460 miles) of position change over the next 22 years leading into the 2029 Earth encounter. But, only 7 years later, the effect on Apophis' predicted position can grow to between 520,000 and 30 million km (323,000 and 18.6 million miles; 0.0035-0.2 AU).

The effect of a small force integrated over years and a few billion miles produces a significant effect. In this case a relatively small deflection gets magnified by the 2029 flyby.

Of course thats presuming an elelastic collision as opposed to the satellite deflecting off the asteroid in a cloud of debris.

Its been a while since I've done any physics, and I'm just grabbing numbers from the article (which are likely to be wrong anyways).

It's obviously been a long time. Any impact will impart momentum to the asteroid. I don't know if you mean "elastic" or "inelastic", but it doesn't matter. Bits of satellite bouncing off the asteroid represent momentum transferred from the asteroid.

But to bring it all together in a car analogy for the fellow /.ers... How does a .22 bullet deflect an oncoming semitruck forcing into the little old lady on the sidewalk?

Bad analogy. The elasticity and friction of the tires cancel out any effect of the impact. These effects don't exist for an asteroid.

A better analogy would be a bowling ball on a lane with one pin. There's a tiny pebble halfway down the lane. How does a 1g pebble deflect a 12 pound bowling ball? By getting run over. If the lane was 100 miles long, a grain of salt would have a significant effect on where the ball ends up.

Apparently, NASA was right after all

[blakbeard0]

"This is within the distance of Earth's geosynchronous satellites. However, because Apophis will pass interior to the positions of these satellites at closest approach, in a plane inclined at 40 degrees to the Earth's equator and passing outside the equatorial geosynchronous zone when crossing the equatorial plane, it does not threaten the satellites in that heavily populated region. " From here. [nasa.gov]

Re:Friday the 13th

[Ralph Spoilsport]

according to a translation in an post below, they're actually talking 98,000x Hiroshima bomb. I'll crackout my handy crackulator and 98,000 x 16 = 1,568,000, or 1,568 megatons (mT), or, 1.5 gigaton (gT).

That's gotta hurt...

The other thing to remember is, even with your calculation at 415 mT, it's 415mT in ONE PLACE - you're not going to want to be ANYWHERE near that. If it hits an ocean, it will vapourise a massive amount of water and create a truly stunning tsunami. You could drop 26,000 hiroshima bombs all at once all over the planet, and removing the issue of radiation, the sheer force of the weapons would be incredible, but not as powerful as putting them all in one place the size of a large shopping mall.

Now, if you "blow the asteroid up" you still don't get away from massive problems, as you still have 200 billion tons of gravel coming down the pike, all in one concentrated area, which would still make for a significant amount of heat and destruction. It' like an atom smasher - the sun dumps an enormous amount of energy on the earth every second, but it is diffuse over an area. Put it all in an area the size of a shopping mall, and you just took blew the city to bits.

So, even something 8x bigger than the Tsar bomb, exploded in the right place, could have massive effects, esp. in water. And if the translation is correct, we're actually looking at something an order or two of magnitude larger...

cheers!

RS

Re:Friday the 13th

[Bender0x7D1]

This asteroid would do 1d4 wombats of damage to each of the 130 million items in the Library of Congress. However, because of their binding (creating a rigid spine area), each of the 29 million books would take an additional 1d4 wombats of damage. So we can call the total damage as 159x10^6d4 wombats of damage to the Library of Congress.

Re:Um, was this by any chance an April Fools paper

[MGROOP]

The force is strong with this one.
Yes it is all a hoax.

Nasa Watch [nasawatch.com] has picked up the story. Turns out to be completely made up. Details here: Apophis risk not increased [blogspot.com]

Re:Other news stories on this

[Kaptain Kruton]

Bad analogy. The elasticity and friction of the tires cancel out any effect of the impact. These effects don't exist for an asteroid.

A better analogy would be a bowling ball on a lane with one pin. There's a tiny pebble halfway down the lane. How does a 1g pebble deflect a 12 pound bowling ball? By getting run over. If the lane was 100 miles long, a grain of salt would have a significant effect on where the ball ends up.

I think this is a bad analogy too. If a bowling ball runs over a pebble, the ball will be deflected. However, the pebble will be pushing against the earth and could not be deflected downward. Assuming that the pebble remained stationary during the collision and the pebble did not sink downward into the ground, the situation would not be an impact of a 12 pound bowling ball vs a 1 gram pebble. It would be a 12 pound bowling ball pushing into the earth. The effects would be negligible. If the pebble did move, the results would not be accurate because the pebble could not move in the direction in which most of the force would push (downward into the floor). You also claim that the tires cancel out the effect of the bullet. However, the satellite is not completely solid. It would be crushed on impact at some of the energy that would deflect the asteroid would be absorbed. Is this not similar to the tires?

Could a satellite potentially deflect the asteroid? Yes, if one even hits it. Will it even hit a satellite much and will it cause it to hit the earth, I don't know.

PoeM

[PoeMangonel]

NASA denies this report: http://www.nasa.gov/home/hqnews/2008/apr/HQ_08103_student_asteroid_calculations.html#maincontent [nasa.gov]

story from "Bild" - what do you expect ?

[Anonymous Coward]

The story apparently originates with german newspaper Bild. Bild is very poplar but also notorious for getting even the most basic facts wrong. There is a German blog ( www.bildblog.de ) which highlights out the quite peculiar world view of Bild reporters.
To name just the latest "highlight" cited in bildblog: "the sun takes 365 days to circle around the earth"

Didn't do enough homework...

[gevantry]

Nope. The kid didn't do his homework. While the asteroid may pass around 38,000 km from earth at the closest point, it will pass the equatorial ecliptic at around 51,000 km, too far away to collide with any geosynchronous satellites. Also to be noted: According to NASA, the kid did not contact anyone there to obtain any data. The kid's bright and engaged and had a heck of an idea for a science fair project, but his lesser-educated, sensation-mongering elders jumped the gun and made him look like a fool.