Asteroid has a chance to strike Mars

MarsRefresh · 2007-12-20 23:34:11

I know this may be a bit too ironic for the "unmanned probe" thread, but check this out:
http://www.msnbc.msn.com/id/22350742/

cIclops · 2007-12-21 01:55:07

Right it is, it would be better in the Science forum as it surely ain't about unmanned probes

It's helpful to readers to know what the link is about, the subject or just the headline would do. BTW the headline is "Scientists say asteroid could hit Mars" - it's only a 1 in 75 chance according to that article but it would be interesting!

MarsRefresh · 2007-12-21 12:08:39

Right it is, it would be better in the Science forum as it surely ain't about unmanned probes
It's helpful to readers to know what the link is about, the subject or just the headline would do. BTW the headline is "Scientists say asteroid could hit Mars" - it's only a 1 in 75 chance according to that article but it would be interesting!

I thought this might be of interest to the terraforming forum too as deflecting asteroids is a popular concept. But I'll edit the post's headline and the mod can move it (no pun intended!).

cIclops · 2007-12-21 12:26:26

Ok, yes the terraformmers might be interested in an asteroid strike.

SpaceNut · 2007-12-21 22:12:51

Hopefully a front row seat will be had by not only opportunity but by the rest of the orbiters circling when the 1 in 75 chance becomes 1 for 1 with a direct hit to not only give the view of the event but also of the past that it will uncover if close enough for the rovers to investigate.

RickSmith · 2007-12-22 06:55:04

If the asteroid hits Mars we have orbiters which can detect changes in the gas content of the planet. I would be very curious to see what types of gases are released from the crater. There are likely nitrates but how much? There is likely carbonated waters but how deep?

It would be a gigantic scientific boon. Even if it just comes close it would get people thinking about Mars again.

Warm regards, Rick.

RickSmith · 2008-01-03 16:30:56

Hi folks,
The odds are now better than 1 in 33.

New report on Mars crossing asteroid.

Warm regards, Rick.

Terraformer · 2008-01-04 07:43:52

I thought the odds were 1 in 25?

MarsRefresh · 2008-01-05 00:53:35

Hi folks,
The odds are now better than 1 in 33.
New report on Mars crossing asteroid.
Warm regards, Rick.

Yes, this is exciting. Of course, it still is not great odds. But I expected the odds to length not improve with better data. Perhaps when we find out more info on the track and mass and classification of the object it might be a candidate for a not so gentle nudge towards our neighbor planet. The delta v needed will probably turn out to be ridiculous though, right?

RickSmith · 2008-01-05 02:20:20

Yes, this is exciting. Of course, it still is not great odds. ... Perhaps when we find out more info on the track and mass and classification of the object it might be a candidate for a not so gentle nudge towards our neighbor planet. The delta v needed will probably turn out to be ridiculous though, right?

Hi MarsRefresh, everyone.
Actually it is coming so close I expect that a fairly modest delta vee (done fairly early) would be enough. I'm curious, let's play with some numbers.

They say that it is 160 foot wide. Most asteriods that size are not round but potato shaped. Let us say that it has the same volume as a 50 meter sphere. (Likely a bit of an over-estimate of its size.)

V = 4/3 PI r^3 = 3/4 PI ( 25 m )^3 = 65,449 cubic meters

Assuming that it has a density of 5.0 tonnes/m^3 (fairly dense rock) we get: ~327,250 tonnes = 327,250,000 kg.

Now the Saturn V rocket has a thrust of:
1st Stage: 34.02 MN (Mega Newton) -- Burns for 150 seconds
2nd Stage: 5 MN -- Burns for 360 seconds
3rd Stage: 1 MN -- Burns for 500 seconds

// From: http://wapedia.mobi/en/Saturn_V

This gives a total thrust of 40.02 MN. The approximate burn time for the whole stack (taking into account the decreasing thrust of the upper stages) is about 215 seconds. I'll conservatively call it 200 seconds.

Force = ma --> F/m = a

40,000,000 N / 327,250,000 kg = a = 0.122 m/s^2

v = a t

v = 0.122 m/s^2 * 200 seconds = 24.4 m/s

Now the report says that the asteroid will likely miss by 22,000 miles ~ 35,000,000 meters.

d = v t --> d/v = t
35,000,000 m / (24.4 m/s) = 1,434,426 seconds ~ 16.6 days.

So if we give it a delta vee of 24.4 m/s we would have to have started the course change about 17 days before it hits Mars.

Now of course, getting a Saturn V docked with the rock is not a trivial job. And we wouldn't use a Saturn V, we would likely use some sort of NERVA rocket. But I think that a fairly modest effort would allow us to crash it. If we could get to it 6 months earlier we would need a lot less effort. (e.g a magnetic sail with a few dozens of Newtons of thrust for 6 months may be enough.)

So the lesson is that a close pass is almost as good as a hit to a terraformer that has space flight.

Warm regards, Rick.

MarsRefresh · 2008-01-05 11:07:22

Thanks for the calculations Rick.
Your estimates seem conservative and reasonable. We have already demonstrated the capability of rendevous with asteroids. If the asteroid turns out to be more volatile rich (I haven't seen any descrition of the asteroids classification, has anyone else?) then it would be easier to move. Still deflecting this asteroid would likely be easier than fetching an object from the main or kuiper belts. A good chance to demonstrate the technology.
By extension, Earth has quite a few rocks that come close. Wikipedia notes:

As of 1 January 2008, 5,118 NEO's have been discovered: 65 near-Earth comets(NEC) and 5,053 near-Earth asteroids(NEAs). Of those there are 427 Aten asteroids, 1,947 Amor asteroids, and 2,671 Apollo asteroids[3]. As of 4 January 2008 there are 165 NEAs on Impact Risk page of NASA website[4]. But none of those NEAs is placed even in 'yellow zone' (Torino Scale 2) meaning that none of those asteroids warrant attention of general public.[5] There are 905 NEO's which are classified as potentially hazardous asteroids. Currently, 136 PHA's and 731 NEA's have an absolute magnitude of 17.75 (effective from 30 November 2006 as per NASA website[6]) or brighter, which roughly corresponds to at least 1 km in size.

So, if Mars has even a fraction of the Earth totals this may be a very useful source of impacters.

Commodore · 2008-01-10 17:54:15

Oh Well, I guess we'll have to nuke it ourselves.

MarsRefresh · 2008-01-12 10:30:44

RickSmith wrote:

But I think that a fairly modest effort would allow us to crash it. If we could get to it 6 months earlier we would need a lot less effort. (e.g a magnetic sail with a few dozens of Newtons of thrust for 6 months may be enough.)

So, a small rocket or magsail could be utilized. And we have repeatedly demonstrated an ability to rendezvous with such tiny objects in the vastness of space. (Targeting technology amazes me!) :!:

RickSmith · 2008-01-15 21:25:17

So, if Mars has even a fraction of the Earth totals this may be a very useful source of impacters.

Everything I've read suggest that being near the asteroid belt, Mars has many more rocks that pass close to it than the Earth. (In fact when they decided that Pluto was not a planet in part because it had not cleaned out its orbit of smaller debris, many scientists pointed out that by this standard Mars was not a planet.)

Warm regards, Rick.

EDIT: IT MISSED. :-(

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#1 2007-12-20 23:34:11

Re: Asteroid has a chance to strike Mars

#2 2007-12-21 01:55:07

Re: Asteroid has a chance to strike Mars

#3 2007-12-21 12:08:39

Re: Asteroid has a chance to strike Mars

#4 2007-12-21 12:26:26

Re: Asteroid has a chance to strike Mars

#5 2007-12-21 22:12:51

Re: Asteroid has a chance to strike Mars

#6 2007-12-22 06:55:04

Re: Asteroid has a chance to strike Mars

#7 2008-01-03 16:30:56

Re: Asteroid has a chance to strike Mars

#8 2008-01-04 07:43:52

Re: Asteroid has a chance to strike Mars

#9 2008-01-05 00:53:35

Re: Asteroid has a chance to strike Mars

#10 2008-01-05 02:20:20

Re: Asteroid has a chance to strike Mars

#11 2008-01-05 11:07:22

Re: Asteroid has a chance to strike Mars

#12 2008-01-10 17:54:15

Re: Asteroid has a chance to strike Mars

#13 2008-01-12 10:30:44

Re: Asteroid has a chance to strike Mars

#14 2008-01-15 21:25:17

Re: Asteroid has a chance to strike Mars

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