Dr Robert Massey, Royal Astronomical Society

Listen Now    Download as mp3

Robert Massey returns with a roundup of news from the Royal Astronomical Society.  This month; The history of astronomical imaging, Near Earth Objects and Auroras above northern Britain...

Part of the show Meeting MIRI and Detecting Dark Matter from the 25th Jan 2012

Related Content

Comments

I am a little confused about a subject that often comes regarding the different techniques that might be applied.

It has been stated that we are given a certain amount of protection from impact objects from our atmosphere.  Objects of a certain mass hit our atmosphere and are destroyed before they reach the ground, Tunguska for example.  I do not understand when scientists in this field say it is not a good idea to blow a larger object into lots of smaller ones.  Surely lots of smaller ones, the more the merrier, would be the ideal solution thus bringing them down to a size our atmosphere can give us some protection from?

I think what these scientists should advise is, please do not use Nukes on these things as we will end up irradiating the whole planet, find a way of creating a massive explosion using some of the antimatter from CERN. Of course they are going to have to learn how to store it for longer hey?

Also one big hit from an object is going to be like a knock out punch from a boxer instead of lots of happy slaps!

In my opinion the best solution is to spot it a long way off, then slow it down into an Earth orbit and use it as a high orbit space station.  Or maybe even a lunar orbit!  ?
Aaron_Thomas, Fri, 27th Jan 2012

Earth gets hit once or twice a century with an object, maybe 1 to 10 meters in diameter.  Then the effect really depends on where it hits.  Oceans (tidal waves?) Rural, or the very few highly concentrated urban areas.

An impact from a meteorite in excess of 1km in diameter would be a whole different story. 

The problem is that it might cost us a $1 trillion to keep a 10m asteroid from impacting in the middle of the Sahara desert. 

If we started building a defense missile  system capable of knocking out a 1km "Planet Killer", it would certainly become obsolete before it was ever needed.  But, if we had to build it from scratch in 12 months, we might not get it finished.

It also depends on the trajectory.  A comet could literally come out of nowhere, and impact Earth on its first pass.  Such an event might be extremely hard to prevent.

For known NEO's, perhaps one could calculate their course a couple of orbits ahead, but maybe only down to a 50% chance of hitting...    somewhere.  That might give us adequate response time to snag the meteorite on a near pass before the final pass.  But, how much would we choose to invest in preventing a small meteorite from impacting somewhere?

I agree.
If one pulverizes the meteorite, it should have less impact, although one would still be left with much of the heavy metals that might survive the atmosphere.  But, say if one had a 100m meteorite, and blew it up into 100, ten meter meteorites...  rather than having one big impact crater, one would get quite a few smaller ones, but still big enough to cause a lot of damage and thus less concentrated damage, but a higher risk of hitting a major city.

A fission triggered H-Bomb would likely cause some fallout.  However, hopefully it would be spread out far enough that it would be less than what we all received from the earlier above ground nuclear testing in the 60's. CliffordK, Sat, 28th Jan 2012

Imagine the politics of one big hit and some possible diversion but not avoidance! 

The further away you obliterate it the more pieces will miss the Earth, more pieces will be destroyed in the atmosphere, and yes more chance of a populated area being hit.  I have heard the analogy of a rifle bullet compared to a shotgun blast.  However what this analogy fails to address is the distance at which this shot takes place.  I would rather be shot with a shot gun at 500mt then a rifle bullet! Aaron_Thomas, Sat, 28th Jan 2012

I do not think one trillion dollars would buy enough anti matter to zap an asteroid considering the rate at which it is produced at present. syhprum, Sat, 28th Jan 2012

I suppose that even if one could trap all the antimatter that is produced...  it would still be a problem.

Making it 1 atom at a time.
It takes 6x1023 hydrogen atoms to make a gram.  So, making a few dozen atoms doesn't amount to much.

I have wondered if it would be easier to make an antimatter trap in space than making it on Earth.

I suppose if one is making a bomb...  Rather than making a fission/fusion bomb, it would be possible to make an antimatter/fusion bomb that would be much "cleaner", and really wouldn't need much antimatter to trigger it.

However if the future of the Earth is at stake, I don't think I'd be too concerned about exploding a single plutonium/fusion bomb in space.  Depending on velocity vectors from the explosion, much of the plutonium and products would never reach Earth, and the radioactive material that would reach earth would be spread out to nearly background levels.

The biggest issue would be if there was a critical failure before the bomb exploded, leaving an unexploded nuclear ordinance on an impact course with Earth, or otherwise having it destroyed in a limited area in the atmosphere. CliffordK, Sat, 28th Jan 2012

If the Earth was at stake I suppose I would expect there to be a few more missiles heading towards the offending target then ONE!  Talk about putting all your eggs in one basket.......  Then the question might be, what levels of radiation can we treat as acceptable in such a scenario. 

I still think we should go out and bring one of the objects into an Earth or Lunar orbit.  I heard this mentioned on the Podcast recently and it has got my imagination spinning....  Somewhere out there is an object that is just right.  We are good at putting satellites into orbits around other objects. 

One way of getting over the problem of fuel required would be to launch a rocket from space.  Is that possible? Aaron_Thomas, Sat, 28th Jan 2012

Capturing an object would require both altering the course, and slowing it down significantly.  Perhaps using  lunar slingshot to dump velocity into the moon.  Could you use atmospheric braking without breaking up the object, or loosing it?

Anyway, the energy requirement would be much greater to capture it than just making it avoid the planet.  And, there may be greater risk.  For example, an atmospheric braking maneuver could go wrong in many ways.

Ideally, one would use the object itself to produce some of the fuel for maneuvers.  An ion engine dumping ions from the object, or perhaps hydrolysis of ice.

How big of an asteroid are you wishing to capture? 
Something 10m in diameter might be possible to capture.
Something 10km in diameter would be great for building a space station, but would push our engineering capabilities to their limits.

As far as refueling in space, or even assembling a rocket in space, I don't see any problem with that.  It wouldn't take too much "extra" energy to stop in an orbit, before escaping Earth's gravity.  Hydrogen and Oxygen are usually stored at a low pressure, but one could build a mirror/heat sink like the JWST to keep the fuel at very low temperatures, then just build a recovery system to recapture any leaking fuel. CliffordK, Sat, 28th Jan 2012

A 10 Km diameter size asteroid would be perfect for building an orbital space station on.  Even better if it had some ice present and other useful resources. 

One solution could be to try and use Jupiter as a target planet to capture it.  Once you then have it under control in a stable orbit around Jupiter the next step could be Mars and finally Earth. 

Another use of this Asteroid would be as a space anchor for a space elevator as well as a large space station.  If you had one around the Moon and Mars you also have the perfect platform for planetary missions.

Ceres is about 900km across.  It orbits the sun in 4.6yrs.  And looks like it is a prime candidate for a new Moon for Mars.  You might even be able to stir the geological activity up a bit on Mars with Ceres as a Moon.

We could also use Asteroids as impactors for objects heading for Earth.

I like the idea of using one for a space station.  The possibilities with an object like that as an artificial satellite are endless.

Aaron_Thomas, Sun, 29th Jan 2012

Moving an object that is 1021 kilos would not be easy.

The ice is likely a resource that one would choose to preserve.  But, one would have to stabilize the ice before attempting to move the dwarf planet.  Otherwise one would undoubtedly loose the ice when it was moved closer to the sun.  Perhaps mining the core and building a shell around the icy planetoid, or stabilizing the rotation, then building a big heat shield (+ solar panels) between the sun and the rest of the dwarf planet.

Then, add a plasma engine... 

And, with a little luck, 100 years later it could be nudged into place.

One might practice aerobraking (somewhere other than at Earth) with an iron core asteroid/dwarf planet, but it would be a very tricky maneuver.  However, ice is likely a resource that one would choose to preserve, and thus, no aerobraking.  More likely, one would choose to slowly reduce orbital energy with something like a robotic controlled solar powered plasma engine over a period of a century or more. 

If one wanted to try to dump something into orbit around Mars, one might try 5261 Eureka.

However, since it is in a good, stable location, with a small gravity well, one might choose to just leave it alone, and pick another one of the many Mars Grazing asteroids that would have less potential for future in-situ utilization.

At this point, however, I think the next big frontier is to build a permanent lunar colony/base/station. CliffordK, Sun, 29th Jan 2012

How big does an asteroid need to be so that when you blow it up, its own gravity pulls it back together? Chemistry4me, Sun, 29th Jan 2012

See the whole discussion | Make a comment