NASA Considers Putting an Asteroid Into Orbit Around the Moon 171
Zothecula writes "To paraphrase an old saying, if the astronaut can't go to the asteroid, then the asteroid must come to the astronaut. In a study released by the Keck Institute for Space Studies, researchers outlined a mission (PDF) to tow an asteroid into lunar orbit by 2025 using ion propulsion and a really big bag. The idea is to bring an asteroid close to Earth for easy study and visits by astronauts without the hazards and expense of a deep space mission. Now, Keck researchers say NASA officials are evaluating the plan to see whether it's something they want to do. The total cost is estimated to be roughly $2.6 billion."
Re:What could possibly go wrong? (Score:5, Informative)
Re:What could possibly go wrong? (Score:4, Informative)
I think that would depend highly upon the composition of the asteroid they capture.
Being scientists, and only getting big bucks on the table for a one shot deal, I would bet on their choosing as heterogenous of an asteroid as possible, preferably one with clear signs of stratification.
This way portions of the asteroid will be rocky, while others will be more iron based, allowing for the greatest possible dataset to be collected from the expense.
Such an asteroid would almost certainly fragment on re-entry, should it fall from orbit. This means many smaller asteroids, instead of a monolithic 500,000kg bombshell. I would expect most of it to burn up, and for it to rain tiny particles over a large area, with a considerable chance it will hit ocean.
Re:What could possibly go wrong? (Score:4, Informative)
For those musing, here's a Asteroid Impact Effect Calculator [purdue.edu]. Should be quite a bang :-)
Well, not quite knowing what density to use, I plugged in the 7m from TFA and chose porous object as a WAG at carbonaceous and left everything else at default and got this:
The average interval between impacts of this size somewhere on Earth is 1.9 years
I need to get out more if we have "quite a bang" every 1.9 years.
Re:What could possibly go wrong? (Score:5, Informative)
1. Find 500,000 kilogram solid-gold asteroid ...
2. Tow into moon orbit for $2.6 billion
3.
4. Sell for current market price of $26 billion
5. Profit!
4.5. Misunderstand macro-economics and intoduce more supply than could possibly be consumed by the demand and cause a collapse of gold prices as a precious metal.
Re:Good. lease do this (Score:5, Informative)
Mars already has a large extant of iron and oxygen on its surface. It is why it is red. (Iron III oxide.)
For venus, I could see it dropping to "still bitching hot, but cool enough to work with on the surface with robots" in about 2000 years.
Venus' surface temp is just a few degrees centigrade below the thermal decomposition temperature of aramid plastics. (Related to kevlar and pals.) Venus has a similar overall quantity of nitrogen in its atmosphere as earth does, just diluted by considerable excess of carbon dioxide.
The secret to venus is to sequester the carbon.
Engineering an extremophile atmospheric microbe to colonize the tops of the sulfuric acid cloud layer (were it's a nice, sunny 70F or so, at earth sealevel pressures.) That uses a stable sulfur cycle based derivitive of photosynthesis, that is engineered to produce aramid plastics, would do just that.
Lacking any natural predators, and having a huge petri dish to colonize, with an excess of "food", the little bitches would rapidly "snow" out thermally stable plastic molecules and deplete the carbon dioxide in the atmosphere, and thereby puncture the thermal equilibrium of the planet.
The issue is the hydrogen scarcity. The microbes would have to be able to produce their own water from their sulfur based respiration cycle from sulfuric acid, excrete sulfur dioxide, and sequester the water inside their cellular membranes. This means they would have to be extraordinarily robust in the face of anhydrous sulfuric acid. That alone is a pretty impressive feat to accomplish with engineered biology. I was thinking that the microbes could use a heavy metal complex with lead to reduce the chemical activity of their cellular membranes, and use of the aramid plastic as internal skeletal structures might work. (One of the interesting features on venus is lead sulfide snow. It volatizes on the surface, then crystalizes in the atmosphere. This makes it a potential raw material for the microbes to use. Lead is very resistant to acidic attack.)
Releasing such microbes on venus would cause a runaway reaction in the atmosphere, transforming venus from a cloudy hot furnace, into a hellish sea of acidic gel oceans, and do so very quickly.
Re:What could possibly go wrong? (Score:5, Informative)
The asteroid's delta vee relative to Earth would be very low by the time it was approaching the neighborhood. That is strictly implied by the idea of "capturing" it. As such it would present very little more danger to the Earth than Sky Lab did. Not pleasant, but not a dinosaur killer, either.
The Tunguska Event may have been an asteroid with a high delta vee. It may have been something else. It was not an asteroid cozying up slowly to the Earth, the way a captured asteroid would.
Re:What could possibly go wrong? (Score:5, Informative)
Perhaps not, but it could still cause a lot of damage
Not really. 7 meters is a *lot* less than 100 meters when we're talking about asteroid impacts. It would break up in the atmosphere.
Here's a more detailed look [ic.ac.uk] at what would happen, I'll highlight the relevant parts:
* Energy before atmospheric entry: 1.63 x 1013 Joules = 0.39 x 10-2 MegaTons TNT
* The average interval between impacts of this size somewhere on Earth is 1.9 years
* The projectile begins to breakup at an altitude of 65500 meters = 215000 ft
* The projectile bursts into a cloud of fragments at an altitude of 41400 meters = 136000 ft
* No crater is formed, although large fragments may strike the surface.
* The air blast at this location [1 km away from the impact point] would not be noticed. (The overpressure is less than 1 Pa).
Re:What could possibly go wrong? (Score:5, Informative)
Why does it matter where you measure it? The mass won't change.
Re:What could possibly go wrong? (Score:4, Informative)
Here's another fucking precedent: the same agency landed people on the Moon with computers no more powerful than that of a pocket calculator. And this same agency explored all of the gas giants and has sent probes to every single planet, including multiple landings on Mars.
Sorry, but one screwup by NASA doesn't obliterate their astounding exploration record. Nobody, but nobody can even compare. There is no better agency in the world that could pull off this mission.