Attn: All Pilots, Engineers, Phy-Sci and Military Nerds (but not just Keefe)

[Benny B]

First off, I said Phy-Sci, not Sci-Fi.  Foreseers of the Star Wars Trek and the Star Trek Wars need not apply.

http://www.nasa.gov/content/nasas-journey-to-mars/#.VL0ne3tLWyF

One of the waypoints on NASA's mission to Mars in the 2030s involves 1) capturing and redirecting an asteroid to orbit the moon and 2) exploring said asteroid.

Someone explain something to me: Why is this a good idea, i.e. how does the benefit outweigh the risk?  The obvious risk here being that you're going to "capture" an asteroid of size large enough that it needs to be explored by a manned Orion mission and then you're going to put said asteroid into close proximity with the Earth.  It would seem that even if you could minimize the margin of error in the process of putting an asteroid into orbit around the moon, if it falls out of the moon's gravitational field, even Ham the Chimp knows where that asteroid is going next.

I've seen Armageddon many times, and even if Ben Affleck is up for saving the world again, we're not talking something from deep space on collision course with the Earth; we're talking close enough to be seen with the naked eye (less than 240k miles away)... to put that in perspective, while it only took me 9 years to put 200k miles on my Cavalier (and I wasn't even a U-Dayton student), I'm pretty sure the asteroid is going to be moving a heck of a lot faster than my former rust bucket.

[FartyEightHours]

Reporting for duty Captain

[jficke13]

First off, I said Phy-Sci, not Sci-Fi.  Foreseers of the Star Wars Trek and the Star Trek Wars need not apply.

http://www.nasa.gov/content/nasas-journey-to-mars/#.VL0ne3tLWyF

One of the waypoints on NASA's mission to Mars in the 2030s involves 1) capturing and redirecting an asteroid to orbit the moon and 2) exploring said asteroid.

Someone explain something to me: Why is this a good idea, i.e. how does the benefit outweigh the risk?  The obvious risk here being that you're going to "capture" an asteroid of size large enough that it needs to be explored by a manned Orion mission and then you're going to put said asteroid into close proximity with the Earth.  It would seem that even if you could minimize the margin of error in the process of putting an asteroid into orbit around the moon, if it falls out of the moon's gravitational field, even Ham the Chimp knows where that asteroid is going next.

I've seen Armageddon many times, and even if Ben Affleck is up for saving the world again, we're not talking something from deep space on collision course with the Earth; we're talking close enough to be seen with the naked eye (less than 240k miles away)... to put that in perspective, while it only took me 9 years to put 200k miles on my Cavalier (and I wasn't even a U-Dayton student), I'm pretty sure the asteroid is going to be moving a heck of a lot faster than my former rust bucket.

1. Don't underestimate our ability to calculate orbits. The "margin of error" would not include accidentally routing the asteroid into a collision path with Earth.

2. Asteroids routinely pass closer to the Earth than the Earth is to the moon without entering Earth's atmosphere. I think you may be over-estimating the risk involved.

3. Ham the Chimp would consider the possibility that the asteroid would fall into the Earth-Moon Lagrange point, and staying there until physically maneuvered out of it.

4. The benefit is field testing a variety of technologies designed to leave Low Earth Orbit (think Space Shuttle/International Space Station) and even Geosynchronous Orbit, while making the rescue/emergency situation being an Apollo 13-esque number of days, not months (disaster en route to Mars). The risk is mostly monetary (loss of equipment, time) not Armageddon-movie.

[Benny B]

1. Don't underestimate our ability to calculate orbits. The "margin of error" would not include accidentally routing the asteroid into a collision path with Earth.

2. Asteroids routinely pass closer to the Earth than the Earth is to the moon without entering Earth's atmosphere. I think you may be over-estimating the risk involved.

3. Ham the Chimp would consider the possibility that the asteroid would fall into the Earth-Moon Lagrange point, and staying there until physically maneuvered out of it.

4. The benefit is field testing a variety of technologies designed to leave Low Earth Orbit (think Space Shuttle/International Space Station) and even Geosynchronous Orbit, while making the rescue/emergency situation being an Apollo 13-esque number of days, not months (disaster en route to Mars). The risk is mostly monetary (loss of equipment, time) not Armageddon-movie.

1. Calculating orbits is easy enough.  Routing a massive object into such an orbit seems like the hard part.

2. I understand that, but these asteroids are typically less than 50m in diameter. Only a handful of asteroids over 100m are known to have come within 240k miles of Earth, and I don't think we're going to land anyone on an asteroid less than 500m in diameter.

3. If it doesn't fall into L4 or L5, it's not going to be in the Lagrange point very long.  And if it's orbiting the moon, I don't see how it gets anywhere near L4 or L5.

4. Can't this be done without re-routing an asteroid?

[forgetful]

1. Don't underestimate our ability to calculate orbits. The "margin of error" would not include accidentally routing the asteroid into a collision path with Earth.

2. Asteroids routinely pass closer to the Earth than the Earth is to the moon without entering Earth's atmosphere. I think you may be over-estimating the risk involved.

3. Ham the Chimp would consider the possibility that the asteroid would fall into the Earth-Moon Lagrange point, and staying there until physically maneuvered out of it.

4. The benefit is field testing a variety of technologies designed to leave Low Earth Orbit (think Space Shuttle/International Space Station) and even Geosynchronous Orbit, while making the rescue/emergency situation being an Apollo 13-esque number of days, not months (disaster en route to Mars). The risk is mostly monetary (loss of equipment, time) not Armageddon-movie.

With all due respect, we didn't catch a unit conversion error before crashing a billion dollar orbiter onto Mars.  A simple error there cost a small fortune.  A miscalculation or error here and we kill millions.

[wildbill sb]

1. Calculating orbits is easy enough.  Routing a massive object into such an orbit seems like the hard part.

2. I understand that, but these asteroids are typically less than 50m in diameter. Only a handful of asteroids over 100m are known to have come within 240k miles of Earth, and I don't think we're going to land anyone on an asteroid less than 500m in diameter.

3. If it doesn't fall into L4 or L5, it's not going to be in the Lagrange point very long.  And if it's orbiting the moon, I don't see how it gets anywhere near L4 or L5.

4. Can't this be done without re-routing an asteroid?


Not sure about the asteroid re-routing in point 4, but you've successfully re-routed this retired English teacher.  IGNORE!

[jficke13]

Well on the off chance that the Armageddon scenario that appears to haunt your dreams ever arises, it would be awfully helpful to have experience intercepting and redirecting a near earth object that poses an actual threat.

[jficke13]

Also, reading some of their publications could shed some light as to why NASA feels like using a part of their limited budget on Asteroid Redirect Mission:

http://www.nasa.gov/sites/default/files/files/IAC-14-A5_3-B3_6_7x26388_Brophy.pdf

1. Potential sourcing of raw materials for deep space exploration that does not require a lift into Earth's orbit).
2. Investigation of potentially using asteroids to shield astronauts from galactic cosmic ray radiation (Again, without having to lift heavy shielding into Earth's orbit).

Actually, it's totally worth reading in its entirety. I would do terrible things to work on this project and even worse things to go into space on it. Hopefully fear mongering doesn't kill projects like this. The fact that no humans have passed low earth orbit in decades is a national and human embarrassment.

[Coleman]

Has NASA mentioned the size of said asteroid?

Perhaps it would be small enough that it would burn up in the atmosphere, should it eventually head towards earth. This happens all the time, FYI. Major impact events require very large asteroids and are exceedingly rare, relatively speaking.

There is an inverse relationship between the size of the object and the frequency that such objects hit Earth. The lunar cratering record shows that the frequency of impacts decreases as approximately the cube of the resulting crater's diameter, which is on average proportional to the diameter of the impactor. Asteroids with a 1 km (0.62 mi) diameter strike Earth every 500,000 years on average. Large collisions – with 5 km (3 mi) objects – happen approximately once every twenty million years. The last known impact of an object of 10 km (6 mi) or more in diameter was at the Cretaceous–Paleogene extinction event 66 million years ago.

[reinko]

Deep Impact was such the better the flick.

[FartyEightHours]

One of those dots is over my house

Asteroid hits, I'm just gonna lay back and take it.  *And buy a lot of canned beans.

[jficke13]

Has NASA mentioned the size of said asteroid?

Per Wikipedia:

NASA has proposed the Asteroid Redirect Mission (or Asteroid Initiative), an uncrewed robotic mission, to "retrieve" a near-Earth asteroid with a size of about 8.2 metres (27 ft) and a mass of around 500 tons (comparable in mass to the ISS).

http://en.wikipedia.org/wiki/Asteroid_Redirect_Mission

[Coleman]

Per Wikipedia:

NASA has proposed the Asteroid Redirect Mission (or Asteroid Initiative), an uncrewed robotic mission, to "retrieve" a near-Earth asteroid with a size of about 8.2 metres (27 ft) and a mass of around 500 tons (comparable in mass to the ISS).

http://en.wikipedia.org/wiki/Asteroid_Redirect_Mission

So while an asteroid that size may cause a significant airburst (the equivalent of a bomb being detonated high up in the atmosphere), it poses almost no risk to humans as it would completely disintegrate before hitting earth.

Asteroids with a diameter of 8 meters enter Earth's atmosphere with as much kinetic energy as Little Boy (the atomic bomb dropped on Hiroshima, approximately 16 kilotons of TNT) about every 5 years, but the air burst only generates a much reduced 5 kilotons of TNT. These ordinarily explode in the upper atmosphere, and most or all of the solids are vaporized.

I think this answers Benny's question in the original post. There is no statistically significant level of risk in a mission dealing with an asteroid this size.

[Benny B]

So while an asteroid that size may cause a significant airburst (the equivalent of a bomb being detonated high up in the atmosphere), it poses almost no risk to humans as it would completely disintegrate before hitting earth.

Asteroids with a diameter of 8 meters enter Earth's atmosphere with as much kinetic energy as Little Boy (the atomic bomb dropped on Hiroshima, approximately 16 kilotons of TNT) about every 5 years, but the air burst only generates a much reduced 5 kilotons of TNT. These ordinarily explode in the upper atmosphere, and most or all of the solids are vaporized.

I think this answers Benny's question in the original post. There is no statistically significant level of risk in a mission dealing with an asteroid this size.

That makes much more sense... the original link stated: "Our next step is deep space, where NASA will send a robotic mission to capture and redirect an asteroid to orbit the moon. Astronauts aboard the Orion spacecraft will explore the asteroid in the 2020s, returning to Earth with samples."  When I saw "astronauts" and "explore" I had assumed they were landing Orion on the asteroid; when in fact, I assume now - due to the proposed size of the asteroid - that they're simply going to "explore" it from the Orion craft.

In other words, I had envisioned something like 800m.  I can deal with 8m.

[Coleman]

That makes much more sense... the original link stated: "Our next step is deep space, where NASA will send a robotic mission to capture and redirect an asteroid to orbit the moon. Astronauts aboard the Orion spacecraft will explore the asteroid in the 2020s, returning to Earth with samples."  When I saw "astronauts" and "explore" I had assumed they were landing Orion on the asteroid; when in fact, I assume now - due to the proposed size of the asteroid - that they're simply going to "explore" it from the Orion craft.

In other words, I had envisioned something like 800m.  I can deal with 8m.

Right, and you could certainly still land a (very small) unmanned probe on such an asteroid.

[jficke13]

You could also rendezvous with an asteroid of that size with a manned expedition.

[77ncaachamps]

An asteroid of a considerable size should be able to throw up enough terra into the atmosphere that climatic changes should be altered for nearly a decade.

[MU Fan in Connecticut]

No Uranus jokes in this thread yet?

[FartyEightHours]

When will man touch down on Uranus?

[jficke13]

When will man touch down on Uranus?

It's a gas giant, so even given an sci-fi-esque technology to resist the crushing force of Uranus... some form of protection perhaps... Uranus transitions from gas to fluid seamlessly so there's really no surface of Uranus that you could touchdown upon... you'd just descend deeper and deeper into Uranus until you were all the way in.

[forgetful]

Per Wikipedia:

NASA has proposed the Asteroid Redirect Mission (or Asteroid Initiative), an uncrewed robotic mission, to "retrieve" a near-Earth asteroid with a size of about 8.2 metres (27 ft) and a mass of around 500 tons (comparable in mass to the ISS).

http://en.wikipedia.org/wiki/Asteroid_Redirect_Mission

Well only 27 ft, that's no asteroid its merely a small space rock.  I had also thought what they would be looking at was much larger.  I have no concern about a 27 ft object and greatly encourage the mission.  I would also kill/maim/injure to be part of the project.

[mu03eng]

Well only 27 ft, that's no asteroid its merely a small space rock. 

That's no moon, that's a space station....sized asteroid.

[keefe]

Interesting game plan. The next century will bring amazing insight into who and what we are if not necessarily the why.