How massive and at what speed would an object have to be to cause an end of earth scenario?

An Earth impacting asteroid larger than about 2-3 kilometers would likely hit with a velocity of about 15 km per second (about 15 times the velocity of a high speed rifle) and it would cause global problems. Even so, most lifeforms would survive. There are no current near-Earth asteroids large enough to cause the type of extinction event Earth witnessed 65 million years ago when the dinosaurs checked out. Don

So what if a huge asteroid is on collision course with us, what do we do??

Thanks for taking your time doing this AMA

It depends on how much warning time we have. If we know 10 years ahead of time, we could send a spacecraft out to ram the asteroid about, say, 5 years before it was predicted to hit. We would only have to change its velocity by something like a centimeter per second or so to make it miss the Earth. PC

All the asteroids larger than about 2 km in diameter that can closely approach Earth have already been discovered. None poses a risk. About 95% of objects > 1 km in diameter (0.6 miles) have been found. Roughly 50% of objects > 0.5 km in diameter have also been found. So the first thing to do is to find the objects and find them early. The overall strategy is to find anything threatening with many years of advance notice so we have plenty of time to figure out what to do. If you check responses to other questions, you'll see mention of some techniques to prevent objects from hitting Earth, but briefly, a kinetic impactor that simply slams into an object and nudges it slightly decades ahead of time is probably one of the best methods. --LB

a kinetic impactor that simply slams into an object and nudges it slightly decades ahead of time is probably one of the best methods

What would a kinetic impactor cost??

There is the ISIS impactor concept that would cost $150-200M altogether: http://www.planetary.org/blogs/guest-blogs/van-kane/20130513-isis-blasting-a-crater-on-Bennu.html

I like the game Asteroid as much as the next.. But why did NASA hire team of experts for it?

Hi, This is Lance. When I was in high school I played "Asteroids" a lot. My girlfriend was delighted because I was the only person who could get a higher score than her brother.

I spent many a quarter on Asteroids. DCA

Is there anything that might not be asked but you want to share?

A primary constraint on the asteroid mission is that it be done under a cost-driven paradigm. That will require NASA be work in a very innovative way both in what we do and how we do it. bkm

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Yes, a captured asteroid could provide raw materials. We'd love to discover a water-rich carbonaceous target that we could maneuver to lunar orbit. With water we could make rocket fuel and use that as a depot for deep space missions, including Mars. bkm

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Water in the form of ice has been found on a few asteroids in the main asteroid belt and hydrated minerals in asteroids (OH radical bound up in minerals) are more common. As you get further and further out in the solar system, water ice is VERY common. Some of the least common asteroids are solid iron-nickel. Don

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No, not in 2036. We are continuing to track Apophis for the small chances of impact in 2060 and later years. The total odds of impact are around 1 in 175,000. http://neo.jpl.nasa.gov/risk/a99942.html SC

So I'm curious; how are these odds calculated? I'm familiar with tracking, but for different applications. What sort of sensors are used? Infrared?

Asteroids are tracked by large optical telescopes which take images of the asteroid, which is a point of light, against the star background. Knowing coordinates of the stars, we can figure out the coordinates of the asteroid at the time the image was taken. We take hundreds or even thousands of these coordinates and compare them against where we calculate the asteroid should have been. If the calculated positions don't match the actual positions, we adjust the orbit elements to make them fit: this is called Least Squares estimation. We calculate the future trajectory and look for close approaches to the Earth, and we calculate the uncertainties in the close approach as well. If the calculated close approach is anywhere near the Earth, even including the uncertainties, we'll calculate the actual probability that the asteroid could hit the Earth using these numbers. -PC

How far do you need to drill into an asteroid to reach the nougat center?

It depends on how thick the chocolate crust is. Steve

Is it true that NASA makes you watch the movie Armageddon and point out all the scientific inaccuracies as part of your training?

Hah! No, as I'm sure you realize, but it was certainly a lot of fun to watch that movie. Even though "Armageddon" didn't try to be scientifically accurate, it did do a lot to raise public awareness in asteroids around the world. --Lance Benner

What is your greatest accomplishment? and what are you most proud of? Btw Thank you for the amazing work you guys do!

In October 2008 we got a report of an asteroid (2008 TC3) that might hit the Earth later the same day. We were able to track it and predict the impact location (northern Sudan), which was later confirmed, not only by observers but later meteorite hunters were able to go and collect samples of the asteroid. That was a busy and exciting day around here. SC

This is Brian Muirhead and I was the flight system manager and then project manager for the Mars Pathfinder mission that landed the first rover on Mars on July 4, 1997

This is John Brophy, my greatest accomplishment is the delivery of the ion propulsion system for NASA's Dawn mission. This is the most capable propulsion system ever flown on a deep-space spacecraft. JRB

What does "capable" mean in this context?

Capable means the ability to change the velocity of the spacecraft. The Dawn ion propulsion system will provide a total velocity change of 11 km/s, the best chemical propulsion system flown on a deep-space mission provided less than 3 km/s. JRB

if an asteroid was on a collision course with earth and there was zero chance of survival, would you tell the public?

We post everything we know on our website: http://neo.jpl.nasa.gov/risk, usually automatically, but sometimes with no more than a few days delay if we need to cross-reference calculations with our international collaborators. The international nature of impact monitoring makes it impractical to even try to control this kind of information. And besides it's always better to be open with what we know than have a policy that feeds into conspiracy theories. SC

All of NASA's computations on near-Earth asteroids are posted on our website (neo.jpl.nasa.gov). Unless a short verification process is underway with our Italian colleagues (they do parallel but independent computations), these possible impacts events are posted immediately. Nothing is held back. Don

Thanks for doing this AMA! Do you guys believe that the asteroid redirect mission would offer more bang for our buck than going out to an actual asteroid in deep space? Could you maybe give us some details on NASA's plan for a deep space asteroid too?

Also, I'm going to University soon; what did you guys graduate in?

Edit: well, for those interested, I looked up some info on the current plans for a Deep Space Asteroid mission.

The current Initial Capability asteroid mission would involve the first launch of a Block 1A SLS with a DSH and a CPS. The CPS would push the DSH into a high elliptical orbit. Then, an Orion crew vehicle and a CPS would be launched on a second SLS. The Orion MPCV would dock with the DSH in orbit and the CPS on Orion would fire again, and then Orion itself does a burn. Once at the asteroid, Orion would burn to rendezvous with the asteroid. Once the mission is complete Orion will burn again and send the 45 ton stack back to Earth where Orion will reenter.

The other missions are even more complicated so I don't feel like typing them all out.

Yes, it provides a very cost effective way for astronauts to get experience in operations beyond earth orbit at a reasonable level of risk. It would be a 21 day mission including two space walks at the asteroid. bkm

Thanks! Could you maybe look at my other questions too? I edited them in later.

A quick poll of the room shows that these were the majors among the team: Physics, applied math, systems science, mechanical engineering, aerospace engineering, math and aeronautics.

I haven't looked at the deep space asteroid mission in a while. The biggest challenge is that it would require astronauts to live in deep space for greater than 200 days. The systems and vehicles that could support such a mission safely and reliability are only at the concept level, so it's several years away. bkm

Hello and thank you for doing this AMA!

What are your thoughts on the B612 Foundation's space telescope, the Sentinel?

Searching for near-Earth asteroids using an infrared telescope is a very efficient technique since asteroids radiate strongly in the infrared. The Sentinel mission plans to put its infrared telescope in an Venus-like orbit and NASA has already agreed to help with spacecraft tracking, navigation and orbit determination. Another concept that has been proposed to NASA is to place the infrared telescope at the so-called L2 point about a million miles inside the Earth on the Sun-Earth line. Either concept would greatly increase our discovery rate of near-Earth objects. Don

Very interesting. If an asteroid was detected early enough, do you believe an attempt to "catch" the asteroid in a lunar orbit would serve useful? If so, how would you go about doing this?

It would depend on the mass and velocity. If it were small enough (100's to 1000's of tons, and slow enough, relative to Earth we could maneuver it, which is what our Asteroid Redirect Robotic mission would do. bkm

When/how did your team become aware of the Chelyabinsk meteor? Did it teach you anything new?

I can answer how we first heard about it, and Don Yeomans will answer the "what did we learn" part. The Chelyabinsk meteor happened the night before the expected flyby of asteroid 2012 DA14. I was on Twitter answering questions sent to @AsteroidWatch when the first eyewitness accounts of Chelyabinsk started coming in. We get a lot of eyewitness reports to that account about fireball sightings (very small meteors burning in the atmosphere) so it wasn't all that unusual.. at first. After looking at a couple of the videos and images I called and emailed Paul and Don. They were able to get to work immediately on it. It was a very exciting night. VM

So does this mean that your team didn't have knowledge of the event prior (like trajectories) or that you were busy doing another observation.

How much are you in contact with the Vanderberg Tracking Station?

The Chelyabinsk object wasn't discovered before it hit the atmosphere. It approached from the direction of the Sun so nobody saw it ahead of time. --LB

One of the things we learned is that even a 20 meter sized asteroid can cause significant ground damage - and there are millions of them in near-Earth space. Our computer models for asteroid ground damage will need to be revised to match the actual Chelyabinsk event. Don

Do JPL engineers play Kerbal Space Program? :) TIA!

Not us! It looks like we're too busy doing the real thing! Steve

What is your daily work like? What exactly did you go through to get to the job your currently at? What sort of schooling was necessary? I've always been interested in space, like most people, so it'd be cool to find out. Thanks!

It often starts at 5:00 am with email with NASA HQ on the east coast. I studied mechanical engineering. BS but an MS helps. But I think that the thing that got me in the door at JPL was the fact I'd been a motorcycle mechanic. bkm

Hi, This is Lance Benner. I spend a lot of time working on observing proposals, editing manuscripts that report results, working with asteroid radar data, responding to email, and planning future observations. I majored in physics as an undergraduate, went to graduate school in Earth and Planetary Sciences at Washington University in St. Louis, and then came to JPL.

With modern technology how possible it is to catch a complete asteroid while its passing by the earth to study it's components ? Or maybe installing some kind of camera to see where it is heading and gather data of its course?? Thanks for the AMA!!

The approach currently being studied would use a high-power solar electric propulsion system to rendezvous with the asteroid. Once at the asteroid the spacecraft instrumentation would provide information to accurately determine its size, shape, and how it's spinning. The spacecraft would then match the primary spin rate of the asteroid, the capture it in a high-strength bag and pull the asteroid up against the vehicle. The spacecraft would then use its chemical propulsion system to despin the asteroid, and then use the ion propulsion system to guide the asteroid's trajectory to a gravity assist flyby of the moon. This gravity assist captures the asteroid and spacecraft into the Earth-Moon system. Additional thrusting by the ion propulsion system then puts the asteroid into a high lunar orbit that is stable for more than 250 years. JRB

Thank you all for taking the time to do this. It's not exactly one of our usual ways of doing outreach, is it? - Michael Busch

JPL, NASA headquarters and other NASA centers have done several AMAs beginning about a year ago with this one featuring scientists and engineers from the Mars Science Laboratory (Curiosity Mars rover) mission: http://www.reddit.com/r/IAmA/comments/ybmmh/we_are_engineers_and_scientists_on_the_mars/

Let's keep on doing them, then.

Absolutely! It may not be "usual" but it is worthwhile! We've enjoyed doing these -vm

Thanks for handing out this opportunity. As of this moment it looks like the Asteroid Catching mission is still on track. Is the selection process of which asteroid might be a suitable target already underway ? Can you elaborate on what a candidate asteroid for capture would roughly have to look like, be made of, etc ?

Yes, we already have two candidate asteroids that are promising, but we need to observe them in the infrared to be sure that they are the right size (We'll use the Spitzer Space Telescope for that). We're also monitoring all the current discoveries to look for candidates, and NASA is planning to enhance the asteroid surveys so that we find more asteroids of all types, including the ones we can retrieve. PC

Some additional information for the audience, Paul: We are doing radar and well as infrared and optical observations of potential retrieval targets, so that we know their orbits well enough to retrieve them and so that we have more precise size, shape, and spin state estimates.

To add to the last post on this thread, Michael Busch is part of the asteroid radar team. --LB

Does anyone in your office have this shirt? http://31.media.tumblr.com/tumblr_ma9ccqzqIU1qzflkho1_500.jpg

No, but I have a custom mouse pad which reads "If you have Asteroids I'm the Doctor to see". :) -- Alan Chamberlin

Are your computers really that amazing that everyone jokes about them being the best for PC gaming.

Hah! Not really. We use systems optimized for numerical computation as opposed to intense graphics processing (sound systems... forget about it ;). We look for systems with a reasonable number of cores and the fastest clock-speed we can get. Perhaps surprisingly, most of our code is not very memory intensive. -- Alan Chamberlin

Hi guys!

What is the craziest idea that you've ever had for deflecting an asteroid?

Thank you and keep doin' what you're doin'!

One of the craziest ideas we've HEARD to redirect an asteroid is to use paintballs. Note: we do not endorse the use of paintballs.

What is the scariest thing that you have encountered in your field of work?

A reddit AMA! Steve

From an earlier answer... The lower size limit for an asteroid capable of causing ground damage is about 20-30 meters in diameter and there are millions of them in near-Earth space. As you get to smaller and smaller near-Earth asteroids, there are more and more of them. Don

is it true that mixed into the asteroid belt there are clutters of tons of Satellites that are no longer is use? and if there is, will it effect the planets in any way or cause any asteroids to fall out of the belt and go towards earth? thank you!!!

There are about 80 old rocket bodies and dead spacecraft in orbits about the Sun that might be mistaken as asteroids. After tracking those for a while, though, we can figure out that they are not asteroids, just by the way they move. There are still way more asteroids than old rocket bodies, and they are spread apart so much that the odds of collisions are tiny, and they are so light that they wouldn't affect the any asteroid or planet that they might collide with. PC

Thanks for doing an AMA, I hope you all can keep this idea going throughout all of NASAs programs!

This one is for Brian, but if anyone else has any input, it's perfectly welcome! What sort of advice can you give to a student wanting to write software in the astrophysics field, or for NASA specifically?

Can't speek for astrophysics but the quality of a great S/W engineer in my experience is they think like a systems person first and are good coders second. By a systems person I mean someone who looks at the whole problem and can formulate a workable solution, when solve it. bkm

Hey, Is there a good way to get the raw data from the JPL NEO pages?

Currently no. I am planning to release our SBDB (small-body database, catalog of asteroid/comet orbits) as a data file (probably XML) some time in the near future (currently about 620,000 objects). This would include Earth close approach data as well. Check our SSD web-site (http://ssd.jpl.nasa.gov/) in a few months or shoot me an email ([email protected]). -- Alan Chamberlin

Dear Nasa folks,

How real is the possibility of mining minerals from an asteroid? How would this impact future missions?

Best regards,

Tombre

There are at least two private companies that are trying to figure out how to do this, so it's clear that there are some people who are serious about it. It's likely that it'll be many years before this actually happens, though. --LB

This one is for Veronica and DC, getting the general public interested in space programs of any sort seems to be very difficult these days. What are you all trying to do differently to get people's attention? Are there perhaps ideas that you've tried that have gotten shot down by upper management? What news/social media campaign are you most proud of?

The last five years have been interesting with the ability to reach the public directly via social media. I would say I've become much more optimistic about the public's interest in science and space. I've been tweeting our missions since 2008 and in the beginning I was blown away by the positive response. The goal now (and always) is to increase the community of space enthusiasts by reaching people who don't yet appreciate what we do. Before I came to JPL I worked for CNN covering NASA missions and it was by coming to JPL that I became fascinated with space. My personal goal has been to bring more people "behind the scenes" to have that same experience but on a mass scale. That means doing it virtually through social media, through Reddit AMAs, or via a face-to-face event that allows the public to meet and speak with our scientists and engineers. It's hard to think of one campaign I'm most proud of, but I have a fondness for the @MarsPhoenix mission because it was the first mission account I did on Twitter, and I'm very proud of creating the first NASA Tweetup event in 2009 (now known as NASA Socials). The idea was quickly adopted by NASA HQ and other NASA centers, as well as by space agencies of other nations as a way to give the public a front-row seat to space exploration. To date, there have been over 60 events held and thousands of attendees. The community curates a wikipedia page about NASA Socials here

I really enjoyed working the close flyby of 2005 YU55 - in which mother nature offered up this great target for our scientist to target with radar. Here is a link to a cool video clip. Kinda looks like ultrasound doesn't it? http://www.jpl.nasa.gov/news/news.php?release=2011-351 DCA

What is being done to prepare for collision like the one that created the Gulf of Mexico?

The Gulf of Mexico was created largely by plate tectonics, although there was also a major contribution to the northern part by sediment deposition from the Mississippi River of the last few tens of millions of years (which has been extending the coast line to the south). Yes, the Chixulub impact hit the northern Yucatan Peninsula, but it didn't create the Gulf of Mexico. --LB

That would be the asteroid or comet that created the so-called KT event 65 million years ago and hit in the present day Yucatan. NASA is searching for asteroids every night. We're quite sure that all the asteroids that big have been discovered. Comets heading towards us from deep space would be harder to discover years in advance, but those are few and far between. PC

What other countries have similar programs and do you partner with them? Is there a data sharing policy?

Currently the vast majority of work to discover near-Earth asteroids is happening in the US and is funded by NASA. However, there are numerous important contributions from other countries.

For example, Japan conducted the very successful Hayabusa mission to asteroid Itokawa in 2005 and is in the process of building a new mission, Hayabusa 2, which will return samples from 1999 JU3. The European Space Agency is considering a proposal called "Marco Polo-R" that would send a sample return mission to 2008 EV5. Our colleagues in Europe are ramping up their efforts to discover and study the physical properties of near-Earth asteroids. Until very recently there was a NASA-funded search program at Siding Spring Observatory in Australia. Numerous professional and amateur astronomers worldwide regularly contribute astrometry (measurements of asteroid positions) to improve asteroid orbits. --LB

Great question! Asteroids are an international problem and tracking them is an international effort. While the vast majority of the search effort is conducted by NASA, every night observers around the globe are backing up the NASA search efforts and adding critical follow up data. As well, ESA is now funding a NEO Coordination Center, and the NEODyS team in Italy is a close collaborator for impact monitoring. The main coordination of asteroid tracking takes place through the IAU Minor PLanet Center at Harvard Univ., which serves as the international clearinghouse and archive for all asteroid tracking data. SC

Why is it that not many asteroids hit earth? There are lots of asteroids floating around, and earth is pretty big, why arent they hitting us?

Tiny asteroids (say, meter size) hit the Earth every year, big ones not so much. Global catastrophes are separated by millions of years. There are a lot of asteroids out there, but the vastness of space works very much in the Earth's favor. For example, the sun is about 12,000 Earth diameters away from us. SC

Does NASA ever hire laymen or people without degrees?

That we do! It takes people with all types of backgrounds to explore the universe. For career opportunities at JPL, check out: http://www.jpl.nasa.gov/work/

Thanks for doing the AMA!

What is the most efficient way of mapping out where NEOs are? I assume radars on the ground around the world, but I can guess that the priority of resources probably isn't high. What would be your dream way of discovering new NEOs (radar in orbit, on the moon, etc)?

Hi, This is Lance Benner again. The best way to find asteroids is to use an infrared telescope in space, although there aren't any currently active. Ground-based optical telescopes are the technique that's being used the most. Although radar is a very capable technique for studying the physical properties of asteroids and for improving their orbits, radar isn't a technique for discovering asteroids because the fields of view of the Goldstone and Arecibo radar telescopes are very narrow (less than the width of the Moon). In addition, with radar we provide our own illumination and the electricity to do that is expensive. The distances to asteroids are enormous, and because the signal strength decreases proportionately to 1/(distance^4), the signal strengths would be tiny if we weren't tracking a specific object. We also have to tune the receiving equipment to the Doppler shifts caused by the objects. To do a meaningful search with radar would require transmitter power many orders of magnitude stronger than any radar currently in existence.

We have already discovered a lot of asteroids and have a good idea of what most of their orbits are. So, we can simulate the whole population of asteroids and then calculate where they would appear in our sky. Most asteroids are discovered by optical telescopes scanning the skies. Usually they are easiest and brightest around the "opposition point", the direction directly opposite to that of the Sun. There are good proposals to discover asteroids using infrared telescope in space, but those aren't fully funded and won't be available for years. PC

Will NASA do the asteroid redirect alone? Are other nations interested in joining in the mission?

The asteroid redirect mission provides significant opportunities for, and would greatly benefit from, international cooperation with other space-faring nations. JRB

Hey, and thanks for taking the time to do this AMA, really appreciate it.

I was wondering about how we could utilize asteroids, such as mining them. Recently some news surfaced that we could nudge (at 500 m/s) some asteroids into Lagrangian points for a stable orbit and use them to mine. How feasible do you think this plan is? Could we possibly nudge these asteroids to where we want them to be and use them in the near future? I'm guessing these are close to L2 but are there others that are at L3 or L4 that could possibly be profitable?

Also, since these objects will be orbiting at Lagrangian points, could we use them as checkpoints to further destinations in the future when those needs arise?

One more question about the possibility of damaging asteroids as everyone is asking. What do you think it will take for people to realize that asteroids are a serious threat and we should be keeping an eye them at all times and be constantly discovering them for safety? After the Russian meteor not too long ago, I thought this would change at least a little but I see no changes. Do we need an asteroid to do some serious serious damage before people (mainly the money-givers) realize they're actually gambling?

Once again, thanks for doing this, love the work you guys do and I think asteroids are the next thing we can realistically conquer. Your research and work is greatly appreciated by spaceheads.

P.S. - Saw your Black Hat talk Mr. Muirhead, great stuff.

A captured asteroid could provide raw materials. We like the so called distant retrograde orbit around the moon because it's been shown to be stable for >100 years. We'd love to discover a water-rich carbonaceous target that we could maneuver to lunar orbit. With water we could make rocket fuel and use that as a depot for deep space missions, including Mars. Yes, asteroids could be a serious threat but I think the probability of a major disaster is low compared to the likelihood of climate change driven problems. bkm

I believe that soon enough VASIMR will start replacing solid-fuel rockets. What sort of changes do you think will need to happen before that switch can be made?

What are your thoughts on using thorium to power space stations or ships?

VASIMR is one of many types of thruster concepts for converting electrical power and propellant into thrust. There are many types of electric thrusters currently in use today. These thrusters ionize xenon gas and accelerate the resulting xenon ions to exhaust speeds of 20,000 to 30,000 meters/s. VASIMR is a much higher-power device than those currently flying and is significantly less mature. If VASIMR can be successfully matured and has attractive performance and operating life, then it's application to future missions would depend on how well it competes with other electric propulsion devices. JRB

Are there any specific NEA's that NASA is currently observing as potential candidates to tow into orbit around the Moon or into orbit around Earth? Also, are there any NEA's that NASA are currently observing as potential candidates for collision with Earth in the near-future?

Yes, 2009 BD and 2011 MD are potential candidates that appear to be roughly the right size and are in favorable orbits. More work needs to be done to confirm that these are the right size, and we'll use the Spitzer Space Telescope to help us confirm the size. We expect to have more candidates show up at a rate of 2-5 per year, and we'll use radar to confirm that those new ones are the right size. Radar wasn't used for the two I mentioned above. PC

Marina, while we were all looking in one direction trying to capture the best pictures of 2012 DA14 some other asteroid hit us from the other side. What is stopping us from leaving that radar switched on permanently so we can at least walk away from the windows if another is about to check on how our space program is coming along ? Would similar technology be able to work outside our atmosphere, like on a satellite pointing outwards or on the earth facing side of the moon to check what zooms between them ?

In addition to what Marina mentioned, NASA is funding a new search telescope system called "ATLAS" that is designed to look for asteroids very close to Earth, including some on their final approach. It's scheduled to start operation in 2015. --LB

Well, keep in mind that our radars (Arecibo and Goldstone) have a very narrow beam-width (~100 arc sec), and it would be very inefficient and expensive to use them to scan our skies (not to mention that FAA would not like it). Space based IR telescopes are the way to go regarding the discovery of the NEOs. (mb)

What is the most terrifying lesser known fact or statistic you NASA ladies and gents have learned in your studies/observations?

Well, the lower size limit for an asteroid capable of causing ground damage is about 20-30 meters in diameter and there are millions of them in near-Earth space. As you get to smaller and smaller near-Earth asteroids, there are more and more of them. Don

If you had unlimited funding what would you primarily focus on?

In terms of near-Earth objects, I'd fund a space-based infrared telescope to more efficiently discover them. Don

Is there any idea on how many asteroids have useful materials in them? and is it worth going to get them? Also what is your favorite asteroid that you know of and did you discover it ?

About half of all asteroids are carbonaceous, and those ones are the most likely to have hydrated minerals. That means we could extract water and oxygen from them. Those aren't minerals, but they would be valuable for spaced exploration. The asteroids could serve as refilling stations for water, oxygen and maybe even propellant. My favorite object was Comet Shoemaker-Levy 9, which was actually 21 cometary fragments which all hit Jupiter in 1994. It was amazing to be able predict when and where those fragments would hit Jupiter, and then actually go out and see the impact scars on Jupiter, right where the math said they would be! PC

Is there already a shorlist of asteroids for the redirect mission?

Yes, but it's more of a working list right now. Only one asteroid on the list (2013 EC20) has been adequately characterized, and it turned out to be smaller than the desired 7-10 meters. The others (2009 BD, 2011 MD, and 2008 HU4) still need to be characterized in detail so that we can be sure they're the right size and mass. We'll be using the Spitzer Space Telescope to get a better size estimate of the first two, which are far from Earth right now. The last one will be coming back near the Earth in 2016 and we should be able to observe it with radar to get a good fix on its precise size. Beyond that, we monitor every night's new discoveries and wait for more candidate asteroids to be discovered. We expect to find about 3-5 new ones per year that could be redirected, which means by the time we have to launch the redirect mission we should have probably a dozen more on our list. PC

For all the engineers:

• What are the new technologies that you're developing to facilitate the Asteroid Redirect mission?
• What TRL are they at? Is any one of them nascent enough for a potential grad student, and mature enough to allow said grad student to get it in space in 5-6 years? :P
• Is the development happening in-house at NASA, or d'you have partnerships with several Universities (This is specifically for the Asteroid capture mission).
• Regarding your career paths: In terms of work experience, did you (engineers specifically) always work on something space-related? Or did you drift in from other areas? (e.g. Software engineering, designing hardware for on-Earth applications)

The new technologies needed for the asteroid redirect mission include the high-power, light-weight solar arrays, the xenon-fueled Hall-effect electric thrusters, and the asteroid capture mechanism.

The solar arrays and Hall thrusters are considered to be at TRL 4 to 5 and the capture mechanism at TRL 3/4.

The development will make the best use of NASA in-house and industry capabilities.

My career path consists entirely of space-related activities. JRB

How close do you think we are to building and launching a rocket capable of intercepting an asteroid? Either for research purposes or for deflection purposes, or both.

We've already done it. Our Deep Impact spacecraft intercepted a comet, Comet Tempel 1, in 2005. The "mother craft" recorded the impactor craft hitting the comet on July 4, 2005. That mission provided excellent science about the comet and also showed we were capable of hitting the target.

What do you think the future holds for asteroid mining companies like Planetary Resources? Do you believe companies have the right to stake claim in celestial bodies?

Planetary Resources has a lot of work to do before they'll be in a position to mine asteroids. It seems unlikely that the incredibly vast quantities of materials outside of the Earth would be off limits for private development. JRB

How does one get in your line of work? Growing up, my biggest fear was the human kind will be destroyed by an asteroid and always wanted to work in research at some point in my life. Thanks for doing this AMA.

Study engineering or science and be passionate about making a difference in the world. Then come join us at NASA. bkm

What's the mineral composition of a typical asteroid like? Given a hypothetical severe shortage of metals on earth, would it be feasible to mine asteroids for metals for use back on earth using near-future technology? What would the biggest hurdles be to this kind of operation?

There's no such thing as a typical asteroid. They have an enormous dynamic range of shapes, spin states, and compositions. Having said that, they cluster into a number of compositional groups. Many have abundant silicate minerals, some have organics and even water locked up in their crystal structures, and a small fraction (about 5%) are metallic. Many of the rocky ones also have small concentrations of metals including some that are rare on Earth.

Two companies announced plans in 2012 to start mining asteroids, although it's likely to be many years before that actually happens.

There are a lot of engineering hurdles to overcome before this happens. It's also going to be very expensive.

--LB

• Aside from the whole hazardous object angle, what types of science has been coming out of NEO tracking and cataloging?

• What's the coolest (to you) part of your work that isn't as sexy to laypeople as asteroid capture, impacts, etc?

One of the coolest things I've done is to weigh an asteroid by studying the Yarkovsky effect on the asteroid Bennu, which happens to be the destination for NASA's OSIRIS-REx asteroid sample return mission. It turns out that Bennu has about the same density as water, which means that there must be a lot of empty space in the asteroid. They are not necessarily all solid rocks! Steve

"The Yarkovsky effect is so cool!" Cameron Diaz (http://www.youtube.com/watch?v=B7YqVCclIQU)

There have been enormous advances in near-Earth asteroid science as a result of efforts to study them with ground- and space-based telescopes and with robotic missions that actually go to asteroids. We've learned a great deal about the variety of compositions, spin states, shapes, the fact that 1/6 of NEAs > 200 m in diameter are binaries, and what they can tell us about the geologic history of the inner solar system. This has become a major field in planetary science with hundreds of active researchers worldwide. --LB

The coolest part is getting those first radar echoes from an asteroid that is hundreds of thousands if not million of miles away, and figuring out what are we looking at. You never know what you will stumble at. We thought that binary asteroids are neat, but now we have two triple systems detected by radars. (mb)

Hypothetical question: How would we(as earth) actually deal with a situation wherin we have an asteroid headed our way, capable of destroying the earth completely??

From an earlier answer to a similar question... It depends on how much warning time we have. If we know 10 years ahead of time, we could send a spacecraft out to ram the asteroid about, say, 5 years before it was predicted to hit. We would only have to change its velocity by something like a centimeter per second or so to make it miss the Earth. PC

There are no large near-Earth asteroids that can completely destroy the Earth. If there was, we could have discovered it by now. But there are still possibly some that could cause global catastrophe, and that's why NASA is working so hard at searching for them. We would want to find it as early as possible, with a lot of warning time, so that we could deflect it early enough. Some practice deflection missions have been proposed. PC

Is it possible to live on an asteroid and use it as a space vessel?

Sure, if it has resources, primarily water, one could imagine living on a good sized asteroid. Using it as a space vehicle would mean being able to change its velocity to go somewhere interesting, and that argues for a smaller body. You'd also want it to spin very slowly. bkm

Who will win the Super Bowl this year?

Go Browns! DC

L.A. Lakers (mb) :)

Hi! Kudos all!

Should folks or bots retrieve a 'roid? If folks, what sorts of expertise and training would you look for in candidates that might differ from the sorts sought in the now run-of-the-mill NASA ISS or Shuttle missions?

The asteroid retrieval mission study indicates that a robotic spacecraft that could be build this decade is capable of traveling to deep-space, capturing, and redirecting the asteroid back to the Earth-Moon system. It would be much more expensive and take much longer to have astronauts to do this. However, it would be a very exciting mission to send astronauts to the asteroid after the robotic spacecraft has delivered it to a high lunar orbit. This would be the farthest away from Earth that humans would have ever traveled and it would be the first time in 50 years that astronauts will have traveled beyond low-Earth orbit. JRB

Hi! Will the space shuttle program ever be rebooted? Its a shame that such an iconic part of NASA is not active.

No. We're working on a new crew vehicle, Orion, and a Saturn V class heavy lift vehicle, the Space Launch System, that will be able to take crew beyond low earth orbit. bkm

The space shuttles have been retired. DCA

Are we facing any serious threats to Earth or humanity as a whole in regards to objects colliding with our planet, if so when or how long until these events may occur. Also if they do occur can we move to any planets right now?

Among the more than 10 000 near-Earth objects currently known, there aren't any with a significant chance of impacting Earth as far as we know. One of the major goals of NASA's asteroid program is to find the objects with decades of advance notice so we have plenty of time to figure what to do. --LB.

Are there no huge NEO to land on in three days?

Hi, This is Lance Benner. No NEOs are predicted to impact Earth with any non-negligible probability for the forseeable future. For a list of upcoming asteroids close encounters, go to: http://neo.jpl.nasa.gov/ca/

Thanks for doing this, guys!

Do you predict that we'll see a large boom in asteroid mining in our lifetime? I've read posts on reddit about asteroid mining, and it seems extremely interesting. How do you determine exactly what an asteroid contains as well?

I think it's possible to see asteroid mining in our lifetime (depending on how long you're planning on living). There currently two private companies (Planetary Resources and Deep Space Industries) who have stated that this is their ultimate objective. JRB

Thank you all for doing this AMA! You guys are doing amazing work! I have a few questions. If the first asteroid retrieval mission were to be a success would you all plan more for the future? If so, how often would you hope to see these types of missions take place? Finally, would you plan on capturing larger asteroids for study or perhaps landing on one in the future?

If the first asteroid retrieval mission is successful, it will demonstrate that such a thing is possible. This will enable a variety of future missions which could include retrieval of other asteroids either by NASA or other organizations. Capturing larger asteroids would be possible by scaling up the size and power level of the robotic retrieval vehicle. JRB

Since NEA 2007 VK184 is still a 1 on the Torino Scale (and the only asteroid on the scale now), do any of you believe that it presents a high risk of impacting Earth on June 3, 2048 or any other future date?

2007 VK184 is definitely interesting for us, with 1 in 1800 chance of impact in 2048. But this does not constitute what we would call a high risk of impact. We expect this object to be recovered with ground-based telescopes around April next year and the orbit (and uncertainties) will be updated. Then we will know a lot more about where VK184 will be in 2048, and later years. Steve

Hello all! Thanks for doing this AMA!

I noticed that Brian Muirhead and John Brophy are involved with the Redirect Robotic Mission Study and Steve Chesley researches asteroid deflection techniques. Is it just a difference in semantics to say redirect and deflection? Or can we redirect an asteroid where we want it to go instead of just deflecting its path?

Interesting question. They sound like the same thing and in one sense they are, since we are just talking about changing an orbit to send an asteroid to someplace other than its current destination. But the redirection mission concept seeks to bring a small asteroid close to the Earth where we can study it and learn better how to work in space.

Deflection usually suggests changing the orbit of a threatening asteroid so that it misses the Earth. We can do that in a variety of ways, but the most straightforward is to smack into it with a spacecraft to knock it off its current course. Steve

I once read that the average McDonalds fast-food outlet has a greater # of employees, compared to the worldwide total # of people dedicated full-time to the task of searching/preventing/planning for asteroid collisions.

Is this true? If so, I think it's a good wake-up call to promote awareness.

That's an old saying that may no longer be true, but it is true that the number of people working on searching/preventing/planning is still small, probably less than 1000 worldwide. But the awareness of the hazard is growing, NASA is giving the issue more attention, and the amount of money invested in this area is growing. PC

How disappointed were you when you first learned that asteroid fields are actually nothing like the one in Star Wars?

That scene from "The Empire Strikes Back" is arguably one of the best in all six "Star Wars" movies. I particularly like the space creature that lives in the cave inside one of them. --LB

Hello NASA people :) Never asked an IAMA question before, but i was curious.

I have a 2 part question;

1) Certain wealthy individuals have been talking about mining asteroids. Is the talk of asteroid mining really viable yet?

2) would the wealth of experience and information that NASA has, be made available to private space sector to ensure the best possible chance for success?

The asteroid redirect mission would demonstrate an approach to bring significant quantities of asteroid material to cislunar space, demonstrating on aspect of the technical feasibility of asteroid mining. This material could provide a benefit to private organizations that may want to test their mining ideas or approaches. JRB

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Hi, this is Lance.
Yes, I find working on asteroids really exciting. I wouldn't be doing this type of work otherwise. One of my favorite aspects about it so to see the first radar images of an asteroid because often we're the first ones in the world to know what individual objects look like.

With all the deflection technologies available, how high on the list would a paint bomb be? The idea being that you could use a darker or lighter shading to alter its course through sunlight

Changing the reflectivity of an asteroid changes its trajectory only very, very slightly, and it would be effective only for very small asteroids. This is just not a realistic technique for deflecting asteroids. PC

Are there any good things that come from asteroids hitting or coming very close to hitting earth?

If the Chicxulub impact hadn't occurred 65 million years ago, the evolution of life ever since could have been very, very different, and humans might not exist. --LB

Hello, mechanical engineering grad student here, getting my Masters in December, two questions:

1. Is there anything amateur astronomers can do to help spot/track/whatever dealing with asteroids?

2. Can I have a job?

Hi, Many amateur astronomers worldwide contribute astrometry to help track asteroids and improve their orbits. By amateur I mean people who aren't paid for their work; in fact, they're incredibly capable, motivated, and well-equipped.

As for discovering asteroids, years ago it was possible for amateurs to discover them, but the search telescopes currently operating are so sensitive that it's very hard for amateur astronomers to find near-Earth asteroids today.

--Lance