Posts Tagged‘asteroid’

NASA’s Plan to Snatch a Space Boulder.

The last decade has seen NASA change tack quite a few times, mostly under the direction of different presidents who had very different ideas about how the venerable agency should function. Much of it came in the form of a lot of hand wringing about whether or not we should return to the Moon or simply go straight to Mars, with the current strategy to put NASA astronauts on our red sister sometime in the 2030s (although they might be too late if SpaceX has their way). This new direction included sending astronauts to a near-Earth asteroid by 2025 in order to vet some of the technology required  to eventually send those astronauts to Mars and NASA has just detailed what that mission will be.

nasa-asteroid-capture-option-b-illustration

The initial mission was going to attempt to capture an entire asteroid, one around 8m in diameter, using an inflatable cylinder that would envelope the asteroid and then return it to a cis-lunar (between the Earth and the Moon) orbit. Now this wouldn’t have been a massive asteroid, probably on the order of 8m or so, but it still would have been a pretty massive endeavour to bring it back to a closer orbit. However there was another potential option for this mission: instead of retrieving the whole asteroid a probe would instead pluck a small boulder from the surface of a much larger asteroid and then return that back to the cis-lunar orbit. NASA announced today that the second option would be the one they’d pursue going forward with the mission timeframe still slated for sometime in the next decade.

Interestingly the second option is significantly more expensive, to the tune of $100 million, however the technology that will be developed to support it was seen as being of much more benefit than the other mission. Once a candidate asteroid has been selected the craft will be launched into orbit around it where it will identify and select a boulder for retrieval. It will then land on the boulder, capture it, and then lift it back off into orbit around the asteroid again. The craft will remain there for some time afterwards to see if the idea of a gravity tractor craft could work to divert a potentially dangerous asteroid from colliding with Earth. Then, depending on how successful that was, the craft will either remain there a little longer or begin the journey back towards earth, it’s newly captured asteroid boulder in tow. Then astronauts from Earth will embark on a month long mission to travel to the asteroid, study it and then potentially bring it (or at least samples) back to Earth.

It’s an ambitious mission but one that will be the proving ground for the vast majority of technologies required to get humans to Mars. Whilst we’ve learnt a lot about long duration spaceflights thanks to the International Space Station there’s a lot more we need to develop in order to support the same duration flights away from the protection of our Earth. Specifically this relates to the radiation shielding requirement (something which still doesn’t have a great solution) but there’s also numerous other questions that will need to be answered before we launch a craft towards Mars. A month to a nearby asteroid fragment might not sound like much but it will be another giant leap forward technology wise.

NASA is stil a far cry from its heydays during the cold war but its starting to rekindle that explorer spirit that drove them to achieve such great things all those years ago. Opting for the more ambitious mission profile means that our understanding will be more greatly increased as a result, hopefully fueling further exploration with a view to us one day becoming a multi-planet species. We’re still a while away from seeing this happen but it’s so good to finally see a light at the end of the tunnel.

Rosetta’s Data Provides Clues to Origins of Water on Earth.

The origin of Earth’s water is still something of an open debate. The popular theory at the moment is that the primordial Earth was far too hot to contain any form of liquid water, its molten surface still reeling from the cataclysmic events that led to its creation. However others postulate that the water was trapped deep below the surface, only to arise later on as the Earth cooled and an atmosphere developed. It’s an interesting question not only because of how fundamental water is to life but also because we seem to have a lot more of it than any other planet in the solar system. Thus the question of where it came from, and why it’s managed to stick around for so long, is one of continuous scientific enquiry, including such missions as the recently celebrated Rosetta probe.

First_measurements_of_comet_s_water_ratio

If we run with the theory that Earth’s water came from some extraplanetary source then the question turns to what the original source might be. Comets seem like a good candidate as they’re primarily water ice by composition and were far more common during the early stages of Earth’s life than they are now. However measurements of isotopes within water of several comets, including Halley, Hyakutake  and Hale-Bopp has shown that they are not likely the primary source of water that’s currently on Earth’s surface. The composition of water found on asteroids and other water formed minerals on the Moon seem to indicate that a source closer to home is far more likely which Rosetta’s latest data appears to confirm.

The comet that Rosetta was investigating, the romantically named 67P/Churyumov–Gerasimenko, has a ratio of isotopes that is completely different to anything that’s seen on Earth. The reason that this is important is due to it’s orbit as 67P is what we call a Jupiter class comet, a collection of various comets that have orbits that don’t extend far past Jupiter. It was thought that these kinds of comets would have been more likely to have been involved in the creation of Earth’s oceans than comets from further out, due to their proximity. However 67P, with its wildly different composition to Earth (and even other bodies in the same vicinity), lends credence to the idea that comets aren’t the likely source of Earth’s oceans. Indeed it’s far more likely that water and minerals trapped in asteroids are the likely source, based on how similar their composition is.

Now this doesn’t rule out comets completely as there’s potential for further out Kuiper belt class comets to have the composition we’re looking for but it’s looking far more likely that objects from within the asteroid belt are responsible for the oceans we have today. What the mechanism was for them making their way to Earth, whether it was early on in the cataclysmic forming of our solar system or later on when things calmed down, is something that’s still an open question. It’s one we might also have answers to very soon as Dawn is scheduled to arrive at Ceres early next year, the biggest object in the asteroid belt. What Dawn finds there might be the key to unlocking the secrets of our Earth’s oceans and, potentially, the asteroid belt itself.

NASA’s Ambitious Asteroid Capture Mission.

Whilst the debate among the space enthusiast community still rages about what the next target for human exploration should be those with the capability seem to have already made a decision: we’re going to Mars. NASA has committed to getting astronauts there some time around 2030 and SpaceX’s founder and CEO, Elon Musk, has long held the dream that he’d be retiring on Mars. There’s also the Mars One which, to my surprise, is still going and garnering attention worldwide even here in my home country. The lack of a return mission to the Moon does raise some questions about the technology that will be used as we don’t have any craft capable of going past low earth orbit, not since the Apollo program ended almost half a century ago.

Orion_with_ATV_SMNASA has been working on a new crew capsule for some time now, dubbed the Orion. Initially this was part of the planned 2020 mission to return to the Moon however the majority of that was scrapped in favour of going directly to Mars. The capsule and the revised launch system were retained however and will form the basis of NASA’s future manned space missions. However if the Moon is no longer the goal for this craft and it’s end goal will be long duration flight there’s a lot of testing that needs to be done before we send one of them to Mars. Interestingly NASA has gone for an incredibly ambitious mission to put the Orion’s long duration flight capabilities to the test: an asteroid capture and analysis mission.

There’s currently two mission profiles being considered, both of them seeming like something straight out of science fiction. The first (and I’ll guess least likely of the two) is a robotic craft will make its way to a large asteroid, break a chunk of it off and then bring it back into orbit around the moon. The second would be a straight up asteroid capture with the craft grabbing an asteroid in its entirety (it would be small, about 7m or so in diameter) and, again, putting it into lunar orbit. Then once the asteroid is in a stable orbit NASA will send crew to it in an Orion capsule to study it, testing out some of the long duration capabilities as well as other rudimentary space activities like EVAs.

Such a mission is actually quite feasible (at least the latter profile) from a technical perspective. Pretty much all the technology required to capture an asteroid of that size is available today and there’s already 6 candidate asteroids identified. The main issue I see with it is time as just getting to the asteroid is planned to take at least 4 years with another 2 to 6 required for it to make the trip back. That means if the mission were to launch today it could potentially take up to 2024 before it returns to us which doesn’t leave a lot of time for NASA to test out the Orion capsule on it, This could be sped up considerably by changing it’s launch profile to include a second stage rocket to boost it rather than relying on the ion thrusters to achieve escape velocity but that would come with additional expense. There’s also the possibility of foregoing the robotic part of this mission completely and just sending humans although that poses just as many challenges as going straight to mars.

I’m glad to see NASA making a return to missions like these, ones that truly push the envelop of humanity’s space capabilities. It’s going to be interesting to see how the mission develops as there’s lots of different variables that need to be sorted out, some that will change the mission dramatically. Still the thought of us being able to capture an asteroid, bring it into lunar orbit and then send humans to study it is just an incredible thing to think about and I truly hope NASA sees this one through to fruition.

 

The Chelyabinsk Meteor: A Fireball We Didn’t (and Couldn’t) See Coming.

You’d have to be under a rock (ha!) to have not heard about the recent meteor that entered out atmosphere over Russia on Friday (which just so happened to be my birthday, what a present!). Thanks to the proliferation of cameras everywhere, predominately the dash cams which are common in Russia to avoid insurance scammers, the Chelyabinsk event was pretty well documented from multiple angles. If you had ever wondered what a decent sized asteroid air bursting in the atmosphere would look like and what it’d eventually do you couldn’t really get a better example, even from the wealth of smaller impacts that are witnessed every year.

There’s been a lot of questions about this particular event and I caught a couple of them when I was reading through the comments on some of the videos. One of them that caught my eye was one asking why there appeared to be 2 contrails (I believe it was on this video). From what I can tell that’s probably some time after the air burst as it took the shockwave approximately 2 minutes to reach the surface after it occurred. Reports from various space agencies afterwards state that there was at least 3 probable impact sites which would corroborate my idea of it breaking up after the air burst. Not that there’d be a lot of it left after that however as it was rated at something like 500kt, about an order of magnitude higher than the first atomic bombs.

By far the most common question was how we could have missed something like this when we were quite capable of tracking a near-miss asteroid that just happened to pass by 15 hours later. There are a couple factors at play here but I’ll start with the most pertinent. For starters this is actually quite a small meteor with current estimates pegging its original size at somewhere around 17m² with a total mass of approximately 7000 tons. 2012DA14 was about 2~3 times the size and several orders of magnitude heavier (~190000 tons) making it a lot easier to spot. Secondly whilst we are capable of spotting asteroids like this prior to them entering out atmosphere we purposely limit ourselves to track the bigger ones since they have a much greater chance of causing extinction level events. With greater funding to NASA and related space agencies it would be possible to get more warning about things like this before they happen.

There would still be ones that we wouldn’t see coming unfortunately as depending on their make up and direction they come from they can be incredibly hard to spot. The Chelyabinsk meteor was, as far as we can tell, rocky and this tends have quite a low albedo which makes them quite difficult to track, especially if they come from certain directions where they won’t get much illumination. Large, primarily metallic asteroids are quite easy to track and the most devastating should they collide with us, but they’re also somewhat rare so the vast majority are simply larger rocky asteroids that have a decent albedo.

It will likely be a long, long time before we bear witness to something like this again. Whilst we’re likely to capture any event of note thanks to the proliferation of cameras everywhere there’s still an awful lot of this earth where us humans just aren’t present to see it and as such many events like this go completely unnoticed. It’s a shame really as they’re quite intriguing events and they can help us learn about what will happen should a larger asteroid cross our path one day.

Mining Asteroids May Not Be Science Fiction For Long.

I’ve long heard tales of how profitable asteroid mining could be. This is because asteroids, unlike Earth, tend to have higher concentrations of rare minerals with some even being almost entirely metallic, in essence taking out all the hard work of digging it up out of the ground. However actually mining asteroids or other heavenly bodies is a devastatingly expensive exercise as you have to haul all your equipment up there, conduct the mining operation, and then safely get the minerals back to Earth. Nothing along the way is trivial and whilst there’s been a great number of advancements making the trip there and back easier no one has yet tried to tackle the problem of mining in space.

However news has started circulating of a new company that’s setting its sights on just such a lofty goal and its name is Planetary Resources.

Now any company with such a lofty goal would attract some attention from the press but Planetary Resources is doing so for additional reasons: the people who are backing this project. We can count amongst them people like Tom Jones (a former NASA astronaut), Larry Page and Eric Schmidt (Google co-founders) and none other than James Cameron himself. The list seems to go on and it’s clear that this company must have some concrete plans to actually achieve their vision in order to attract such talent and some of those plans have just come to light.

Planetary Resources has already done some of the groundwork required in order for their business model to work. They’ve set their sites initially on Near Earth Asteroids of which there are about 8,840 known (although more are discovered every year). Of those known objects approximately 150 of them are thought to be water rich and require less energy to reach than going to the moon. They are then going to launch a high powered space telescoped designed to prospect these asteroids from afar within the next 2 years. It is likely that they will attempt to find the largest of these asteroids that are close enough together, allowing one launch to reach multiple asteroids.

Part of Planetary Resources goal is to make accessing such asteroids cheaper and this will be accomplished by establishing orbital refuelling stations on the way to those near earth objects. I’ve written in the past how these kinds of stations are required if we want to be serious about exploring and establishing a human presence beyond that of our current planet and it thrills me to see a company making this idea a reality. Such stations will not only make their activities much more economically feasible it will also allow agencies like NASA to be far more ambitious with their future projects, something which they’ve been lacking of late.

Details beyond that however are somewhat scant. Planetary Resources has declined to say when they’ll be breaking ground on an asteroid so the only solid timeline we have from them is that they’ll launch a telescope in under 2 years. Whilst there’s been some research showing that a mission could potentially be done by 2025 that was entirely theoretical and put the cost somewhere north of $2 billion. Now that’s not out of reach of Planetary Resources, several of their backers have fortunes that amount to several times that, but there’s no indication that they’ll be able to meet that schedule. I’m hopeful that they’ll be able to reach their goal eventually but until we start to see some real progress from them it’s best to not speculate too heavily.

Regardless of my apparent scepticism I’m still very excited by this announcement. We’re starting to see the combined efforts of many disparate companies beginning to create a snowball effect, one that’s creating a flourishing private space industry that was only recently a science fiction fantasy. We are so incredibly lucky to be living in a time that’s akin to the aviation revolution of the last century. I’m a fervent believer that within our lifetimes we’ll see commodity level space travel and I cannot wait to be a passenger.

Asteroids, Moon and Mars: Humanity’s Next Step in Space Exploration.

To put it bluntly we’ve been spinning our wheels in terms of human space exploration. It was well over 40 years ago that we first placed one of our own on the moon and in the time since then we’ve tentatively sent out our robotic companions to do the exploring for us, staying in the relative safety of low earth orbit ever since. There is no one entity that we can blame for this, more it is a sign of the malaise that took over once the space race was won and there was no longer any political motivation to push the final frontier further. The last decade has seen a few ambitious plans put into motion in order to start pushing that envelope once again, but none of them are to bear fruit for at least a decade.

Of course I’m not expecting that we’ll see another space race any time soon, we’re far too engaged in fixing economic problems right now for another pissing contest between superpowers. However that doesn’t mean that the groundwork can’t be done for a time when countries are ready to pursue space travel with renewed vigour and NASA is doing just that with their roadmap for space exploration:

Human and robotic exploration of the Moon, asteroids, and Mars will strengthen and enrich humanity’s future, bringing nations together in a common cause, revealing new knowledge, inspiring people, and stimulating technical and commercial innovation. As more nations undertake space exploration activities, they see the importance of partnering to achieve their objectives. Building on the historic flight of Yuri Gagarin on April 12, 1961, the first 50 years of human spaceflight have resulted in strong partnerships that have brought discoveries, innovations, and inspiration to all mankind. Discoveries we have made together have opened our eyes to the benefits of continuing to expand our reach.

NASA’s roadmap lays out 2 options for the future of manned missions beyond low earth orbit with both of them converging on the ultimate goal of sending humans to Mars. The first being called “Asteroid Next” which would see our next target being a near earth asteroid favouring the development of deep space technologies. The second is “Moon Next” which would see humanity return to our celestial sister and use it as a test bed for technologies that would enable humans to survive in Mars’ harsh climate. Both options are equally valid, but they are not without their drawbacks.

First let’s have a look at Asteroid Next. The most interesting part of this idea is the establishment of a Deep Space Habitat at the Earth-Moon lagrangian point. Now you might think that this is somewhat pointless when we have the International Space Station but establishing a base beyond the comforts of low earth orbit poses many significant challenges. The ISS as it stands doesn’t have the required shielding to protect it’s occupants past its current orbital altitude and a habitat at L1 or L2 would need significant redesigns. However such rework would form the basis of the module that would carry our explorers to Mars as the requirements for a habitat and interplanetary transport are nearly identical.

Having a base at the lagrangian points also opens up nearly any destination within our solar system and could serve as an excellent base for future missions. The energy required to go from one such points to anywhere in the solar system is quite minimal and well suited to high efficiency engines like ion-thrusters. Having a presence out there would make a perfect base for sending up unmanned equipment prior to sending them to Mars or beyond.

Asteroid Next however doesn’t make any mention of technology development for Mars settlement meaning that the missions to Mars that followed would probably be short lived like their Apollo ancestors were. Asteroid Next then is very much like its predecessors in that regard, being a lot more like a one-shot event that something that would be repeatable for decades to come. This would see us push the boundaries much more aggressively (we could conceivably send a DSH to Mars by 2030) but at the risk of history repeating itself, seeing such missions as one offs.

Moon Next then sees us forego advancing deep space technologies in favour of returning to the moon and establishing a base there. This delays developing deep space technologies in favour of developing, testing and deploying habitats and supporting infrastructure in a much hasher climate than what will be faced on Mars. Technologies like the Deep Space Habitat will still need to be developed as they are crucial for the journey to Mars however Moon Next would see them developed  well over a decade later than Asteroid Next. Moon Next would also see humanities base of operations be that of a small moon colony rather than a base at a lagrangian point which is advantageous in terms of resources (if we can develop technology to harvest some of the Moon’s resources) but does require much more energy in order to launch missions from there.

Going to the Moon before Mars might seem like we’re just repeating what we’ve already done but establishing a base there would be highly advantageous to future missions, and not just future exploration. There are many cases for radio telescopes on the far side of the moon (shielded from all the signals that currently pollute Earth) and there’s the very tantalizing prospect of constructing giant optical observatories that make us of the non-existent atmosphere and low gravity. However going for the Moon first means that a potential Mars shot will be delayed much longer than it would be if we pursued deep space technologies first.

After considering both options I believe our best bet is to go with the Moon Next option. If Mars was the only goal we had Asteroid Next would be the way to go but the potential benefits of a lunar base are just too good to pass up, even if it means not getting to Mars for another decade. Many of the technologies used in developing a lunar base will be transferable to both Mars missions as well as other deep space activities. It’s a tough choice for NASA though as the arguments are equally strong for supporting Asteroid Next and I’ll be watching the debate over these two ideas unfold with a keen interest.

How Would We Defend Against a Killer Asteroid?

Earth is constantly being bombarded with all sorts of things from space. The sun constantly smashes us with solar winds and radiation, asteroids are constantly making their fiery descents and every so often we’ll have one of our own bits of equipment come back down once its reached the end of its life (or sometimes, sooner). Thankfully our atmosphere does a pretty good job of breaking these things up before they reach the ground and most of the time debris from space lands in an unpopulated area, causing little to no harm. Still there’s evidence littering our planet that tells us that large objects from space make their way down to the surface, often with very deadly consequences.

Probably the most famous piece of evidence to support this, even though people don’t usually know it’s name, is the Chicxulub crater on the Yucatan peninsula. This is the crater that is currently believed to be responsible for the mass extinction event that happened approximately 65 million years ago, the one that wiped out the dinosaurs. The impactor, a fancy name for the asteroid that made that giant crater, was estimated to be about 10KM in diameter. The collision has been estimated to have a total energy output of something like 96 teratons of TNT, 2 million times more powerful that the largest nuclear weapon ever detonated. With that kind of power being unleashed it’s then very plausible that it was responsible for the extinction of many species.

The most recent example we have of something like this, although many orders of magnitude less severe, is the Tunguska event which happened in Russia back in 1908. Whilst not technically an impact from an asteroid (or comet, possibly), it is believed that the Tunguska asteroid exploded about 5~10KM above the surface, it still managed to level an area of over 2,000 square kilometres. That’s still powerful enough to take out a major metropolitan area however, so you’d hope that we’d have some strategies for dealing with potential events like this.

Turns out, we do.

Now many people would say “Why wouldn’t you just nuke the bastard” figuring that our most powerful weapon would be more than enough to vaporize a potential threat before it could materialize. The thing is though whilst nuclear weapons are immensely powerful they derive much of their power from the blast wave that they create upon detonation. In space however there’s nothing for them to create a blast wave with so much of the nuke’s devastating power is lost, leaving just the thermal radiation to do its work. Depending on the type of asteroid¹ it will either make the problem worse or simply do nothing at all.

The better option is something called a Gravity Tug, a specially designed spacecraft launched well in advance of the potential impact event to steer the asteroid off course. In essence they’re a simple idea the spacecraft simply approaches the asteroid and then stays next to it, using ion thrusters to keep a set distance between them. Whilst the gravitational effect of the spacecraft on the asteroid is minuscule over time it adds up to be enough to steer the asteroid away from its crash course with earth. Indeed this exact idea is being proposed to deflect the potential impactor Apophsis who’s got a small chance of hitting earth in 2036. Of course this only works for asteroids we know about but our tracking is good enough now that it’s quite hard for a potential disaster causing asteroid to slip through unnoticed.

When it comes down to it having an asteroid cause significant damage is a distinctly rare event with our first line of defence (our atmosphere) doing a pretty good job of breaking up would be impactors. Still it’s good to know that despite the vanishingly small possibility of such a thing happening we’re still prepared for it, even if it means having to launch something years in advance. Maybe we’ll eventually be able to modify that technology to be able to capture asteroids in our orbit so we could utilize them as bases for further operations in space. I’m not holding my breath for that though, but it’s a nice fantasy to have none the less.

¹There are 3 main types of asteroid. The first is basically solid rock compressed together, so the asteroid is one solid object. The second is a collection of rubble that’s held together by the tenuous gravity between all the small fragments. The last are iron asteroids which are solid lumps of metal, which are the really scary ones.