QuantumG's Blog

I've been posting lately about the threat large asteroids pose to Earth, human missions to smaller asteroids, and the opportunities that will exist in the next few decades to do so. Up until this point, my analysis has been mostly for my own education and amusement, but I'd like to make a suggestion now which I haven't seen published in the literature or seriously discussed in either NASA working groups or even in the space advocacy community. I'd like to suggest that we need not wait for an appropriate asteroid to come within range of Earth and plan human missions around just those opportunities - we can engineer a perfect close approach. Next year, at the start of June, the asteroid 2009 BD will pass within the orbit of the Moon . Even though it is not a rare occurrence, few opportunities such as this have been identified, and realistically, no-one is going to be ready to send a human mission to an asteroid for years to come. It seems a shame to let this clos...

I don't think he's given a better lecture than this.

With the exception of Hayabusa, all asteroid missions to-date have been to targets bigger than 1 km in "spherical radius". Date Encounter Asteroid Radius (km) Spacecraft 1991 Flyby 951 Gaspra 6.1 Galileo 1993 Flyby 243 Ida 15.7 Galileo 1999 Flyby 9969 Braille ~1 Deep Space 1 2000 Flyby 2685 Masursky ~8 Cassini 2001 Landing 433 Eros 8.42 NEAR Shoemaker 2002 Flyby 5535 Annefrank 2.4 Stardust 2005 Sample Return 25143 Itokawa 0.165 Hayabusa 2006 Flyby 132524 APL ~1.1 New Horizons 2008 Flyby 2867 Šteins ~2.8 Rosetta 2010 Flyby 21 Lutetia 95.8 Rosetta This has led a number of people to express dismay that all the asteroids which have been identified for human exploration missions have significantly smaller estimated sizes. Date Asteroid Radius (m) 2016 2008 HU4 ~5 2017 1991 VG ~45 2019 2008 EA9 ~6 2020 2007 UN12 ~4 2025 1999 AO10 ~35 2026 2008 JL24 ~2.5 2028 2006 RH120 ~2.5 2029 2000 SG344 ~22.5 Notice that the scale has changed from km to m. Of course...

Anyone who has enjoyed my recreational attempts at designing a human mission to a near-Earth asteroid should check out the newly released mission to an asteroid by a team at Lockheed Martin*. The report ends with these important words: The Plymouth Rock study shows that the first visits to asteroids can be easier and earlier than we have previously thought. The United States does not need to wait for more advanced technologies or develop expensive dedicated deep space vehicles. We can explore the asteroids within a decade, using spacecraft already being developed and tested. This is a reasonable statement which I agree with. As far back as Apollo the question of "are we ready?" has been asked, and despite the success of Apollo it is still being asked. I have tried to make the argument that a Dragon capsule would be sufficient for a bare-bones mission to an asteroid, assuming some modifications to life support systems, dual use of propellant and supplies as radiation s...

Video by Eric Brueton Summer studies of space settlements by Gerard O'Neill and NASA in the 70s and again in the early 90s both determined that significant amounts of mass is required for passive radiation shielding. Although structurally, most designs call for refined steel, it has been suggested that mass for the shielding could just be raw lunar regolith, left-over slag from future on-orbit industrial processing, or obtained from the asteroids. The asteroids are seen as preferable as, in terms of delta-v, they are most easily available. The typical argument is that a long duration mission to rendezvous with a near-Earth asteroid or comet (collectively, near earth objects, or NEOs) could skip a lot of launches from deep gravity wells, either digging into the NEO or dismantling and processing it to make a nearby structure, or both. The wrinkle, however, is in that "long duration" part. In terms of delta-v, there are NEOs which are easier to hit than the Moon, ...

There have been over 535,000 asteroids discovered to date and they're all different. Some 7,121 of them are known to cross the orbit of the Earth and so are referred to as the near-Earth asteroids. If you're interested in flying a robotic mission to an asteroid, you need some idea of how much delta-v your spacecraft is going to need. I've written on this before . However, if you're interested in flying humans to an asteroid, you also need to know how long the round trip is likely to be. To answer this, one needs to know both how far away the asteroid is at closest approach to Earth, and for how many days it will remain that close. To the interested public, finding this information out using the available NASA tools is a slow process, and understanding what you've discovered is difficult without good visualization. Introducing the Prospector's Skymap , a tool for visualizing Earth-centric plots of asteroid trajectories over the next 20 years, in 3d. Include...

As a target of study, NASA has identified the asteroid 1999AO10 as the 2025 destination for human exploration. We've heard that NASA plans to build a giant heavy lift vehicle to make the trip, but is it really necessary? I previously described a human asteroid mission, but I assumed the logical choice of asteroid with the lowest known delta-v (and included analysis for the second lowest too), but for some reason this isn't as interesting to NASA, so let's consider how one might do the trip to their preferred target, using existing SpaceX hardware. The reference numbers are: Earth departure stage 3291m/s, and storable propellant 3939m/s of total delta-v. We could improve this by carefully measuring the boiloff of LOX in Falcon 9 upper stages and analyzing the required insulation to do the arrival rendezvous using non-storable propellants, but I don't really have that information handy, so I'll just go with the storables. Like last time, we'll use the ...

Day one of the Exploration of Near Earth Objects Objectives Workshop saw the presentation of three key reasons to send humans to visit asteroids: science, mining and planetary protection. Of these, the last has has been shown to be an issue that attracts mainstream support, no doubt we have Bruce Willis to thank for this. The workshop began with presentations of the robotic missions that have been flown to asteroids and comets. The recently returned sample return mission Hayabusa , taking pride of place. All the presenters had war stories of the operational difficulty of flying to these objects, and some expressed surprise that their missions succeeded at all. They also talked about the high cost of these missions in terms of remote sensing equipment and the lack of good ground truth information to calibrate these instruments. Unsurprisingly then, they all support a human mission to an asteroid or a comet near Earth to more efficiently gain scientific results. However, when ...

I was recently asked, "if a killer asteroid was approaching Earth, how much would they actually tell us?" This is my response. They'd tell you numbers which you wouldn't understand. Then the pundits would turn those numbers into something they can scare you with, probably overblowing the threat while they do so, and Concerned Citizens would go to their Congressmen demanding answers. NASA would provide those answers.. in a completely unintelligible way, and someone would interpret those answers as dismissing the threat. Then there'd be a big argument over whether it's a threat or isn't it. Eventually one of the egg heads with a wife will get a lecture about talking like a normal person once in a while and a press statement would be released saying exactly how likely and excessive the threat is (after it went through a few committees to ensure it was easy enough to understand, and defend). By this time the media will be completely bored with the story ...

Back in 1978, following three successful free flights of Space Shuttle Enterprise the year before and the first lift-off of Space Shuttle Columbia only 3 years away, planetary scientist Gene Shoemaker and astronomer Eleanor Helin collaborated on a paper which presented the then shocking conclusion that some near-earth asteroids required less delta-v to reach than Mars. The near-term availability of the Space Shuttle was key, as the high flight-rate it promised meant a manned mission to an asteroid could be staged in low Earth orbit for as little as 23 flights. At the time, it wasn't unreasonable to suggest that within a few years that would be as little as 6 months of staging, and the vehicle would be reusable! Of course, the Shuttle's flight rate never got that high, and today's mission designs to Mars are measured in International Space Station masses to remind us of how long it takes to amass payload in orbit. This paper, however, remains important for the math i...

Deriders of the new NASA direction have latched on to the announced human asteroid mission in the 2025 timeframe as something they "can't imagine" and therefore is not worth doing. Of course, the administration is talking up the "science" that can be done on an asteroid, and how this could better inform us should the need arise to divert or destroy one that threatens Earth. This is good politics as nothing motivates like fear, but for those of us who think the human spaceflight program is really about preparing us to live at the future homes of humanity, asteroids would seem to be just a stop on the way - I disagree. As I've written previously, the new NASA direction isn't about asteroids - it isn't about destinations - it's about going and specifically, it's about going to Mars. I'm not sure NASA knows yet why they're going to Mars, but they're focusing on the technology to get there and get back safely, and some of the ...