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Thursday, November 20, 2014

Day late and a dollar short

Last week the ESA's Rosetta mission successfully landed the Philae probe onto the surface of Comet 67P/Churyumov–Gerasimenko. Philae bounced several times before finally landing on the side of a cliff. A gentle reminder that for more critical missions which require landing, there is real virtue in having an actual human pilot at the controls.

The total number of bodies in the solar system we have successfully landed anything on intact now stands at seven; the Moon, Venus, Mars, Titan, the asteroids Eros and Itokawa, and comet Chury-Gery. We have returned samples only from the Moon, and asteroid Itokawa.

The next big robotic exploration destination will be when the Dawn spacecraft reaches Ceres next spring. I'm inclined to think that the Dawn Ceres data will be a game-changer in how we prioritize our upcoming human space exploration missions. As such, we'll be following it closely, here.

Friday, November 14, 2014


45 years ago today, this happened. Apollo 12, 37 seconds after liftoff, was struck by lightning, which wiped out all of its onboard electronics. The day was saved, the mission went on successfully. And "SCE to AUX" became t-shirt code for "I am the biggest geek in the room."

Ice Castles

Apparently this is still so classified that it cannot be read by a blogspot embed code, but the URL here is good.

This is a previously classified video about the US Army's nuclear powered under-ice facility in Greenland, called Camp Century. It didn't work very well, because the Greenland ice sheets were far more mobile than had been previously understood. But the techniques used here could be adapted to Ceres, Europa, or Enceladus. Note however the enormous logistics that were required to make this happen.

Sunday, November 9, 2014

Kung Fu

If I wanted to fly to London from Seattle, it would cost me about $1300 round trip on a Boeing 747-8. On the other hand, if I needed to purchase a Boeing 747-8 for myself to get to London, that would cost me around $370,000,000. If I had to purchase my own Boeing 747-8 to fly to London, but I could only fly it one time and one way, and would need to buy a second 747-8 (which could also be used only one time) in order to get back to Seattle, now we're looking at almost 3/4 of a billion dollars just in aircraft alone, for a single round-trip flight to London. I like London, it's an amazing city, but not for that price. Divide $740,000,000 by 470 passengers and that comes down to about a million and a half dollars per person; still pricey but I personally know people who could do it, if they sold all of their stuff. If, instead of only using the aircraft for a single one-way trip we could use it over and over, in only six hundred trips at $1300 a seat we will have paid for the aircraft.

So, if I translate this for a colonization mission to Mars, in order to build any permanent colony of any size at all (on Mars, or the moon, or really anywhere) then I need my rockets to leave earth, land on Mars, leave Mars and then land back on earth, in more or less the same configuration it took off in. This is reasonable, but unfortunately this is not, to date, the way spaceflight has been able to work.

If we look at the Apollo/Saturn V moon landings as a baseline of the physics needed to send and return humans to and from another world, it is apparent that in order to reach space and return from it, a spacecraft must almost continually shed excess weight. Saturn V stood some two million kilograms on the launch pad, whereas the Apollo command module which ultimately splashed down weighed maybe a thousand kilograms. This is sloppy, expensive and wasteful, but it is the only way to get a payload of this size into space with current technology.

Tsiolkovsky's rocket equation;

in which the weight of the rocket and fuel at the beginning of the launch and at the end of the launch must not exceed the effective exhaust velocity of the rocket. With existing propellants, it is nearly impossible to lift a payload of any real size even to low earth orbit with only a single rocket stage.

So, almost certainly, the first spacecraft to land humans on Mars will be of this Saturn V-type design, either SLS/Orion, or something very much like it. For exploration missions, this is fine, albeit expensive. The advantage is, we already know how to do this. For a colonization mission, the spacecraft are going to need to be much more like a 747, as far as re-useability. Elon Musk is going to want his rockets back, so he can use them again. Simply piling up hardware on the Martian surface, or at the bottom of the Atlantic, is a lousy business model.

SpaceX has already developed a vertical takeoff and landing rocket prototype, called Grasshopper. It is elegant, but burns lots and lots of heavy propellant to be able to control its landings. It is noteworthy that to date, no SpaceX cargo rocket to the ISS has actually utilized this technology, opting instead for multistage rockets and parachute descents. Adding the fuel weight for a Martian descent and surface escape launch, and still having the delta-v to reach orbit, is challenging at best. But necessary, if Martian colonization is going to be available to anybody but the very, very wealthy.

Tuesday, November 4, 2014

To Europa, by Bush-Pilot

In retrospect, probably the single biggest flaw in the space shuttle concept was creating a spacecraft to carry crews and cargo at the same time. No other method of transportation typically works this way. Whether you're talking about aircraft, trains, ships or whatever, passenger vessels carry passengers and cargo vessels carry cargo. Yes, a large passenger vessel might incidentally take very small amounts of cargo, and once upon a time cargo ships might take a handful of passengers, but nobody was going to mistake a passenger vessel for a cargo vessel. Except, you know, Alaskan Airlines flights inside Alaska. NASA seems to be steering its SLS rocket in the direction of alternating flights between crews and very high-dollar cargoes, rather than trying to accommodate both in a single flight. It's a subtle but important next step in mainstreaming spaceflight into the transportation industry as a whole.

According to Chris Bergin at (probably the best free space blog in the world, and its attendant pay site L2 is without parallel) NASA has padded its newest internal manifest for SLS with flagship robotic missions to Mars and Europa, and single-launch space stations interspersed with Orion crewed missions, in order to boost the launch rate to at least one per year. Taking advantage of SLS's enormous speed for robotic missions to the outer solar system seems a very logical extension of this, and further integrates crewed and uncrewed space exploration into a single, more unified program. For deeper space exploration, the payload capacity to carry space telescopes which could dwarf the James Webb has interesting potential as well. This program is evolving into a deep-space workhorse, analogous to what the space shuttle was supposed to be for Low Earth Orbit. Interesting times.