QuantumG's Blog

There's so many things packed up in this clip. For a start, the House isn't trying to cut the James Web Space Telescope (JWST) because "we don't have the money" or to save money or for any budgetary reason what-so-ever. The House is trying to cut JWST because the Government Accountability Office reported that NASA, and the contractor, have been mismanaging this program. They reported this three different times and required reports on what NASA was going to do about it - NASA didn't provide those reports. The House even said that the reason they were looking to cut JWST was to send a message that ignoring oversight will not be tolerated. Does that mean the JWST isn't important? No.. no-one is saying that. Everyone agrees that JWST is important and that it will give results of significant scientific discoveries should it ever be completed and launched.. but when will that be? Within a two week period - after the House suggested cutting the budget ...

It seems pretty obvious that we don't currently have the technology to become a spacefaring civilization. Certainly there is stuff in space we could be doing using existing technology, and with great expense, but to really begin the human utilization and colonization of space we need a large variety of technological innovations. Jon Goff gave a great list of short term technologies that need to be developed before we can really consider society to be spacefaring. This should be the start of the story.

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, ...

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 ...

Back in 1967 the Bellcomm put together a study for the then Manned now Marshall Spaceflight Center. The mission was a one year human flyby of Venus . The study included some innovative stuff, like using the Earth departure stage tanks as a living module after venting any remaining fuel into space, but it also contains a fair bit of misinformation about radiation exposure, advocating that no attempt be made to shield against galactic cosmic radiation. This is to be expected. What isn't expected is that this is still the general consensus today, even though a more recent computational study has provided some interesting numbers for various shielding materials. Shield Material (5g/cm^2) Annual radiation dose (mSv*) Aluminum 542 Polyethylene 450 Iron 581 * Quality factor recommended in ICRP-60 is assumed. This looks pretty good when the astronaut lifetime radiation limits are considered. Astronaut age Career effective dose limits (mSv, average life loss) Males Female...

In my last post about the Russian space program I said that cosmonauts regularly throw stuff in space so it will burn up and not result in permanent space junk. A reader asks whether you can actually do this.. Man, way to ask a hard question. Orbital mechanics says "if a space vehicle comes within 120 to 160 km of the Earth's surface, atmospheric drag will bring it down in a few days, with final disintegration occurring at an altitude of about 80 km", and we can work out how much delta-v a cosmonaut has to impart to get the semi-major axis of the orbit of the debris below 160 km. dVA = sqrt(GM*(2.0/rA - 1.0/((rA + rB) / 2.0))) - sqrt(GM/rA) where rB = 160km + roE where rA = 278km + roE to 460km + roE where roE = 6378.1km where GM = 6.67300 * 5.9742 * 10^24 * 10^-11 with the ISS at 278km the delta-v retrograde is 34.684365m/s or 77.5867148 mph, which is major league baseball. with the ISS at 428km the delta-v retrograde is 77.243278m/s or 172.788292 mph, with is sp...

In James Dewar's latest book he proposes the development of a new solid core highly enriched uranium rocket engine based on the B-4 core developed in the Rover/NERVA program, but unlike that program he recommends starting small, testing in a dedicated exhaust processing facility and building successive generations of engine to prove safety and gain operational experience. The first engine to be put into operation would have 40,000lbf (800MW), an ISP of 1,000s and weigh 6,000lb. It would have a maximum burn time of 15 minutes. The gross mass for the stage would be 91,000lb with 45,000lb of LH2 fuel, and a 3,000lb cocoon to recover the engine, to deliver a 17,000lb payload to LEO*. The stage would be dropped from 50,000ft by a cargo plane (such as the C-5A), and solid rocket boosters would carry it to 100,000ft before the solid core engine engages. The deorbited engine in its cocoon would be recovered from a splashdown for processing, as the U-235 would only be ~1% spent in the...

The public is incredibly easy to fool. Way back in 2004, Mike Melvill made history by flying Burt Rutan's beautiful creation SpaceShipOne across the unofficial border to space, twice, and later that year Brian Binnie did it again, winning the Ansari X-Prize and raising the hopes of all that private access to space had finally arrived. But how did they do it? There is no question that Burt Rutan is a natural genius at aircraft design. His true innovation on SpaceShipOne was the shuttlecock styled effortless reentry system, and in particular, the ease of replacing these two large booms after a few flights to mitigate wear. SpaceShipOne/Two is a glider, and just like the Space Shuttle the wings are "only" used on the way down. There are wings used on the way up, of course, they are on WhiteKnightOne/Two, but once separated from the carrier aircraft the only lift is generated from the rocket. As smart as Burt Rutan is, he's not a rocket guy. For SpaceShipOne he...

I forget what inspired me, probably discussions about propellant depots, but after an hour of two playing around in the great spaceflight simulator Orbiter I decided to give the old orbital mechanics another go. I've written dynamic physics simulators before which have really nice accuracy and can handle the big numbers required for orbital simulations, including three body problems, but I never managed to tackle the classical orbital mechanics - too much Greek terminology I guess - until today. I set myself a somewhat difficult task: Given a position vector r and a velocity vector v , somewhere above a reference (say, a planetary body) calculate all the required classical orbital elements: a - semi-major axis e - eccentricity i - inclination l - longitude of the ascending node w - argument of periapsis t - true anomaly There's others, but they can be derived from these. You'll also note I haven't used any Greek letters that my keyboard doesn...

The Book Of The Week this week is Peter F. Hamilton's "Fallen Dragon". Although there's some similarities to military tales like Starship Troopers, the book is primarily a commentary on the ever encroaching power of multi-national corporations on our society and the individualist to community to national government struggles to live with it, along with some transhumanist alternatives. Corporations in the future described by the book have taken over space colonization and found a somewhat inelegant solution to the problem of how to turn a profit: armed robbery. Of course, legally they're on sturdy ground - euphemistically referring to the practice as "asset realization" - but it's nothing more than tax extraction through force and so serves as a neat covert commentary on the origins of government power. Hamilton's gift is his efficiency of description, and with space technology he manages to simultaneously summarize the great concepts for t...

The Book Of The Week this week is Stephen Baxter's "Manifold Time". The reason I love this book: rugged individualism. Sure, there's other great threads in this book and some interesting cosmology, but the memorable part of this story is the huge balls on the main character. Reid Malenfant is an unapologetic space cadet and serial entrepreneur, who has a plan just crazy enough to work: he's going to claim an asteroid. With a shout out to Robert Heinlein he ignores a recently passed law preventing his liftoff, not to mention a few laws related to non-proliferation of nuclear materials, and heads off to his very own squid-infested home among the stars. Oh, I didn't explain the squids did I? :) Buy it on Amazon .

Once again, SpaceX's launch schedule has slipped, this time to no earlier than May 8, 2010 .  The previous date was April 12, but it seems they were never going to hit that date.  Of course, this doesn't mean the date hasn't been widely circulated.  The upcoming "space summit", at which President Obama is reportedly going to rally the troops to get behind commercial crew, was planned for 3 days after the launch.  For those out there who would assign some intricate public relations oriented reasoning to SpaceX's latest schedule slip, I'd like to remind them that slippages are nothing new for SpaceX.  The simple fact is, SpaceX has no idea what they're doing when it comes to PR.  If they did, they would have *made it clear* that they were not going to take advantage of the April 12 launch date long before now.  They would issue press releases about what the public is interested in, not about contracts they've signed for missions that are contingent o...

"NASA will immediately begin to realign programs and organization, demonstrate new technical capabilities, and undertake new robotic precursor missions to the Moon and Mars before the end of the decade."   - President George W. Bush, Vision For Space Exploration, 2004. “What is needed is a carefully thought out plan to characterize and demonstrate ISRU on the lunar surface first with a series of robotic precursor missions, building up knowledge and capability with time, and ultimately supporting and provisioning human presence on the Moon. Such an architecture is possible within the proposed budget envelope.”   - Dr Paul Spudis, The Once And Future Moon, 2010.   (and you have no idea how much violent agreement went into getting that quote.) There's no question that robotic missions are valuable precursors to manned missions.  Without the results of the seven spectacular Surveyor landings the design of the Apollo missions would have been a lot different, and may ...