Asteroid space elevators/NEO exploration missions
I'm pleased to see the idea of asteroidal and lunar space elevators
has seen a bit of discussion lately
. I was also delighted/disappointed to discover that I had not been the first to think about them at all - some of the pioneering work was done in 1981.
There's been a 75k grant to study a lunar space elevator
Paul Penzo extended the idea of space elevators and tethers to Phobos, the closer the moon of Mars. He also proposed using a rotating tether to attach a spacecraft to asteroids, to change its orbit without rockets, like a gravitational assist. Pearson and Guy Pignolet of Germany almost simultaneously conceived of the idea of a rotating tube about an asteroid, to throw asteroidal material into space, providing rocket thrust to retrieve the asteroid.
Another possibility is to use the Artsutanov-Moravec rotating tether to catch suborbital payloads and throw them into Earth orbit. The payloads could be launched either by rockets or by electromagnetic guns.
I hate all the speculation about Earth based space elevators. To me, even talking about it - as much as it excites reporters and the general public - denigrates the concept. Earth based tethers require materials made of a perfect composite of carbon nanotubes and unobtainium
. I'm not big on Lunar space elevators, either - at a length to L1 of approximately 58,000 km above the surface of the Moon, they only require pushing current technology a mere 1000x further than it has gone before...
I note, wistfully, that the last batch of asteroids I ran the numbers on
(all rubble piles
), had useful, and buildable today
tether lengths of 20 to 60km.
I haven't bothered re-running the numbers on the recently discovered class of "fast rotators"
or on the group of asteroids discovered between earth and venus's orbit (usually within a few weeks travel time from Earth, given chemical propulsion), or co-orbitals such as Cruithe
, because I'm waiting on an unpublished paper by Chris Hall
that describes how quickly a long tether would despin rocks of such little mass (which will apply to the larger NEOs to a far lesser extent)
Establishing a base on the moon, with its paucity of worthwhile materials, is establishing a road to nowhere. IMHO, NEOs have much greater material potential than the moon does. With huge concentrations of metals and basic volatiles such as water, near earth objects (NEOs - both asteroids and dead comets) are not a threat
- but an opportunity
The US is planning to spend billions on the moon in the next 16 years, and nearly nothing on asteroids and dead comets, except for Dawn
and Deep Impact
. Of the two, I love Deep impact (as our knowledge of the solar system is only skin deep), and have issues with Dawn (as the mission length is so long as to basically be a jobs program for the scientists involved, the hardware is obsolete and a dead end, and the probe's only collecting data on two distant (albiet large) bodies). Ceres was exciting back in the 60s when it was one of 12 known, but there are a few thousand rocks
that are closer and more interesting (to me, at least, I know my attitude on the subject infuriates jupiter and plutophiles, and my relationship with the Dawn project is none too good either).
The European space agency, on the other hand, has no less than 5 programs in the works to explore NEOs. Gaia
, ISO, Rosetta
, and Don Quijote
I had a brief, frustrating conversation about NEO exploration with NASA Administrator O'Keefe
at the first SpaceShipOne
launch for the Xprize
. I talked about SIMONE
, in particular, as being a low cost, fast turnaround, easily mass manufacturable, rigorously scientifically consistent and far reaching, completely useful set of exploration missions - all the things that made it mo' "faster/better/smaller/cheaper" than a multitude of other missions - and he turned the conversation over to saving the Hubble
(pricetag now 1 billion and climbing) and developing the robotics technology needed to do that one shot mission.
It was like talking to a being from another planet. All I could think of as my vision darkened around the edges was "Scuttle the hubble" - "Kill Jimo
" - "Disband NASA" - I could briefly feel the man eminating gravity waves that sucked the light from an otherwise wonderful day....
In the wake of the billions spent on Cassini
, and the billions burned on the absurdly named "Pluto Express" (technologies now retargeted as Jimo) - I wish we would focus our attentions on the small, raw material rich objects closer than Jupiter, and only a further out from the moon. But how to draw people's attention to these small worlds? Orgs like the B612 Foundation
continue to pound the fear of asteroids button, damnit.
Well, kids are getting asteroids named after them in contests
- maybe we could fund an asteroid mission by promising to name craters after each of the major sponsors?
All it would take is one rich find - on one nearby NEO - to start a gold rush. Just one.
Bonus link: Linux in space