DARPA's Secret Space Slingshot?
A Trident missile is not the only way of putting a warhead anywhere in the world on target at short notice. A couple of weeks back I mentioned the Slingatron, which appeared in a US Army report on possible low-cost routes to space. The idea of a giant spiral Hula Hoop, somewhat bigger than a football stadium and oscillating at about nine revolutions a second, may seem a bit radical to some people. But – if you didn’t know already – no idea is too radical for DARPA. Budget documents reveal that they are not just doing studies. They have their very own Slingatron program , budgeted at at $3 million for 2006 rising to $4 million in 2007. Here's how it's described:
The Slingatron program will use modern engineering and physics concepts to accelerate masses to extremely high velocities. This mechanical mass acceleration concept, based on using centripetal body forces, is fundamentally different from electro-magnetic accelerators and hence avoids the limitations of those machines. Initial studies have demonstrated the fundamental feasibility of the Slingatron concept. This program will explore the concept’s bounding limits and seek to develop uses for the technology within those limits. Included in this program will be studies of the key technologies that will allow the accelerator to achieve very high projectile energies.
The program plans are nothing if not ambitious, aiming to:
- Fabricate experimental launchers.
- Demonstrate mass launchers that range in capabilities over three to four orders of magnitude.
- Demonstrate mass velocities on the order of several km/s and perhaps higher than 10km/s.
However, a perusal of DARPA’s latest plans showed no sign of the Slingatron. I checked with the Agency itself, and spokeswoman Jan Walker advised me:
"We did some preliminary investigation and results were not promising, so we decided not to proceed further."
This could mean one of two things. Either the idea is too crazy even for DARPA, and it really cannot be made to work. Or else it does work, and the whole thing has gone underground, with a giant black program somewhere to construct one of these things. If a huge rotating structure appears in your neck of the woods, accompanied by occasional whooshing sounds and shooting stars…I’d advise you to stay quiet about it.
THERE'S MORE The U.S. Air Force has its own ideas about ground-based space launchers according to this piece in New Scientist magazine. The work is being carried out by LaunchPoint Technologies who are working on an innovative magnetic space launch system. It’s based on a sled which works like a maglev train running on a circular track. When it reaches a high enough speed - which might take a large number of revolutions - it is diverted off the track and off into space. LaunchPoint suggest that they will be able to put payloads into orbit for as little as $750/lb for their first system, perhaps later dropping to $100/lb, against current costs of $4,000/lb or more. Such a device could also be used to launch projectiles. The initial capital cost would be expensive – but then Trident submarines are not cheap either, and they're not so useful for putting up satellites.
-- David Hambling
Sorry, scientific papers are here:
http://www.slingatron.com/publications.htm
Especially this:
http://www.slingatron.com/Publications/Linked/The%20Spiral%20Slingatron%20Mass%20Launcher.pdf
On the physcis of using a slingatron for space launch
Posted by: David Hambling at June 6, 2006 3:51 PM