SpaceHab together with ULA (Lockheed Martin) is proposing a simple cargo capsule to ISS, launched on existing rockets like Atlas V. This seems good.
Background of COTS
The space shuttle will be retired, and it takes a while before Orion starts flying, and even when it flies, it will be expensive. So NASA is looking for a cheap commercial provider to send some cargo to the ISS in the nearish future. COTS is the name of that program. Eventually it could involve moving some humans too, but that’s far out there.So far most of the proposals have been by small companies and very weird – ranging from huge aircraft carrying big pressure fed rockets to some parallel staged hybrid stacks propelling complex lifting body shapes. The picked COTS proposals were Kistler’s K-1 vehicle and SpaceX:s Dragon capsule flying on a SpaceX Falcon 9. And it has seemed already for a while that Kistler is out of the game, failing to have raised the huge money needed for their fully reusable two-stage launcher-taxi system.
SpaceX is happily working at their task and making progress but they have formidable obstacles yet to pass – so far even their simpler Falcon 1 rocket hasn’t yet reached orbit. But all the power to them.
I wondered for a while already why all the COTS proposals involved such weird and esoteric concepts when the problem could be tackled straight forward. And along came Arctus which had just that solution making perfect sense.
- Take a Centaur (Atlas V upper stage with a good and long flight record).
- The shortened LOX tank can act as the pressurized cargo container. Throw away the LH2 tank.
- Attach a CBM (Common Berthing Mechanism) to the rear of the pressurized section for attaching to the station.
- Double the Centaur’s RCS system so translation becomes possible and add more propellant.
- Add some adapters (stock Atlas V ones), one at the bottom for attaching to the upper stage, one to the top for attaching an unpressurized cargo.
- Put a Spacehab cargo mounting platform on the top adapter
They also added a heat shield to the top of the pressurized compartment (remember the CBM is at the bottom!) and a ballute for re-entry. This is a bit of an unproven technology, but could work fine, it just has not been tested very much. Only the pressurized compartment seems to re-enter intact, other parts are discarded.
Then the final leg is flown with a parafoil at low speed and low sinkrate, which enables a helicopter catch and a gentle lowering to ground. They have a video of a test on the site.
First the launcher’s upper stage (if it’s launched on Atlas V, it will be a Centaur) will fly the Arctus to a parking orbit from where it is easy to go to the ISS with fairly small RCS use. Then when it has rendezvoused with the station and is holding position nearby, the station uses its robotic arm to catch and berth the Arctus against a port. The hatches can then be opened and pressurized cargo retrieved. The unpressurized cargo can be picked up from the rear with the robotic arm or on a spacewalk.
This thread on Nasaspaceflight has some good info on it as well.
This could be a very important spacecraft in the future – an american Progress at first but expanding to something even more.
It is flexible, brings up unpressurized or pressurized cargo or both, perhaps
takes some cargo back to Earth as well if the recovery system turns out to work well. And it could be a tanker too (more about this later).
It could also be a vehicle that can launch on multiple launchers with only small modifications.
Finally something sensible from the operational US spaceflight sector!
I suggest adding the Arctus to the watch list.