http://itar-tass.com/en/non-political/774837So no more cheap rides on Dnepr for cubesats and other smallsat friends.
What kinds of current or near term upper stage concepts exist oriented for smallsat and smaller (microsat,cubesat) heterogeneous cluster launches? With Dnepr stepping out of the market, is there enough of a market now for a such an upperstage, or do the cost metrics potentially swing towards single smallsat/small number of cubesats type dedicated launchers now?
For reference, Dnepr's upper stage, called the "Space Head", a repurposed ICBM MIRV bus, is a tractor rocket configuration upper stage, but it does a 180 turn after being released then goes on it's merry way. It can be configured with one or two main cargo deck platforms, the largest cargo centered on the deck platform, and assorted other ride-along cargo ringing the large payload on the deck. While actively tractor thrusting, the Space Head drops payloads at a precise orbital parameter as it jets up and away, a convenient leftover of it's MIRV bus heritage to provide precision targeting for MIRV warheads (compared to traditional upper stages that shutdown the thruster and coast before payload release, with associated sloppiness in orbital parameters due to uncertainties from engine shutdown thrust).
Assuming russia doesn't restart cheap commercial launches via Rockot or similar (russian navy is currently itching for SLBM launch practice, but has there been any movement for a Bulava based commercial launcher?), non-US (and thus non-ITAR restricted) launch opportunities are not so great, in terms of both availability/opportunity and cost.
So how would one design a mass heterogeneous cubesat carrier style upper stage, preferably sized to allow riding on multiple commercial launchers? As a working concept, one could imagine a DragonLab with an extended trunk might be workable, assuming the pressurized cargo in the Dragon capsule has no serious orbital preference. Though how one would go about ejecting the the subpayloads is a bit of an issue. Replicating the Space Head method and having a deck or two inside the trunk and lightly thrusting while dropping sats might work. A small arm picking cargo out of the trunk and tossing them overboard is another method. If a smallish momentum exchange tether can be deployed, one could sling payloads higher while also lowering DragonLab, though that would have to be near the end of a DragonLab run to respect zero-g needs of pressurized cargo.
A from-scratch concept might also look like a corn-cob, with a traditional cubesat ejector per sat. The same arm thrower or MX tether thrower would also work here. Going slightly crazier, use some sort of linear catapult frame in the core/spine of the upper stage to eject payloads faster for orbit raising (maybe use an ED tether as a power source). Though that tends to resemble a railgun with a magazine of oversize bullets.
Thoughts? I suspect Jim will shoot this down in a heartbeat, but he may have a hard time denying this is a major market shift.
