Darpa, the infamous and occasionally astounding research and development arm of the US military-industrial complex, has a bold plan to cut the cost of launching satellites: Strap a rocket to the bottom of a fighter jet and launch it into space from high altitude.
While this isn’t exactly a novel approach—Orbital Sciences’ Pegasus platform does something similar, and Virgin Galatic’s planned Launcher One system would also use a plane-rocket combo—what is impressive are the metrics: Darpa wants to be able to launch 100 lbs (45 kg) satellites on 24 hours notice, at a cost of less than $1 million.
Boeing is the main contractor on project ALASA—Airborne Launch Assist Space Access program—and expects to launch 12 test missions starting in 2016.
Right now, launches are scheduled years in advance, and while satellite pricing is opaque, the cost of putting such a payload in orbit would likely be in the tens of millions of dollars, depending on the rocket used. That has hurt satellite development, since it’s hard to launch and test them on the fly. And it has limited the ability of the US government to replace ailing satellites quickly.
While some of the savings comes from the use of the jet aircraft to carry the satellite to high altitude, Darpa says its biggest technological leap is in the fuel tank, where researchers hope to combine fuel and oxidizer, typically separate in liquid rocket engines, in one fluid. If successful, this fuel could also contribute to advances in much larger rockets.
Of course, 100 lbs is a relatively small payload for orbit—where the average known satellite’s weight is 4,623 lbs (2097 kg)—or for taking humans on exploratory missions. But there is increasing excitement about the possibility of using large constellations of small, relatively low-flying satellites for everything from photography to terrestrial internet access, and this experiment represents perhaps the cheapest way to deploy such a constellation into orbit.