Spaceplane - DARPA's Reusable Idea

We've been round this loop a few times before, but DARPA is never shy of trying again. So the agency plans another attempt at developing a reusable launch vehicle capable of aircraft-like operations.

A proposers' day is planned on Oct 7 for DARPA's new XS-1 program to demonstrate a reusable Mach 10 aircraft capable of deploying an upper stage to insert 3,000-5,000lb payloads into low Earth orbit, with a target cost of less than $5 million per launch at a rate exceeding 10 flights per year.


XS-1 graphic: DARPA

XS-1 is a complement to the agency's Airborne Launch Assist Space Access (ALASA) program, which aims to modify an existing conventional aircraft to air-launch 100lb-class satellites on expendable upper stages at a cost of less than $1 million a time, including range costs.

DARPA announcement says XS-1 technologies could be transitioned to support not only next-generation government and commercial space launchers, but also global-reach hypersonic and space-access aircraft (another of the agency's favorite topics to revisit).

XS-1 will need a robust, reusable first stage capable of suborbital operation, with durable, low-maintenance thermal protection, and "reusable, long-life, high thrust-to-weight and affordable" propulsion - DARPA's notional graphic suggests rocket-powered vertical launch and unpowered return to horizontal landing.

Streamlined "clean pad" operations and automatic launch, flight and recovery systems would reduce infrastructure and manpower requirements, DARPA says, and enable flights from a range of loactions (a key attribute touted for the easily and rapidly redirected and relocated ASALA).


ALASA graphic: DARPA

The XS-1 program is to have three phases, culminated in the hoped-for demonstration of 10 flights in 10 days, flight to Mach 10 as least once, and delivery of a payload into orbit at least once. The solicitation for Phase 1 initial design and risk reduction is due out shortly.