DARPA seeks to bring satellite costs back down to Earth
The Defense Advanced Research Projects Agency is looking for “disruptive” new ways to improve access to space while exploring novel approaches to slashing the skyrocketing cost of military satellites.
A pair of initiatives overseen by DARPA’s Tactical Technology Office focus on developing re-useable rockets and an experimental space plane to reduce the cost of launching payloads. Another high-risk initiative focuses on the feasibility of using robots to assemble and service satellites in orbit. The program would also seek to use modular satellite components called “satlets.”
DARPA’s R&D efforts are aimed at transforming the way satellites are designed, launched and built. Pamela Melroy, a former space shuttle commander who joined DARPA in January 2013 to help oversee space systems R&D, stresses the need to get a handle on satellite and launch costs.
"One of the things that we're very concerned about is the rising cost of access to space,” Melroy says. "We think that these long development times [five years for military satellites] are what caused a substantial amount of the cost growth in these programs. So the cost of access to space is one of our major focus areas."
The price tag for military satellites is skyrocketing. Greater redundancy has yielded greater reliability but also higher cost and complexity. That means extended life cycles but longer development times.
As an example, Melroy cites cost growth for the next-generation GPS constellation now in development. A GPS satellite cost $43 million to build and $55 million to launch in early 1990s. GPS III satellites will cost an estimated $500 million each and $300 million to launch.
To get military payloads to orbit faster, DARPA has launched two programs: Airborne Launch Assist Space Access and an experimental space plane designated XS-1. ALASA would leverage a re-usable first stage to launch 100 pounds to low-Earth orbit for about $1 million, a total that includes integration and range costs.
Despite skepticism about these goals, Melroy notes, "We are well on the track for this. We plan on launching a set of 12 tests flights in late 2015 or early 2016. We're working to line up our payloads now."
Part of what is driving the effort is the cost and time required to launch satellites using reliable but expensive expendable rockets. It takes between two and three years to launch an ELV, too long to reconstitute a failed satellite capability, Melroy says.
She adds that there is military utility in 100-pound payloads, citing the possibility of launching small sensors on short notice to collect real-time data.
"Even if you really are starting with drawings and you know the system very well, building a satellite can take two to five years and then two years to launch. So there's no agility and flexibility currently in our launch capability,” Melroy said.
DARPA launched its experimental space plane program in November 2013 that would also employ a re-useable first stage capable of hypersonic speeds and a smaller second stage to boost payloads between 3,000 and 5,000 pounds into geosynchronous orbit.
DARPA’s goal for XS-1 turnaround times is 10 flights in 10 days, but one flight a week would also yield launch savings, Melroy argues.
The research agency expects to begin receiving industry proposals for how to build the XS-1 experimental space plane in January 2014.
The other key piece of DARPA’s space access is a robotic system that would be used to assemble and maintain satellites called Phoenix Satellite Servicing. "The fundamental goal is to change how satellites are built," Melroy said. "We'd like to shift to on-orbit assembly and servicing. That's going to enable us to upgrade our satellites" to extend their lifetimes.
Phoenix also would seek to adopt commercial practices like high volume, lost cost manufacturing of satellite components to transform the way satellites are designed. Expensive assets like sensors could also be reused and satellites would be more modular.
Melroy argues that future satellites should adopt the architecture used for the Hubble Space Telescope, which was designed to be serviced in space.
DARPA's vision also includes modular satellites, or interchangeable "satlets." The emerging technology could be used in a future demonstration to try to bring a retired satellite back to life. "Once you have that capability [to service satellites], could you not have a whole platform made of satlets that is essentially immortal because you just come in and you stick a new payload on it?" Melroy asks.
The basic concept underpinning satlets, including the ability to operate and communicate with each other, has been demonstrated by a California company called NovaWurks Inc.