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access to space is one of our major focus
Indeed, the price tag for military sat-
ellites is soaring. Extensive redundancy
has yielded greater reliability but also
higher cost and complexity. at means
extended life cycles but longer develop-
As an example, Melroy cited 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 now in development
will cost an estimated $500 million each
and $300 million to launch. e Air
Force is scheduled to begin launching
jam-resistant GPS III satellites as early
To get military payloads to orbit fast-
er, DARPA has created two programs:
Airborne Launch Assist Space Access
and an experimental space plane, des-
ignated XS-1. ALASA would leverage
a re-usable rst 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 said, "We are well on the track
for this. We plan on launching a set of
12 tests ights in late 2015 or early 2016.
We re working to line up our payloads
Part of what is driving the e ort 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 said.
ere is military utility in 100-pound
payloads, she said, citing the possibility
of launching small sensors on short no-
tice 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
ve years and then two years to launch.
So there s no agility and exibility cur-
rently in our launch capability," Melroy
DARPA launched an experimental
space plane program in November 2013
that would employ a re-useable rst
stage capable of hypersonic speeds. A
smaller second stage would then boost
payloads weighing between 3,000 and
5,000 pounds into geosynchronous or-
bit.DARPA s goal for XS-1 turnaround
times is 10 ights in 10 days, but one
ight a week would also yield launch
savings, Melroy said.
e research agency planned to begin
receiving industry proposals for how
to build the XS-1 experimental space
plane in January 2014.
e 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. " e
fundamental goal is to change how sat-
ellites are built," Melroy said. "We d like
to shi to on-orbit assembly and servic-
ing. at s going to enable us to upgrade
our satellites" to extend their lifetimes.
Phoenix also would seek to adopt
commercial practices such as high-
volume, lost-cost manufacturing of sat-
ellite 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 an architecture similar
to that used for the Hubble Space Tele-
scope, which was designed to be ser-
viced in orbit.
DARPA s vision also includes modu-
lar satellites, or interchangeable "sat-
lets." e 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.
Industry watchers note that the
DARPA initiatives are part of a trend
toward reducing the cost of launching
and maintaining satellites. Phoenix is
an "interesting combination of very
far-term technologies" that neverthe-
less addresses an immediate need in
the satellite industry, says Paul Guthrie,
senior economist with the Tauri Group,
a technology consulting rm based in
e robotic assembly and servicing
components of the Phoenix initiative
build on earlier "proximity operations"
e orts designed to automate critical
rendezvous and docking maneuvers in
space. NASA expects to launch demon-
stration ights as early as 2014 to test
new proximity ops techniques.
Phoenix is also part of an e ort to
"disaggregate" satellite components as
a way to reduce soaring costs. One goal
is to build modular satellites based on
common components like buses and
"The fundamental goal is to change
how satellites are built. We'd like to shift
to on-orbit assembly and servicing."
-- PAMELA MELROY, DARPA
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