BOULDER,
Colo. - Scientific and technical teams from NASA and the European Space Agency
(ESA) are fleshing out ideas for the next mission to fly to an outer planet -
either to Jupiter or Saturn. A decision on which of those two exploration targets
will be the destination for the space agency's next multibillion-dollar
flagship mission is expected by year's end.
"We have
the outer planet flagship mission in the [NASA] budget ... I do believe it will
happen," said Fran Bagenal, a professor of astrophysical and planetary sciences
at the Laboratory for Atmospheric and Space Physics at the University of
Colorado, Boulder. "I couldn't have said that four years ago ... now I have great
confidence that this will happen."
Bagenal is
chair of the Outer Planets Assessment Group (OPAG), which was established by
NASA in late 2004 to identify scientific priorities and pathways for
exploration in the outer
solar system.
In 2007,
NASA completed a series of studies for flagship missions, honing down the list
to the two candidate missions that now are under further study by both NASA and
ESA.
Down-selection
this year
During a
two-day OPAG meeting in late March, officials provided a status report on the
two outer planet exploration concepts now on the table: a Europa-Jupiter System
Mission and a Titan-Saturn System Mission. Each of those mission scenarios has
multiple components with both ESA and NASA contributing to whichever outer
planet investigation is down-selected.
The
Europa-Jupiter mission involves two orbiters with instruments designed to
operate in the severe radiation environment of Jupiter. In addition to ESA and
NASA, Russia also has expressed interest in the mission, proposing a Europa
lander.
The
Titan-Saturn flagship entails a main spacecraft that would orbit Saturn and
deployment of secondary spacecraft to the surface
of Titan. For the secondary spacecraft, there are proposals that would
include elements such as a balloon for exploring the atmosphere, surface probes
and even a mini-submarine for exploring lakes on Titan.
"We are no
longer doing studies ... we are now getting ready for a mission," said Curt
Niebur, program officer for outer planets research at NASA headquarters in
Washington. Money to push forward on an outer planets flagship, he said, is contained
in NASA's 2009 budget - with ESA conducting a down-select process through its
Cosmic Vision process.
Potential
partners
"There are
between one and five different spacecraft elements that comprise these
missions," Niebur noted, along with potential contributions from the Japan
Aerospace Exploration Agency, as well Russia's Federal Space Agency.
"At this
point we have firm agreement with ESA. We don't have firm agreements with other
potential partners," Niebur added.
For NASA,
the outer planet flagship mission is cost-capped at $2.1 billion, Niebur said.
"That's all the money we have ... that's all the money NASA has to put towards
this."
NASA and
ESA will both down-select to one outer planet mission this fall, Niebur
explained. The mission to the outer planet would be launched via an Atlas 5, a
Delta 4 Heavy or an Ares V no later than 2017. The launch would be
designed to send the spacecraft on a lengthy cruise toward its destination but
one that would be no longer than seven years.
Leonard
Dudzinski, NASA's program officer for radioisotope power capability, said the
outer planet flagship would make use of Multi-Mission Radioisotope Thermoelectric
Generators.
At present,
there is enough plutonium-238 dioxide allocated for 800 watts of power for an
outer planet flagship mission - although due to the shortfall
of the nuclear fuel, "we've encouraged studies this year to look at reduced
power requirements to save some of that plutonium," Dudzinski advised the OPAG
attendees.
Eyes
wide open
NASA and
ESA also are planning to issue a joint Announcement of Opportunity for
scientific experiments to fly on the mission. The first of three NASA-hosted Outer
Planet Flagship Mission Instrument Workshops is to be held June 3-5 in
Pasadena, Calif., Niebur said.
"Whether or
not it's Europa or Titan as the major target isn't at all clear," Bagenal said.
Two large science definition teams are working hard to make these missions
happen, she said.
Bagenal
emphasized that by careful, early study of these missions it is hoped that any
cost overrun can be short-circuited.
"There's no
point in having an outer planet flagship mission that ends up costing so
much that we can't afford to go to another target in the outer solar system for
another 15 years or 20 years," Bagenal pointed out. "So we really have the
pressure on us to make sure that we can do something that is technically and
fiscally responsible."
Whatever outer
planet target is chosen - likely to occur this November - getting to that
locale is tough, Bagenal told SPACE.com, be it taking a payload to the
surface of Titan or going into orbit around Europa.
"The
technologies are being worked ... they are being lined up," Bagenal said.
"It's just
an issue of can you be clever and squeeze things down and do things very
efficiently to save money. And it's money, money, money," Bagenal said. "All
these studies are being done to make sure we're going in carefully ... with our
eyes wide open."
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