NASA has
chosen the rocket to launch its next robotic probe to Jupiter. An Atlas 5 model
551 rocket, provided by Lockheed Martin Commercial Launch Services, will send
off NASA's $700 million Juno mission in August 2011, the space agency said.
"Getting
the launch vehicle contract this early in the process is very helpful for us,"
said Scott Bolton, principal investigator for Juno's mission
at the Southwest Research Institute in San Antonio, Texas. The early decision allows Bolton and other researchers more time to prepare
Juno's science instruments for launch conditions.
The
solar-powered Juno
spacecraft is scheduled to arrive at Jupiter in 2016, where it will spend a
year in polar orbit peering beneath the gas giant's clouds. Unlike spacecraft
that have swiveling cameras to look around, Juno will spin in orbit so its
outward-looking cameras get continual glimpses of the planet. That will allow
its instruments to study Jupiter's interior, atmosphere, and polar
magnetosphere.
Juno will
take gravitational measurements to detect the influence of any ice-rock core
hiding beneath the hydrogen and helium haze, revealing the planet's internal
structure. The probe will also use a microwave spectrometer to study how much
water and ammonia compose the planet's
atmosphere.
Because Jupiter contains most of the water in the solar
system, studying its current water abundance may help scientists understand how
much ice was present when the planets were just forming.
Several
instruments onboard Juno will also observe Jupiter's magnetic field and
magnetosphere. The Jovian Auroral Distributions Experiment (JADE) will study
the charged particles that interact with the planet's
magnetic field to make up Jupiter's aurora – a phenomenon similar to the
Aurora Borealis or "northern lights" of Earth.
Meanwhile, the Juno Ultraviolet Spectrograph (UVS) will
study the ultraviolet emissions of the aurora by taking images directly above
the north and south poles of Jupiter. Scientists can then combine the
simultaneous observations with direct images of the aurora to get an overall
picture of the planet.
An earlier
delay in the Juno mission proposal allowed Bolton and his colleagues to add an infrared instrument supplied by the
Italian Space Agency. The infrared spectrometer will provide additional views
of both Jupiter's atmosphere and aurora.
Previous
missions that involved flybys or long term orbits of Jupiter – including
Pioneer, Voyager, and Galileo – laid the groundwork for scientists to further focus
their attention on the solar system's largest planet. The Cassini and New
Horizons probes also performed
flybys.
"What we
learned was that Jupiter is very important if we're going to understand origin
of planets and how they're made," Bolton said. By selectively studying certain planetary features, Juno will help
further that understanding, he added.
Juno will
be the second mission in NASA's New Frontiers program. The planned spaceflight
will undergo design reviews in May, after which it will receive flight
confirmation and enter the critical design phase.
NASA also
chose an Atlas 5 rocket to launch a separate science mission, the
Earth-watching Landsat Data Continuity Mission, slated for a July 2011 liftoff.
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