NASA Chooses Rocket for Next Jupiter Probe

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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