— After a thorough review of cost, technology and risk factors, NASA announced Nov. 24 it had approved plans for Juno, a solar-powered mission to Jupiter, to proceed into development as it heads toward a 2011 launch.

The Juno mission, scheduled to reach Jupiter in 2016, will travel in an elliptical polar orbit gathering clues on the formation and composition of the largest planet in the solar system. By studying Jupiter, scientists hope to learn how the solar system formed.

“Jupiter contains more matter than all the other planets combined,” said Scott Bolton, Juno principle investigator at the Southwest Research Institute in
San Antonio
. “It must have formed before the other planets. If you want to understand the first step in formation of the solar system, you look at the first object formed.”

In addition, the Juno mission will explore Jupiter’s structure.

Scientists do not know, for example, whether Jupiter’s core is made of ice and rocks or is simply a more condensed version of the planet’s gaseous atmosphere. “If Jupiter has a rocky core, the solar system needed to form rocks before it could make Jupiter,”
said. “But how did it do that? What is its composition?”

NASA plans to spend approximately $250 million on the Juno mission in 2009,
said. The overall budget of slightly more than $1 billion, when adjusted for inflation, includes the cost of the spacecraft to be built by Lockheed Martin Space Systems of Denver, nine scientific instruments, launch aboard a United Launch Alliance Atlas 5 rocket and the salaries of the staff overseeing all aspects of the program from design to post-mission data analysis. NASA’s Jet Propulsion Laboratory in
, manages the mission.

The next key decision point for the Juno mission, the critical design review, is scheduled to occur this spring. If the mission clears that review, Juno contractors will begin building flight hardware and preparing for an August 2011 launch,

During the current design and development phase, Juno program officials are making detailed plans for the mission and building component parts. Electronic cards, solar panels and propellant tanks are just a few of the items already under construction, according to Al Herzl, Juno program manager for Lockheed Martin. In addition, Lockheed Martin has built 20 spacecraft emulators which are being used by each of Juno’s instrument teams in the
United States
. A Jet Propulsion Laboratory team already is building the spacecraft’s telecommunication subsystems, Herzl added.

One focus of the mission’s development phase is extensive testing of batteries and solar cells,
said. Jupiter is more than 644 million kilometers from the sun. The Juno spacecraft will be exposed to less sunlight and more radiation than any of NASA’s other solar-powered spacecraft. To compensate, Juno is designed to carry extremely efficient solar arrays and to travel in a path that helps it avoid Jupiter’s radiation belts.

“We have a very special orbit for Jupiter that avoids high radiation regions,”
said. “Radiation damages solar cells.”

Previous missions to the solar system’s outer planets relied on nuclear generators for power. By relying exclusively on solar power, Juno avoids the cost and potential delays associated with an uncertain supply of radioactive material,

The Juno spacecraft is designed to carry nine instruments in addition to a camera built by Malin Space Science Systems of San Diego to capture color images of Jupiter in red, blue and green. To study Jupiter’s atmosphere, Juno will carry a Microwave Radiometer, built by the Jet Propulsion Laboratory and the Jovian Infrared AuroralMapper designed by the Italian Space Agency.

Jupiter’s magnetic field will be studied with three instruments: a Flux Gate Magnetometer built by the Goddard Space Flight Center,
; a Scalar Helium Magnetometer made by the Southwest Research Institute; and an Advanced Stellar Compass manufactured by the

In addition, scientists will study Jupiter’s poles with a JovianAuroral Distribution experiment designed by the Southwest Research Institute, an Energetic Particle Detector built by
, a Radio and Plasma Wave Sensor made by the
Iowa City
, and an Ultraviolet Spectrograph designed by the Southwest Research Institute. The Italian Space Agency also will build a high-frequency Ka-band transponder for the spacecraft.

Juno is the second mission in NASA’s New Frontiers Program. The first mission was the Pluto-bound New Horizons mission launched in 2006. The nuclear-powered probe is en route to a July 2015 encounter with Pluto and its moon Charon.