Juno is on the clock for August blastoff to Jupiter
BY STEPHEN CLARK
Posted: April 11, 2011
TITUSVILLE, Fla. -- Engineers and scientists eagerly unpacked the Juno spacecraft from its shipping crate Saturday, kicking off nearly four months of launch preparations before the $1 billion mission is shot toward Jupiter this summer.
"It looks exactly the same as we left it," said Tim Gasparrini, Lockheed Martin's Juno program manager. "That's a great feeling."
A first look at the 3,000-pound spacecraft revealed it survived the arduous trip, which began early Friday at Lockheed Martin's facility on the southwest side of Denver.
After launching this August, the mission will get to Jupiter in 2016 for a year's worth of science observations and research aimed at digging up clues on how the giant planet formed in the violent early years of the solar system. Researchers say Juno's work at Jupiter will yield information on how all the planets formed in the wake of the collapse of a star-forming cloud of dust, or nebula.
But first Juno must pass through another four months of integration and testing in Florida.
Enclosed within a specially-built cargo container, Juno left its factory in a convoy that winded through Denver freeways to Buckley Air Force Base, where a C-17 Globemaster waited to receive it.
The six-sided spacecraft was loaded into the C-17 along with a separate box containing its high-gain communications antenna. The cargo plane also hauled hardware to help open Juno's shipping crate.
NASA and Lockheed Martin paid the Air Force about $120,000 to use the plane. It's safer for the spacecraft and is easier on the workforce to ship Juno on an aircraft than take it on a winding overland route lasting several days.
The aircraft, fresh off overseas duty in the Middle East and Southwest Asia, took off from Buckley for a three-hour flight to Florida, where it touched down at the Kennedy Space Center's space shuttle landing strip just before 8 p.m. EDT. The spacecraft was trucked to the Astrotech processing facility here a few hours later.
"The vast majority of our investment is sitting right there in that box," Rick Nybakken, Juno's deputy project manager from the Jet Propulsion Laboratory, said as the Air Force crew delicately unloaded the spacecraft from the cargo plane.
"It's phenomenal to see Juno here in Florida," said Jan Chodas, the mission's project manager at JPL. "This is the culmination of months and years of long, hard work on both sides of of the Rockies."
Crews have 20 days of schedule margin between now and Juno's Aug. 5 launch date, so there's plenty of time to address any problems that might develop in final testing.
That's because Lockheed Martin shipped Juno on the date the company advertised when the mission's launch was set for August 2011.
"This is a huge step in the process," said Tim Halbrook, manager of Juno's final launch preparations. "We're shipping on the day we intended to ship from the beginning four or five years ago."
Juno will blast off on the most powerful version of the Atlas 5 rocket with five solid rocket boosters. Liftoff is set for Aug. 5 at 11:39 a.m. EDT (1539 GMT).
Because NASA must launch Juno on a narrow trajectory to reach Jupiter, the mission only has about three weeks to get off the ground. The launch period closes Aug. 26.
Officials don't expect to need the 20 days of "slack time" in the processing schedule this summer. The spacecraft, measuring about the size of helicopter, was put together in Denver over the winter and thoroughly tested in the environments it will encouter during launch and at Jupiter.
Halbrook said Juno has had its growing pains with avionics and scientific instruments, but everything worked perfectly when engineers assembled all the parts together.
"When those components arrived and we threw it all together, they have worked," Halbrook said. "It's a very well-behaved spacecraft based on my experience."
Juno was supposed to be moved from the base of its shipping container to a work dolly Monday. Officials expect to power up the spacecraft for functional testing Tuesday.
"Then we'll go into a series of powered tests until April 20, when our command and data handling and flight computers arrive from Denver," Gasparrini said. "They were undergoing a little testing. They'll get here on the 20th, then we'll put them in and get into another test program after that to fully check out the spacecraft and get it prepared for launch."
The three solar arrays and high-gain antenna will be bolted to the spacecraft by early June, then engineers will ready the probe for filling of maneuvering propellants, a milestone slated for the end of June.
Juno will weigh about 7,992 pounds at launch.
Then all that's left before moving the craft to the launch pad is encapsulating Juno inside the Atlas 5 rocket's 5-meter payload fairing, a procedure scheduled to get started around July 17.
Juno will be trucked to Complex 41 to meet the Atlas 5 rocket about a week later, when United Launch Alliance will take responsbility for the spacecraft.
Lockheed Martin engineers will have a last chance to work on Juno four days before liftoff, when workers will crawl through doors in the Atlas 5 nose cone to pull off covers from the spacecraft's scientific sensors.
When Juno leaves Earth, it will embark on a five-year journey to the solar system's most massive planet, a gas giant with an overwhelming magnetic field, harsh radiation belts and a turbulent atmosphere scientists are antsy to learn more about.
Juno will fire its main engines twice after launch to tweak its trajectory, then the probe will return to Earth for a flyby in October 2013, using the planet's gravity to slingshot the spacecraft toward Jupiter.
The mission will reach Jupiter in July 2016, enter a large, looping preliminary orbit for three months, then fire its thrusters to stabilize its trajectory in an 11-day science orbit that takes Juno within 3,000 miles of Jupiter's blustery cloud tops more than 30 times in one year.
From that vantage point, the closest range from which any spacecraft has ever repeatedly observed Jupiter, Juno will gain insights into how Jupiter formed, investigate the planet's hypothesized solid core, map its magnetic field and measure the water, ammonia and other molecules in Jupiter's atmosphere.
Juno will also capture the first images of Jupiter's poles, a region unexplored by the Voyager and Galileo probes that previously visited the planet. Juno's orbit will also allow the mission to study Jupiter's aurora storms.