It’s three down and two to go for NASA’s Jupiter-bound Juno probe, which marks a major milestone today, Aug. 5, celebrating its launch exactly three years ago—on Aug. 5, 2011—from Cape Canaveral Air Force Station, Fla., on a journey to discover the genesis of Jupiter hidden deep inside the planet’s interior.
“The Juno spacecraft is doing great and is on the way to Jupiter,” Juno principal investigator Scott Bolton of the Southwest Research Institute (SWRI), San Antonio, Texas, told me today in response to a query about the spacecraft’s status on the 3rd anniversary since blastoff.
The solar-powered probe has now traveled 80 percent of the distance on its five-year and 2.8-billion-kilometer (1.7-billion-mile) outbound trek to the Jovian system and the largest planet in our Solar System.
And the vehicle is healthy.
“The instruments and spacecraft have been checked out,” Bolton told AmericaSpace.
When it finally arrives at Jupiter on America’s Independence Day, July 4, 2016, Juno will become the first polar orbiting spacecraft at the gas giant.
The probe and its trio of huge solar panels are cart wheeling through interplanetary space on the long voyage to Jupiter.
Upon arrival at Jupiter, in July 2016, JUNO will fire its braking rockets and go into polar orbit and circle the planet 33 times over about one year. The goal is to find out more about the planets origins, interior structure, and atmosphere, observe the aurora, map the intense magnetic field, and investigate the existence of a solid planetary core.
“Jupiter is the Rosetta Stone of our solar system,” says Juno PI Bolton. “It is by far the oldest planet, contains more material than all the other planets, asteroids and comets combined and carries deep inside it the story of not only the solar system but of us. Juno is going there as our emissary — to interpret what Jupiter has to say.”
The $1.1-billion Juno was launched atop the most powerful version of the Atlas V rocket, augmented by five solid rocket boosters and built by United Launch Alliance (ULA).
Check out the photo album below of Juno’s launch from the AmericaSpace team of Alan Walters, Mike Killian, and Ken Kremer.
What activities is the Juno team focusing on right now? I asked Bolton.
“The team is busy planning our July 4, 2016 arrival at Jupiter. In the coming months we will continue to test and checkout various subsystems as part of our nominal plan for arrival at Jupiter,” Bolton told me.
During a one-year long science mission—entailing 33 orbits lasting 11 days each—the probe will plunge to within about 3000 miles of the turbulent cloud tops and collect unprecedented new data that will unveil the hidden inner secrets of Jupiter’s origin and evolution.
Juno will use its nine science instruments to conduct science investigations of both the surroundings of the Jovian system and deep inside the planet.
As of today, Aug. 5, Juno is more than was 404 million miles (650 million kilometers) from Earth. It has traveled 1.39 billion miles (2.2 billion kilometers, or 14.97 AU) since launch. See graphic below.
It is moving at a velocity of approximately 35,800 miles per hour (16 kilometers per second) relative to the Sun, and 95,700 miles per hour (43 kilometers per second) relative to Earth.
The current one-way radio signal travel time between Earth and Juno is currently about 36 minutes.
Despite the launch of Juno on the powerful Atlas V, the rocket was not powerful enough to place Juno on a direct trajectory flight to Jupiter. Therefore, the team included a critical Earth flyby maneuver to gain the necessary speed to propel Juno all the way to Jupiter.
The crucial speed boosting slingshot maneuver around Earth took place on Oct. 9, 2013.
During the flyby, Juno probe snapped a dazzling gallery of portraits of our Home Planet over the South American coastline and the Atlantic Ocean and conducted science investigations.
See our mosaics of land, sea, and swirling clouds above and below, including several shown in false color.
But an unexpected glitch during the do-or-die swingby sent the spacecraft into “safe mode” and delayed the transmission of most of the raw imagery and other science observations, while mission controllers worked hastily to analyze the problem and successfully restore Juno to full operation a few days later on Oct. 12—but only temporarily!
Because less than 48 hours later Juno tripped back into safe mode for a second time. Five days later engineers finally recouped Juno, and it’s been smooth sailing ever since, the top scientist told AmericaSpace at the time.
“Juno is now fully operational and on its way to Jupiter,” Juno principal investigator Scott Bolton of SWRI said then. “We are completely out of safe mode!”
With Juno now completely healthy and the nail-biting drama past, engineers found the time to send the stored photos and research data back to ground station receivers.
As Juno sped over Argentina, South America, and the South Atlantic Ocean, it came within 347 miles (560 kilometers) of Earth’s surface.
During the flyby, the science team observed Earth using most of Juno’s nine science instruments, since the slingshot also served as an important dress rehearsal and key test of the spacecraft’s instruments, systems, and flight operations teams.
Fortunately, the Juno team knew right from the start that the flyby of Earth did accomplish its primary goal of precisely targeting Juno toward Jupiter—to within two kilometers of the aim point, despite going into safe mode.
“We are on our way to Jupiter as planned,” Juno Project manager Rick Nybakken, said in a phone interview soon after the flyby of Earth. Nybakken is from NASA’s Jet Propulsion Lab in Pasadena, Calif.
“None of this affected our trajectory or the gravity assist maneuver – which is what the Earth flyby is,” he said.
It also accelerated the ships velocity by 16,330 mph (26,280 km/h), thereby enabling Juno to be captured into polar orbit about Jupiter as planned on July 4, 2016.
The safe mode did not impact the spacecraft’s trajectory one smidgeon!
It was likely initiated by an incorrect setting for a fault protection trigger for the spacecraft’s battery when Juno was briefly in an eclipse during the flyby.
The raw images were taken by the Junocam camera and are collected in strips, like a push broom. So they have to be carefully reconstructed and realigned to match up. But it can’t be perfect because the spacecraft is constantly rotating and is speeding past Earth at over 78,000 mph.
So the perspective of Earth’s surface features seen by Junocam was changing during the imaging.
And that’s what is fascinating: to see the sequential view of Earth’s beautiful surface changing as the spacecraft flew over the coast of South America and the South Atlantic toward Africa, from the dayside to the nightside.
It’s rare to get such views since only a few spacecraft have swung by Earth in this manner—for example, Galileo and Messenger—on their way to distant destinations.
With Juno now on course for our Solar System’s largest planet, there will be no new planetary images taken until it arrives at the Jovian system in 2016.
Juno will then capture the first ever images of Jupiter’s north and south poles. We have never seen Jupiter’s poles imaged from the prior space missions like Galileo and the Voyagers, and it’s not possible from telescopes on or near Earth.
Based on what we’ve seen so far, Junocam is sure to provide spectacular views of the gas giants poles and cloud tops.
Only 698 days to go!
Want to keep up-to-date with all things space? Be sure to “Like” AmericaSpace on Facebook and follow us on Twitter: @AmericaSpace