Juno gets mission extension to complete science objectives
NASA's Juno orbiter mission to Jupiter has been thrown a lifeline with the space agency approving a 41-month extension. With additional funding through fiscal year 2022, the unmanned spacecraft will have additional time to complete its primary science observations of the gas giant and its magnetic field, with the extra time required due to the spacecraft taking longer than planned orbits.
Since Juno arrived at Jupiter in 2016, it's returned a remarkable catalog of discovery's about the Solar System's largest planet, including unprecedented close ups of the clouds and the polar regions. However, during the arrival maneuvers, a pair of malfunctioning helium valves in the propulsion system prevented mission control from carrying out a correction burn that would have put the spacecraft into a 14-day elliptical orbit.
Trapped in a 53-day orbit, the Juno mission was hampered because the spacecraft is in a very eccentric trajectory that allows it to pass under Jupiter's deadly radiation belts to make observations of the cloud tops at a closer distance than any previous mission. These flybys are much as originally planned, but there was a problem with the time factor.
If it had achieved its intended 14-day orbit, Juno would have had time to carry out all of its primary science experiments, but the 53-day orbit at a distance of between 3,000 mi (5,000 km) and five million mi (eight million km) of the cloud tops meant that it spends much more time in the outer Jovian system than planned, and subsequently has less time for observations.
According to NASA, an independent panel of experts reviewed the mission and in April confirmed that Juno's instruments are in good condition and can still meet all of its objectives if given time. In light of this, additional funding was released to allow the orbiter to gather more data until July 2021, followed by data analysis and shutdown operations in 2022. By that point, radiation damage to the craft is expected to be severe and it will be ordered to make a controlled entry into the Jovian atmosphere, where it will burn up.
The Juno mission launched from Space Launch Complex 41 at Cape Canaveral Air Force Station, Florida atop an Atlas/Centaur rocket on August 5, 2011. It took almost five years to reach Jupiter after a roundabout route that sent it on a flyby of Earth in 2013 to build up speed to match orbits with Jupiter. It is expected to complete its 13th science flyby of the planet on July 16, 2018.
"This is great news for planetary exploration as well as for the Juno team," says Scott Bolton, principal investigator of Juno. "These updated plans for Juno will allow it to complete its primary science goals. As a bonus, the larger orbits allow us to further explore the far reaches of the Jovian magnetosphere – the region of space dominated by Jupiter's magnetic field – including the far magnetotail, the southern magnetosphere, and the magnetospheric boundary region called the magnetopause. We have also found Jupiter's radiation environment in this orbit to be less extreme than expected, which has been beneficial to not only our spacecraft, but our instruments and the continued quality of science data collected."