The Juno spacecraft has turned a corner. Having reached the farthest point in its first capture orbit of Jupiter, it is heading back towards the giant planet, this time with all its scientific instruments operational.
The most distant point, known as “apojove”, is 8.1 million kilometres from Jupiter. It passed that at 7:40 pm UDT. After that, Jupiter’s gravity began pulling Juno back toward it.
This is the first of two long orbits the spacecraft is making after travelling five years from Earth. Each one takes nearly two months, but after that Juno will fire its engine to enter the much shorter science orbits.
Each of those will take 14 days.
The science mission is designed to provide clues as to Jupiter’s formation and evolution by analysing atmosphere and the physics of the planet’s powerful magnetic field.
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Mission scientists can barely disguise their impatience.
“For five years we’ve been focused on getting to Jupiter. Now we’re there, and we’re concentrating on beginning dozens of flybys of Jupiter to get the science we’re after,” said Scott Bolton, Juno principal investigator at Southwest Research Institute in San Antonio.
But they will get a taster of the data to come later in this orbit when Juno skims 4,200 kilometres above Jupiter’s clouds on 27 August.
When Juno arrived at the planet on 4 July, all its scientific instruments were turned off to simplify spacecraft operations during the orbit-insertion manoeuvre. Everything will be functioning this time as scientists test systems ahead of the serious science orbits to follow.
“We’re in an excellent state of health, with the spacecraft and all the instruments fully checked out and ready for our first up-close look at Jupiter,” said Rick Nybakken, Juno project manager at NASA’s Jet Propulsion Laboratory in California.