Juno Spacecraft In Orbit Around Jupiter After Five-Year Journey in 2016

The second dedicated mission to be sent to Jupiter, NASA Juno will run for 20 months before its instruments are severely damaged by radiation.

A Hubble space telescope image showing an aurora over one of Jupiter’s poles. Credit: NASA/ESA

The romance of Jupiter is its size, its world-sized storms and aurorae, its cloud of moons, its caustic radiation. As the fifth planet from the Sun, and 588 million km from Earth, the gas giant is a mystery for many reasons despite its obvious presence in many night skies. That’s why Juno is there – the spacecraft launched by NASA in 2011 to study the planet, and just under an hour ago, successfully firing its engines to slow down enough to be captured by Jupiter’s gravity into a loopy orbit around the planet. This is the second dedicated mission to be sent to Jupiter, and will run for 20 months before it gets very close to the planet and burns up.

Beginning at about 8 am, Juno’s onboard computer began preparations to allow Jupiter’s prodigious gravity to capture the spacecraft. For this, Juno had to slow down considerably by firing its main engines, stabilise itself by slowly spinning, to 5 rpm up from 2 rpm, as well as keep itself protected from radiation. If Juno had flown too fast, Jupiter wouldn’t have been able to capture and the mission would’ve ended. This is why the main engine was fired for 35 minutes – to bring its velocity down from 265,000 kph to around 2,000 kph. At the same time, even if it took Juno five whole years to fly to the planet, it also had to ensure that locked itself into an orbit around Jupiter within a 35-minute window (with a puny 10-minute margin). If this window was missed, then Juno would’ve either run into one of Jupiter’s moons and crashed or become damaged by radiation surrounding the planet.

As it happens, Juno got itself into orbit around Jupiter with an error of one second. Let the precision sink in.