Juno spacecraft finally in Jupiter’s gravitational grip

31 May 2016

NASA’s Juno spacecraft has finally escaped the sun’s grip – having ditched Earth years ago – with Jupiter’s gravity now controlling its mission.

Launched back in 2011, Juno – which is the size of a basketball court – is on a mission to study Jupiter, orbiting the planet to get a proper picture of the world hidden beneath clouds.

Having left Earth’s gravitational pull a long time ago, NASA scientists have said even the sun is now playing a minor role as Jupiter’s powerful gravitational pull takes effect.

The Jovian world will be seen from as near as 5,000km at Juno’s nearest point, with Jupiter’s gravitational pull (which is almost three-times that of Earth’s) the main factor controlling Juno’s route.

“We project Jupiter’s gravity will dominate as the trajectory-perturbing effects by other celestial bodies are reduced to insignificant roles,” said Rick Nybakken, Juno project manager, as the mission reached a new exciting phase.

Juno will circle Jupiter 37 times in total for its mission, creeping under the copious cloud network that shields the planet from most astronomical views. It will study Jupiter’s auroras to learn more about the planet’s origins, structure, atmosphere and magnetosphere.

Juno Jupiter

At the start of the month, Juno was close to Jupiter and approximately 724m km from Earth, with radio signals taking 40 minutes to travel one-way. It will arrive at its destination at the start of July.

Jupiter is one of the most interesting planets in our solar system for NASA to investigate, now that several of its moons are thought to harbour bodies of water.

Two of the moons, Europa and Io, are the homes of hugely important discoveries in recent years.

The latter is the most volcanically active body in the solar system, due to the fact that Jupiter’s massive gravitational pull is continually putting pressure on Io’s core.

The former, though, has oceans. NASA estimates it has subsurface bodies of water up to 25km deep, over double the volume of Earth’s entire oceanic network.

As for what’s on Jupiter itself, Juno will eventually teach us plenty. Its mission brief is to understand the origin and evolution of the planet, look for its solid planetary core, map its magnetic field, measure water and ammonia in deep atmosphere and observe the auroras.

The latter has been done before, from Earth, but a close-up view will be far more spectacular.

The images of Jupiter showing the X-ray auroras. Image via NASA/CXC/UCL/W.Dunn et al, Optical: NASA/STScI

The images of Jupiter showing the X-ray auroras. Image via NASA/CXC/UCL/W.Dunn et al, Optical: NASA/STScI

Jupiter image via Shutterstock

Gordon Hunt was a journalist with Silicon Republic