A Nasa spacecraft is about to arrive at the largest planet in the solar system – Jupiter. The probe launched five years ago and has travelled nearly three billion kilometres to reach its destination.
Here are 10 things you need to know about this mission.
1. The Juno probe reached Jupiter at 4.18 am GMT this morning after a five-year, 1.8 billion-mile journey from Earth. Following a successful braking manoeuvre, it has now entered into a long polar orbit flying to within 3,100 miles (5,000 km) of the planet’s swirling cloud tops. The probe will skim to within just 4,200 km of the planet’s clouds once a fortnight – too close to provide global coverage in a single image.
2. No previous spacecraft has orbited so close to Jupiter, although two others have been sent plunging to their destruction through its atmosphere.
3. To complete its risky mission Juno will have to survive a circuit-frying radiation storm generated by Jupiter’s powerful magnetic field. The maelstrom of high energy particles travelling at nearly the speed of light is the harshest radiation environment in the Solar System.
4. To cope with the conditions, the spacecraft is protected with special radiation-hardened wiring and sensor shielding. Its all-important ‘brain’ – the spacecraft’s flight computer – is housed in an armoured vault made of titanium and weighing almost 400 pounds (172kg).
5. Juno was launched on 5 August, 2011. During more than 30 orbital flybys of the Jovian world, it will probe beneath the obscuring ammonia and hydrogen sulfide cloud cover and study the auroras to learn more about the planet’s origins, structure, atmosphere and magnetosphere.
6. Juno’s name comes from Greek and Roman mythology. Jupiter, the father of the Roman gods, drew a veil of clouds around himself to hide his mischief. But his wife – the goddess Juno – was able to peer through the clouds and reveal Jupiter’s true nature.
7. Juno will be one of the fastest human-made objects in history, moving approximately 260,000 kilometers per hour (165,000 mph) relative to the Earth. That’s roughly ten times the top speed of the Space Shuttle.
8. 48 minutes, 19 seconds, that’s the time it takes for radio signals from Jupiter to reach EarthW. When Juno phoned home to tell us that its orbital insertion maneuver went off smoothly, the signal it sends to Earth was be roughly a billion times weaker than what you’d receive in a typical cell phone call.
9. Two stations in the Deep Space Network—one in Goldstone, California, another in Canberra, Australia—are going to be listening for Juno’s call; arraying several of their antennae to maximize detection power and focusing on Juno’s position in the sky with laser precision.
10. 20 months, that’s how long the mission will last. Because Juno is in a harsh radiation environment, its delicate electronics are housed in a special titanium vault. Eventually, Juno will succumb to the intense radiation and will be commanded to plunge into Jupiter’s atmosphere to avoid any collision with the planet’s moons.