NASA’s Juno probe has successfully arrived in Jupiter’s orbit.
The satellite, which left Earth five years ago, had to fire a rocket engine to slow its approach to Jupiter and get caught by its gravity.
A sequence of tones transmitted from the spacecraft confirmed the braking maneuver had gone as planned.
Receipt of the radio messages prompted wild cheering at NASA’s Jet Propulsion Laboratory in Pasadena, California.
“All stations on Juno co-ord, we have the tone for burn cut-off on Delta B,” Juno Mission Control had announced.
“Roger Juno, welcome to Jupiter.”
NASA scientists plan to use Juno to sense Jupiter’s deep interior. They think the structure and the chemistry of the planet’s insides hold clues to how this giant world formed some four-and-a-half-billion years ago.
Engineers had warned in advance that the engine firing was fraught with danger.
No previous spacecraft has dared pass so close to Jupiter; its intense radiation belts can destroy unprotected electronics.
One calculation even suggested the orbit insertion would have subjected Juno to a dose equivalent to a million dental X-rays.
Jumo is built like a tank with titanium shielding, and the 35-minute rocket burn appeared to go off without a hitch.
While the radiation dangers have not gone away, the probe should now be able to prepare its instruments to start sensing what lies beneath Jupiter’s opaque clouds.
July 5 orbit insertion has put Juno in a large ellipse around the planet that takes just over 53 days to complete.
A second burn of the rocket engine in mid-October will tighten this orbit to just 14 days. It is then that the science can really start.
This will involve repeat passes just a few thousand of miles above the cloudtops.
At each close approach, Juno will use its eight remote sensing instruments – plus its camera – to peer down through the gas planet’s many layers, to measure their composition, temperature, motion and other properties.
A priority will be to determine the abundance of oxygen at Jupiter. This will be bound up in its water.
The probe will also try to settle old arguments over whether the planet hosts a solid core or whether its gases go all the way down to the centre in an ever more compressed state.
It will look for the deep swirling sea of liquid metallic hydrogen that theory suggests is the driver behind Jupiter’s immense magnetic field and its spectacular auroras.
NASA plans to run Juno through to February 2018, assuming any radiation damage has not made it inoperable by then. The performance of the camera is expected to degrade rapidly within a few months.
In line with the practice on many previous planetary missions, Juno will be commanded to end its days by ditching into the atmosphere of Jupiter.
This ensures there is no possibility of Juno crashing into and contaminating the gas giant’s large moons, at least one of which, Europa, is considered to have the potential to host microbial life.
A recent study suggests that geometry was being used by the Ancient Babylonians at least 1,400 years earlier than previously thought.
The new study, published in Science, shows that the Ancient Babylonians were using geometrical calculations to track Jupiter across the night sky.
Previously, the origins of this technique had been traced to the 14th Century.
The study’s author, Prof. Mathieu Ossendrijver, from the Humboldt University of Berlin, Germany, said: “I wasn’t expecting this. It is completely fundamental to physics, and all branches of science use this method.”
The Ancient Babylonians once lived in what is now Iraq and Syria. The civilization emerged in about 1,800 BC.
Clay tablets engraved with their Cuneiform writing system have already shown these people were advanced in astronomy.
However, this latest research shows they were also way ahead when it came to maths.
It had been thought that complex geometry was first used by scholars in Oxford and Paris in Medieval times.
They used curves to trace the position and velocity of moving objects.
Now scientists believe the Babylonians developed this technique around 350 BC.
Prof. Mathieu Ossendrijver examined five Babylonian tablets that were excavated in the 19th Century, and which are now held in the British Museum’s archives.
The script reveals that they were using four-sided shapes, called trapezoids, to calculate when Jupiter would appear in the night sky, and also the speed and distance that it travelled.
Prof. Mathieu Ossendrijver said that there was evidence that the Greeks used a “more straightforward” form geometry, which dealt with the spatial relationships between the Earth and the planets rather than the concepts of time and velocity.
According to US scientists, diamonds big enough to be worn by Hollywood film stars could be raining down on Saturn and Jupiter.
New atmospheric data for the gas giants indicates that carbon is abundant in its dazzling crystal form, they say.
Lightning storms turn methane into soot (carbon) which as it falls hardens into chunks of graphite and then diamond.
These diamond “hail stones” eventually melt into a liquid sea in the planets’ hot cores, they told a conference.
The biggest diamonds would likely be about a centimetre in diameter – “big enough to put on a ring, although of course they would be uncut,” says Dr. Kevin Baines, of the University of Wisconsin-Madison and NASA’s Jet Propulsion Laboratory.
Kevin Baines added they would be of a size that the late film actress Elizabeth Taylor would have been “proud to wear”.
“The bottom line is that 1,000 tonnes of diamonds a year are being created on Saturn.
“People ask me – how can you really tell? Because there’s no way you can go and observe it.
Diamonds big enough to be worn by Hollywood film stars could be raining down on Saturn and Jupiter
“It all boils down to the chemistry. And we think we’re pretty certain.”
Kevin Baines presented his unpublished findings at the annual meeting of the Division for Planetary Sciences of the American Astronomical Society in Denver, Colorado, alongside his co-author Mona Delitsky, from California Speciality Engineering.
Uranus and Neptune have long been thought to harbor gemstones. But Saturn and Jupiter were not thought to have suitable atmospheres.
Kevin Baines and Mona Delitsky analyzed the latest temperature and pressure predictions for the planets’ interiors, as well as new data on how carbon behaves in different conditions.
They concluded that stable crystals of diamond will “hail down over a huge region” of Saturn in particular.
“It all begins in the upper atmosphere, in the thunderstorm alleys, where lightning turns methane into soot,” said Kevin Baines.
“As the soot falls, the pressure on it increases. And after about 1,000 miles it turns to graphite – the sheet-like form of carbon you find in pencils.”
By a depth of 6,000km, these chunks of falling graphite toughen into diamonds – strong and unreactive.
These continue to fall for another 30,000km – “about two-and-a-half Earth-spans” says Kevin Baines.
“Once you get down to those extreme depths, the pressure and temperature is so hellish, there’s no way the diamonds could remain solid.
“It’s very uncertain what happens to carbon down there.”
One possibility is that a “sea” of liquid carbon could form.
“Diamonds aren’t forever on Saturn and Jupiter. But they are on Uranus and Neptune, which are colder at their cores,” says Kevin Baines.
The conjunction of Venus and Jupiter in the sky will reach its closest point in the coming days.
Despite being vastly far from one another in space, the conjunction will make them appear just a few degrees apart in the sky – about the width of a pair of fingers held at arm’s length.
The pairing of Venus and Jupiter can be seen to the west-southwest, shortly after sunset.
Venus is the brighter of the two, and Jupiter will appear to move in a line past it for the rest of the month.
The conjunction of Venus and Jupiter in the sky will reach its closest point in the coming days
The Slooh network of telescopes will be broadcasting the conjunction live on the web from 02:30 GMT on Monday morning.
This is an active period for planet-watchers. Last Monday, Mars made its closest approach to Earth in more than two years.
But the spectacle is not over. February saw the Moon join the celestial dance with the planetary pair; it will return in late March, appearing to head up and past the descending Jupiter and then Venus.
The most anticipated planetary event for 2012 will be the transit of Venus in early June, when it will appear from some locations on Earth to pass in front of the Sun.