Media captionCelebrations at Nasa as the Juno satellite is now orbiting Jupiter
The US space agency has successfully put a new probe in orbit around Jupiter.
The
Juno satellite, which left Earth five years ago, had to fire a rocket
engine to slow its approach to the planet and get caught by its gravity.
A sequence of tones transmitted from the spacecraft confirmed the braking manoeuvre had gone as planned.
Receipt of the radio messages prompted wild cheering at Nasa's mission control 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."
Scientists
plan to use the spacecraft to sense the planet's deep interior. They
think the structure and the chemistry of its insides hold clues to how
this giant world formed some four-and-a-half-billion years ago.
Image copyrightNASAImage caption
Artist's impression: Juno will fly more than 30 times around Jupiter in the course of its mission
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.
But the probe is built like a tank with titanium shielding, and the 35-minute rocket burn appeared to go 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.
Tuesday's 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 kilometres 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.
"How
much water Jupiter has tells us a lot about where the planet formed
early in the Solar System," explained team-member Candy Hansen.
"We
think that Jupiter may not have formed where it is today, and if it
formed further away or closer in - that tells us a lot about how the
Solar System in general formed. Because when we look at planets around
other stars we see quite a menagerie of possibilities."
Jupiter is 11 times wider than Earth and 300 times more massive
It takes 12 Earth years to orbit the Sun; a 'day' is 10 hours long
In composition it resembles a star; it's mostly hydrogen and helium
Under pressure, the hydrogen becomes an electrically conducting fluid
Most of the visible cloudtops contain ammonia and hydrogen sulphide
Jupiter's 'stripes' are created by strong east-west winds
The Great Red Spot is a giant storm vortex twice as wide as Earth
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.
And 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.
Media captionBefore beginning the orbit insertion, Juno caught sight of its quarry Principal investigator Scott Bolton said he wanted
particularly to understand more about the Great Red Spot - a long-lived,
giant storm.
"I love that Great Red Spot. We see it evolving, and
it's been getting smaller ever since I first got amazed by it which was
when I was a child," he told reporters.
"The fact that it's
lasted so long - there are records of it going back hundreds of years -
means that it must have fairly deep roots.
"It looks a little like
a hurricane on the Earth but we know it can't be working exactly like
that because hurricanes on the Earth need an ocean underneath and feed
off the liquid and then change when they go on land. At Jupiter, it's
all gas."
Media captionScott Bolton: "Absolutely you can have rain on Jupiter"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, for example, is expected to degrade rapidly within a few
months.
In line with the practice on many previous planetary
missions, the probe 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. Image caption
For scale: No solar-powered spacecraft has worked so far from the Sun, hence its huge panels
Media captionThe attack occurred soon after sundown at during the holy month of Ramadan
A suicide bomber has killed
four security officers and injured five others near one of Islam's
holiest sites in the Saudi city of Medina, according to the interior
ministry.
The bomber detonated his explosives after being stopped outside the Prophet's Mosque, a statement said.
The mosque is the burial place of the Prophet Muhammad and Medina the second-holiest city in Islam after Mecca.
Suicide blasts also struck two other Saudi cities on Monday.
That
an attack happened in Medina at such a place is likely to leave Muslims
around the world aghast, BBC World Service's Middle East editor, Alan
Johnston, says.
Suspicion is likely to fall on so-called Islamic State (IS), he adds.
Image copyrightReutersImage caption
Images showed a blazing vehicle near the mosque in Medina
Al-Arabiya
gave a different account of the incident, saying the bomber had
targeted the security officers by pretending he wanted to break his
Ramadan fast with them.
Qari Ziyaad Patel, 36, from South Africa,
who was in the mosque, told the Associated Press news agency people had
at first thought it was the sound of the cannon fire that marks the
breaking of fast.
The ground shook, he said, adding: "The vibrations were very strong. It sounded like a building imploded." Image copyrightEPA/SaudipressagencyImage caption
The site is one of Islam's holiest
Earlier, at least one explosion rocked Qatif, an eastern city which is home to many minority Shia Muslims.
The blast appeared to target a Shia mosque. The attacker was killed but no other casualties were reported.
A suspected suicide bomber also died after detonating a device near the US consulate in the city of Jeddah. Two security officers were slightly injured as they tackled the man, but no-one else was hurt.
No-one has yet said they were behind any of the attacks.
They come with the holy month of Ramadan drawing to a close and ahead of the Eid al-Fitr holiday.
Saudi Arabia has been the target of attacks by IS over the past two years.
In June, the interior ministry said there had been 26 "terror attacks" in the kingdom in that time. A series of deadly attacks worldwide were either claimed by, or blamed on, IS over the past week:
সৌদি আরব ও আমিরাতে ঈদ বুধবার
০৫ জুলাই ২০১৬, ০০:১৭
সৌদি আরব ও সংযুক্ত আরব আমিরাতের আকাশে আজ সোমবার সন্ধ্যায় পবিত্র শাওয়াল মাসের চাঁদ দেখা যায়নি। ফলে সৌদি আরব ও সংযুক্ত আরব আমিরাতসহ আশপাশের কয়েকটি দেশে পবিত্র রমজান মাস ৩০ দিনে হবে। সে ক্ষেত্রে ৩০ রোজা পূর্ণ করে সৌদি আরব ও সংযুক্ত আরব আমিরাতে আগামী বুধবার উদযাপিত হবে পবিত্র ঈদুল ফিতর।
গালফ নিউজের খবরে এসব কথা বলা হয়েছে। খবরে বলা হয়, আজ সোমবার আরব আমিরাতের চাঁদ দেখা কমিটির বৈঠক শেষে কমিটি সদস্যরা সৌদি আরবের সঙ্গে মিল রেখে এই ঘোষণা দেন।
সৌদি আরবের একদিন পরে বাংলাদেশে পবিত্র রমজান মাস শুরু হয়েছিল।
