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Rosetta on Final Approach to Comet Landing

Posted: August 7th, 2014 | Author: | Filed under: Applied Science, Astrophysical, Favorite New Thought, From The Web | Tags: , , , , | Comments Off on Rosetta on Final Approach to Comet Landing

In the most complex space mission since the moon landing, an attempt to land a spacecraft on a comet. Launched by the European Space Agency, Rosetta has become the first ever spacecraft to catch up with a comet, a landmark stage in a decade-long space mission that scientists hope will help unlock some of the secrets of the solar system.

The Rosetta spacecraft has travelled six billion kilometres using the gravitational forces of Earth and Mars to slingshot towards the five-kilometre-wide comet. The craft is now within 100 kilometres and considered to be on its final approach ::::

European Space Agency senior scientific adviser Mark McCaughrean says he hopes the project can uncover the answers to some “really big questions”.

“Where do we come from? Where does this solar system we live in come from? How was it put together? And how did water get to this planet which we live on?” Professor McCaughrean said, “For 10 years, we’ve been in the car waiting to get to scientific Disneyland and we haven’t even got out of the car yet and looked at what’s outside the window … it’s just astonishing.”

[Video] After a ten year journey through space, ESA’s Rosetta spacecraft will reach comet 67P/Churyumov-Gerasimenko in August 2014. After catching up with the comet Rosetta will slightly overtake and enter orbit from the ‘front’ of the comet as both the spacecraft and 67P/CG move along their orbits around the Sun.

Rosetta is set to carry out a complex series of manoeuvres to reduce the separation between the spacecraft and comet from around 100 km to 25-30 km. From this close orbit, detailed mapping will allow scientists to determine the landing site for the mission’s Philae lander. Immediately prior to the deployment of Philae in November, Rosetta will come to within just 2.5 km of the comet’s nucleus. 

The above animation isn’t to scale: Rosetta’s solar arrays span 32 m, and the comet is approximately 4 km wide.

Ten Years in the Making

The 10-year chase, taking it billions of kilometres across the solar system, the Rosetta spacecraft made history Wednesday as it became the first probe to rendezvous with a comet on its journey around the sun.

“Thruster burn complete. Rosetta has arrived at comet 67P. We’re in orbit!” ESA Tweeted.

Rosetta fired its thrusters on its final approach to Comet 67P/Churyumov-Gerasimenko on Wednesday morning. Half an hour after the burn, scientists announced that the craft had entered into the orbit of the comet.

“After 10 years, five months and four days travelling towards our destination, looping around the sun five times, we are delighted to announce finally ‘we are here’,” Jean-Jacques Dordain, ESA’s Director General, announced. “Europe’s Rosetta is now the first spacecraft in history to rendezvous with a comet, a major highlight in exploring our origins. Discoveries can start.”

ESA tweeted a photo of the comet after Rosetta’s maneuver. Comet 67P and the space probe now lie some 400 million kms from Earth, about half way between the orbits of Jupiter and Mars.

The first spectacular and detailed images taken from just 125 kms away shows craters,  steep cliffs and are already causing much excitement.

“Comet 67P looks like it’s been through the wars” Dr Robert Massey of the Royal Astronomical Society said. “With that odd looking ‘neck’, either we’re looking at two objects that merged together or so much material has been lost in its many passes around the sun that the comet is a shadow of what it started out as. The pictures coming back so far look intriguing, imagine the kind of scenes we can expect when Philae lands this coming November.”

To get to its destination the spacecraft has covered more than three billion miles and as the comet hurtles towards the sun it will reach a speed of about 62,000 miles per hour.

The mission has now achieved the first of what it hopes will be a series of historic accomplishments. In November mission controllers aim to place the robotic lander Philae on the surface, something that has never been done before.

Previous missions have performed comet fly-bys but Rosetta is different. This probe will follow the comet for more than a year, mapping and measuring how it changes as it is blasted by the sun’s energy.

Mission controllers had to use the gravity of Earth and Mars to give the probe a slingshot acceleration to meet its target on the right trajectory. Rosetta also had to be put into hibernation for more than two years to conserve power before being woken up successfully in January this year.

Wednesday’s thruster burn was the tenth rendezvous maneuver Rosetta has performed since May to get the probe’s speed and trajectory to align with the comet’s — and if any of those operations had failed, the mission would have been lost, according to ESA.

For the next few weeks, ESA says the spacecraft will be in a triangular orbit until it gets to about 18 miles of the surface when it starts its close observations.

Scientists hope to learn more about the composition of comets and perhaps whether they brought water to the Earth or even the chemicals that make up the building blocks of life.

“It really is such a step forward to anything that has come before,” project scientist Matt Taylor said.

Rosetta will begin mapping the surface of Comet 67P, finding out more about its gravitational pull. This will help to find a suitable landing site for Philae and allow engineers to keep Rosetta in the right orbit.

As comets approach the sun, any ice melts and is turned into an ionized gas tail. The dust produces a separate, curving tail. It’s these processes that Rosetta scientists hope to be able to study from close proximity.

Mr Taylor explained that the survey will show the team what the comet nucleus looks like now and when it gets closer to the sun.

“We’ll be able to make a comparison to now, when its relatively inert, to when it’s highly active … making this measurement over a year when we’re riding alongside at walking pace and observing how a comet works and interacts with the sun,” Mr Taylor said. “We are there for over a year to see this complete development to the extent that you may even be able to measure the decrease in the volume of the nucleus … see how much material has left the comet.”

Comet 67P is known as a short-period comet. It reappears every six years as its orbit brings it close to the sun. Halley’s comet has a period of about 76 years and is not due to return close enough to Earth to be visible until 2061. Others only return after thousands of years.

Mr Taylor says it is unlikely that you will be able to see comet 67P with the naked eye but you can follow the progress of the mission on Rosetta’s blog

Timeline of the mission:

March 2, 2004: Liftoff from European Space Agency (ESA) launch pad in French Guiana by an Ariane 5 rocket.

March 2005: Rosetta encounters the Earth, using the planet’s gravity as a slingshot to boost speed.

February 2007: Flies around Mars at a distance of just over 200 kilometres for a gravitational assist.

November 2007: Second Earth flyby.

September 2008: Rosetta flies by asteroid 2,867 Steins at a distance of around 800 kilometres.

November 2009: Third Earth flyby. Rosetta now at top speed as it flies through the asteroid belt.

June 2011 – January 20, 2014: At maximum distance (800 million kilometres) from the Sun and a billion kilometres from home, Rosetta goes into hibernation to conserve energy.

January – May 2014: Rosetta gets the wakeup call to end its long slumber, fires thrusters to gradually brake its speed and near the comet.

August 6, 2014: Rosetta scheduled to arrive at the comet and begin triangular orbits around it at a height of 100 kilometres. Over the next three months, it will scan the comet’s surface and sub-surface with 11 onboard cameras, radar, microwave, infrared and other sensors.

November 11, 2014 (scheduled): Rosetta sends down a 100-kilogram robot laboratory, Philae. The lander, equipped with 10 instruments, is released at a height of about one kilometre, touching down at walking speed. It fires a small harpoon to anchor itself, starts to send back pictures and conducts chemistry experiments on rock samples.

November 2014 – 2015: Comet Churyumov-Gerasimenko loops around the Sun, approaching on August 13, 2015 to within 186 million kilometres of our star.

December 2015: Scheduled end of mission. Escorted by Rosetta and with little Philae piggybacking on it, the comet heads out of the inner Solar System. At this point, Rosetta will once again come close to Earth’s orbit, more than 4,000 days after its odyssey began.

Australian Links to Rosetta

Sydney engineer Warwick Holmes helped build the spacecraft and a satellite dish in New Norcia, two hours out of Perth, and has been vital in communicating with it.

“I worked for four-and-a-half years on the project, for more than 8,000 hours and every day, I used to go and touch this thing and it never used to occur to me how important it was or … what would really be happening 10 years in the future,” he said.

“It was just a box of electronics.” Mr Holmes said, as an engineer, he got “involved in the most exciting part with the building and testing of the final spacecraft. To be able to be involved in such an exciting mission, the first attempt ever for mankind to do the orbit of a comet and a landing, was just something I could never imagine my whole life.”

And during the critical rendezvous phase of Rosetta’s mission, a 600-tonne, 35-metre satellite dish two hours out of Perth helped to deliver the clearest signal of the entire mission.

New Norcia’s great weather and low radio interference made it the perfect place to host the dish but scientists had one hurdle to overcome. The town was home to Roman Catholic monks.

Monk Dom Chris Powers remembers the first visit well. “It was a surprise to us. On a Sunday afternoon, a Spanish scientist arrived [and] rang the bell … he said he was interested in finding the right place for a deep space station which wasn’t the kind of question you’d expect to be asked on a Sunday afternoon during siesta,” Chris Powers said. “We had some people say to us: ‘Aren’t you worried they might discover there’s nobody up there?’ But right from the outset, our Abbot at the time thought we’re all after the same things – the truth, the big questions and with that, there really was no conflict.

Mr Powers has described the project as a “very happy marriage”.

“The scientists and engineers who’ve come here have been really interested in our way of life, joining us for prayers, doing the washing up from time to time,” Mr Powers said.

Rosetta will now spend the next few months mapping the comet before making its final landing attempt in November.

Wake-up Call

January 21, 2014: The comet-chasing probe Rosetta has woken up and is operational after a 31-month hibernation, according to the European Space Agency.

The ESA sent out a tweet confirming Rosetta’s awakening, mimicking the signal sent back from deep space by the probe.

A webcast showed jubilant scientists at mission control in Darmstadt, Germany, as the all-is-well signal came in.

Europe’s most ambitious exploration of space, the craft was launched in 2004 on a trek of 7 billion kilometres around the inner Solar System.

Its goal is to rendezvous in August with a comet, 67P/Churyumov-Gerasimenko, and in November send down a lander to carry out experiments on the icy wanderer.

Comets are clusters of ice and dust which are believed to be remnants from the very birth of our star system.

Analysing this primeval matter should unlock secrets of how the Solar System formed and possibly how life on Earth was sparked.

Rosetta was placed in hibernation as it was so far from the Sun that light was too dim to power its solar array.

Scientists had to wait more than eight hours before getting the precious signal, sent from a distance of more than 800 million kilometres, to confirm that it had woken up

“It was a fairy-tale ending to a tense chapter,” ESA said in a statement.


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source: esa
source: abc
source: cnn
source: exeter
image source: youtube

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