SCIENTISTS have taken another key step in the unfolding drama of what is being hailed as one |of the great scientific achievements of all time: sending a spacecraft to catch a comet and land a probe on its surface as the comet continues its headlong rush towards the sun.
This week, less than three weeks after
The comet, which some observers suggest is shaped like a duck with two big sections joined by a narrow neck - technically, it has a "bi-lobate" form - has a nucleus about 4km across and each elliptical landing site covers about 1km2.
"Choosing the right landing site is a complex process," said the
"That site must balance the technical needs of the orbiter and lander during all phases |of the separation, descent |and landing, and during operations on the surface with the scientific requirements of the 10 instruments on Philae."
There have been previous comet fly-bys to collect data, but
It will study the comet at close range "as it transforms from a quiet nugget of ice and rock, frozen solid by years spent in deep space, to a sun-warmed dynamo spewing jets of gas and dust into a magnificently evolving tail", Dr
Then, with its destination finally in sight - but still |9 million kilometres away - it was "woken" on
Ten orbital correction manoeuvres were carried out
"Each of these manoeuvres was critical: if any had failed, no rendezvous would have been possible."
When the odd couple paired up, they were 405 million |kilometres from Earth, about halfway between the orbits |of Jupiter and Mars, and |were rushing towards the inner Solar System at nearly 55 000 km/h, ESA said.
Scientists calculated that the average temperature of the comet - comprising rock and ice, comets are often described as "dirty snowballs - to be about -70°C.
This week, Stephan Ulamec, Philae lander manager at the German Aerospace Centre in
"The candidate sites that we want to follow up for further analysis are thought to be technically feasible on the basis of a preliminary analysis of flight dynamics and other key issues. For example, they all provide at least six hours of daylight per comet rotation and offer some flat terrain.
"Of course, every site has the potential for unique scientific discoveries."
For each possible landing zone, important questions had to be asked, ESA explained: Will the lander be able to maintain regular communications with
"The process of selecting a landing site is extremely complex and dynamic; as we get closer to the comet, we will |see more and more details, which will influence the final decision on where and when we can land," said
"We had to complete our preliminary analysis on candidate sites very quickly after arriving at the comet, and now we have just a few more weeks to determine the primary site. The clock is ticking and we now have to meet the challenge to pick the best possible landing site."
The landing of Philae is expected to take place in mid-November when the comet is about 450 million kilometres from the Sun, ESA said.
"This will be before activity on the comet reaches levels that might jeopardise the |safe and accurate deployment of Philae to the comet's |surface, and before surface |material is modified by this cometary activity."
Sylvain Lodiot, ESA's
The mission is due to finally shut down at the end of next year.
For more, see the website: http://www.esa.int/rosetta
Hispanic #1 Breaking News for Entrepreneurs, Professionals and Small Business Owners - HispanicBusiness.com
OCTOBER 31, 2014
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