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Two spacecraft head to the moon

13 Sep

You can get as poetic concerning the moon as you wish to have — and everybody from lovers to lyricists to astronauts have had their go at it. However the fact is, the thing’s a lump — beautiful to be sure, but a lump the entire same, created greater than four billion years ago when a Mars-sized planetesimal whizzed by, collided with Earth and blasted out a mass of molten debris which eventually cooled into the moon.

In fact, the moon is a sequence of lumps within lumps. Whilst it was congealing, it did so unevenly, with scattered areas of high density which senologists labeled mascons — for mass concentrations. The highlands and the plains are made from differing materials too. Higher local density means higher local gravity, which is able to not just wreak havoc on precisely calibrated spacecraft orbits, it might probably also reveal so much in regards to the innards and the history of the moon itself — provided you understand how to read those gravitational flutters. NASA is now preparing to do exactly that, launching the GRAIL mission (Gravity Recovery and Interior Laboratory) on a nine-month journey to deepen our understanding of Earth’s closest neighbor.

The GRAIL spacecraft, which launched on Sept. 10, is definitely two spacecraft, each in regards to the size of a bathing machine. Named, prosaically enough, GRAIL-A and GRAIL-B, they were lofted aboard the similar booster after which released in space for separate but closely coordinated flights to the moon.

A translunar journey typically takes not up to three days, however the GRAIL ships will exceed that by just a little — not arriving until New Years Eve in relation to GRAIL-A and New Year’s Day in relation to GRAIL-B. In place of covering the 239,000-mi. (385,000 km) distance from the Earth to the moon in a straight, as-the-crow-flies shot, the ships will follow a looping, 2.5 million mi. (4 million km) trajectory. The longer route and slower speed allow the spacecraft to hold less fuel and make sure that once they do arrive on the moon they are often inserted into orbit more precisely — and precision is everything on the subject of the GRAILs.

During the 3 months the ships will spend actively studying the moon — from early March to late May — they’re going to maintain a distance of 100 to 225 km (62 to 140 mi.), dependent on what a part of the lunar anatomy they’re surveying. A tracking system aboard the ships will measure any change in range between the 2 within a difference of some microns — or concerning the size of a red blood cell. And that shifting distance is strictly what the scientists might be in search of. Flying over a mascon may be like driving over a speed bump, jolting the 2 ships and causing them to shake a little relative to one another. The denser the mass concentration — and the larger the gravity jolt — the greater the degree of disruption will be.

“We’ll use the moon’s gravity to inform us what’s throughout the moon, right down to the core,” says principal investigator Maria Zuber of MIT.

NASA is ready for glitches and false positives within the data. No unmanned spacecraft have ever flown in such balletic tandem around another world, and flight planners will thus be refining their navigational skills in real time. Even the solar wind — the stream of charged particles that flow outward from the sun — could disrupt the readings. Indeed, another reason for the roundabout translunar route was in order that scientists could measure the wind precisely and proper for it because the data is analyzed.

Assuming the mission achieves what it’s designed to achieve, the GRAILs will do greater than reveal new insights in regards to the innards of the moon and the origin of the solar system. They’re going to also help NASA select promising sites for future lunar landings. Such ambitious missions, of course, require both funding and programmatic clarity that may be nowhere in evidence in this day and age. But within the event policymakers ever do set their sights moonward again, GRAIL can assist tell them precisely where to aim.



Source: TIME.com: Top Stories

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Posted by on September 13, 2011 in Magazine

 

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