Mercury Orbited Tomorrow

This places the first satellite inorbit around Mercury and will be a trove of new data.  As this item makes clear, it was a tough nutto crack even though we are doing this routinely with other planets.

I expect we will soon have a goodgrasp of the possibilities in terms of establishing a real presence on theplanet itself or even landing a Lander as we have done on Mars.

I wonder if there is a majormountain on Mercury as on Mars?

Watch the video simulation.

Finally! NASA Prepares to Orbit Mercury

March 15, 2011: On March 17th, NASA's MESSENGER probe will becomethe first spacecraft to orbit Mercury. It's a seminal moment in planetaryexploration. Researchers can finally take a good long look at a rocky worldthat is both akin to Earth and shockingly alien.

An artist's concept of MESSENGER gliding over the surface of Mercury.[more]

There's just one question: What's taken so long? Mercury is one of theclosest planets to Earth and, at first glance, would seem to be readilyaccessible. Jim McAdams, mission design lead engineer, explains the problem:

"Mercury is going so much faster than Earth that a spacecraft mustgain about 65,000 mph to catch it. And once you get there, you're face to facewith the searing heat of the sun."

Only Mariner 10, which flew past the small planet briefly in 1974 and1975, and MESSENGER itself have made the attempt to go there. Even afterMESSENGER's own flybys in 2008 and 2009, Mercury remains the least exploredplanet.

Deep in the sun's gravitational well, Mercury is the planet mostsubject to the sun's powerful grip. The closer a planet gets to the sun, thefaster it has to travel to balance the pull of gravity. Mercury travels at anaverage speed of 106,000 mph.

"MESSENGER must gain tremendous speed to catch Mercury,"explains McAdams. "That's quite a challenge with current propulsionsystems. But Chen-wan Yen, an engineer from JPL, came up with a clevertrajectory that uses gravity assists from Venus and Mercury. I started withthat trajectory, adding additional flybys to adjust both the launch and Mercuryarrival dates."

The resulting loop-de-loop path MESSENGER has followed to slip intoplanet number one's orbit has covered about 5 billion miles, including 15 loopsaround the sun, and flybys of multiple planets.

As a spacecraft flies by a planet, the tug exerted by the planet flingsthe spacecraft in a new direction, giving it a boost and reshaping its orbit.The final itinerary for MESSENGER included flybys at Earth, Venus and Mercuryitself to accelerate the spacecraft and deflect its path inward towardMercury's path – all using very little fuel.

"With each flyby, MESSENGER's average speed relative to the sunincreased," explains McAdams. "But the spacecraft's speed relative toMercury decreased." (Sound confusing? Read the footnote.1)

Meanwhile another challenge awaits – Mercury's "warm"welcome. The sun blazes up to 11 times brighter there than at Earth, andsurface temperatures at Mercury’s equator can reach 450 degrees Celsius (840degrees Fahrenheit). The small planet's hot dayside radiates much of thatthermal energy back into space at a rate four times that at Earth.

Watch thisanimation to view the Mercury orbit insertion maneuver and thespacecraft’s first orbit around the planet.

"We solve this problem with a large sunshade made of ceramicfabric that withstands heat and protects the rest of the spacecraft,"explains principal investigator Sean Solomon. "And the mission is designedto limit the time the spacecraft spends over Mercury's hottest areas."

Other high-tech materials are used in the solar arrays and scienceinstruments to keep them within their working temperature ranges.

Researchers are anxious for new discoveries at Mercury. It's a planetof many mysteries: the most active planetary exosphere in the whole solarsystem, a surprisingly "live" magnetic field that has puzzledscientists for years, a core that makes up 60% of the planet's mass and is atleast partially liquid, an intriguing landscape pitted with an interestingvariety of craters and volcanic vents and marked by towering scarps that snakehundreds of miles across the planet's face. And that's just for starters.

MESSENGER is bristling with scientific instruments – high resolutionimagers, lasers, and magnetometers – designed to solve these mysteries once andfor all.

Author: DaunaCoulter | Editor: Dr.Tony Phillips | Credit: Science@NASA

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