Messenger spacecraft to fly-by Mercury

[Hum]

A NASA spacecraft has a date with Mercury next week for a flyby that will return the first detailed views of the small planet in more than 30 years. The Messenger probe will skim just 124 miles (200 kilometers) above Mercury's uncharted hemisphere during its closest pass at 2:04 p.m. ET Monday, marking the first of three flybys to bleed off speed and enter orbit around the planet.

"Our spacecraft is lined up and ready to go," Marilyn Lindstrom, NASA's Messenger program scientist, said during a Thursday briefing, adding that the probe has already returned its first images of its target.. "Mercury, here comes Messenger."

Launched in August 2004, Messenger ? short for the bulky moniker MErcury Surface, Space ENvironment, GEochemistry and Ranging ? is the first spacecraft to visit Mercury since NASA's Mariner 10 probe swung past the planet three times between 1974 and 1975. But unlike its predecessor, Messenger will rendezvous with Mercury four times, making three flybys before ultimately entering orbit in 2011 for a one-year science campaign.

The $446 million mission is aimed at probing the secrets of Mercury, ranging from its wispy thin atmosphere to an unusually dense interior. The mission will also generate the first maps of the 55 percent of the planet's rocky surface that Mariner 10 missed during its three planetary passes.

"More than half the planet's never been seen before," said Messenger principal investigator Sean Solomon, of the Carnegie Institution of Washington. "That will change on Monday."

Messenger's Mercury flyby actually begins in earnest around midday Sunday, when the probe will turn itself away from Earth to bring its science instruments to bear on its planetary target. The spacecraft will snap more than 1,200 photographs of Mercury during its first rendezvous while a protective sunshade keeps its cameras and other instruments at room temperature. The sun-facing side of the shade may reach temperatures of around 600 degrees Fahrenheit (315 degrees Celsius), researchers said.

For 14 minutes, the probe's power-generating solar panels will be in Mercury's shadow, forcing the spacecraft to briefly rely solely on its batteries, said Eric Finnegan, Messenger systems engineer. The probe will use the gravitational pull of Mercury to slow its speed by about 5,000 miles per hour (8,046 kilometers per hour) during the flyby, he added.

Messenger is expected to re-establish contact with Earth about midday on Tuesday, 22 hours after the closest Mercury approach, and then beam back images to its eager science team. The probe has already flown past Earth once and Venus twice as it spiraled down the solar system on the 4.9 billion-mile (7.9 billion-kilometer) trek to Mercury.

"Now, we're just a few days away from our first glimpse of Mercury in 33 years," said Solomon. "It is an understatement to say that the science team is extremely excited."

source

[Slimy]

Very cool, I'm interested in seeing those pictures!

[Hum]

:) Picture results:

Mercury, named for the fast-footed Roman messenger of the gods, is the closest planet to the Sun. Doing justice to its name, Mercury circles the Sun in a mere 88 days, compared to 365 days for Earth, and travels through space at nearly 50 kilometers (31 miles) per second, faster than any other planet in the solar system. Mercury's surface temperatures range from a scorching 467 degrees Celsius (872 degrees Fahrenheit) to a bone-chilling -183 degrees Celsius (-300 degrees Fahrenheit). Like our Moon, the planet is heavily cratered, showing impact scars from countless meteor bombardments. Old lava flows and quake faults also mark its crust. Although it has very little atmosphere, scientists have found water ice inside deep craters at the north and south poles of this hot little globe.

Diameter 4,879.4 km (3,031.92 miles)

Higher rez @

http://www.dailymail.co.uk/pages/live/arti...in_page_id=1965

[MGS4-SS]

So beautiful!

So hard to believe that the surface is ultra hot. Looks so peaceful.

[guru]

its got water!!!

[CrashG]

So beautiful!

So hard to believe that the surface is ultra hot. Looks so peaceful.

That pic looks like our Moon, not at all what I expected Mercury to look like. Really didn't expect to see all the craters, figured the surface and internal temp would keep the surface molten. Cool article, thanks Hum.

[Hum]

NASA Photos Reveal Mercury Is Shrinking

WASHINGTON (AP) --The first pictures from the unseen side of Mercury reveal the wrinkles of a shrinking, aging planet with scars from volcanic eruptions and a birthmark shaped like a spider.

Some of the 1,213 photos taken by NASA's Messenger probe and unveiled Wednesday help support the case that ancient volcanoes dot Mercury and that it is shrinking as it gets older, forming wrinkle-like ridges. But other images are surprising and puzzling.

The spidery shape captured in a photo is ''unlike anything we've seen anywhere in the solar system,'' said mission chief scientist Sean Solomon of the Carnegie Institution of Washington. The image shows what looks like a large crater with faint lines radiating out from it.

Mercury, the closest planet to the sun, has often been compared to Earth's dull black-and-white moon. But the new photos, which reveal parts of Mercury never seen, show the tiny planet is more colorful and once had volcanic activity.

With the help of NASA high-tech enhancement, Messenger photos showed baby blues and dark reds.

''It has very subtle red and blue areas,'' said instrument scientist Louise Prockter of Johns Hopkins University, which runs the Messenger mission for NASA. ''Mercury doesn't look like the moon.''

The last time a NASA spacecraft went to Mercury was Mariner 10 in 1975. It took pictures of just 45 percent of the planet.

Messenger, which will do a couple more flybys of the planet before going into a long-term orbit, already has taken pictures of another 30 percent of Mercury, Prockter said. The rest will be seen eventually.

Planetary scientist Robert Strom, who was part of both the Mariner 10 and Messenger teams, said, ''This is a whole new planet we're looking at.''

And Prockter noted ''there are some features we haven't been able to explain yet.''

Example No. 1 is what scientists are calling ''the spider.'' It is in the middle of a basin formed billions of years ago when space junk bombarded an infant Mercury.

Mariner had only seen part of the crater. When Messenger took a look with sharper cameras and a better angle, it photographed this odd central plateau jutting up, about half a mile high with dozens of tiny ridges radiating out.

It is as if ''something is pushed up,'' said MIT planetary scientist Maria Zuber, who is part of the science team.

Prockter guessed that it could be remnants of a volcano. Other scientists think the leg-like features could be the same ridges seen all over Mercury.

First seen in the 1970s, the ridges now seen more widely provide evidence that Mercury is contracting, the scientists said.

Scientists had theorized that as the core of Mercury cools, it contracts and the whole planet shrinks. That was even a 19th Century theory for why Earth had mountains, but one that later proven wrong, Solomon said. But with Mercury that seems to be the case. As the planet shrinks, a bit of crust is pushed over another, forming what Prockter calls ''wrinkle ridges.''

Besides having what looks like the leftovers from volcanoes, Mercury has at least one crater that seems to be filled with what would be that planet's version of lava, Prockter said.

NASA launched the $446 million Messenger on its nearly 5 billion-mile mission in 2004. It will fly by Mercury two more times, this October and September 2009, before settling into orbit around in 2011. Messenger will take pictures, measure the planet's tenuous atmosphere, hills and valleys and unusual magnetic field -- Mercury is the only solar system planet other than Earth to have a magnetosphere.

Quirky Mercury is one of the bigger question marks in the solar system, probed not nearly as much as Mars, Jupiter, Venus or Saturn.

Strom, a retired University of Arizona scientist who worked on Mariner 10, said that as he awaited Messenger's flyby earlier this month, ''I couldn't sleep at all. I was like a kid on Christmas Eve.''

Only he had to wait 30 years for his presents. It was worth it, he said: ''What I saw was astounding to me.''

NASA Messenger site: http://www.nasa.gov/messenger

source