MESSENGER mission to Mercury

[Rick]

The Messenger probe is nearing the halfway point of 7.9 billion kilometre journey, which when completed will make it the first man-made object to orbit the planet Mercury.

During the craft's first three years and three months in space since its launch in August, 2004, Messenger has flown by Earth once and Venus twice. Now Messenger is nearing the goal of its mission, when it will pass the closest planet to the Sun three times before attempting to lock into orbit.

More: http://www.theregister.co.uk/2007/11/21/mercury_probe_halfway_mark/

[Rick]

NASA's Messenger has beamed back the first picture of Mercury's hitherto unseen side, snapped from a distance of about 17,000 miles after its first fly-by of the planet yesterday.

NASA explains: "The image shows features as small as six miles in size. Similar to previously mapped portions of Mercury, this hemisphere appears heavily cratered. It also reveals some unique and distinctive features. On the upper right is the giant Caloris basin, including its western portions never before seen by spacecraft. Formed by the impact of a large asteroid or comet, Caloris is one of the largest, and perhaps one of the youngest basins in the solar system."

More: http://www.theregister.co.uk/2008/01/16/mercury_hidden_hemisphere/

[Rick]

he smallest planet in the Solar System has become even smaller, studies by the Messenger spacecraft have shown.

Data from a flyby of Mercury in January 2008 show the planet has contracted by more than one mile (1.5km) in diameter over its history.

Scientists believe the shrinkage is due to the planet's core slowly cooling.

More: http://news.bbc.co.uk/2/hi/science/nature/7489557.stm

[Ian]

to start with I thought the IAU were having another pop at Pluto. But then, that's not a planet anymore. Unless it puts on a growth spurt...

[mickw]

Volcanoes on Mercury Solve 30-year Mystery

More:   http://www.space.com/scienceastronomy/080703-mercury-messenger.html

It might have just sprung a leak 

[mickw]

A NASA probe has begun beaming back stunning new images from its successful second flyby of Mercury, the planet closest to the sun.

NASA's MESSENGER probe captured never-before-seen views of the Mercury during its encounter on Monday. The spacecraft zipped past Mercury for the second time this year and used the planet's gravity to adjust its path as it continues en route to become the first probe to orbit the planet in March 2011.

More:   http://www.space.com/scienceastronomy/081007-messenger-mercury-flyby.html

[Rick]

The Mercury Messenger probe has returned another batch of stunning pictures of the innermost world.

The Nasa spacecraft swept over the surface of the planet on Tuesday, passing just 200km above the rocky terrain at closest approach.

Some 1,200 images were obtained - many of regions never before been seen up close by a probe.

The flyby also gave Messenger the gravity tug it needed to get on to the right path to go into orbit in 2011.

More: http://news.bbc.co.uk/2/hi/science/nature/7659250.stm

[Rick]

NASA's Messenger has delivered its second set of postcards from Mercury, following a successful low-altitude fly-past on Monday which saw the spacecraft swoop to within 125 miles (200km) of the planet's surface, snapping furiously as it went.

More: http://www.theregister.co.uk/2008/10/08/messenger_mercury/

...and earlier: http://www.theregister.co.uk/2008/10/02/messenger_mercury/

[Rick]

NASA's Messenger spacecraft has now imaged 80 per cent of the surface of Mercury following its second fly-past of the planet on 6 October, meaning that around 95 per cent has been revealed by various missions, the agency reports.

More: http://www.theregister.co.uk/2008/10/30/messenger_mercury_imaging/
NASA: http://www.nasa.gov/mission_pages/messenger/main/index.html

[mickw]

Mercury should have trouble hanging on to its atmosphere. It is the closest planet to the sun , its searing daytime temperatures top 800 degrees Fahrenheit (450 degrees Celsius and its gravity is weak, only about 38 percent of Earth's. These conditions don't hold air.

New clues to why Mercury does have a thin atmosphere have been discovered by the MESSENGER spacecraft.

"Mercury's atmosphere is so thin, it would have vanished long ago unless something was replenishing it," James Slavin of NASA's Goddard Space Flight Center, Greenbelt, Md., said in a statement.

More:   http://www.space.com/missionlaunches/090608-mm-mercury-tornadoes.html

[mickw]

A NASA spacecraft that completed its third and final flyby of the planet Mercury yesterday, snapping new pictures of the innermost planet, had a small data hiccup that has delayed release of the images, mission engineers said today.

The MESSENGER probe skimmed just 142 miles (228 km) above Mercury at its closest approach as it whipped around the planet during the flyby, the last of three designed to guide the spacecraft into orbit around the planet in 2011.

The spacecraft did snap several new images of the rocky planet on the inbound leg of its close approach.

"We do have some new science from the flyby," said MESSENGER project scientist Ralph McNutt of Johns Hopkins University Applied Physics Laboratory.

More:   http://www.space.com/scienceastronomy/090930-messenger-hiccup.html

[mickw]

During its most recent flyby of Mercury, NASA's MESSENGER spacecraft caught another glimpse of the innermost planet's mysterious bright spot.

The MESSENGER probe skimmed just 142 miles (228 km) above Mercury at its closest approach as it whipped around the planet during the flyby, the last of three designed to guide the spacecraft into orbit around the planet in 2011.

The $446 million probe snapped several new images of Mercury during the flyby, despite a minor data hiccup that delayed the downlink of some of the images.

One of the new images shows a bright spot on the planet's surface, a feature that scientists cannot yet explain.

The new view was the third of the spot, which was first seen in telescopic images of Mercury obtained from Earth by astronomer Ronald Dantowitz. The second view was obtained by the MESSENGER Narrow Angle Camera during the spacecraft's second Mercury flyby Oct. 6, 2008. At that time, the bright feature was just on the planet's limb (edge) as seen from MESSENGER.

More:   http://www.space.com/scienceastronomy/091001-mercury-bright-spot.html

[mickw]

A NASA spacecraft has spotted what appears to be changing seasons on Mercury and found much more iron on the surface of the small, rocky planet than previously thought.

The MESSENGER probe made the observations during its third flyby of Mercury on Sept. 29, when it took a host of measurements and images of the innermost planet's surface and atmosphere. Only about half of the planned measurements were made because of a data glitch that affected the spacecraft during the flyby.

The $446 million probe's third flyby brought it within 142 miles (228 km) of Mercury's surface to cover more uncharted terrain, leaving 98 percent of the planet now mapped. The flyby was also a gravity assist meant to guide the spacecraft into orbit around the planet in 2011.

Tenuous exosphere

Mercury's atmosphere is what scientists call an "exosphere," and is made up of atoms kicked up from the surface. It is very tenuous and has a very low density, meaning atoms in the atmosphere rarely run into each other. It also has a tail that streams away from the planet in the opposite direction of the sun.

MESSENGER looked at differences in three atoms in the exosphere — sodium, calcium and magnesium — between the probe's three flybys. They detected much less sodium during the third flyby than they had during the second.

"While this is dramatic, it isn't totally unexpected," Vervack said. This is because radiation pressures from the sun change as Mercury moves through its orbit, which changes the amount of sodium liberated from the surface.

In essence, Mercury's atmosphere experiences seasonal effects during the planet's orbit.

More:   http://www.space.com/scienceastronomy/091103-mercury-new-images.html

[Rick]

It is only now thanks to the Messenger spacecraft that researchers have the imagery necessary to construct a truly global map of the innermost planet.

The probe's latest pictures added to those of the earlier Mariner 10 mission give near-total coverage.

Mapping experts at the US Geological Survey have been working to piece together all of these images in their possession into a giant mosaic.

More: http://news.bbc.co.uk/1/hi/sci/tech/8415421.stm

[mickw]

Here:   Mercury