Messenger spacecraft primed for Mercury Pass

[trekz 7]

Messenger primed for Mercury pass

By Jonathan Amos

Science reporter, BBC News

 

Messenger has a shield to protect its instruments

 

The first spacecraft to visit Mercury in more than 30 years passes the planet on Monday at a distance of just 200km. The fly-by is the first of three the Messenger probe will make in the coming years as it slows itself to enter into orbit around the small world in 2011.

 

The US spacecraft will collect more than 1,300 images and make other observations during the encounter.

 

No probe has viewed Mercury up close since the Mariner 10 mission's third and final fly-by in March 1975.

 

"[Messenger] is lined up and ready to go; the team is ready and really pumped," said Marilyn Lindstrom, the US space agency (Nasa) mission's programme scientist.

 

"Mercury, here comes Messenger!"

 

The researcher said the entire planetary science community was impatient to get back to the nearest planet to the Sun.

 

The moment of closest approach is 1404 EST (1904 GMT).

 

Lindstrom added: "[Messenger's] goal is to understand the surface, the interior, the magnetosphere and the atmosphere of this innermost planet; but in the process of doing that we hope to apply that [knowledge] to understand how all four of the terrestrial, Earth-like, planets formed."

 

Messenger is half-way through what will be a seven-year tour of the inner Solar System.

 

Messenger is closing on its quarry

It is not due in orbit around Mercury until the March of 2011. To get there, it must perform a series of fly-bys and engine firings to put it on a correct course and, crucially, slow its final approach.

 

This week's pass, which takes place some 53 million km (33 million miles) from Sun, will reduce the spacecraft's velocity by 8,000km/h (5,000mph). Even so, it will still pass over the cratered surface at a relative speed of 25,000km/h (16,000mph).

 

"Messenger's orbital period around the Sun will be decreased by 11 days thus setting up a planetary car race with Mercury," explained Eric Finnegan, mission systems engineer at Johns Hopkins University Applied Physics Laboratory.

 

"Using its engine and future gravity assists, the spacecraft after being lapped by Mercury many times in its race around the Sun will eventually match the 88-day orbital period of the innermost planet."

 

Strange world

 

Messenger has already begun its flyby observations. The probe's instruments are expected to gather about 700GB of data in total over a period of 55 hours.

 

The final look will be on Tuesday at about midday EST (1700GMT), after which the probe will turn its communications equipment towards Earth to download the data treasure.

 

THE PLANET MERCURY: Closest planet to the Sun Diameter: 4,800km

Mercurian year: 88 days Has global magnetic field

 

Messenger is operating in an extremely harsh environment.

 

Its electronics and observational instruments are protected behind a shield that allows them to operate at "room temperature". The Sun-facing side of he shield, however, experiences temperatures in excess of 300C.

 

All the terrestrial planets are believed to have formed at the same time by common processes - but Mercury itself is a bit of an oddball.

 

It is so dense that more than two-thirds of it has to be of an iron-metal composition.

 

It so close to the Sun that the temperature variation between day and night at the equator is 1,100 degrees; and yet there may be water-ice at the poles in craters that are in permanent shadow.

 

Europeans to follow

 

"Mariner 10 showed us a surface that was so heavily crater that it looked like geological activity on Mercury ended very early in the history of the Solar System," said Sean Solomon, Messenger's principal investigator from the Carnegie Institution of Washington.

 

"And yet, Mercury is the only other inner planet which like Earth has a magnetic field that we believe means it must have a very dynamic molten iron core.

 

"So how to reconcile this ancient surface with this modern-day internal dynamic activity is one of the mysteries we hope to solve."

 

On Friday this week, the European Space Agency (Esa) will sign an industrial contract with EADS Astrium to build BepiColombo.

 

This mission will be launched to Mercury 2013. It consists of two spacecraft - an orbiter for planetary investigation, led by Esa, and one for magnetospheric studies, led by the Jaxa (Japan Aerospace Exploration Agency).

 

The satellite duo will reach Mercury in 2019 after a six-year journey towards the inner Solar System.

 

Jonathan.Amos-INTERNET@bbc.co.uk

[ussvwbeetle 0]

That's amazing that we haven't sped up the journey to the planets. When will warp be invented? :)

[trekz 7]

UPDATE:

 

Spacecraft Beams Back Images of Mercury

Posted: 2008-01-17 20:28:57

Filed Under: Science News

 

Scientists are sifting through their first new views of the planet Mercury in more than three decades thanks to images beamed home by NASA's MESSENGER probe.

 

Scientists got a good look at Mercury for the first time since 1975 Monday when NASA's MESSENGER probe beamed back 1,200 new images of the planet closest to the sun.

 

The car-sized spacecraft zipped past Mercury in a Monday flyby and is relaying more than 1,200 new images and other data back to eager scientists on Earth.

 

"Now it's time for the scientific payoff," MESSENGER principal investigator Sean Solomon of the Carnegie Institution of Washington told SPACE.com after the flyby. "It's just a complete mix of results that we're going to get."

 

In one new image, released today, the planet's stark surface is shown peppered with small craters, each less than a mile (1.6 km) in diameter and carved into an area about 300 miles across. MESSENGER used its narrow-angle camera to photograph the scene, which is dominated by a large, double-ringed crater dubbed Vivaldi after the Italian composer. While the crater was last seen by NASA's Mariner 10 probe, MESSENGER's camera observed it with unprecedented detail, researchers said.

 

Another new view reveals the first look at the half of Mercury left uncharted by Mariner 10.

 

"It is already clear that MESSENGER's superior camera will tell us much that could not be resolved even on the side of Mercury viewed by Mariner's vidicon camera in the mid-1970s," said MESSENGER researchers at the Johns Hopkins University's Applied Physics Laboratory (JHUAPL) in a Wednesday statement. JHUAPL engineers built MESSENGER for NASA and are managing its $446 million mission for the space agency.

 

MESSENGER, short for MErcury Surface, Space ENvironment, GEochemistry, and Ranging, trained its seven instruments on Mercury on Monday for the first of three planned flybys to guide itself toward a March 18, 2011, arrival into orbit around the small, rocky planet. The mission is the first to visit Mercury since 1975, when Mariner 10 made its third and final swing past the planet.

 

"These flybys are the only time that we fly by the surface of Mercury at low latitude near the equator," Solomon said.

 

MESSENGER is due to make a second rendezvous at Mercury in October, then swing by on third pass in September 2009. The probe launched in August 2004 and flew by Earth once and Venus twice during its 4.9 billion-mile trek toward Mercury orbit.

 

During Monday's flyby, MESSENGER skimmed just 124 miles above Mercury's surface and snapped photographs of about half of the estimated 55 percent of the planet that remained uncharted after Mariner 10's mission. In addition to imagery, the probe is expected to return a wealth of new observations made by its seven instruments to scrutinize Mercury's surface composition, magnetic field, tenuous atmosphere, unusually high density and other features.

 

"It will take upwards of a week to get all of the data off the spacecraft," said MESSENGER systems engineer Eric Finnegan before the Monday flyby. "Within that week, the scientists will start receiving some of the images of the flyby and processing that data."

 

Researchers hope MESSENGER's findings will not only answer long-standing questions about Mercury, but also shed new light on how planets formed in the early days of the solar system. The probe will generate complete maps of Mercury's surface, measure the planet's gravitational field and search for any hints of ice at the bottom of permanently shadowed craters near the poles as part of its mission.

 

"I just can't wait," said Mark Robinson, a MESSENGER science team member at the University of Arizona. "I want to see what's around the corner."

 

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