File photo showing the planet Mercury is seen from Mariner 10's first image of Mercury acquired on March 24, 1974. REUTERS/Nasa-Jpl/File
Posted on 01/10/2008 2:18:43 PM PST by NormsRevenge
WASHINGTON (Reuters) - A NASA probe next week will become the first spacecraft in 33 years to fly by Mercury, a sojourn scientists hope will unlock the secrets of the small sun-baked planet.
NASA's car-sized MESSENGER spacecraft is scheduled to zip about 124 miles above the cratered, rocky surface of the closest planet to the sun on Monday, part of a mission designed to place it into orbit around Mercury in 2011.
"I think we're in for some big surprises," Faith Vilas, one of the scientists involved in the mission, told reporters during a conference call on Thursday.
"You know that we can't get cocky about this and say, 'Oh, it's going to look like this.' Every solar system body looks very different from every other solar system body," she added.
MESSENGER is expected to get the first spacecraft measurements of the mineral and chemical makeup of Mercury's surface, and to also retrieve key data about the planet's internal structure including its core.
The probe will also study Mercury's global magnetic field, and scientists also hope the mission will add to the understanding of the planet's gravity field.
MESSENGER's instruments will collect more than 1,200 images and make other observations during this initial fly-by. It will be the first up-close measurements since the Mariner 10 spacecraft's third and final fly-by in 1975.
MESSENGER, which stands for Mercury Surface, Space Environment, Geochemistry and Ranging, was launched in 2004. The probe has meandered through the inner solar system on the way to Mercury, already having flown past Earth once and Venus twice.
THE OTHER SIDE
Scientists said MESSENGER is expected to retrieve far more data about Mercury than did Mariner 10, which surveyed only one hemisphere of the planet. During next week's fly-by, scientists will begin to collect images of the other hemisphere.
"Mercury really has been long ignored -- too long," NASA's planetary science chief James Green said. "With MESSENGER, we believe that many of Mercury's secrets will now be revealed."
With Pluto demoted from planetary status, Mercury is now recognized as the smallest planet in the solar system. Its diameter is about 3,000 miles, about a third the size of Earth and only a bit larger than our moon. Mercury's surface is a mix of craters, plains and long, winding cliffs.
The planet's average distance from the sun is 36 million miles, about two-thirds closer than the Earth. It orbits the sun once every 88 Earth days, or about a quarter of an Earth year.
The spacecraft is due to make its closest approach to Mercury at 2:04 p.m. EST on Monday (1904 GMT).
Mercury, along with Venus, Earth and Mars, are the solar system's family of four rocky inner planets.
"But Mercury, as a family member, is a real oddball," said Sean Solomon of the Carnegie Institution of Washington, the mission's principal scientific investigator.
He cited its extreme density and wide surface temperature swings from day to night due to its proximity to the sun.
Surprisingly considering its proximity to the sun, there may be water ice on the permanently shadowed crater floors at Mercury's poles, scientists think. A huge iron core is believed to make up more than 60 percent of Mercury's total mass.
MESSENGER is due to make three passes of Mercury -- next week, this coming October and again in September 2009 -- before finally starting a yearlong orbit during a fourth encounter in March 2011. The mission also includes fly-bys of Earth and Venus as the probe positions itself for orbiting Mercury.
The mission is expected to cost about $446 million.
File photo showing the planet Mercury is seen from Mariner 10's first image of Mercury acquired on March 24, 1974. REUTERS/Nasa-Jpl/File
http://www.nasa.gov/mission_pages/messenger/main/index.html
NASA Spacecraft to Make Historic Flyby of Mercury
On Monday, Jan. 14, a pioneering NASA spacecraft will be the first to visit Mercury in almost 33 years when it soars over the planet to explore and snap close-up images of never-before-seen terrain. These findings could open new theories and answer old questions in the study of the solar system.
I believe Mercury has the largest known impact crater. As I understand it the impact caused shockwaves to converge on the opposite side of the planet and caused some interesting jumbled terrain.
Mercury has a huge iron core as if it was supposed to be a much larger planet.
Crematoria all back of the bus.
“...place it into orbit around Mercury in 2011...”
This is 2008. Why wait 4 years to orbit Mercury. Why not do it now while it’s going to be so close?
I suspect it will take that long for the orbit to be converted from a highly elliptical orbit to a more circular orbit. Once it's in a circular orbit it can begin it's tests.
MESSENGER performed a successful Earth swingby a year after launch, on 2 August 2005, with the closest approach at 19:13 UTC at an altitude of 2,347 km (1,458 statute miles) over central Mongolia. On December 12, 2005, a 524 second long burn ('Deep-Space Maneuver' or 'DSM-1') of the large thruster adjusted the trajectory for the upcoming Venus swing-by[1]. MESSENGER made its first flyby of Venus at 08:34 UTC on October 24, 2006 at an altitude of 2992 km. A second flyby of Venus was made at 23:08 UTC on June 5, 2007 at an altitude of 338 km. On October 17, 2007, 'Deep-Space Maneuver-2' or 'DSM-2' was executed successfully, putting MESSENGER on target for its first flyby of Mercury[2]. MESSENGER will make three flybys of Mercury on 14 January and October 6, 2008 and September 29, 2009, successively slowing down the spacecraft. Mercury orbit insertion will be on March 18, 2011, beginning a year-long orbital mission.
MESSENGER, which stands for Mercury Surface, Space Environment, Geochemistry and Ranging, was launched in 2004. The probe has meandered through the inner solar system on the way to Mercury, already having flown past Earth once and Venus twice.
A more detailed view from here:
They have four flybys between now and 2011.
And unlike Mars, Mercury doesn’t have an atmosphere so there will be no aerobraking possible.
It’s one of them space topics.
Wow, your post led me on an interesting mini-vacation:
http://www.space.com/scienceastronomy/070125_mars_atmosphere.html
“Mars’ atmospheric pressure today is only... about 0.008 bars, or about 0.7 percent of the average surface pressure at sea level on Earth.”
http://filer.case.edu/sjr16/advanced/mercury.html
“Mercury’s atmosphere is essentially a vacuum. It exerts a pressure of only approximately 10-15 bars. [that’s 10 to the minus 15] If you drop a feather on your hand, it exerts a pressure of about 10-3 bars, which is one trillion times more than the atmospheric pressure on Mercury.”
Of course, NASA could go the other route and just accidently smash the probe into one of the poles of Mercury. That would slow it down some.
Maybe because it’s only three years? /funpokin’
The “Atmosphere” of Mercury
Courtney Seligman, Professor of Astronomy
http://cseligman.com/text/planets/mercatmos.htm
Mercury doesn’t have any atmosphere in the normal sense of the word... various kinds of atoms and molecules can persist at the surface for a moderate time. The major sources are (1) the Solar Wind, which delivers free electrons and bare atomic nuclei (primarily of hydrogen and helium) to the planet, (2) meteoritic impacts, which vaporize portions of the surface rocks, as well as the incoming objects, providing small amounts of oxygen, silicon, iron, and other components of vaporized rock to the gaseous mixture, and (3) very occasional “burps” of volcanic gases through cracks in the crust of the planet, which of course deliver various kinds of sulfurous gases... The amount of gas is measured in trillionths of a percent of the amount in our atmosphere... Mercury, being smaller, only runs into a few hundred pounds of meteoric material, each day. BUT when this stuff hits Mercury, it does so with VERY high speeds... somewhere between 100 and 150 thousand miles an hour. [27-40 miles per second] ...This produces a gas made primarily of the same things that rocks are made of — about half oxygen, a quarter silicon, and a quarter other metal atoms, primarily iron, aluminum, potassium, calcium, magnesium, and ‘most importantly’, SODIUM... we can actually observe the fluorescence (glowing) of sodium vapor at the surface of Mercury, from the Earth, on some occasions... because it’s easy to observe... you will read about sodium vapor surrounding Jupiter, in the orbit of Io.
Mercury’s spin reveals molten, not solid core
Reuters | Thursday, May 3, 2007 | Julie Steenhuysen
Posted on 05/03/2007 10:51:50 PM EDT by SunkenCiv
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