|
Space
Scientists Gear Up For Mercury Mission Flyby Of Venus
06/04/07
University of Colorado at
Boulder researchers will scan Venus during a spacecraft flyby
this week using an $8.7 million instrument they designed and
built for NASA's MESSENGER Mission, launched in 2004 and speeding
toward Mercury.
Built by CU-Boulder's Laboratory for
Atmospheric and Space Physics, the instrument will make
measurements of the thick clouds and shrouded surface of Venus
during the June 5th flyby, said LASP Senior Research Associate
William McClintock, a mission co-investigator who led the
CU-Boulder instrument development team. Known as the Mercury
Atmospheric and Surface Composition Spectrometer, or MASCS, the
instrument will compare the atmosphere of Venus with data from
other spacecraft that have visited the planet in the past four
decades.
"This is our first opportunity for a close
flyby of a solar system object with MESSENGER, and we should be
able to tell if the atmosphere of Venus has been changing in
recent years, " said McClintock. "As importantly, we
are using Venus as a test case to learn more about our instrument
performance in preparation for the spacecraft's ultimate
destination of Mercury."
Carrying seven instruments,
MESSENGER will be the first spacecraft ever to orbit Mercury and
the first to return data from the hot, rocky planet in more than
30 years. The circuitous, 4.9 billion mile journey to Mercury,
which requires more than seven years and 13 loops around the sun,
is using the gravity of Venus during its flyby this week to guide
it closer to Mercury's orbit.
MESSENGER will make its
first flyby of Mercury in January 2008, zipping by it again at a
top speed of 141,000 miles per hour in October 2008 before flying
by a third time in September 2009 and finally settling into orbit
in March 2011. "This is a mission that requires some
patience," said Mark Lankton, LASP's program manager for the
MASCS instrument. "We are anticipating a brief symphony of
action at Venus, and we have a lot of data to take in a hurry."
Dozens of CU-Boulder undergraduate and graduate students
will be involved in data analysis from MESSENGER in the coming
years, said Lankton.
MASCS's ultraviolet and visible
spectrometer will be looking at the cloud composition of Venus.
While the surface of Venus is hot enough to melt lead and its
atmosphere is filled with noxious carbon dioxide gases and acid
rain, Earth and Venus were virtual twins at birth, scientists
believe.
The miniaturized MASCS instrument, which took
more than three years to develop, weighs less than seven pounds
and was built to last, said McClintock. "Many space
instruments have a lifetime of only three to four years," he
said. "But we knew we had to make this one robust enough to
work for more than a decade under harsh conditions."
The
MESSENGER spacecraft is about the size of a small economy car and
is equipped with a semi-cylindrical thermal shade to protect it
from the sun. More than half of the weight of the 1.2-ton
spacecraft consists of propellant and helium. "We like to
call it the little spacecraft that could," said McClintock.
"This event at Venus will be a very good tune-up for
our first flyby of Mercury next January," said LASP Director
Daniel Baker, also a co-investigator on the MESSENGER team. "The
first encounter with Mercury will be extremely valuable, as it
will essentially double the amount of information we now have
about the planet."
A space physicist, Baker is
interested in the magnetic field of Mercury and its interaction
with the solar wind, including "substorms" associated
with Mercury's magnetic field that occur in the planet's
vicinity. Understanding Mercury's surface, tenuous atmosphere and
magnetic field are the keys to understanding the evolution of the
inner solar system, he said.
Mercury was visited only
once before by a spacecraft, in 1974 and 1975, when NASA's
Mariner 10 spacecraft made three flybys and mapped roughly 45
percent of the planet's rocky surface at the time.
MASCS
will probe the mineral composition of Mercury's surface, the
distribution of gases in its tenuous atmosphere and the workings
of a giant, comet-like sodium gas cloud enveloping the planet,
said McClintock. The researchers also hope to determine if
Mercury ever had volcanoes on its surface and if the permanently
shadowed craters at Mercury's poles contain water-ice.
MESSENGER is equipped with a large sunshield and
heat-resistant ceramic fabric because Mercury is about two-thirds
of the way nearer to the sun than Earth and is bombarded with 10
times the solar radiation. Sandwiched by the sun and Mercury --
which has daytime temperatures of about 800 degrees Fahrenheit --
the spacecraft will "essentially be on a huge rotisserie,"
said Baker.
Managed by Johns Hopkins University's Applied
Physics Laboratory for NASA, MESSENGER involves about 20
scientists. Sean Solomon of the Carnegie Institution in
Washington, D.C., is MESSENGER's principal investigator.
Data
from MESSENGER will be sent to NASA's Deep Space Network tracking
antennas, then to Johns Hopkins and finally to LASP's Space
Technology Building in the CU Research Park.
Source:
University of Colorado at Boulder
|
Scientific
Frontline®
The
Comm Center
Space
Weather Alerts
Stellar
Nights®
Imagineers
The
E.A.R.®
World
News Report
Photo,
Sketches, & Video Gallery
|
