LAUREL, Md. - For the
first time in 33 years, a space probe zoomed by the planet Mercury with cameras
blazing on Monday while eager scientists looked on from Earth.
NASA's MESSENGER spacecraft successfully flew
past its target planet at 2:04:39 p.m. EST (1904:39 GMT) as applause filled
its mission control room here at the Johns Hopkins University Applied Physics
Laboratory.
"It went
right according to script, so that was very comforting," MESSENGER principal
investigator Sean Solomon, of the Carnegie Institution of Washington, told SPACE.com
after the flyby.
MESSENGER -
short for MErcury Surface, Space ENvironment, GEochemistry, and Ranging - skimmed
just 124 miles (200 km) over the surface of its target planet during the first
of three planned flybys to guide the spacecraft toward an eventual orbit around
the small rocky world on March 18, 2011.
Not since
NASA's Mariner 10 probe, which flew past Mercury three times between 1974 and
1975, has a spacecraft taken such a close look at the planet. Researchers hope
MESSENGER's $446 million mission will answer
long-standing questions over Mercury's oddly high density, magnetic field and
thin atmosphere, as well as shed new light on how planets formed during the
solar system's infancy.
"To understand the excitement of the scientists, you have to
think of this as the first Super Bowl in 30 years," said Marilyn Lindstrom,
NASA's MESSENGER program scientist, before the flyby. "We've been waiting to go
back to Mercury that long."
Mariner 10,
for example, only mapped about 45 percent of Mercury's surface during
its three flybys. MESSENGER turned its cameras and other instruments on
half of the planet's
uncharted surface during today's flyby and will ultimately spend an entire
year in orbit around the planet.
"The real
question is, 'Does it all look the same?'" said Rob Gold, MESSENGER's science
payload manager at the Applied Physics Laboratory. "We just don't know."
If all goes
well, MESSENGER will begin beaming more than 1,200 new images of Mercury back
to Earth along with other data around midday tomorrow.
Mark
Robinson, a science team member from the University of Arizona, said he is
looking forward to MESSENGER's views of the Caloris Basin, a large impact
crater that Mariner 10 only saw half of during its flight.
"They are
imaging, basically, the largest single unexplored piece of real estate in the
inner solar system," Alan Stern, associate administrator for NASA's science
mission directorate, told reporters today.
A vital
sunshade, just one example of advances in technology between the Mariner 10 and
MESSENGER missions, allows the new probe to keep its sophisticated instruments at
about room temperature while the sun-facing side reaches a scorching 600
degrees Fahrenheit (315 degrees Celsius).
"It's like taking
a 2008 Jaguar and comparing it to a six-year-old's toy bike," Stern said of the
improvements since Mariner 10.
Mission scientists said they are already
planning MESSENGER's next Mercury flyby, set for October, and expect the
spacecraft to finish relaying all of the imagery and other data from today's rendezvous
by next week.
"I will be
just simply chomping at the bit to see data that come down," said Faith Vilas, a
MESSENGER participating scientist and director of the MMT Observatory in Mt. Hopkins, Ariz.
MESSENGER was expected to swing by Mercury at a speed of about 16,000 mph (25,749 kph) and use the planet's gravitational pull to slow down by about 5,000 mph (8,046 kph). It has completed just over half of its 4.9 billion-mile (7.9 billion-kilometer) flight to orbit Mercury.
Monday's flyby marked the fourth planetary pass for MESSENGER, which has swung
past Earth once and Venus twice since its August 2004 launch. The success
of those previous flybys gave mission controllers vital experience for today's rendezvous,
mission researchers said.
"They made
it look easy," Solomon said.
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