MESSENGER Team Releases First Images From Venus 2 Flyby

http://messenger.jhuapl.edu/news_room/status_report_06_14_07.html

MESSENGER Mission News
June 14, 2007

MESSENGER TEAM RELEASES FIRST IMAGES FROM VENUS 2 FLYBY

The first images from MESSENGER's second flyby of Venus are in! The
Mercury-bound probe flew within 338 kilometers (210 miles) of Venus on
June 5, obtaining a gravity assist that shrank the radius of the
probe's
orbit around the Sun, pulling it closer to Mercury. But the encounter
also allowed the MESSENGER team to give its two cameras, known as the
Mercury Dual Imaging System (MDIS), a thorough workout.

The MDIS consists of wide-angle and narrow-angle cameras that will map
landforms, track variations in surface spectra, and gather topographic
information at Mercury. It snapped a series of images
<http://www.nasa.gov/mission_pages/messenger/multimedia/
venus_flyby.html>
as it approached Venus.

"Venus is enshrouded by a global cloud layer that obscures its surface
to the MDIS," explains Arizona State University's Mark Robinson, a
MESSENGER science team member. "This single frame is part of a color
sequence taken inbound to help us calibrate the wide-angle camera in
preparation for its first flyby of Mercury next January. Over the next
several months the camera team will pore over the 614 images taken
during the Venus 2 encounter to adjust color sensitivity parameters
and
better understand the geometric properties of the instrument."

Robinson says that both tasks address two key goals for the instrument
once the spacecraft gets to Mercury: understanding surface color
differences and their relation to compositional variations in the
crust;
and ensuring accurate cartographic placement of features on Mercury's
surface. "Preliminary analysis of the Venus flyby images indicates
that
the cameras are healthy and will be ready for next January's close
encounter with Mercury," he says.

After acquiring hundreds of high-resolution images during close
approach
to Venus, MESSENGER turned its wide-angle camera back to the planet
and
acquired a departure sequence. The first image was taken June 6 at
12:58
UTC (8:58 p.m. EDT on June 5), and the final image on June 7 at 02:18
UTC (10:18 p.m. EDT on June 6). During this 25 hour, 20 minute period
the spacecraft traveled 833,234 kilometers (517,748 miles-more than
twice the distance from the Earth to the Moon) with respect to Venus
at
an average speed of 9.13 kilometers per second (5.67 miles per
second).

"These images provide a spectacular good-bye to the cloud-shrouded
planet while also providing valuable data to the camera calibration
team," says Robinson.

"As a gravity assist and dress rehearsal for Mercury, MESSENGER's
Venus
flyby was a huge success," said MESSENGER principal investigator Sean
Solomon, from the Carnegie Institution of Washington. "The spacecraft
hit its aim point to within 1.3 kilometers (0.81 miles), removing the
need for another trajectory correction in July. Every instrument
returned data from the Venus encounter, and the Science Team is hard
at
work analyzing the new observations. We plan to release further data
as
fast as we can."

The Venus 2 flyby pictures are online at
http://www.nasa.gov/mission_pages/messenger/multimedia/venus_flyby.html.
For more mission news and images, visit http://messenger.jhuapl.edu/.

MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and
Ranging) is a NASA-sponsored scientific investigation of the planet
Mercury and the first space mission designed to orbit the planet
closest
to the Sun. The MESSENGER spacecraft launched on August 3, 2004, and
after flybys of Earth, Venus, and Mercury will start a yearlong study
of
its target planet in March 2011. Dr. Sean C. Solomon, of the Carnegie
Institution of Washington, leads the mission as principal
investigator.
The Johns Hopkins University Applied Physics Laboratory built and
operates the MESSENGER spacecraft and manages this Discovery-class
mission for NASA.

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