The first mission to orbit the planet Mercury took a big step toward its
scheduled March 2004 launch when NASA’s MESSENGER project received approval
to start building its spacecraft and scientific instruments.

MESSENGER – which stands for MErcury Surface, Space ENvironment,
GEochemistry, and Ranging – passed a thorough four-day critical design
review last week, during which a project advisory panel and NASA assessment
team examined every detail of the mission and spacecraft design.

“The review was very successful,” says Max R. Peterson, MESSENGER project
manager at the Johns Hopkins University Applied Physics Laboratory (APL),
Laurel, Md. “Both panels confirmed that our designs are sound and meet the
mission’s science and engineering requirements. We’re ready to move to the
next stage.”

MESSENGER team members are building flight hardware now and will begin
integrating parts on the spacecraft this November, Peterson says. After
launch and a five-year journey through the inner solar system, MESSENGER
will orbit Mercury for one Earth year, providing the first images of the
entire planet and collecting information on the composition and structure of
Mercury’s crust, its geologic history, the nature of its thin atmosphere and
active magnetosphere, and the makeup of its core and polar materials. While
cruising to Mercury the spacecraft will fly past the planet twice – in 2007
and 2008 – snapping pictures and gathering data critical to planning the
orbit study that begins in April 2009.

A key MESSENGER design element deals with the intense heat at Mercury. The
sun is up to 11 times brighter than we see on Earth and surface temperatures
can reach 450 degrees Celsius (about 840 degrees Fahrenheit), but
MESSENGER’s instruments will operate at room temperature behind a sunshield
made of heat-resistant Nextel fabric. The spacecraft will also pass only
briefly over the hottest parts of the surface, limiting exposure to
reflected heat.

“The project is well on its way,” says Dr. Sean C. Solomon, MESSENGER
principal investigator from the Carnegie Institution of Washington (D.C).
“Exploring the many mysteries of Mercury will help us to understand all of
the terrestrial planets, including Earth. The team is eagerly looking
forward to assembling and launching the spacecraft and to the first new data
from the innermost planet.”

In July 1999, NASA selected MESSENGER as the seventh mission in its
innovative Discovery Program of lower-cost, highly focused space science
investigations. APL manages the $286 million project for NASA’s Office of
Space Science and will build and operate the MESSENGER spacecraft.

MESSENGER Mission Web Site:

NASA Discovery Program Web Site: