From: LARRY KLAES (ljk4_at_msn.com)
Date: Fri Jul 02 2004 - 14:26:22 PDT
----- Original Message -----
From: MESSENGER News<mailto:MESSENGER-News_at_APLMSG.JHUAPL.EDU>
Sent: Friday, July 02, 2004 1:42 PM
Subject: Upon Reflection
MESSENGER Mission News
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Upon Reflection . . .
MESSENGER will rely on solar panels for power during its long voyage to and orbit around Mercury. The custom-developed panels, installed on the spacecraft June 24-25, were the next-to-last major components to be attached before the spacecraft is moved to the Delta II launch vehicle this month. This week's annotated Webcam image<http://messenger.jhuapl.edu/webcam/annotatedimages/annotated-20040702.html> captures the installation in progress.
To run MESSENGER's systems and charge its 23-ampere-hour nickel-hydrogen battery, the panels, each about 1.5 meters (5 feet) by 1.65 meters (5.5 feet), will support between 385-485 watts of spacecraft load power during the cruise to Mercury and 640 watts during the science orbit. The panels could produce more than two kilowatts of power near Mercury, but to prevent stress on MESSENGER's electronics, onboard power processors take in only what the spacecraft actually needs.
The panels are 67 percent mirrors (called optical solar reflectors) and 33 percent triple-junction solar cells, which convert 28 percent of the sunlight hitting them into electricity. Each panel has two rows of mirrors for every row of cells; a total of 648 cells and 1,296 mirrors per panel. The small mirrors reflect the Sun's energy and keep the panel cooler. The panels also rotate, so MESSENGER's flight computer will tilt the panels away from the Sun, positioning them to get the required power while maintaining a normal surface operating temperature of about 150 degrees Celsius, or 302 degrees Fahrenheit.
Major events before moving the spacecraft include fueling - the team is loading the hydrazine fuel and nitrogen tetroxide oxidizer this week - and final installation of the sunshade.
(Click here for large<http://cps.earth.northwestern.edu/DMOVIES/20040624-Solar_Panel_Install-q10-704x480.mpg> and small<http://cps.earth.northwestern.edu/DMOVIES/20040624-Solar_Panel_Install-q10-352x240.mpg> time-lapse movies of the solar panel installation.)
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This Week at the Cape: Launch Targeted for August 2
With the successful launch of the Air Force Delta/GPS mission last week, MESSENGER's launch has been rescheduled and is now targeted to occur August 2. While the previous launch date of July 30 may have been achievable, the additional margin now being built into the schedule will provide greater confidence in meeting this new launch date. Check the latest status report<http://messenger.jhuapl.edu/news_room/status_report_06_29_04.html> for details.
(The status report is posted at http://messenger.jhuapl.edu/news_room/status_report_06_29_04.html --------------------------------------------------------------------------------
Vaughn Named Engineer of the Year
MESSENGER team member Robin Vaughn of the Johns Hopkins University Applied Physics Laboratory has been named Engineer of the Year by the Baltimore Chapter of the American Institute of Aeronautics and Astronautics (AIAA). The award cites her work as lead engineer for MESSENGER's guidance and control system. Click here<http://www.jhuapl.edu/newscenter/pressreleases/2004/040629.htm> to read more about the award and the winner!
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MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) is a scientific investigation of the planet Mercury, and the first NASA mission designed to orbit the planet closest to the Sun. Dr. Sean C. Solomon, of the Carnegie Institution of Washington<http://carnegieinstitution.org/>, leads the mission as principal investigator. The Johns Hopkins University Applied Physics Laboratory <http://www.jhuapl.edu/>in Laurel, Maryland, built and will operate the MESSENGER spacecraft and manages the Discovery<http://discovery.nasa.gov/>-class mission for NASA<http://www.nasa.gov/>.
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