|
MESSENGER sports two high-gain phased array
antennas that will serve as the main communications link for transmitting
science data to Earth. Shown in this view is the recently installed
aft phase array antenna; the bracket for the forward antenna was
installed last week. A temporary
cover was also placed over the Launch Vehicle Adapter to protect
the newly installed MASCS instrument.
To limit the possibility of failure the antennas
are fixed - that is, they "point" electronically across
a 90-degree field and have no moving parts. Depending on the spacecraft's
orientation, at least one of the two phased array antennas will
be pointed at Earth during normal operations. If one antenna fails,
data can be stored on the spacecraft's solid-state data recorder
(similar to a desktop computer's hard drive) for later transmission
through the other antenna. Currently the antenna has a red cover,
which protects it while engineers work on the spacecraft around
it.
In addition to the two phased array antennas,
MESSENGER has two fanbeam antennas and four low-gain antennas
for low-data-rate communications near Earth - spacecraft operating
commands, for example - or in case the high-gain antennas accidentally
point away from Earth.
Last updated: June 11,
2003
|
