Geoscience Reference
In-Depth Information
3. Overview of SELENE/TC Operation
The SELENE will be injected into a Moon circular orbit of 100 km altitude,
and revolve in 118 min around the Moon. A visible operation time for the
Moon explorer at one ground space station is at longest 12 h and possi-
bly about 8 h/day. Considering this restriction, SELENE has onboard data
storage of about 100 Gbit memory and performs the transmission data rate
of 10 Mbps from the explorer to the Usuda Deep Space Center (UDSC) in
Japan. The data amount of TC and MI will be very large since these are
high-resolution imaging cameras. For example, the TC nominal data rates
onboard that can be calculated from the active pixel number of 3500 for
nominal swath mode and A/D converter rate of 10 bit are 10.8 Mbps for
TC stereo observation mode and 5.4 Mbps for TC mono-telescoping mode.
The total data amount per day will be about 500 Gbit. The mission data
recorder on SELENE has no partition by mission instrument and a large
amount data will overwrite other mission data. Therefore, an allotment
for data volume of 50 Gbit/day has been required to LISM. The operation
policies of LISM to satisfy this requirement is that
(1) TC and MI will not operate simultaneously,
(2) TC/MI will take images in a scheduled longitude range, and
(3) TC/MI will compress their data onboard.
In practice, appropriate solar elevation angles for TC and MI are differ-
ent, thus such an isolated operation of TC and MI is not of disadvantage.
During the SELENE nominal mission period of 1 year or 13 moon cycles,
we are planning to execute as follows:
(1) TC stereo-mapping in three moon cycles,
(2) TC mono-telescope mapping at illumination conditions of eastward
and westward lower solar elevation angles for 60N-60S in two moon
cycles, and
(3) MI mapping in 6 months.
The first two months will be used for checkout of instruments.
We are planning to execute two type TC observations regularly in one
revolution as follows:
(1) nominal stereo-mapping observation or mono-telescope mapping, and
(2) SP support observation by one telescope system with a high-
compression mode to reduce the data to a few percentage.
