Geoscience Reference
In-Depth Information
In 2007, Japan will launch a three axes stabilizing lunar orbiter Seleno-
logical and Engineering Explorer (SELENE). One of the most important
purposes of SELENE is to obtain source data to provide global lunar mor-
phological maps with higher resolutions than those of past missions. In the
14 mission instruments on SELENE, especially Lunar Altimeter (LALT)
and Terrain Camera (TC) are expected to provide data attaining this pur-
pose. The nominal sampling rate of LALT is 1 s that is corresponding to
1.6 km interval on the lunar surface and the ranging error of LALT will
be <
5m. 6 The TC will take global stereo pair data with a spatial reso-
lution of 10 m from SELENE nominal altitude of 100 km to provide DTMs
with height resolution of about 20 m. In this paper, we address the TC
mission with specification, operation plan, and ground data systems of this
instrument.
±
2. Overview of TC Mission Objectives and
Specification of TC
On SELENE, three optical cameras are installed: the TC, the Multi-band
Imager (MI), and the Spectral Profiler (SP). The TC is a stereo mapping
imager, 7 - 10 MI is a multi-color imager with five-bands in visible range and
four-bands in near-infrared range, 11 and SP is a continuous spectral profiler
of the range from visible to near infrared. 12 These cameras share some parts
of structures and electrical circuits to reduce mission resources of weight,
space, and electrical power. We call the three optical cameras of SELENE
as the Lunar Imager/Spectrometer (LISM), generally.
The mission objectives of TC are to produce
(1) global high-resolution and high-contrast mosaicked maps of the Moon,
(2) DTMs for the entire surface of the Moon that are expected to be base
maps and models of future lunar sciences and lunar explorations.
The TC consists of two slant telescope systems (see Fig. 1). Each system
has a linear detector with a panchromatic filter in a visible range of 0.43-
0.85 µ m. The TC takes images by push-broom method. The slant angle is
±
15 from the nadir vector, thus the base-height ratio of TC is 0.57. The
instant field of view (IFOV) of TC is 0.00553 . The number of each detector
pixel is 4096. The TC has three swath modes: (1) full swath mode that uses
all detector pixels of 4096, (2) nominal swath mode that uses 3500 pixels,
and (3) half swath mode that uses 1750 pixels. The field of view will be
22.4, 19.3, and 9.65
for full, nominal and half swath mode, respectively.
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