Lunar approach and landing scenario
Arecibo Observatory/Cornell Univ. (courtesy D. Campebell)
The planned EuroMoon 2000 mission sequence in lunar orbit
- Injection of the Orbiter + Lander composite
spacecraft into polar Low Lunar Orbit (LLO) at an altitude of 200
km (possibly 500 km).
- Separation of the Orbiter from the
Lander. Spacecraft commissioning (three weeks) and Sun-pointing
- Preliminary gravity-field
determination in the 200 km orbit by tracking the orbit from
Earth (for deciding at what altitude to operate the gravity
experiment), and preliminary low-resolution mapping (one month).
- Lowering of the Orbiter's altitude to 100 km, with nadir-
pointing attitude, whilst the Lander remains parked at the
original 200 km altitude, in a Sun-pointing attitude.
Release of a subsatellite into a 'frozen' orbit at about 100 km
- Gravity experiment lasting two to three months,
depending on the subsatellite's lifetime. The Orbiter should not
be manoeuvred during this experiment (thrusters used as little
as possible), which implies that the operation of other
experiments needing precise pointing is temporarily impaired. The
microwave instrument, for example, may be operated during this
phase, but not the high-resolution camera.
- High-resolution imaging from the Orbiter for about one
month, during which the necessary sophisticated image processing
would be conducted back on Earth. In principle, landing may be
attempted during any orbit, but communications constraints will
determine the duration of this period in terms of phasing
- Descent and touchdown of the Lander. This
may occur as soon as processed gravity-field and high-resolution
imaging data are available and the communications constraints are
The duration of the Lander's surface operations is, in
principle, not limited (permanent sunlight). The primary mission,
however, may last in the order of four months, whilst the
Orbiter's global mapping and other science operations will
continue for a further 8 9 months.
An alternative mission concept would use the Lander and the
Orbiter as satellite and subsatellite, respectively, for the
gravity experiment (although this has not yet been analysed in
EuroMoon 2000 (BR-122).
Published December 1996.
Developed by ESA-ESRIN ID/D.