LUNETTE - A Discovery Class Mission to the Moon to Establish a Geophysical Network

Lunette is a Discovery mission concept that is designed to deliver three landed geophysical packages (“nodes”) to widely spaced (3000-5000 km) locations on the lunar surface. This mission will provide detailed information on the interior of the Moon through seismic, thermal, electromagnetic, and precision laser ranging measurements, and will substantially address the lunar interior science objectives set out in “The Scientific Context for the Exploration of the Moon” (NRC, 2008) and ”The Final Report for the International Lunar Network Anchor Nodes Science Definition Team” (NASA, 2009). Each node will contain: a very broad band seismometer that is at least an order of magnitude more sensitive over a wider frequency band than the seismometers used during Apollo; a heat flow probe, delivered via a self-penetrating “mole” device; a low-frequency electromagnetic sounding instrument, which will measure the electromagnetic properties of the outermost few hundred km of the Moon; and a corner-cube laser retroreflector for lunar laser ranging. These instruments will provide an enormous advance in our knowledge of the structure and processes of the lunar interior over that provided by Apollo-era data, allowing insights into the earliest history of the formation and evolution of the Moon. The instruments that comprise the individual nodes are all optimized for low power operation and this mission will not rely on a radioisotope power supply. Improvements in solar energy and battery technology, along with an Event Timer Module which allows the lander to shut down its electronics for most of the lunar night, enables a solar/battery mission architecture with continuous instrument operation and a two-year nominal lifetime. The instruments have a combined mass of <12 kg, and the dry mass of each lander will be on the order of 100 kg, including solar panels, batteries, and communications. The most power hungry instrument is the heat flow “mole”, which requires ~ 11 W during penetration and ~5-6 W during the active heating tests for thermal conductivity measurements. Normal operations of the mole only require 2.2 W. The nodes will operate during the lunar night in a low power mode where only systems required for data acquisition are powered. Communications back to Earth will only occur during the lunar day so there is data storage on the order of 3-4 Gbits to enable continuous operations during the lunar night (up to 16 earth days). The direct-to-Earth link is S-band at 120 kbps to a DSN 34 m ground station. UHF cross-links from remote units to the communications hub will utilize small, low power UHF transceiver for two-way communication at 128 kbps.