SMART-1 spacecraft and payload take shape for Moon journey
2 February 2000It was with added enthusiasm that the key players in the SMART-1 mission gathered at ESTEC on 31 January and 1 February for their sixth Science and Technology Working Team meeting. It was the first reunion since ESA's lunar mission and its science and technology payload were given the final go-ahead last November. SMART-1 is the first of the Agency's Small Missions for Advanced Research in Technology.
For all the scientists and engineers present, representing the six science and technology instruments and related investigations aboard the spacecraft, 'going to the Moon' now means meeting deadlines in order to be ready for an Ariane-5 launch scheduled for October or November 2002.
The phase C-D activities that started last November require that the precise design of the spacecraft be finalised by the end of this February and that a Structural and Thermal Model of the spacecraft be available by the second half of the year. In August the prime contractor Swedish Space Corporation will begin a series of five Bench Test Models (BTM) verifications to check the mechanical, electrical and software compatibility of all the experiments.
"It is the first time Swedish Space Corporation is prime contractor for ESA and the mission is a real challenge for us" says Bo Ljung, Project Manager at SSC. "We have a very compressed time schedule and the payloads will be delivering engineering and then flight models of their instruments very soon. Although we will allow a certain flexibility in the schedule, it is crucial that we have the spacecraft ready on time".
After a reminder of this schedule by Bo Ljung and by SMART-1 Project Manager Giuseppe Racca, the meeting reviewed all the individual aspects of the mission. This covered technical questions such as the way SMART-1 will be storing and sending back data with contact possible for just 8 hours every 4 days during its long cruise phase to the Moon. The mission's organisation was also reviewed, for instance its Science & Technical Operations Co-ordination Centre (STOC) and the SMART-1 Mission Operations Centre (S1MOC) which will be situated respectively at ESTEC and ESOC. An Experiment Planning System (EPS) and a Project Testbed simulator will allow all the SMART-1 experimenters to optimize their technology demonstrations and science observation opportunities during the mission. Developed at ESTEC, EPS is also being used by the Rosetta and Mars Express missions.
The SMART-1 investigators reported on the payload development, which is now proceeding at full speed. Amongst the new technical issues mentioned, Richard Browning (Rutherford Appleton Laboratories, UK), experiment manager for the 'D-CIXS' instrument, presented the shutter-like door that will now give their compact X-ray spectrometer more protection against damaging protons. Andreas Nathues (MPAe Lindau) outlined that an additional cooling for their 'SIR' compact infrared spectrometer would probably be required to increase the signal to noise ratio for their detectors. Jean-Luc Josset (CSEM, CH), PI of micro-imager 'AMIE', showed the final design of the instrument, with additional shielding against radiation. Zoltan Sodnik, guest investigator of 'Laser Link', using 'AMIE', announced a new filter design of the camera allowing the use ESA's Optical Ground Telescope at Tenerife without modifications.
The STWT meeting was given the status on SMART-1's two technology experiments 'EPDP' and 'SPEDE'. These will not only be monitoring the mission's main feature, its solar electric propulsion, but will also have science objectives such as the study of the interaction between the solar wind and the Moon and the distribution of plasma around the Earth. Alister Winton, representing the 'KaTE/RSIS' Deep-Space communications package and Radio Science Investigations presented plans to provide a backup/supplementary Ka and X-band ground station.
There was also an examination of the lunar operational orbit of SMART-1. "At present the baseline foresees a 14 hour elliptical orbit approx. 300-1000 km (perilune - closest point) x 10000 km (apolune - farthest point)" explains Project Scientist Bernard Foing. "Participants involved in remote sensing expressed the improvement to spiral down further with the Solar Electric Propulsion. Having an apolune closer to the Moon would increase the efficiency for lunar mapping at higher resolutions than carried out by the Clementine and Lunar Prospector probes. The feasibility of this is to be examined".
The next SMART-1 Science & Technology Working Team meeting will take place during the European Geophysical Society Assembly to be held on 25-29 April in Nice, France, at which an Open Session on Lunar Exploration, and a SMART-1 sub-session are organised.