Smart-1 photo album
SMART-1, Europe’s first mission to the Moon
SMART-1, Europe’s first Moon probe was developed by the Swedish Space Corporation on behalf of ESA. SMART-1 was the first of ESA’s Small Missions for Advanced Research and Technology with the purpose to test new technologies to be used in larger ESA science projects. The main mission objective of SMART-1 was the flight demonstration of electric propulsion for deep space missions, an objective that was successfully achieved with the spectacular capture into lunar orbit on November 15, 2004.
This sophisticated lunar probe of brand-new design was developed in only 39 months. SSC's project team that managed and carried out the development of the spacecraft and several of its subsystems consisted at a maximum of 75 persons including consultants for specific development tasks. In addition to the Prime Contractor task, SSC was responsible also for the system engineering, the development of the onboard system unit based on the CAN (Controller Area Network) protocol, the star tracker based attitude control system, onboard applications software, spacecraft simulator and Electrical Ground Support Equipment.
Design drivers for the spacecraft included the high power needed for the electric propulsion, the severe radiation environment encountered during the slow Earth escape trajectory and the need for onboard autonomy. SMART-1 made a 100-day travel through the radiation belts, during which the spacecraft encountered periods of exceptional solar activity in October/November 2003. Minor radiation effects were indeed encountered on the electrical propulsion system, the main computer and the star trackers, all of which were readily overcome.
Power was provided by a large solar array with almost 2 kW of initial power using highly efficient triple-junction cells and a 220 Ah Li-ion battery. The spacecraft’s attitude control was based on reaction wheels and hydrazine thrusters as actuators, and compact star trackers and gyros as sensors. The spacecraft platform contains several new technology elements in addition to the electric propulsion.
Autonomy was a major design driver for the spacecraft in order to minimize the operations costs during the long transfer to the Moon. The avionics was entirely new and its architecture was designed so that the on-board software could autonomously manage all fault detection, isolation and recovery (FDIR).
The spacecraft used a 70 mN Stationary Plasma Thruster (PPS-1350) developed by the French company Snecma. Approximately 65 kg of Xenon was used to provide 3.5 km/s of increased velocity bringing SMART-1 from the geostationary transfer orbit to a polar lunar orbit in 13.5 months. The remaining 17 kg of Xenon were used to achieve and maintain the science orbit or around 300 km x 3000 km.
The Lunar observation phase, initially planned to last six months, could be increased to 22 months thanks to two reboost manoeuvres performed with the electric propulsion system. In lunar orbit, the spacecraft used different pointing scenarios, including nadir pointing and target pointing in order to carry out a comprehensive programme of scientific observations.
The spacecraft carried a scientific payload weighing 19 kg which contained miniaturized instruments such as an imager for visible and near-infrared light, an infrared spectrometer, an X-ray spectrometer and instruments to measure the effect of the electric thruster on the space plasma environment. Important science objectives of SMART-1 were the conductance of lunar crust studies in order to test the current theories of the formation of the Moon, and to establish whether the large hydrogen deposits detected near the South Lunar Pole by the US Probes Clementine and Lunar Prospector, indeed contain water. During the cruise phase to the Moon, experiments related to autonomous spacecraft navigation were carried out using images from the star trackers and the miniature imager.
SMART-1 was launched by an Ariane-5 rocket on 27 September 2003 and reached an orbit around the Moon in mid November 2004. From the end of September, 2005, Smart-1 was left in a natural orbit determined by lunar gravity and the perturbations by Earth and the Sun. As planned, Smart-1 impacted the moon´s surface in the so called Lake Excellence area on the Moon´s front side on September 3 at 05:42:22 UT. The impact is estimated to have caused a three to ten meter crater in diameter. The crash site was predicted with high precision by the European Space Operations Centre (ESOC) and the impact could be imaged in real-time by the 3.5 m Canada-France-Hawaii Telescope IR-telescope in Hawaii.
Technical characteristics of SMART-1:
• Platform: 3-axis stabilised
• Launch mass: 367 kg
• Scientific payload mass: 19 kg
• One 68 mN electric thruster (PPS-1350, SNECMA)
• Xenon propellant mass: 82 kg to provide 4000 m/s deltaV
• Life time: 2 years designed for at least 500 eclipse periods, onboard resources dimensioned for an extension of 6 months.
Actual life time 38 months.
Read more about Smart-1 (pdf)
