ESA Science & Technology - Publication Archive
We propose number of targets observed with SMART-1 for follow-up studies with LRO. We shall also discuss SMART-1 lunar highlights relevant for science and exploration, in relation with LRO/LCROSS and future lander missions.
The SMART-1 spacecraft started from 15 March 2005 with a lunar orbit 400-3000 km for a nominal science period of six months, with 1 year science extension. During these 18 months, the AMIE camera aboard the spacecraft acquired about 32.000 images. We report on the coverage at various resolutions and the pointing accuracy.
SMART-1 is Europe's first lunar mission, the current step in developing an international program of lunar exploration. The spacecraft was launched on 23 September 2003 as an Ariane 5 Auxiliary passenger to Geostationary Transfer Orbit (GTO), performed a 14 month long cruise using the tiny thrust of electric propulsion alone, reached lunar capture in Nov 2004, and lunar science orbit in March 2005. SMART-1 carries seven hardware experiments (performing 10 investigations, including three remote sensing instruments, used during the cruise, the mission's nominal six months and one year extension in lunar science orbit. The remote sensing instruments contribute to key planetary scientific questions, related to theories of lunar origin and evolution, the global and local crustal composition, the search for cold traps at the lunar poles and the mapping of potential lunar resources.
The paper will show the pros and contras in some of the choices made for Smart-1 together with the developments and the solutions implemented to mitigate the problems found during the mission:
- Impact of on-board problems on operations
- Ground Segment automation
- Keeping the mission control team reduced
- The increased importance of the Mission Planning System
- Fast distribution of spacecraft data through internet for anomaly identification and analysis
- Summary of lessons learnt
SMART-1, launched in fall 2003, is Europe's first moon satellite. It shall demonstrate Solar-Electric Propulsion using a PPS-1350 hall thruster. One of the main mission investigations is the characterization of the thruster's charge-exchange ion environment. Two instruments support this analysis: EPDP, consisting of a Langmuir probe, RPA analyser and a solar cell sample, and SPEDE, consisting of two current collection spheres supported by two short booms. ARC Seibersdorf research developed a Particle-In-Cell plasma simulation to support and predict the thruster's induced plasma environment around SMART-1. This paper will give an overview of the modeling approach and a comparison of the model will test results gained during the STENTOR ground test campaign using a similar thruster. We will also report a first interpretation of the measurements from EPDP and SPEDE on SMART-1 and will compare them with the actual model predictions. This analysis shall be used to actually validate the simulation tool to reliably predict charge exchange plasma environments on future missions using electric propulsion.
ESA's SMART-1 is at the Moon! Launched by Ariane-5 in Sept. 2003, it used primary solar electric propulsion to reach lunar capture on 17 November 2004, and to spiral down to lunar science orbit. First data and results from the cruise approach and lunar commissioning will be presented.
Electric propulsion represents one of the most promising technologies for application in future space missions. The knowledge of the plasma plume evolution in the thruster surrounding space is still of fundamental importance, at system design level, for new generation satellites, in order to integrate the propulsive subsystem with the other vehicle subsystems. Furthermore, the necessity to simulate realistic configurations leads to the need of powerful and flexible 3-D tools. Alta S.p.A. and Consorzio Pisa Ricerche developed a three-dimensional particle-in-cell code capable to simulate conditions found both in space and in ground vacuum facilities, for realistic satellite configurations for Hall Effect Thrusters and Gridded Ion Engines. The present article will present a brief description of the PICPluS 3D code, including the various physical models that can be used and the code validation. Numerical results related to the ESA's SMART-1 satellite, launched on 27 September 2003, will then be compared with flight data. Finally, an analysis of the influence of the simulation paramaters on the results will follow.
Onboard the ESA SMART-1 spacecraft, (Small Mission for Advanced Research in Technology), the Xenon feeding system operates since the September 30th 2003. EPS Contractor, ESTEC, and EPS manufacturer, SNECMA MOTEURS, present in detail the major performances of the Pressure Regulation System, with a comparison to the ground tests results. The PPS® -1350 Hall Effect plasma Thruster needs a regulated xenon pressure as input of the flow controller. Such pressure is delivered and controlled by two pieces of hardware, the "Bang-Bang Pressure Regulation Unit" and the "Pressure Regulation Electronic Card". The concept is described as well as its main features: the robustness by design that cannot allow a direct communication between the high-pressure parts (the xenon tank) and the low-pressure parts (the thruster input). The paper highlights the possibility for various parameters to be tuned by telecommands in order to reach different performance levels of the pressure regulation. The real flexibility of the concept allows smoothing the pressure regulation. This paper describes the performances results of the pressure regulation in space environment compared to the ground tests results. It discusses also the advantage of the regulation tuning capability during the first flight phase. This new features of primary electric propulsion subsystem demonstrates its robustness and flexibility toward thruster initial requested tuning to keep the thruster loop fine pressure regulation in an adequate range.
Onboard the ESA SMART-1 spacecraft, (Small Mission for Advanced Research in Technology), the primary Electric Propulsion Subsystem (EPS) operates since the 30th September 2003. EPS Contractor, ESTEC, and EPS manufacturer, SNECMA MOTEURS, present in detail the major performances of the complete electric propulsion system, with a comparison to the ground tests results. The PPS®-1350-G Hall Effect plasma Thruster and its Power processing unit, developed in the frame of the CNES Stentor Program, was tested at Snecma facilities. The main feature of the Smart-1 system is its variable power supply. Integrated into the whole spacecraft the electric propulsion system was tested at ESTEC before the in-flight first firing after the successful Ariane V launch. Results of these main tests demonstrate a good prediction of the in flight EPS behavior including the robust bang-bang xenon pressure regulation for the input pressure and variable electrical power supply. This paper describes the performance results of the PPS®-1350-G firing in space environment. It discusses also the consequences of the Van Allen radiation belt crossing during the first flight phase, particularly the behavior of the floating potential of the thruster with respect to the satellite electrical ground. The initial successful results obtained supports the first technological experience objective of the SMART-1 mission. These new features of primary electric propulsion subsystem and especially the low-power start-up and variable power features can be also a significant added value for any commercial application using electric propulsion for station-keeping and/or orbit transfer.
Present simulation techniques for plasma thrusters plume simulations usually implement a Particle In Cell / Monte Carlo approach to a plasma flow considered in a quasi-neutral state, with the possibility of a residual atmosphere (typical of a vacuum chamber test facility). Nonetheless it is difficult to compare directly results, even with measurements taken in very similar laboratory configurations, because it's not yet achieved the possibility to simulate at the same time realistic chamber geometry, pumping system performance and effect of the sputtering caused by the ion beam impinging the chamber walls. The present article will show the results of a series of PIC/DSMC simulations executed with CPR/Alta codes on HET plumes, considering a wide range of realistic laboratory configurations, and considering also the effect of different physical models; results will be also compared with experimental ones from literature and Alta testing facilities and flight data from the European SMART-1 mission.