ESA Science & Technology - Publication Archive
This article is based on a talk given by Professor Nicolas Thomas of the Physikalisches Institut of the Universität Bern to the Pro ISSI.
AbstractThe Solar Orbiter mission is presently in assessment phase by the Science Payload and Advanced Concepts Office of the European Space Agency. The mission is confirmed in the Cosmic Vision programme, with the objective of a launch in October 2013 and no later than May 2015. The Solar Orbiter mission incorporates both a near-Sun (~0.22 AU) and a high-latitude (~ 35 deg) phase, posing new challenges in terms of protection from the intense solar radiation and related spacecraft thermal control, to remain compatible with the programmatic constraints of a medium class mission. This paper provides an overview of the assessment study activities, with specific emphasis on the definition of the model payload and its accommodation in the spacecraft. The main results of the industrial activities conducted with Alcatel Space and EADS-Astrium are summarized.
Ten to twenty years from now, a succession of clever new spacecraft will need to be ready to fly in ESA's continuing Science Programme, now called Cosmic Vision. They will tackle some of the big scientific questions that are high on the agenda of research across Europe (and, indeed, worldwide) concerning the Universe and our place in it:
- what are the conditions for planet formation and the emergence of life?
- how does the Solar System work?
- what are the fundamental physical laws of the Universe?
- how did the Universe originate and what is it made of?
This brochure gives a detailed overview of the Cosmic Vision 2015-2025 plan. The opportunities under the above four main headings are presented, and specific aspects of each general theme that are judged to be especially ripe for investigation by new space tools in the period 2015-2025 are identified. A review of the technology that will have to be developed is given.
The presented planning on behalf of the scientific community and aerospace industry takes into account the Science Directorate's preliminary reckoning of the practical constraints of technology. In the section 'Proposed Strategies and Their Implementation', the outcome of these deliberations is summarised in four tables that correspond to the above four key questions.
- The Near-Earth Solar Wind
M. L. Goldstein, et al.
- The Foreshock
J. P. Eastwood, et al.
- The Magnetosheath
E. A. Lucek, et al.
- Cluster at the Bow Shock: Introduction
A. Balogh, et al.
- Quasi-perpendicular Shock Structure and Processes
S. D. Bale, et al.
- Quasi-parallel Shock Structure and Processes
D. Burgess, et al.
- Cluster at the Bow Shock: Status and Outlook
M. Scholer, et al.
- Magnetopause and Boundary Layer
J. Keyser, et al.
- Cluster at the Magnetospheric Cusps
P. J. Cargill, et al.
- Magnetopause Processes
T. D. Phan, et al.
ESA's ambition of inter-planetary exploration using a fast-track low cost industrial programme was well achieved with Mars Express. Reusing the platform architecture for the service module and specifically the Propulsion system enabled Venus Express to benefit from several lessons learnt from the Mars Express experience. Using all existing components qualified for previous programmes, many of them commercial telecommunication spacecraft programmes with components available from stock, an industrial organisation familiar from Mars Express was able to compress the schedule to make the November 2005 launch window a realistic target. While initial inspection of the CPS schematic indicates a modified Eurostar type architecture, - a similar system using some Eurostar components - would be a fairer description. The use of many parts of the system on arrival at the destination (Mars or Venus in this case) is a departure from the usual mode of operation, where many components are used during the initial few weeks of GTO or GEO. The system modifications over the basic Eurostar system have catered for this in terms of reliability contingencies by replacing components, or providing different levels of test capability or isolation in flight. This paper aims to provide an introduction to the system, address the evolution from Eurostar, and provide an initial assessment of the success of these modifications using the Mars Express experience, and how measures have been adopted specifically for Venus Express.
An insufficient amount of pressurant gas in the propulsion system or a working temperature in the pressurant tank outside the qualification limits can cause a decrease in the performance of the thrusters or even the loss of the mission. This paper presents an engineering tool used able to compute the Pressurant budget of a mission and the effects of influencing parameters. The updated tool allows to also compute the temperature, pressure and mass evolution inside the pressurant tank during the various mission phases. The tool has been used to verify the calculations done by Astrium Stevenage for Mars Express and Venus Express. The pressurant gas used for both cases was helium. The tool permits to use other combinations of pressurant gases and propellants for different propellant systems (monopropellant and bipropellant systems).
The gamma-ray observatory INTEGRAL was launched in October 2002 and produces since then a wealth of discoveries and important new results. I will present a selection of scientific highlights obtained during the first 2.5 years of the mission.
A new concept of a high-resolution near-IR spectrometer consisting of an echelle grating combined with an acousto-optic tunable filter (AOTF) for separation of diffraction orders, is developed for space-borne studies of planetary atmospheres. A compact design with no moving parts within the mass budget of 3-5 kg allows to reach the resolving power 20 000-30 000. Only a small piece of spectrum in high diffraction orders can be measured at a time, but thanks to flexibility of the AOTF electrical tuning, such pieces of spectrum can be measured randomly and rapidly within the spectral range. This development can be used for accurate measurements of important atmospheric gases, such as CO2 in terrestrial atmosphere, isotopic ratios and minor gases. A spectrometer, based on this principle, SOIR (Solar Occultation InfraRed) is being built for Venus Express (2005) ESA mission. Instruments based on this principle have high potential for the studies of the Earth, in particular for measurements of isotopes of water in the lower atmosphere, either in solar occultation profiling (tangent altitude <10 km), or observing solar glint for integral quantities of the components. Small size of hardware makes them ideal for micro-satellites, which are now agile enough to provide necessary pointing for solar occultation or glint observations. Also, the atmosphere of Mars has never been observed at local scales with such a high spectral resolution. A laboratory prototype consisting of 275-mm echelle spectrometer with Hamamatsu InGaAs 512-pixel linear array and the AOTF has demonstrated a resolving power of 30 000 in the spectral range of 1-1.7 µm. The next set up, covering the spectral ranges of 1-1.7 µm and 2.3-4.3 µm, and the Venus Express SOIR are briefly discussed.