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to the SOLARNET PageFrom eric@dcs.st-and.ac.uk (Eric Priest)
7 Apr 1998
After a lot of hard debate and discussion, a genuine consensus was achieved which I hope will form a strong basis for the future of European Space Solar Physics.
Below you will find a copy of the Resolution that was agreed at the workshop and which has been forwarded to ESA and its committees. We all hope that ESA responds positively to it.
In addition you will find a copy of the press release that the Royal Astronomical Society in the UK has issued about the workshop
Eric Priest
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The international workshop `A Cross-roads for European Solar and Heliospheric Physics', held on March 23-27, 1998 at Puerto de la Cruz, Tenerife, and attended by over 100 active researchers from Europe (including Russia), Japan and the US was presented with overviews of key open scientific questions and status reports on the scientific achievements of SOHO.
The workshop participants debated and compared plans for major future solar and heliospheric missions. There was general agreement that the next major scientific breakthroughs are expected from high-resolution in-situ and remote measurements, as well as three-dimensional and polar imaging. The workshop participants concentrated on several main mission concepts:
They discussed the potential scientific achievements and challenges of solar probes, near-Sun orbiters and of solar and heliospheric polar and stereo missions.
They also explored the ways European solar physicists could take the lead in extremely high-resolution observations, for example through interferometry.
The workshop participants came to the conclusion that several realistic studies of innovative missions now exist and that the field will benefit greatly from international assessment of the overall context of such missions: a proper coordination will exploit the synergies between missions of various agencies.
The participants of the workshop strongly urge ESA to negotiate with ISAS, NASA and RSA to:
Given the advanced state of NASA plans for STEREO and PROBE (AO releases expected later this year) and the need for endorsement by ESA's advisory structure, an early start of ESA negotiations with NASA is advisable. ESA endorsement (not implying ESA funding) will facilitate national and PRODEX funding.
In considering interferometry, it was felt that high-resolution observations of the Sun are very important scientifically, but that further developments are needed before this can be used as a major mission. The participants therefore strongly recommend that ESA set up a study for Solar Interferometry on the Smart 2 mission.
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Solar physicists from the UK and other European countries are urging the European Space Agency (ESA) to build a new spacecraft to orbit the Sun. The Solar Orbiter would circle much closer to the Sun than any previous spacecraft, approaching the within 20 million km of the Sun's surface-3 times closer than the innermost planet, Mercury. Following a special workshop sponsored by ESA and organised by Professor Eric Priest of the University of St Andrews, the scientists are suggesting that the Solar Orbiter project should be part of a coordinated international approach to learning more about the Sun. It would follow up the success of Ulysses and SOHO, two spacecraft currently being used to study the Sun.
A hundred of the world's leading solar physicists met at the ESA workshop, held at the Instituto de Astrofisica de Canarias on the Spanish island of Tenerife at the end of March. They considered various solar space missions being planned by different groups of scientists around the world. The Sun is in its own right an important subject for research by ESA, and, as our nearest star and a means to study basic cosmical processes in great detail, it is also of great significance for astronomy as a whole. In addition, it affects Earth's environment and can cause damage to satellites and disrupt electricity supplies. The scientists concluded that the Solar Orbiter, provided by ESA in collaboration with other space agencies, would be a key part of a coherent international programme.
"Space missions take many years to plan" says Professor Priest. "From time to time we have to stand back and decide what key scientific questions we should try to answer in the future. In what direction should we head? What might be technologically feasible in 10 or 20 years from now? Such exciting ideas for studying the Sun are on offer, it is hard to choose between them."
In addition to the Solar Orbiter, workshop participants looked at three other proposed space missions:
STEREO is a proposal to send several spacecraft to different positions in the Solar System. By viewing the Sun from different directions they could build up 3-D pictures (stereoscopic or tomographic). These would reveal clearly, for the first time, the complex contortions of gas and magnetic fields involved in solar eruptions. The consequences include solar flares and the mass ejections of gas which, arriving at the Earth, can cause satellite failures and power black-outs.
SOLARNET is a rival scheme, aiming to inspect the stormy surface and atmosphere of the Sun in much sharper detail. A combination of three telescopes in an interferometer could achieve a clarity of vision 40 times better than that of the present instruments in space. The immense magnetic explosions responsible for heating the Sun's atmosphere and for sparking solar flares occur in regions too small to be clearly resolved by available telescopes.
PROBE is a scheme to send a spacecraft into the Sun's hot atmosphere, where it could sample its atoms directly and measure the magnetic fields. Probe would fly by the Sun at a distance of only 2 million kilometres from the surface, compared with 150 million kilometres for the Earth-Sun distance. Remarkable heat shields would have to maintain the spacecraft at an operable temperature in sunshine 2500 times stronger than at the Earth.
After a lively debate, the following consensus emerged. A coherent international programme of missions should be set up. Stereo and Probe are likely to be realized within NASA's programme, but it was agreed that they would benefit greatly by participation of European scientists with ESA endorsement. Solar-Net was recognized to be of high scientific interest and was considered suitable for a small demonstration mission. Solar Orbiter was recommended as the main ESA element in the programme.
In contrast to Probe, which would fly right past the Sun in less than a day, Solar Orbiter would remain above the same region of the Sun for several days and would continue to orbit the Sun many times. At a later stage the aim would be to observe in detail, for the first time, the mysterious polar regions of the Sun. And Solar Orbiter would be able to see the regions through which Probe was flying.
Commenting on the choice of Solar Orbiter, Professor Priest said, "What tipped the scales was the exciting new science, its key role in the overall international programme, and the broad backing of the world's solar scientists. By selecting Solar Orbiter as the project for which we will all now be pressing, we can be certain that Europe will create a fitting successor to SOHO, which is already revolutionizing solar science.
As with any proposal like this, Solar Orbiter will have to go through ESA's procedures for mission selection before it can be authorised. Assessments by expert committees and detailed studies of the science, engineering and costs are required. Any collaboration with other space agencies has to be negotiated. However, the support of the specialists in solar physics helps strengthen the case for Solar Orbiter as ESA's next solar project, to be considered for possible launch between 2005 and 2010.
Images to support this story can be found at:
http://www-solar.dcs.st-andrews.ac.uk/~eric/tenerife.html
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