1. Solar Orbiter - Remote Sensing Payload Working Group Mid-term meeting - 25-26 November 2002, ESTEC Monday 25 November & Tuesday 26 November (Room: Einstein) Start: 11:00 PWG Plenary #1 - Welcome and introduction (Marsden) - Aims of meeting (Marsden and Rando) - Status of Solar Orbiter in ESA (Marsden/Peacock) Remote Sensing Splinter #1 - Status of PDD inputs (Appourchaux) - Discussion of each instrument PDD in turn (Harrison/Fleck) (what is needed, what is outstanding and who can supply details?)

2. Solar Orbiter - Remote Sensing Payload Working Group Mid-term meeting - 25-26 November 2002, ESTEC Remote Sensing Splinter #2 Feasibility/Technical Actions and Studies - Summary of status of actions (Harrison) - Open discussion on recommendations to ESA based on actions - What next? Completion of remaining actions? Report? How do we relay recommendations to ESA? - Solar Orbiter Scientific Goals Plenary #2 - Summary of Splinter Sessions (Harrison/Wimmer) - Future PWG activities - AOB

3. Solar Orbiter - Remote Sensing Payload Working Group Mid-term meeting - 25-26 November 2002, ESTEC Feasibility/Technical Studies & Actions Aim: To demonstrate feasibility of paylaod, especially given the thermal & particle environment and the mission limitations (e.g. telemetry, autonomy). Make recommendations to ESA. Co-ordinate/request studies. Method: By identifying the technical challenges (last meeting) and addressing specific actions. [Remember: We are demonstrating feasibility, nothing more.] Comment: The PDD activity is an ‘extra’, parallel demand on us, but it is necessary for us to do what we can to take advantage of it.

4. Solar Orbiter - Remote Sensing Payload Working Group Mid-term meeting - 25-26 November 2002, ESTEC Feasibility/Technical Studies & Actions Last Meeting: Technical challenges identified and listed. Action list set up and assigned. Web site: Web site set up at http://www.orbiter.rl.ac.uk/solarorb/rspwg/, lists actions, provides notes from initial meeting, action spread sheet, Action Completion reports. Other documents (e.g. PDDs) can be found at http://zeus.nascom.nasa.gov/~bfleck/Orbiter/PLWG/Documents/.

5. Solar Orbiter - Remote Sensing Payload Working Group Mid-term meeting - 25-26 November 2002, ESTEC Feasibility/Technical Studies & Actions Progress to date: 73 actions listed. 22 ticked off, i.e. 30 %. Not very impressive response from some – especially as some of the actions are rather basic, e.g. telemetry ‘back of the envelope’ calculations. Next Step: Assess remaining actions; Pull out recommendations/requests; Discuss report/schedule. Warning: Next Chair of SSWG (Peter Cargill) – ‘better demonstrate feasibility by Spring 2003’. AO June 2004 (1 year after BC)?

6. Solar Orbiter - Remote Sensing Payload Working Group Mid-term meeting - 25-26 November 2002, ESTEC Recommendations: 1. Pointing: It is recommended that a hard mounted, joint-pointing policy be adopted, which is in keeping with the science goals of the mission, but will save mass and power. 2. Image Stabilisation: It is recommended that the VIM signal be used for all instruments that use an image stabilisation system, to save mass and complexity. 3. Resources: All options should be considered by the Project to maximise the payload mass, telemetry, memory capacity and power; the scientific return is increased with increased payload resource.

7. Solar Orbiter - Remote Sensing Payload Working Group Mid-term meeting - 25-26 November 2002, ESTEC Other Recommendations from Actions: Some completed actions make recommendations. If they are concerned with critical technologies (especially involving more than one instrument) or are spacecraft-wide/mission issues, then they must be discussed and passed on to ESA – if ESA are serious about performing studies, we must request them formally now.

8. Solar Orbiter - Remote Sensing Payload Working Group Mid-term meeting - 25-26 November 2002, ESTEC Other Recommendations from Actions: 4. Thermal Control: Given the extreme thermal environment, it is recommended that there be a study of a spacecraft-wide approach to thermal control (Action 1.1/1.2 EUS). e.g. What actions can be taken at a spacecraft level to dampen the thermal variations, to dissipate heat, to allow access to open space etc…

9. Solar Orbiter - Remote Sensing Payload Working Group Mid-term meeting - 25-26 November 2002, ESTEC Other Recommendations from Actions: 4. Thermal Control (continued): Note: The RAL/Cranfield and MSSL studies stress that it is not so much the absolute temperatures that kill you, as the variations! (Possible actions: Reduce aphelion? Heat switches? Heaters? Adaptive optics?…) e.g. 1500 mm CFRP will expand by 50-75 micron with variation of 100 o C. - How do you interface to spacecraft? Same materials? - Do we use adaptive optics or is optical depth of focus OK for this? - Note also: the use of CFRP probably means a 100-130 o C upper limit (outgassing, glue)?

10. Solar Orbiter - Remote Sensing Payload Working Group Mid-term meeting - 25-26 November 2002, ESTEC Other Recommendations from Actions: 4. Thermal Control (continued): However, only one instrument input has addressed the thermal ‘action’. Thermal feasibility has NOT been demonstrated for almost all insruments. This must be done a.s.a.p. if our desire to have a Solar Orbiter mission is to be taken seriously. However, the lack of any spacecraft input on the thermal interface between instrument and spacecraft is hindering thermal modelling. It is a design driver. We need input from the Project on the thermal interface, on thermal policy and views to space. This is a request to the Project – now.

11. Solar Orbiter - Remote Sensing Payload Working Group Mid-term meeting - 25-26 November 2002, ESTEC Other Recommendations from Actions: 5. ESA Study of LCVRs: Liquid Crystal Variable Retarders (LCVRs) may be critical to the operation of VIM & UVC - (as polarization modulators). No LCVR has been in vacuum for a long period & put into extended operation after a long time, & the radiation impacts must be considered. Is this a spacecraft issue or just for the instrument(s) involved? (Action 2.2).

12. Solar Orbiter - Remote Sensing Payload Working Group Mid-term meeting - 25-26 November 2002, ESTEC Other Recommendations from Actions: 6. Contamination Control: (i) Instrument teams must adopt a stringent contamination policy in the laboratory, but also in operations (e.g. long out-gassing period) (Action 3.1). (ii) A test activity on the degradation of selected optical surfaces under high irradiation and particle flux levels should be recommended as part of a Solar Orbiter development programme (Actions 3.1 & 3.5). Can we define such a test and the materials to test?

13. Solar Orbiter - Remote Sensing Payload Working Group Mid-term meeting - 25-26 November 2002, ESTEC Other Recommendations from Actions: 6. Contamination Control (continued): Test 1: Contamination of optical surfaces under high irradiation levels. Basic test – EUV/UV reflectivity of optical surfaces at normal incidence under extreme temperatures, under vacuum. Surfaces: SiC, SiC gold coated, what else?… Temperatures: 0 o C to 100 o C, perhaps higher? Cycles to represent orbit. What facilities are available for this? Who can do it? Action to define test: Udo, Luca?? To be relayed to ESA now.

14. Solar Orbiter - Remote Sensing Payload Working Group Mid-term meeting - 25-26 November 2002, ESTEC Other Recommendations from Actions: 6. Contamination Control (continued): Test 2: Degradation of optical surfaces from particle impacts. Basic test – Examine optical surfaces/coatings after exposure to selected particle environments, perhaps also under high temperatures. Look for blistering and sputtering effects. Surfaces: e.g. SiC gold coated, what else?… (see note on multilayers later) Particles: Proton and ion beams. What facilities are available for this? Who can do it? Extend previous CDS study? Action to define test: Harrison? To be relayed to ESA now.

15. Solar Orbiter - Remote Sensing Payload Working Group Mid-term meeting - 25-26 November 2002, ESTEC Other Recommendations from Actions: 7. Detector Development: Most instruments call for detector systems now under development, e.g. 4kx4k 5 micron back-thinned APS or diamond. (Actions 10.3-10.5). Does this require any effort from ESA or is it all under control?

16. Solar Orbiter - Remote Sensing Payload Working Group Mid-term meeting - 25-26 November 2002, ESTEC Other Recommendations from Actions: 8. Autonomous Target Selection/Pointing: After a feasibility study (Action 10.7), we recommend that this facility be adopted for Solar Orbiter, to ensure the best scientific return. Concerns over instrument/mission safety must be addressed. 9. Planning and Operations Cycle: A study of the possible planning and operations scenario (Action 10.9) has recommended a 150-day planning cycle, possibly with a dedicated science centre. ESA must examine the study report and decide on an approach prior to the AO.

17. Solar Orbiter - Remote Sensing Payload Working Group Mid-term meeting - 25-26 November 2002, ESTEC Other Recommendations from Actions: 10. Operations Scenario & Memory: It is recommended that the Solar Orbiter mission is run with a full 150-day observation period and that on-board memory is maximised in order to obtain the best encounter observations. (Action 10.9). 11. Solar Orbiter Goals: The Solar Orbiter goals are NOT well/properly defined. This is beginning to ‘hurt’ – i.e. potential proposing groups are not really able to ‘tune’ their instruments to the priority goals. (See post-Tenerife document). It is recommended that the SOPWG address this now.

18. Solar Orbiter - Remote Sensing Payload Working Group Mid-term meeting - 25-26 November 2002, ESTEC Other Recommendations from Actions: 12. Multilayers: Action 1.6 not completed. However presentation by David Windt (Columbia, New York) at MSSL on multilayer stability: (i)For ‘traditional’ multilayers, e.g. Mo/Si, Mo 2 C/Si, have tested to high temperatures (see Stearns et al. J. Appl. Pys. 67, 2415, 1990). No effects up to 100 o C. No real concerns up to 150 o C but degadation seen at 200 o C. Can we arrange repeat tests with 0- 100 o C cycling to mimic orbit and long-term effects? (ii) No reports of degradation due to radiation (e.g. Kortright et al., J. Appl. Phys. 69, 168, 1991).

19. Solar Orbiter - Remote Sensing Payload Working Group Mid-term meeting - 25-26 November 2002, ESTEC Other Recommendations from Actions: 12. Multilayers (continued): (i)The effects of particles have not really been tested. Possibly a problem is the multilayers are not well protected. Should we include multilayers in the particle test activity on surfaces?

20. Solar Orbiter - Remote Sensing Payload Working Group Mid-term meeting - 25-26 November 2002, ESTEC Real Concerns: 1.Thermal feasibility has NOT been demonstrated for most instruments 2.Thermal policy/interfaces from S/C required to progress beyond basics 3.Multilayer and optical surface integrity at high temperatures and particle fluxes needs to be established 4.Instruments must be able to cope with latch-up 5.We must have an automated instrument safing policy/plan/procedure 6.We really need a set of focused goals for Solar Orbiter!

21. Solar Orbiter - Remote Sensing Payload Working Group Mid-term meeting - 25-26 November 2002, ESTEC Schedule/Remaining Activities:  Refine PDDs as much as possible - because that will influence the mission we get!  Complete action studies by end of February 2003.  Write final report by April/May 2003 (based on Action Response Forms) - including all recommendations.  Any clear recommendations MUST be passed to ESA as they come up.  Define any studies/test activities as agreed, and pass on to ESA now!  Recommend a set of focused goals for the mission!