# Presentation: 073064

## Task Definition

- Realistic assessment of strawman payload
- Mass, size, power requirements
- Demonstrate *feasibility*
- Task is *NOT* to provide complete instrument designs
- Uncover any items which will drive system design for S/C
- Input for Payload Definition Documents (PDD), which will be prepared by ST before industrial S/C studies get underway
- Identify key problem areas arising as a result of the extreme thermal and radiation environment
- Identify necessary technological developments to cope with these challenges
- Studies and tests to be initiated
- Identify operational concerns and devise plans how to tackle them

## Product of Study

- Study Report to ESA
- Recommendations for tests/investigations/strategy etc..
- Anything we feel is appropriate

##     Agenda Splinter Session

- Intro: Approach / Brainstorm
- Revisit Instrument List
- Taking Stock
- What are people working on?
- What development work/tests are planned at national laboratories?
- What should be initiated/coordinated through ESA?
- Instruments
- Identify, for each instrument, key areas requiring development or test activities
- Environmental and spacecraft issues
- Operations / S/C
- Identify next steps

##      Status of the Project - Background

- “Tenerife Crossroads” Workshop (March 1998) Resolution
- “Launch a Solar Orbiter, as ESA’s F2 mission, with possible international participation, around 2007; there are two main candidates for this, namely a mission approaching the Sun to 30 solar radii, and a polar orbiter at about 0.5 AU.
- ESA Pre-Assessment Study conducted in 1999
- Solar Orbiter proposed as a Flexi-mission in 2000 by E. Marsch et al.
- ESA “delta”-Assessment Study conducted in 2000
- Solar Orbiter selected by ESA’s SPC in October 2000 for launch after BepiColombo (2008-2013 timeframe)
- Solar Orbiter recommended by ESA’s SSAC in May 2002 for implementation with BepiColombo as a single project in 2011/2012
- ESA’s SSAC also encouraged further international collaborations, specifically involvement of NASA in Solar Orbiter as part of the ILWS program, linked to European participation in other LWS/STP elements.
- Industrial study to start in fall 2002, tightly coupled to BepiColombo

## SSAC Recommendation                                                          103rd Meeting, 2-3 May 2002, ESA/SSAC(2002)1 - excerpts

- The SSAC ... recommends a scenario which rests on the following assumptions:
- The implementation of BepiColombo and Solar Orbiter as a single project under a cooperative arrangement, leading to significant savings.
- ... the SSAC reommends to the SPC the following scenario for approval:
- .... 2011/12   BepiColombo/Solar Orbiter
- ... elements of flexibility and uncertainty, which should be exploited to the best advantage of the overall programme:
- Within each combined set of missions (... BepiColombo/Solar Orbiter) the launch sequence can be optimised.
- Further international collaboration on mission and payloads is encouraged. Specifically a significant contribution from NASA on Solar Orbiter as part of the ILWS programme may be linked to European participation in other elements of the LWS/STP programme.

## ESA/NASA Collaboration

- Several meetings between ESA and NASA to discuss collaboration within ILWS programme
- ILWS signed at IACG meeting in Padua, January 2002
- Last ESA/NASA meeting: 15 April
- US participation in Payload Working Group endorsed and supported by NASA
- Agreed to form “Joint ESA/NASA Solar Orbiter/Solar Sentinels Working Group”
- Memo to ESA SPC delegates: “... with well grounded confidence that the US will be able to contribute to the Solar Orbiter payload in a substantial way”

##        Joint Solar Orbiter/Solar Sentinels WG

- Discussed at ESA/NASA bi-lateral in Villafranca von 15/16 May
- Kick off planned for fall 2002, after new NASA Roadmap and NAS Decadel Survey have been issued
- 5-6 members each from European and US community
- Charter
- Study how to modify existing concepts of the Solar Orbiter and Solar Sentinels to more effectively achieve their combined science goals by looking for synergies and complementarities between the two programs:
- (1)    Synthesize the goals of the Solar Orbiter and Solar Sentinels as presently defined to determine a prioritized set of science objectives that will enable the LWS and ILWS programs to achieve their stated goals.
- (2)    Optimize the scientific cost benefit by devising an implementation strategy that combines NASA and ESA resources.
- (3)    Identify key science objectives that can only be accomplished jointly, but not separately.
- (4)    Suggest combined mission scenario options to accomplish the ILWS goals.

## Solar Orbiter Schedule

## 	Heliospheric in-situ Package

## Remote-sensing Instruments

- + Hard X-ray imager + Gamma-ray instrument

##   Instrumental Challenges

- Thermal (up to 34 kW/m2 on surfaces exposed to full disk)
- Long external baffles to limit FOV
- Grazing incidence primary optics
- Radiation Environment
- up to 25 higher particle flux
- Aging
- Limited S/C resources
- Mass
- Telemetry
- Power
- Balance in-situ/remote sensing
- Mass         - 	   24:105
- Telemetry - 	12.5:62.5