Solar Orbiter – Mission Update ESA’s Solar Encounter and High Latitude Mission

Solar Orbiter – Mission Update

ESA’s Solar Encounter and High Latitude Mission


What’s happening?

July 2000 – Formal proposal to ESA

Sept 2000 – Presentation to ESA committees, by Marsch & Harrison

Selected! October 2000

ESA reassessed science programme Autumn 2003 – survived!

Last meeting - reported AO late 05/early 06, Launch 2013? Since then launch seemed to move quietly to 2015…

BUT… ESA Science Programme in difficulties. Orbiter is vulnerable as the last mission in the schedule

SPC met Feb 2006. SSAC suggestion - move Orbiter to 2017 - part of a package to complete approved missions. Support from nations for Orbiter, in particular for 2015 launch. Formal SPC report?


What’s happening?

May 2006? – Next SPC meeting – Not in the clear yet!

Internal meeting at ESTEC this week to discuss 2015 launch

Anticipate request for letters of intent later this year

AO next year?

October 16-20 2006 – Athens, Greece – 2nd Solar Orbiter Workshop – See handout

Adv. Space Research 36, 2005, 1415 – EUS concept paper from Paris COSPAR Orbiter session


Industrial Studies

Orbit : Basic idea of solar orbits achieving high heliographic latitudes (up to 38°) with perihelion ~0.2 AU, and co-rotation phases, has not changed

Launch: Was 2013 or 2015? ; windows every ~ 19 months; Soyuz-Fregat from Baikonur baselined. Pressure for 2017, but 2015 not dead yet! Later than 2017 hits solar max in high latitude phase

Spacecraft: 3-axis stabilised, Sun-pointed. Original plan: SEP benefits from BepiColombo; Now ballistic options baselined. 1296 kg lift-off mass

Mission duration: Original plan: Cruise phase ~1.9 years (3 orbits); nominal mission ~2.9 years (7 orbits); extended mission ~2.3 years (6 orbits). Ballistic options not much longer – details depend on date

Payload resources: Was 130 kg, 127 W, 74.5 kbit/s. Ballistic option allows more payload mass (removes SEP overhead)


Industrial Studies

Astrium and Alcatel led studies on spacecraft and flight options. Periodic reports to ESTEC – attended by PWG chairs as community reps.

Strawman instrument studies well developed and providing input to industrial studies. Done through PDD.

Next version of PDD due now – in theory is final input before AO (forms part of AO documentation)


Strawman Payload

Instrument Mass

kg

Power

W

Rate

kbps

Plasma Package (SWA) 15.5 11 14

Fields Package (MAG +RPW + CRS) 11 13 5.8

Particles Package (incl. Neutrons,gammas & dust)

15 15 4.5

Visible Light Imager & Magnetograph (VIM) 30 25 20

EU Imager (3 telescopes incl. FSI) 30 25 20

EU Spectrometer 25 25 17

Spectrometer/Telescope Imaging X-rays (STIX) 4 4 0.2

Coronagraph (COR) 10 10 7

Total 140.5 128 88.5


The need for an EUV Spectrometer

Solar EUV spectrometer – to identify & analyse emission lines from trace elements in the solar atmosphere, providing plasma diagnostic information for many applications – it is a general purpose solar plasma diagnostic tool!

Builds on the highly successful solar UV/EUV experience of the team (CDS, SUMER, EIS, CHASE, SERTS, EUNIS, etc…)

CDS observation of twisted flows in a loop


This is the best we can do now: EUV imaging with 0.5” (350 km) pixels and EUV spectroscopy with 2” pixels.

We know that the solar atmosphere is composed of fine-scale structures/phenomena and must aim to develop appropriate tools.

Our target is spectroscopy at ~150 km (1” at 0.2 AU, 0.2” at 1 AU).

The need for an EUV Spectrometer


Instrument Requirements

Spatial Resolving Element (pixel) 1 arcsec 150 km at perihelion Spectral Resolving Element (pixel) 0.01-0.02 Å/ pixel lower the better

Field of View (minimum) 34 x 34 arcmin2 AR size at perihelion

Exposure time (minimum) <1 s

Maximum Exposure Time Few 100 s cosmic ray limit

Wavelength Bands 170-220 Å 580-630 Å > 912 Å

Prime bands f rom Tenerif e meeting

Pointing To anywhere on Sun and low corona

Wavelengths – lines from chromosphere, transition region & corona is a major driver.

Pointing – payload bolted together, common pointing JOP approach.

Spacecraft limitations - <1 m class instruments, <30 kg

Extreme thermal and particle environments

Autonomy – during solar passes


EUS Consortium

Consortium has met five times – in 2001-2004, and dedicated wavelength meeting in 2003

Consortium Web site - http://www.orbiter.rl.ac.uk

But - the goal posts keep moving – we have been in limbo due to continually moving AO/launch dates and uncertainty that we even have a mission!

The result: Many good ideas but little need to force decisions. In effect, maintained instrument concepts with occasional bursts of activity.

In parallel, played full part in PWG/ESTEC activities and the Payload Definition Document


EUS Consortium

Baseline - Off-axis NI spectrometer with VLS grating and APS detector system. GI option still open.


EUS Consortium - Progress

APS detectors – 4k x 3k 5 micron back-thinned array developed and tested - Nick

Trade-off optical study – Kevin, Luca, Roger – including possible NI option with all three bands

EUS VLS grating ready to fly on EUNIS – Roger/Joe

Progress in thermal, mechanical, throughput analysis

Consortium responsibilities/contributions – all groups have stated possibilities


EUS Consortium – Burning Issues?

Wavelength Selection

Can we have all three in one instrument? Are the solar people asking too much?

There are excellent arguments for all bands and groups who are only interested in the instrument if certain bands are included – we have kept all options open to date!

Decision time! – Can we find a design that can do this for us with the required optical performance? If ‘no’ – we have to choose.

If this is the NI approach, are we happy that the multilayer coatings will work in the extreme conditions?

If we are looking to detect all three bands we are almost certainly looking at both filter/backthinned APS detectors and another option (e.g. MCP/APS) for the long wavelength band. What does this do for mass/power?



NI vs GI Selection

Can we show that the NI (or even the GI) design can cope with the thermal load?

If ‘yes’ – and if the shorter wavelength can be catered for - do we forge ahead with the NI baseline as top priority?



Detectors

Can we decide on a baseline wavelength band selection and assess the impact on detector requirements – i.e. long wavelength option (MCP/APS?), short/mid wavelength options (APS backthinned/filter)

Given all of the above – can we see a viable thermal/mechanical/optical approach?

Given all of the above – can we define the consortium responsibilities?


EUS Consortium – Responsibilities?

Detectors

Can we decide on a baseline wavelength band selection and assess the impact on detector requirements – i.e. long wavelength option (MCP/APS?), short/mid wavelength options (APS backthinned/filter)

Given all of the above – can we see a viable thermal/mechanical/optical approach? Or at least a path to get there!

Given all of the above – can we define the consortium responsibilities?

Solar Orbiter – EUV Spectrometer (EUS)

Consortium Responsibilities – ‘Wish list’:

PI institute/Project Management/Systems EngineeringRAL

Electronics (CDHS) MSSL/RAL/MPI/SWRI

Power supply (EPS) MSSL/MPI/SWRI

Mechanism drive electronics NRL/SWRI

Detectors RAL/MPI

Primary mirror procurement Padua/MPI/IAS/NRL

Grating procurement GSFC/Padua/IAS/NRL/SWRI

Mirror scanning system NRL/Padua/RAL/SWRI

Slit change mechanism NRL/RAL/Padua

Slits GSFC/NRL

Optical design RAL/Padua/GSFC

Stray light analysis/design RAL

Structure design and procurement RAL


Consortium Responsibilities – ‘Wish list’:

Thermal design and hardware RAL

Cleanliness control and monitoring RAL

Grating focus mechanism NRL

Shutter NRL

AIV RAL

EGSE/ground software OSLO/GSFC

EGSE hardware MSSL

Calibration RAL/GSFC/PTB

Onboard software RAL/MSSL

Filters MSSL

Door mechanism NRL (Likely to be s/c supplied)

Slit Jaw camera SWRI (Not in baseline design)

Other UK CoI teams: Aberystwyth, Armagh, Cambridge, Imperial College, UCLAN etc…


Consortium Next steps:

This meeting: – decisions/pointers on key issues…

From this: - better definition of consortium responsibilities

Set up regular telecons and visits, and schedule

Expand Web site – documents, drafts, papers

Documents

Solar Orbiter – Mission Update ESA’s Solar Encounter and High Latitude Mission