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Solar Orbiter - October 2003
Solar Orbiter
Status of Solar Orbiter
Scientific Goals
Spectrometer Update
Richard Harrison
Rutherford Appleton Laboratory
Solar Orbiter - October 2003
Status of Solar Orbiter
Recent & On-Going Activities:
Payload Working Group
Science Definition Team
International Status
ESA Reconstruction of Science Programme
Solar Orbiter - October 2003
PAYLOAD WORKING GROUP Payload Working Group – established 2002, to address payload-
related challenges Remote Sensing (Chairs: R. Harrison and B. Fleck) In-Situ (Chairs: R. Wimmer-Schweingruber and R. Marsden)
Tasks: To study instrument feasibility, and produce payload definition documents
Reports delivered to ESA May/June 2003 – including a number of recommendations concerning, e.g. thermal loads, telemetry, low mass options, detectors.
No show stoppers
Status of Solar Orbiter
Solar Orbiter - October 2003
Baseline mission (SDT)
Instrument Mass
kg
Power
W
Rate
kbpsPlasma 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
Solar Orbiter - October 2003
Status of Solar Orbiter
SCIENCE DEFINITION TEAM
Chair: E. Marsch. reviewing the scientific goals of the mission as presently
understood refining these goals where needed prioritising them in order to achieve a well-balanced, and highly
focused scientific mission defining the sets of measurements needed (baseline and
minimum) to achieve the mission’s scientific goals, taking into account the output of the Payload Working Group
Output: Science Requirements Document to be completed by SDT in November 2003
Solar Orbiter - October 2003
Status of Solar Orbiter
INTERNATIONAL STATUS Solar Orbiter – ESA’s contribution to the International
Living with a Star (ILWS) programme US as well as European support in Payload Working
Group and Science Definition Team, anticipating some US-led instrumentation
NASA contribution to mission anticipated Solar Orbiter has been highlighted as important for
the US community in a number of documents, such as the Sun-Earth connection Roadmap and the Decadal report of the National Science Foundation
Solar Orbiter - October 2003
Status of Solar Orbiter
The ESA Science Programme – Reconstruction On-going activity – ESA committees and working groups
reassessing missions – urgent need to balance the books – i.e. ESA cannot afford all of the missions on its books.
Missions could go! The Missions:
BepiColombo Eddington GAIA Netlander LISA Solar Orbiter SMART-2 (LISA Pathfinder) Note: No JWST and Venus Express
Solar Orbiter - October 2003
Status of Solar Orbiter
The ESA Science Programme – Reconstruction Committee/Working Group Meetings:
SPC Sept 25 FPAG Sept 29-30, Oct 7-8 SSWG Oct 6-8 AWG Oct 7-9 SSAC Oct 7, 13-14 SPC Nov 5-6 Council Dec 10-11
Solar Orbiter - October 2003
Status of Solar Orbiter
The ESA Science Programme – Reconstruction UK Space Science Advisory Committee:
Assess UK priorities prior to ESA assessment; brief UK SPC delegates
18 Sept Meeting – top priority for UK (equal) = LISA, BepiColombo, Solar Orbiter, Eddington, GAIA (Eddington and BC lander are lowest of the high priorities!).
Solar Orbiter - October 2003
Status of Solar Orbiter
The ESA Science Programme – Reconstruction 7th October SPC/SSAC/Working Group Presentations
at ESTEC Each mission presented NASA and Japan present (NASA stressed support for LISA
and Solar Orbiter; Japan stressed support for BepiColombo)
No conclusions until November/December BUT, general feeling seems to be that Solar Orbiter is in
good shape (despite links to BepiColombo) Tone Peacock already contacted me to talk about next
phase of studies from PWG activity; industrial ‘payload integration’ ITT is out and due to start later in year…
Solar Orbiter - October 2003
Solar Orbiter Scientific Goals
Science Definition Team
Solar Orbiter ‘firsts’
Solar Orbiter rationale
Solar Orbiter Goals (Science Definition Team)
Underlying Questions
Solar Orbiter - October 2003
Science Definition Team (SDT)
Chair: E. Marsch. The SDT is currently: reviewing the scientific goals of the mission as
presently understood refining these goals where needed prioritising them in order to achieve a well-balanced,
and highly focused scientific mission defining the sets of measurements needed (baseline
and minimum) to achieve the mission’s scientific goals, taking into account the output of the Payload Working Group
Output: Science Requirements Document to be completed by SDT in November 2003
Solar Orbiter - October 2003
Solar Orbiter firsts
Explore the uncharted innermost regions of our solar system
Study the Sun from close-up (45 solar radii)
Fly by the Sun tuned to its rotation and examine the solar surface and the space above from a co-rotating vantage point
Provide images of the Sun’s polar regions from heliographic latitudes in excess of 30°
Solar Orbiter - October 2003
Solar Orbiter rationale
The Sun's atmosphere and heliosphere are - uniquely accessible domains of space, - excellent laboratories for detailed study of fundamental processes common to astrophysics and solar physics
Remote sensing and in-situ measurements, - much closer to the Sun than ever before, - combined with an out-of-ecliptic perspective,
promising to bring about major breakthroughs in solar and heliospheric physics
Solar Orbiter - October 2003
Main scientific goals
With Solar Orbiter we will, for the first time:Determine the properties, dynamics and
interactions of plasma, fields and particles in the near-Sun heliosphere
Investigate the links between the solar surface, corona and inner heliosphere
Explore, at all latitudes, the energetics, dynamics and fine-scale structure of the Sun’s magnetized atmosphere
Probe the solar dynamo by observing the Sun’s high-latitude field, flows and seismic waves
Solar Orbiter - October 2003
Nature of the Inner Heliosphere
What is the character and radial evolution of solar wind structures in the inner heliosphere?
What is the nature of solar wind stream interactions in the inner heliosphere, and how does it depend on latitude?
What is the influence of CMEs on the structure of the inner heliosphere?
What is the nature of particle acceleration and transport in the near-Sun environment?
What is the role of shocks and flares in accelerating particles near the Sun?
How does the solar wind microstate evolve with radial distance?
Solar Orbiter - October 2003
Nature of the Inner Heliosphere
What are the sources and properties of dust in the inner heliosphere. Do Sun-grazing comets contribute to the dust?
What is the role played by the near-Sun dust for the interplanetary pick-up ions?
What are the fluxes and spectra of low-energy solar neutrons? Can one probe remotely nuclear reactions and ion acceleration
on the Sun? Is there a neutral solar wind, and what are its properties? How does the solar corona look like when being imaged by
energetic neutral atoms? How does the solar luminosity vary, and does it change
globally (depend on latitude)?
Solar Orbiter - October 2003
Linking Sun and Heliosphere
How does the evolution of the solar magnetic field affect the heliosphere at all scales?
What are the sources of the slow solar wind, and what is its temporal and spatial evolution?
What are the sources and the global dynamics of eruptive events and what are their effects on the inner heliosphere?
What are the relevant physical processes that lead to turbulence in the tenuous magnetofluid of the inner heliosphere, and how does this turbulence interact with heliospheric particles?
What is the solar source of the solar wind plasma (including that of CMEs) and energetic particles seen in the interplanetary medium (IPM)?
What regions at the Sun are the sources of the magnetic field lines in the IPM?
Solar Orbiter - October 2003
The Sun’s Atmosphere at all Latitudes
How is the polar high-speed wind generated and how does this relate to the polar plume phenomenon?
How does the structure and evolution of polar coronal hole regions project into the inner heliosphere?
What is the nature of coronal hole boundaries, how do they evolve and how do they project into the inner heliosphere?
What is the nature of fundamental processes in a stellar atmosphere, including wave activity from source to the corona, the physics of transient events and flux emergence, over all latitudes?
Solar Orbiter - October 2003
The Polar Magnetic field & Dynamo
How does the high-latitude field of the Sun evolve on a range of scales?
What are the properties of the Sun's surface and sub-surface meridional flow and differential rotation at high latitude, and how do these vary with time and position?
How do the average properties of granular and supergranular flows depend on latitude?
What are the properties of emerging flux at high latitudes? How is field removed from the solar surface around the
high-latitude polarity inversion regions? What are the signatures of the solar dynamo action near
the bottom of the convective envelope?
Solar Orbiter - October 2003
Key component of Baseline Payload
Required for basic plasma diagnostic capability on Orbiter, for a range of scientific questions
Proposed next-generation CDS led from RAL has been proposed at PPARC SOI
Proto-consortium has met three times – full meetings in 2001, 2002 and wavelength meeting in 2003
Pre-proposal to PPARC due at end of October
EUV Spectrometer: Update
Solar Orbiter - October 2003
Instrument Mass
kg
Power
W
Rate
kbpsPlasma 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
Baseline Payload (SDT)
Solar Orbiter - October 2003
The Need for a Spectrometer
• This is the best we can do now: EUV imaging to 0.5 arcsec (350 km) and EUV spectroscopy to 2-3 arcsec. We know that the solar atmosphere is composed of fine-scale structures and must aim to develop appropriate tools. Our target is spectroscopy at ~70 km (0.5 arcsec at 0.2 AU, 0.1 arcsec at 1 AU).
Solar Orbiter - October 2003
The EUS Instrument Requirements
Spatial Resolving Element (pixel) 0.5 arcsec 75 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 Å580-630 Å> 912 Å
Prime bands f romTenerif e meeting
Pointing To anywhere on Sun and low corona
• SDT Resolution = 150 km target
• Spectral resolution critical – polar flows
• Wavelength bands – lines from chromosphere, transition region & corona is a major driver from the community
• Pointing – payload bolted together, common pointing JOP approach
Solar Orbiter - October 2003
The EUS Instrument Requirements
Other Factors Which Influence the Design
Solar Orbiter - October 2003
The EUS Instrument Environment
1. Thermal Loads
149 day cycle = 2,142 to 34,275 W/m2 (0.8 to 0.2 AU).
Need to address thermal balance for high load values and for variation of thermal input.
We must validate the designs through extensive modelling. Can we define test activities and facilities which could be used for such testing? What about optical degradation?
Solar Orbiter - October 2003
The EUS Instrument Environment
2. Particle Environment at 0.2 AU
Cosmic Rays:- Non-solar cosmic rays about the same as for SOHO, or less.
Solar Wind:- Projecting naively from 1 AU values (~10 p/m3) we might expect 250 p/m3 in ‘normal’ conditions at 0.2 AU, with v ~ 400 km/s. Thus, we expect 106 hits/cm2.s (25x SOHO flux). Is this a worry? Perhaps not so much if the detectors are ‘buried’ (don’t view space directly) and if the protons are low enough energy (will be plenty of 100 keV protons, for example). (Note: 109 direct proton hits ‘will kill a CCD’ - not so an APS…)
Neutrons:- We might expect to see some. 15 min half life means that we may expect them - possibly only from flares but more often than for 1 AU. Concern over their cross section at the silicon lattice relative to protons. Needs investigation.
Solar Orbiter - October 2003
The EUS Instrument Environment
2. Particle Environment at 0.2 AU (continued…)
Flares and shock (CME) particles:- Dose difficult to predict. Could argue that the chance of being hit by a flare proton(/neutron) ‘beam’ is the same as for, e.g. SOHO. What about from larger shocks? Would suggest that there is a greater chance of seeing energetic particles, but hard to calculate.
Note: Hadrons can cause damage to the silicon lattice which causes traps that can ‘steal’ charge which can be transferred to other parts of the image. The APS minimises the problem by not transferring charge.
Note: What about particle effects on optical surfaces? See CDS proton-gold coating study (subsurface bubbling).
Solar Orbiter - October 2003
EUS - Concept & Initial Design Strategy
Two design concepts now under discussion
Off-axis single mirror NI telescope with VLS grating (Roger Thomas)
Wolter II GI telescope with VLS grating (Luca Poletto)
Solar Orbiter - October 2003
EUS Web site http://www.orbiter.rl.ac.uk
1. Concept document (‘Blue Book’)
2. Technical notes (TN1 - Wavelength selection; TN2 - Orbiter goals; TN3 - Optical design requirements; TN4 - Detector requirements etc…)
3. Meeting reports, including ppt talks.
4. Contact info., links, Solar Orbiter information, notes/documents...
Solar Orbiter - October 2003
The EUS Instrument The consortium
Rutherford Appleton Laboratory, UK
Mullard Space Science Laboratory, UK
Birmingham University, UK
Max Planck, Lindau, Germany
Padua University, Italy
Goddard Space Flight Center, USA
Oslo University, Norway
IAS, Orsay, France
NRL, Washington, USA
Scientific CoI Groups – e.g. UCLAN, Armagh, Aberystwyth …
Solar Orbiter - October 2003
EUS Design Comparisons
I = intensity of line [erg.cm-2.s-1.ster-1]. Want to convert to measured intensity, M [count.s-1]
M = (Iλ/hc) (abA/f2) ε [count.s-1]
λ = wavelength of line
h = Planck’s constant [6.626 x 10-34 Js]
c = Speed of light [3 x 108 ms-1]
ab = Dimensions of slit [m2]
A = Aperture area [m2]
f = Focal length [m]
ε = Efficiency product (εt x εg x εf x εm x εd) (i.e. efficiency product of telescope, grating, filter, scan mirror, detector)
Compare different designs to CDS, i.e. an existing instrument that works! Tabulate the function (abA/f2)ε.
Solar Orbiter - October 2003
EUS Design Comparisons
EUS7 EUS5 EUS8 CDSAperture 100mmx100mm 100mx100mm 50mmx50mm 3430 mm2
A 0.01 m2 0.01 m2 0.025 m2 0.0034 m2
Total Length 1400mm 1400mm 1400mm Slit 2.6μmx5.3mm 3.0μmx3.7mm 2.1μmx8.6mm 25μmx3mmSlit 0.5“ x 650“ 0.53“ x 650“ 0.5“ x 2048“ 2“x240“Slit 75km x 97500km 80km x 98113km 75km x 307200km 1,500 km x 180,000 km
Resolution (λ) 0.0128 Å/pixel 0.0147 Å/pixel 0.0133 Å/pixel 0.08 & 0.14 Å/pixelResolution (λ) 2.56 Å/mm 2.95 Å/mm 2.66 Å/mm 3.17 & 5.56 Å/mmλ range* 50 Å 64 Å 52 Å 73 &120 ÅResolution (x)** 0.25 arcsec/pix 0.16 arcsec/pix 0.5 arcsec/pix 1.68 arcsec/pix
Plate scale 20 μm/arcsec 31.5 μm/arcsec 10 μm/arcsec 12.5 μm/arcsecFOV 1024“ (17.1’) 650“ (10.81’) 2048“ (34.1’) 240“ (4’)a 5 μm 5 μm 5 μm 21 μmb 5 μm 5 μm 5 μm 21 μmεt 0.04 0.04 0.04 0.25εm - - - 0.80εf 0.2 0.2 0.2 -εg 0.07 (SERTS) 0.07 0.07 0.02εd 0.4 0.4 0.4 0.13Eff product, ε 2.24 x 10-4 2.24 x 10-4 2.24 x 10-4 5.2 x 10-4
Eff. Area (A ε) 2.24 x 10-6 2.24 x 10-6 5.6 x 10-6 1.8 x 10-6
f 1.072 m 1.176 m 0.886 m 2.57 m(abA/f2)ε 4.87 x 10-17 4.05 x 10-17 1.78 x 10-16 1.2 x 10-16
* assumes 4kx4k, 5 micron pixels (CDS has 1024 pixels)** ignores PSF
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