Radio & Plasma Wave Investigation (RPWI) Team Meeting

1. Radio & Plasma Wave Investigation (RPWI) Team Meeting • Welcome! • Focus on: • ESA response to DoI • Mechanics • S/W • Certain aspects of MF & HF • AO response preparations starts • Twiki home page (secure) • http://space.irfu.se/twiki/bin/view • JgoRpwi group Jan-Erik Wahlund, RPWI Team Meeting (Warsaw), January 10-11, 2011

2. Project Status • EJSM/Laplace (JGO) one of three L-class projects • The other two: IXO/XEUS and LISA • L-class down selection • L-class mission presentations – 3 February (Paris) • NASA report: New Worlds, New Horizons in Astronomy and Astrophysics (2010) • 1) WFIRST – Dark energy, exoplanets, IR • 2) Augmentation to Explorer program – rapid response to opportunities • 3) LISA: Awaits LISA Pathfinder (2012), req. NASA participation • 4) IXO: VERY Expensive, req. NASA participation • The extra ESA M-class call – if an L-class mission delayed

3. Project Schedule Aug-2011

4. EJSM project schedule

5. Meetings • Cosmic Vision L-class Presentations • February 3, Inst. Océanographique de Paris • Valerie.Lecuraud@esa.int • Next RPWI team meeting? • Suggest Uppsala before the summer • So far no other ESA meetings announced

6. New Team Additions!? • Robert Ergun (Boulder) • Operations, Science • Keith Yearby (Shefield) • Data processing, Science

7. Plans for AO response • Need defined & agreed system design! • Should be ready before summer • Still many open items • Need start write certain sections in proposal • No options in proposal. • Changes from PDD will be noted though. • Will use structure of previous ESA proposals (e.g., ROSETTA). • Will start iterate texts of certain sections. In particular the Science case. • Should be a reasonably ready proposal before the summer that can be formed into the format of the AO response definition.

8. Agency funding & commitments • RPWI DoI proposals have been sent to (certain?) national agencies • Sweden, France, UK, Czech Rep. • Poland? Austria? • NASA will make their own selection of US contributions based on ESA AO-proposals (in close discussion with ESA). • Japan? • Please be in close contact with you national agencies! • Most national agencies will send out support letters after AO announcement.

9. ESA response to DoI reports • ESA internal review of • EJSM/JGO o/A doc:s • Industrial study doc:s • Instrument DoI study reports • General comments • Comparisons between PDD documents (Feb-2010) and DoI reports (Aug-2010) show a trend toward increased Mass and Power. This will be monitored carefully. • In several instrument designs there are single-point failures (SPF:s) with few backup solutions. Devise proper strategies. • Instrument redundancy concepts (including sharing data processing) shall be given attention to minimize resources.

10. Overall P/L development status • Significant instrument heritage is available, but specific issues on performance & sensitivity need be addressed due to the radiation environment. • Some instruments rely on immature new sensors or technologies and are therefore viewed as high risk. • Instrument mechanisms (scanning platforms, shutters & covers of optical systems, filter wheels, etc) should be traded off against optimized accommodation and/or additional sensor heads to ensure the required FOV. • Radiation hardened lenses makes it difficult to achieve achromatisation of cameras. Care must be taken with assumed suppliers.

11. Radiation issues • Radiation shielding guidelines applicable to all instrument teams will be established at system level. • An integrated radiation analysis approach will be implemented with platform + instruments for optimized allocation of shielding mass. Requires instrument design activities start immediately after P/L selection. • Detector systems sensitive to high-energy electrons shall undergo special science performance analysis. • Yaw steering • Continuous yaw steering is baseline around Ganymede. Impact on nadir facing instruments. More detailed analysis needed on science performance impact.

12. Electrostatic charging • High level surface electrostatic charging will occur. Applicable to S/C subsystems & instruments in contact with the plasma environment. Materials for instruments must be studied w.r.t. SEE & resistivity effects (low T, high-radiation). • Magnetic cleanliness • Ambitious magnetic cleanliness requirements. BDC at magnetometer locations < 0.2 nT precision (Swarm class, 2 orders of magnitude better than BepiColombo). ESA will implement a detailed magnetic cleanliness programme. Units will be procured minimizing magnetic materials & characterized w.r.t. magnetic moments. Years before system tests. Instrument teams need design wiring such that magnetic field is minimized.

13. Conclusions • Mass critical • Mission system design is mass critical. • P/L resources need be controlled. Mass & power savings shall be studied and measures be taken. Max science output with mature P/L budgets. • Review the redundancy approach & consider resource sharing (e.g., data processing units). • Instrument development • Start a.s.a.p. after selection. Focus on radiation effects on sensors, optics and electronics. • Radiation system simulations • Will start shortly after selection. Need detailed instrument designs for efficient shielding strategy at S/C level.

14. RPWI Specific • Dust distribution • RPWI propose to measure the dust distribution of particles >1 μm. How? What requirements for this measurement? • Pre-amplifiers • Located outside the S/C. Total radiation dose >1 Mrad (unshielded). Radiation testing of these components must be carried out early in the design of the instrument. • Deployment of antennas, sticks and booms & Thermal • Mission involves a Venus flyby (hot) & Jupiter eclipse (-230 °C). Elements, materials, and subsystems will need a thermal analysis proving these elements will survive.

15. RPWI Specific (cont) • Planetary protection • RPWI discuss components that withstand >125°C (Dry Microbial Heat Reduction). Not necessary for JGO. Simplify design? • 1 Volt potential difference requirement • Still very challenging. vxB larger over S/C dimension near Ganymede!? Follow-up study needed that states which part of S/C this requirement applies. • Mass impact of fall back options • No mass assessment given on fall-back options. Table with impact on mass & power is required.

16. Near DC (sub Hz) E-field capability • Baseline:Four 3m booms with 10 cm diameter sensors • Preferred option: Four 1m sticks at tip of solar panels • “EJSM Electrostatic cleanliness” (C. Cully) • The potential difference between any two surfaces on the S/C shall not exceed 1 V, assuming an ambient current density to the surface of 2 nA/cm2. • Max error: 6-7 mV/m for long Debye lengths • Jupiter convection field near Ganymede = 10-20 mV/m • The ability of LP-PWI to measure magnetospheric convection fields requires a conductive S/C • Denser plasma near Ganymede  short λD (30 cm – 1m)  better than 1 mV/m accuracy • Solar panel mounted sticks + sensors improve by at least a factor 5 (longer separation distance & less photoelectrons from S/C & more symmetric configuration)

17. RWI antenna • Fall-back options are of new design & potential suppliers not identified. Give more detailed design and find suppliers as soon as possible.

18. ESA INTERNAL REVIEW RECOMMENDATIONS COMMENTS ON ELECTRONICS • System: • We have to look into single point failure areas in the system design. • It looks like the magnetic requirements will govern the system grounding • concept and we urgently have to find a way to prevent that to happen. • Instrument: • ESA just reminds us of the pre- amplifier radiation environment, which we have under control. However, ESA needs to give the specifications how to test parts. • Mass and power impact on fall back options need to be estimated. • The thermal environment for the pre-amplifiers and the boom mechanisms need to be identified.

19. RPWI Baseline Operations • Deployment of sensors & booms just after launch • RPWI Science operations: • Periodically during interplanetary transfer (Cruise) • Jupiter approach & orbit insertion (Jupiter Insertion) • During magnetosphere cruise past Callisto & Ganymede, until Ganymede orbit insertion (Jupiter Magnetosphere Monitoring) • During targeted flybys (Callisto & Ganymede Flybys) • During Ganymede orbit phases (Ganymede Orbit, both elliptic & circular)

20. PEP & MAG I/F:s • PEP I/F: • They want USC in the cold plasma environment around Ganymede. • On-board SpaceWire? • Otherwise on ground post-analysis will have to be provided. • The specification of the requirements is to be formulated prior to the payload AO. • MAG I/F: • RPWI want B for on-board data processing. • On-board SpaceWire? • MAG team is in favor.