Radio & Plasma Wave Investigation (RPWI) Team Meeting

Jan-Erik Wahlund, RPWI Team Meeting (Warsaw), January 10-11, 2011

• 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

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

Project Schedule

Aug-2011

EJSM project schedule

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

New Team Additions!?

Robert Ergun (Boulder)– Operations, Science

Keith Yearby (Shefield)– Data processing, Science

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.

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.

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.

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.

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.

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.

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.

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.

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.

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)

RWI antenna– Fall-back options are of new design & potential suppliers not

identified. Give more detailed design and find suppliers as soon as possible.

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.

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)

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.