ESOC | Chris Watson | ESA/ESOC | Page 1 Mosaics Operational aspects CHRIS WATSON ESAC

ESOC | Chris Watson | ESA/ESOC | Page 1

MosaicsOperational aspects

CHRIS WATSON

ESAC


Introduction

Here we are only concerned with Spacecraft-actuated raster/mosaics as part of normal science planning

• Spacecraft points sequentially through a pattern of pointings to build a mosaic, to expand the area to be sampled with high resolution imagers

• Complicated for a mission built around parallel observing of all instruments

Purpose of this discussion?

• Agree the proposed planning approach for Spacecraft mosaics.

• Understand foreseen science cases, including typical integration time.

• If possible, remove complicated unneeded cases from SOC development


Example diagram

Example show is 3x3 raster on disk centre, at 0.28 AU.

FoV used is the SPICE FoV for any slit size below 30” with full scanning. Relevant FOV depends on driving instrument. If combined science (e.g. SPICE+EUI+PHI) then co-alignment becomes relevant as well, since it is the intersection of the individual FoVs that matters.

Overlap in planning to - allow for APE (*) - allow for differential rotation and SC movement between pointings - aid post-processing co-registration of acquisitionsActual overlap necessary is debatable. We don’t have firm numbers other than SC APE.

(*) Strictly speaking the overlap - needs to allow for both SC + relevant instrument internal effects - does not need to be the full APE, but that part of this error that occurs for two pointings separated by some specific but short time-interval (kind-of a shorter term APE, often called “Spatial Relative Pointing Error”). We don’t have a firm number for this.Diagram simply shows 3.5 arcmin, equivalent to SC APE

16’

11.1’

“Guaranteed” coverage in this example 41’ x 26.3’9 dwells and 8 internal slews within the raster

3.5’


Planning Approach

Background• The principal of the planning skeleton file (“E-FECS”) to be distributed from SOC to

instrument teams prior to MTP is that it contains ALL information necessary for each instrument to do their planning

• Changes in pointing matter because• Pointing performances are not met (e.g. image acquisitions will be blurred)• Possibly other complications as well

Planning Approach• Any Raster/Mosaic operation will need to be agreed at LTP within SOWG• Fix number of dwells and dwell-time at each (even if actual pointing of each not fixed at

this stage). …Obviously integration-time at each dwell <= the dwell-time.• Allows SOC to construct a robust planning skeleton with fixed times for the raster slews

that then forms the basis of the individual instrument planning from MTP onwards. Slewtime baseline

• We foresee assigning a fixed “worse case” duration for every slew, regardless of slew size• We expect duration to be order of 5 mins or less

• Depends on assumptions of SC coast rate and ramp acceleration/deceleraton • E.g. 0.01 deg/sec coast plus ramp assumption => 4 mins• E.g. 0.1 deg/sec coast plus ramp assumption => 40 sec

Can we agree this approach via MoM?


Cruise phase and Remote Sensing Checkout Windows

RSCWs will NOT support rasters/mosaic operations

• Not within scope of instrument checkout.

• Only exception are identified pointing patterns that are mandatory for instrument characterisation during RSCWs of which the only known examples are

• The standard pseudo-raster for EUI/PHI flat-fields. BTW Within nominal phase this pseudo-raster will be handled according to the planning approach described previously.

• METIS straylight

• (TBC) co-alignment campaign

Can we agree this via MoM?


Timeline at LTP

Contained within the planning skeleton: Identified windows with fixed times, during which the raster slews will occur

Time

Expected duration order of 5 mins or less


Aside: How is this different from slews during normal operations?

It isn’t different in principle, but it is different in practice• Yesterday we already discussed (simple) sequential pointing schemes

through RSWs where perhaps we do pointing-X for e.g. 12 hours, then pointing-Y, then back to pointing-X

• During VSTP feature tracking, there will be a slew window once per day to allow the opportunity to make a proper motion correction

• Mosaics are thus special because• They involve slews much more often that once-per-day, thus harder to

work around.• Often they will be driven by the needs of few (one to three) instruments


What do you really need?

Various possibilities

• Square rasters, 2x2 3x3? 4x4? 5x5?

• Also superimposed on feature-tracking

• Linear raster (1 Dimensional)

• Packing across a pole

• Full-disk packing


Example non-rectangular case

Packing round a pole, down to some specific lattitude


Example non-rectangular case

Packing round the pole, down to some specific latitude, whilst the SC is rolled

Example of how things can become complicated

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ESOC | Chris Watson | ESA/ESOC | Page 1 Mosaics Operational aspects CHRIS WATSON ESAC