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- L1a data should be downlinked at minimum, NOT L0 (useless without ancillary data). Cannot reconstruct L0 and L1a (or it is difficult) from L1b, since it is normalized to sensor units (takes away raw data) – since we then use sensor calibration (sensor stability factors) to process to L1b. Gene is not happy with ESA giving L1b products since they are difficult to reconstruct. L2 does not make sense when chl-a conc. isn't appropriately correlated to ToA radiance. Radiometric calibration, geometric calibration and atmospheric correction need to be applied L1b->L2. Huge dataset for L1a, so need to consider that for downlink (he suggests X-band, maturity today is high).
- For L1b data do we want to recalibrate the sensor per imaging, or let it stay as it is until really necessary? L1a dataset will change based on the recalibration. Essence with L1a is to characterize the image based and understand degradation of optics, FoV coefficients etc. With recalibration we cannot figure that out.
- Things move after launch and in each operations, that's why we also need L1a at all times to see how the sensor+image data changes with time.
- Ground truth is really bad for in-situ validation: instantaneous sampling on ground and remote imaging from space won’t happen.
- Why? Ground point-to-point in-situ validation is not reasonable since it is difficult to map this to the pixels on the sensor and also this does not give any information about how the whole image should be calibrated/corrected. Sampling across large area can give you a better clue but difficult to do. You can’t take a point and sample it and say hey this is how the water looks like at that point. Water is way more heterogeneous than you think from point to point.
- Doing it across a e.g. 30x30 km grid makes sense though impossible to do operationally/physically. Things change very quickly over the course of the imaging operations and imaging on fine scale and sampling. We can't get a coherent structure in that way. Radiance values vary too much across pixels and where you take images. Need many many assets out there to get a better idea but will never be perfect. Algal blooms and ocean in general are too dynamic and highly varying – esp. wrt. currents and waves.
- Apply deconvolution and super-resolution between L1b and L2: Correct. Minimum success criteria is to do super-resolution on ground, don't risk doing it onboard (at least in the first season of operations).
- Slew maneuver ambitious to achieve perfect GSD as proposed. Baseline should be to point Nadir, have 500 m spatial in-track resolution and view a 50 km line for 8 seconds. Slewing shall be full success criteria, we don't know the precision.
- Our theoretical SNR is ok, but need to find out what it is in practice. Good that we redesigned from V4 to V6!
- Hawkeye mission: Gene is working on this mission. They are using X-band for downlink and has deployable antennas. Suggestions:
- S-band is ok, “touch the water before jumping into it” and since we will have a S-band ground station at NTNU and may want to also downlink there. But it really doesn’t matter location in terms of real-time to downlink "fast", data will be distributed quickly and use S-band Ground Station across the globe.
- TRL for X-band is high enough today to downlink higher amount of data – send a lot more data in shorter time – save energy and operations complexity. Think about it for next mission.
- Use a RGB camera to geo-reference the HSI FoV instantaneously and on image grid. Hawkeye uses FinderScope (a RGB camera - same principle).
- Skepticism on HSI, esp. on the spectral binning branch. Increase SNR thru more binning and get less spectral resolution which would already be great at 20 nm-40 nm.
- Processing in SeaDas would be great. Ensure format is readable.
- Downlink to NASA GSFC is not necessary - they can download from our website/server.
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