Attendance: Amy, Nick B., Marcel S., Raphael F., Alex vE, Colin H., Dan G.
Notes by: Karl
Concerning the Executive Summary, I think that it is too detailed and is missing some really big picture motivation and description - especially for those not into CMB details.
I think you need to get across that there is a lot that we have learned about cosmology - largely from the CMB - but much that we still do not understand (dark matter, dark energy, inflation, etc.). There are now growing tensions between cosmology data sets. As our only probe of the early universe, future precision studies are essential for all of these problems, as well as for new questions that will arise in the intervening years.
You give lots of justifications for PICO, but the number of justifications will not carry the day as well as one or two really compelling stories - told in the most general terms: what's dark energy? what's dark matter? how did the universe begin? is GR right? (These are clearly understood to be important questions and I doubt that any exoplanet mission, for example, will answer them. That's why PICO is needed.)
Similarly, I think that your case for space in terms of multipole moments is too detailed and debatable. Instead, I think you should appeal to the generic advantages of a well-designed space mission in obtaining conditions that the ground can never match: (no atmosphere/weather, precision full sky coverage linking a wide range of angular scales, thermal stability, solar shielding, low magnetic fields, no ground pick-up, etc.).
Hi Shaul,
The audience is the decadal so I think one should be a bit broader than one would with a mission proposal template. Here are thoughts:
1) For why space, surely you want to highlight getting the complete B-mode spectrum, accessing both the reionization and recombination bumps. That's stronger than 'multiple patches' that one can do from the ground.
2) All-sky multi-frequency polarization data from Planck sets the stage for precision foreground control. We are building on this information that was not available in 2010. I think Raphael was saying the 'worst-case' foreground model now has decorrelation at limits from Planck, but could become better? If I got that right it would be a useful selling point.
I think you can make the points about technology and maturity with more favorable spin. E.g.
3) We are building on the legacy of Planck, which demonstrated multi-frequency detectors operating near background limits and accessing large angular scales. The cooling system leverages Planck's accomplishment of stable 100 mK operation. The main technology advance needed are large arrays of detectors operate near Planck's level of demonstrated performance. Significant advances have been made in the last decade with arrays and there are multiple approaches that can meet PICO's requirements.
4) Planck has shown methods for systematic error control especially on large spatial scales. Ground-based experiments have now demonstrated systematics control to < 50 nK deg-2 on degree scales, close to PICO's target sensitivity. We are building on these as well.
5) One might consider a figure to summarize the above flow of technology and systematics that will help make it stick in reader's minds.
The “points remaining necessary steps forward” section seems problematic. Technology adjustments are ok but I don't think we can ever make a foreground or systematics demonstration that is fully representative, so I would not offer them up as being necessary.
I like the idea of recommendations for endorsement, especially technology development and demonstrations. I'm not quite sure how to play the mission recommendation. Technically one would only have to ask for the probe mission class, but the inflation probe is a special case in that it was a recommended mission in 2010 and I would hate to give that up since it conveys some advantage in nasa support that would not be available as one of many potential probes.
Jamie
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