Telecon 20171010

Attending: Jamie, Brian, Julian, Kris, Shaul, Karl, Qi, Roger, Jeff F.

Agenda:

• Large and small aperture presentation
  • optical systems: large aperture and small aperture options (Qi)
  • noise model and focal plane options (for large and small apertures) (Young)
• Scan pattern (Gorski, Delabrouille)

Notes:

Status of optics (Shaul)

• Matrix of larg v. small and open v. crossed.
  • large, open is baseline. Noise, weights, etc calculated and posted on Imager wiki page
    • current version is un-optimized optics. A/I UMN to use coma corrected and optimized open dragone. Recalculate noise.
  • small open and crossed designs work. Noise is calculated.
    • What alpha, beta angles are allowed? A/I UMN to investigate.
    • Motivation is to have a cost savings option
      • Question from group: Does cost truly scales with aperture? Or is complexity the bigger issue.
        • focal plane size, detector count, readout and power demands, etc. likely bigger driver.
        • Suggested: Are there other rocket options? If the payload is smaller this could be a savings location.
          • Likely that Falcon 9 is only choice.
  • large, crossed dragone still has sidelobe problems. 1.2m version is promising. A work in progress.
• Note: Al says PIXIE can observe with same scan strategy as imager. Kris would like to see the details of how this works.

50 cm systems (Karl/Qi)

• 3x hit in resolution
• 4 K and 30 K systems.
• 4 K gives better performance than baseline at high frequencies, ~> 300 GHz.
• 30 K is worse at all frequencies.
• Is > 300 GHz sensitivity very useful?
  • May not increase dust removal accuracy much.
  • High frequencies are largely for extra-galactic science and galactic dust science.
    • The 3x lower resolution may make these unappealing anyway.
      • General opinion that the resolution loss is a high price to pay.
      • Makes the science less appealing. This makes it less likely to appeal to Decadal Panel
• open dragones (30 K and 4 K) are smaller and fewer pixels than baseline.
  • likely a cost savings.
  • 4 K assumes cooling an additional ~1m mirror, which adds cost.

Scan (Kris)

• Higher spin rates a concern. Data rate may become an issue.
  • Past work by Amy said telemetry not an issue. May need to be revisited.
• possible spin rates in the 1-3 RPM range. Being studied at JPL, Amy organizing.
  • needed for 1/f, data rate, ect.
• Kris to present concerns with scan next week.