Meeting Minutes (DRAFT) - OST STDT Bi-Weekly Telecon - December 1, 2017


Origins Space Telescope (OST)

Science Technology and Definition Team (STDT) Telecon


Purpose: To discuss science activities for OST.Facilitator/Host:Margaret Mexiner/Spitzer Science Center

Telecon: WebEx Online

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Meeting Number:

1-855-749-4750 (Toll Free)


Access Code: 194 170 917

Scribe:Sydney Jones

Discussion Topics 

OST Study Office Presentation - Leisawitz, Carter 

  • Table would be useful for evaluating priorities of instruments

Concept 2 STDT Survey Results

  • Question 3: Consider JWST as a baseline. Do we want something smaller than JWST. Feedback included suggestion that OST should not be smaller than JWST. If it were smaller, it would be perceived as taking a step backward . Understanding that a larger telescope would cost more.
    • Results: Roughly 65% were in agreement and roughly 35% were not in agreement. 
  • Alex Pope - Don't have to be bigger than JWST. It is up to OST to sell it to the community. We are an order of magnitude longer in wavelength than JWST. 
  • Susan - Bigger telescope is better in terms of resolution. 
  • Kevin - Telescope aperature is smaller than JWST collecting area. 
  • Weidner - Don't need to get as big as Concept 1. 
  • Leisawitz - Dont want the CATE to not believe us and do not want them to say we are off by a point. 

Instrument prioritization for Mission Concept 2

  • Discuss instrument prioritizations for Mission Concept 2 with rescopes and science in mind, focus on FIP & HERO (Relative ranking of FIP and HERO)
    • Think about relative ranking keeping in mind MISC conversion will be there and MRSS will be there. 
    • Presented Insrtument Quick Rescope Exercise - Run down on descopes and motivation for them
    • Goal will be to work down the instrument prioritization in trying to accommodate as many instruments as feasible with constraints on mass, volume and cost.
    • What  is the relative ranking of FIP and HERO looking at the top 4 programs and keeping in mind that MRSS/HRS  and MISC as rescoped, will be on board MC2?
    • What  is the relative ranking of FIP and HERO looking at the programs that are uniquely OST and keeping in mind that MRSS/HRS  and MISC as rescoped, will be on board MC2?

    • HERO

      • Spatial pixels: Reduced number from 32 to 18 and 128 to 32
      • Smaller telescope means bigger beam, smaller telescope makes us closer t
      • O channels would be 32 KG limit. 
    • FIP
      • Trades are: original instrument has two arms with to detectors enabled polaimtery and 4 total power band observation simultaneouly. Scale back would be to take out one of the arms. Total power modes would now be simultaneous observation at two bands. 
      • Optics reduce number of pixels in remaining detectors by a factor of two. 
      • The mapping speed goes down by a factor of 2. 
      • Cutting more would then cut off more bands. 4 bands would be the minimum. 
      • Can build such an instrument at 2 KGs. 
      • Will have a rotating imager.
      • James has made field of view square. Will this be a detriment? No it should be fine (has same aperature).
      • Comments for descope of FIP and/or HERO
        • No one has said that descoping the instruments is crippling. 
        • Pontoppian - Descope has no real impact. The o-channel may be slightly impacted. 
        • Melnick - Would like to know the spectral resolving power for MRSS as a function of wavelength with the fibre pero option (from short to long wavelength)
          • Original 43000 over 1 micron over lambda 
          • Now 150K over 12 microns
          • R value can be boosted 
        • Mexiner: Keep in mind what we want to measure. In understanding the turbulence question, the balloon is fine. We need the science floor, we can't just

        • Is not pushing FAR IR and polarimetry an issue? For large surveys, total power mode would be the only option we have. 

          Mexiner - Added that last time we tried to prioritize the instruments and provided overview of insrtument quick rescope exercise. 
        • Ned: Thinking we could have MRSS in long slit mode and move fast given detectors are moving fast. You will see outer solar system objects. This will be with moderate spectral resolution. Detectors must be background limited. 
        • Staghun: Need to do drift scanning. Large area may not allow us to obtain sensitivities. 

        • Descope Options for FIP and HERO/MRSS



Action Items
#Action ItemOwner Due Date
1Formulate one or two science questions for spectral resolution (line self absorbtion)

Gary Melnick

Klaus Pontoppidan

2Write up summary of using long survey. 

Meeting Minutes (DRAFT) - OST STDT Bi-Weekly Telecon - December 1, 2017

Meeting Minutes (DRAFT) - OST STDT Bi-Weekly Telecon - December 1, 2017