Far-IR STDT Bi-Weekly Telecon Meeting Notes

1. Proposed to switch the cadence and hold a one-time meeting on March 31, 2017.
   1. Concerns were expressed about meeting weekly, and mentioned that this may interfere with existing schedules. Alex can talk on April 7, 2017.
2. The OMAA deadline is on a Thursday April 20, 2017; the team plans to still have the telecom on April 7, 2017 and see who shows. 

Instrument Working Group Summary - Coronograph

1. Itsuki mentioned that he will be able to provide more discussion on this at the face-to-face meeting at the Jet Propulsion Laboratory (JPL). Has spoken with Tom on the coronagraph element at NASA AMES.
   • Mike asked if anything will be presented regarding the guider. The entire telescope needs to be guided by a mid-IR camera. Itsuki mentioned that they are examining the optics for a camera, however the planning and examination of this is in the basic stages or beginning stage of development. He will give an overview of the camera that will be planned for use during the face-to-face meeting. Margaret mentioned that the engineers have recommended using a mid-IR camera to guide. The Mid-IR instrument will cover the wavelengths at a certain amount of microns. It depends on how much downlink capability is available, the mid-IR instrument will have to be kept on. There is no other plan at the moment; the team needs to decide on whether to moving forward with this or not. It may not need to be in the light path, or in the instrument suite.
   • Are there near-iR detectors that will work at 4 Kelvin? The teams highly doubts it. Detectors can be heated without having to heat everything else. The team should focus on achieving a short wavelength, multiplexers have to be 30 kelvin. A lower kelvin should not be decreased.

1. Have had a couple of telecons; are currently trying to understand constraints and determine what bands and frequencies they will have. Johannes will touch on this later (possibly at the JPL face-to-face meeting) as far as the science requirements; they are getting closer with where they need to be with science cases. They still have to develop science cases for polar meter. Alex mentioned that the optics lab has produced the first shot of what the instrument will look like; it will be a large instrument, and will not be compatible with other instruments; the team will need to develop some real conclusions.
   • The number of bands will have implications on instrument size for re-imaging optics. There is a possibility of reducing parameters to smaller rays. Joe is looking at not maximizing the field of view, but getting the instrument more compact and putting in more constraints. The team stated that they do not need to use long wavelengths but they may need to decrease the field of view.
   • Kartik asked how the design of this instrument is similar or different than Hershel.
     • The design with OST is similar to Hershel and Sophia by only using only two rays; the sensitives of integration bands are very wide; it is very good to have maximum size array, which will operate with individual bands, using a filter wheel plus a wheel with optics that can change the speed. The baseline is different for polarimetry for a second array; the team may have to compromise on this. It may not be efficient to do a single filter(Asantha).
       • Margaret mentioned that this would be a good discussion to have at the meeting. An instrument should be made for easy surveying. Johannes changing the timing on this. 

Europe will meet with other science case teams next week. They have talked with Gary and Doug regarding the overlap of spectrometer science requirements. The idea is to have a more array; and a visual line channel at 62 microns; the heterodyne is well defined for the high resolution spectrometer. All of this has to be defined in the coming months. Margaret is hoping to get requirements such as the field of view better defined. 

Had telecon a week and half ago to discuss the science cases that can be addressed with MSRS. Some groups have suggested writing two pagers on how MRS can be applied. 

Have had joint high resolution telecons every Tuesday. The heterodyne presentation will be given by Martina. The team has tried to be more specific about domains for each instrument and project to use in tandem for high resolution leading the way. Meanwhile we are joined by Harvey on Tuesday (at the face-to-face) and will deliver/present on the high resolution incoherent detector sensitivity to light. The status is that Harvey had a Hermes PDR today and will meet with Johannes on Monday (3/13/2017) to get status of this. The heterodyne team is deciding on the appropriate number of pixels to include in heterodyne instrument. In March (at the face-to-face meeting), we will have better defined elements for the team to go back and apply. 

So far they have 18 or 19 applications. The March meeting will include further discussion on the coronagraph and exoplanet. 

Introductions: Lisa Kaltenegger and Kevin Stevenson, new Exoplanet WG Chairs

Asked Lisa and Kevin to join the exoplanet working group. Lisa and Kevin will be meeting next week to go over assignment selections for the working group. Lisa and Margaret may invite speakers from JPL to speak on exoplanets. May not want others to speak on exoplanets other than Lisa and Kevin on exoplanets.

1. Review of on axis vs. off axis trade chart
   • Mechanical considerations are rated for on axis structural concerns; will only be able to talk to this quantitatively. INT was weighted more for on axis. There are various categories such as programmatic considerations such as; weather or not the heritage look like JWST, maintaining low risk, ensuring the cost is affordable and determining the risk posture. This is not finalized; it is due in a few weeks and all requirements are not provided. Margaret mentioned that in doing a concept study, we have to decide. Ruth mentioned that instrument packaging will be different for on axis and off axis; because the team will visit the Instrument Design Lab (IDL) in April 2017 and May 2017 all design plans need to be better defined by then. The team needs to decide on the telescope configuration to figure out instrument Volume. All science requirements have to be settled on by December 22,2017.
   • What is the difference between volume for on axis and off axis? The volume is slightly bigger. The shape is also very important in accommodating 5 instruments; this is very important for the engineering team. 

1. Concerns for unclarity in terms of scientific priortites.
   • Need instrument parameter inputs ASAP.
   • The IDL for the 2 GSFC instruments will begin very soon after the March face-to-face.
   • The team currently has top science cases; the instrument needs to fulfill those is very disproportionate in terms of proposed instruments.
   • The team has no guidelines on requirements for “general observatory capabilities”.
   • How important it is to discuss the overlap of spectrometers? Gary mentioned that this is critical and that it would be very beneficial to discuss the spectrometer at the face-to-face meeting. Ted and Gary are not fully positive that they have captured all requirements. Hopefully this can be completed at the face-to-face.
2. Overview of pre-work deliverables for the IDL
   • If STDT members are interested in participating, they should let us know as soon as possible to participate in trade studies.
   • The IDL will be the engineering support at Goddard used to define Far-IR and spectrometer.
     • Need concepts from Instrument Teams to better define requirements. There is a large team of engineers that will dedicate a week to integrating science requirements with what the observatory requirements are.
   • The more detail and defined the science requirements are the better (instrument design and cost estimate). Need to identify one scientist during the IDL week to make serious decisions on silence requirements.
   • April 21, 2017 – pre-work meeting will include review of all requirements; all requirements must be prepared a week before the pre-work meeting.
   • Key technical parameters for instruments – [spectral bands, resolution, field of view)
     • Science instrument concepts
     • Mission overview
     • Engineering design allocation
   • Is there a direct trade between aperture volume and instrument?
     • The field of view (large field of view) drives the secondary optics. May have to downscale the field of view by reducing the color. Mapping field of view should also be achieved in the instrument, to avoid having so many pixels; very low luminosity but diffused emission.
   • The instrument should fit into a 5 meter fairing. Given the decadal says to include the SLS, why use a five meter fairing?
     • There are two different studies so the question of using an SLS is unclear at the moment.
     • Use the SLS to achieve a lower volume; instrument compromises may not be a simple achievement; which would cause complete redesign of the instrument. 

Summary of f2f meeting agenda, and head count of planned attendance (Meixner, 10 min)

1. Total number of participants /headcount (for catering purposes) – 34 total participants (including 6 NRESS members)
2. Face-to-face meeting – Keith Spaliding Building, Caltech – March 21-22, 2017
3. 2 web forums  - NRESS travelers and non-nress travelers – non-ress travelers will be expected to pay for their own food.
4. Conducted review of agenda (see confluence for agenda)
5. Day 2
   1. OST instrument changes
   2. Discuss the MISC on day 2 (will do sequential discussion) and do planned and organized plenary discussion (develop agenda as we progress through the meeting). Make sure everyone understands field of regard and drivers for field of regard. Solar system observations can influence field of regard. May include tracking as well.
   3. Simplify the Far-IR discussion to discuss the spectrometer and FIP.
   4. Next telecom will be on April 7 instead of March 25^th, since the face-to-face meeting is that week.