20070913teleconnotes [PPPDT Wiki]

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==== Telecon Notes ====

September 13, 2007, 3pm EDT

__Topic 1: Review of the BEPAC deliberations and findings by Mark Devlin and Stephan Meyer,__ 

DEVLIN: Competition for top three slots in survey (JDEM, Con-X, LISA) was very tough.  Two missions have broad appeal (Con-X, LISA ) and they serve larger communities. LISA had very exciting science compared with other Beyond Einstein (BE) missions. JDEM, all flavors, returns much more data than that needed to get the single Dark Energy measurement, also had very little technology development needed.

Costs were not that big a discriminator. 

Technology not in place for CMBPol, measurement fantastically difficult to make, raw challenge for sensitivity in the face of unknown systematics and foregrounds.  Potential of a null result. Interest level not high in general for the science. The Inflation Probe was categorized as an 'experiment'.

KRAUSS: sounds like "they wanted LISA, but it's not ready so we'll take JDEM".  

DEVLIN: Even if JDEM does not produce any exciting science about dark energy, which is a real possibility, one gets 3000 Hubble Deep Fields. 

The committee had to take cost and risk into account, and therefore the committee could not saddle NASA with a long term LISA program with unknown technology development costs. That is part of the reason LISA was not chosen to be first. 

MEYER: Committee focused on the question of BE science. All missions, with some caveats about Con-X, were worthy BE science. So question is where do you start?  LISA's goals are very hard to match in fitting the BE science goals, but it is not the place to start, given the technical challenges. 

JULIAN: The report said Con-X is not really a BE mission.  Could someone elaborate?

MEYER: There was a prception that Con-X was shoe-horned into BE. It is really too broad. It¹s primary strength is not the BE central themes.

DEVLIN: Con-X does many BE things, but not as well as specific missions like LISA, JDEM.

MEYER: if w=-1, then you learn nothing more than you know now.  However it
nails it down for good. LISA should get a s/n of 100 on details of gravity wave signal. That is very exciting. But LISA Pathfinder results must be known before NASA can move forward.

DEVLIN: CMB science not well favored, community too small, too divided. There is a "who cares" (about inflation) factor combined with the possibility for a null result. Should also note that Cosmic Inflation Probe (CIP) is easier technology, and it gets broader ancillary science. 

HINSHAW: But CIP doesn't get the energy scale of inflation.

DEVLIN/MEYER: Political factors did not enter the BEPAC report deliberation.  That is, there was no consideration of how US DOE/NASA/NSF interact, how ESA may move, etc.

HANANY: Clearly the CMB science needs better explanation, more support from broader astrophysics and particle physics crowd. Case for ancillary science needs to be made stronger; need to enlist the community that cares about galactic dust, for example. 

DEVLIN: CMB scientists should give talks to particle physicists, making the Inflation Probe an inevitable mission. Currently this is not the case. Other groups (JDEM, LISA, Con-X) had an air of inevitability to them.

Committee had a discussion of how much needs to be invested to keep a mission alive (5-10% of a mission costs).  If however, you spend enough to keep all 5 BE missions alive, you can never new start.

KRAUSS:  Would ground based CMB results move up the time scales for the CMB space mission?

MEYER: If this committee (PPPDT) could change the perception of the rest of the community about the CMB world that might help the case.  A more unified front would be better.

Krauss(?): A plus for CMB, is that the theoretical understanding is extremely well developed. 

__TOPIC 2:  COMMON CMB proposal__

Shaul reports that through discussions over the last week the following course of action takes shape: the CMB community will submit an omnibus proposal which is likely to be funded and approved by NASA. The report emerging from this proposal will have the science and foregrounds sections done together. There will be few (one to three) example missions, one or two aligned around current bolometric missions, and perhaps another HEMT mission. The PI will coordinate science and foreground with subgroups working on daughter mission concepts. Julian notes that commonality in data analysis could be factored in as well.

Jamie notes that decisions will need to be made in the future regarding the relative ranking of the different mission concepts. 

People voiced strong sentiment that the report emerging from this omnibus proposal should build upon and amplify the Weiss committee report, which concluded that a mission in the near future means that bolometers would be the choice. 

Is everyone on board for one proposal?  One report will be more coherent, as a community.  YES would seem to be the answer.

Next steps are to select a PI for the proposal. S/he will coordinate the proposal and the report. Also, to inform the broader CMB community and to solicit inputs and suggestions. 

Shaul will compile a draft letter to the community. The letter will advertise the work of the PPPDT, will inform of the plan for an omnibus proposal, and will solicit input.
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