LBNL-2016: Complementarity of Ground, Balloons, and Space

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Framing of S4 with regard to Satellite Mission and Ongoing Ballooning program

  • Driver 1: S4 should not rely on uncommitted space-based mission
  • Driver 2: To optimize chance of funding for satellite mission and for ongoing ballooning program, S4 message should be that sub-orbital complementarity, and ultimately a space-based mission is crucial

Is it possible agree on a specific message that articulates "optimal" if not "required" complementarity?


  • Should concentrate on doing what cannot be done from the ground
  • provides complementary observations at higher frequency
  • easier access to large angular scales than ground
  • low background-loading testbed for technologies for next generation satellite.


  • l < 10-20 particularly challenging
  • ~30 < f < 270 in specific bands available from the ground optimal?
  • Only way to get science requiring high resolution, so needs to be done on ground


  • Don't do what can be done from the ground or balloons.
  • l < 1000 - Make sure instrument can de-lens to a reasonable level
  • 0(30) < f < 0(500) complete coverage
  • Need low frequency (30,40 GHz) channels as well as high frequency to monitor sync. It will probably not be done from the ground at low ell sufficiently well.


  • r < 0.01 will be challenging for all measurements
  • Very reassuring, probably required by the larger community, to see a detection with completely different instruments with different systematic effects and mode content.
  • Balloons are an excellent complement for ground based measurements (and vice versa).
  • If there is a detection we will want to know n_T and that will likely require space.

Specific Questions for S4 Design (and do these rely on what happens in ESA/JAXA planning?):

  • What are minimum and maximum frequency that we should design for?
  • Should l < 10 be a design requirement, goal, or a nice to have that emerges for S4?

Discussion From this morning

Amber Miller: Moderator

Charles Lawrence: Space Bill Jones: Balloon

With the Decadal Review coming in less than 5 years, NASA seeking input on the role of probes for CMB, collaborative space opportunities potentially available with European and Japanese mission(s), and S4 planning, it would be valuable to identify the specific roles to be optimally played by each available platform. What information is necessary to reach a consensus as to what the optimal parameter space is for each platform, where overlap should be, etc., and when will we have that input?


1) In 5-10 year timescale, what is appropriate target parameter space (sky coverage, angular resolution, frequency coverage) for experiments in Space, on the Ground, and on Balloons?

2) Given financial and practical constraints, is this parameter space well-defined, or do we need more information to define appropriate ranges? Specifically what data do we need to reach these conclusions, and what is the timeline for this data coming in?

3) Are these timelines compatible with design timelines for Inflation Probe and other space opportunities, S4?