1. S. Rinehart NASA’s GSFC Interferometry at Altitude: Galaxies, Stars, and Exoplanets BETTII, BENI, and Other Fantastical Notions With contributions from R. Lyon (BENI PI), the BENI team, and the BETTII team

2. October 27, 2009 S. Rinehart Interferometry at Altitude 2 Motivation Angular Resolution! Contrast (nulling)

3. October 27, 2009 S. Rinehart Interferometry at Altitude 3 Design

4. October 27, 2009 S. Rinehart Interferometry at Altitude 4 How Does it Work? Observe at different times to get sky rotation Enables accurate derivation of relative positions Effective resolution of ~0.5 arcsec By stroking the delay line, we obtain fringe packets Can derive the spectrum of the sources from the fringes Spatially-Resolved Spectroscopy

5. October 27, 2009 S. Rinehart Interferometry at Altitude 5 BETTII Science I Star formation: Does star formation in clusters differ from that in isolated regions? What FIR emission arises from disks of individual sources? From inner envelopes?

6. October 27, 2009 S. Rinehart Interferometry at Altitude 6 BETTII Science II Active Galactic Nuclei: What are the energetics in the core of an AGN? How do different regions contribute to the FIR flux?

7. October 27, 2009 S. Rinehart Interferometry at Altitude 7 What is BENI? Fizeau interferometry o 3 10-cm collectors o 1.5 meter baseline o Visible Nulling Interferometer Technologically challenging o Reactionless payload tracking o Fine pointing with 3 FSMs o Active wavefront control The VNC Testbed: BENI on a Bench

8. October 27, 2009 S. Rinehart Interferometry at Altitude 8 Visible Nulling Mach-Zehnder Interferometer Light split at first beamsplitter Recombined at second Combine beams from 3 telescopes (Fizeau) Arm #1: Catseye reflector (flips image and rotates polarization 180°) Arm #2; deformable mirror (feedback from bright output)

9. October 27, 2009 S. Rinehart Interferometry at Altitude 9 BENI Science I Exoplanets Directly image a Jovian planet Image a debris disk Exozodiacal Light Hidden planets?

10. October 27, 2009 S. Rinehart Interferometry at Altitude 10 BENI Science II Characterize the high altitude atmosphere Turbulence Scintillation Greenwood frequency Estimates made via modeling now indicate: Turbulence: r o > 50m Scintillation < 0.1% f G << 1 Hz

11. October 27, 2009 S. Rinehart Interferometry at Altitude 11 Follow-on There’s great science with BETTII, and her daughters (longer booms, cold telescopes, nulling, moveable siderostats…..) will be able to do even more! The same is true for BENI; could we do spectroscopy of exoplanets on a balloon? Both also pave the way for potential space missions…

12. October 27, 2009 S. Rinehart Interferometry at Altitude 12 Thanks The BETTII Team: S. Rinehart 1 (PI), C. Allen 1, R. Barry 1, D. Benford, W. Danchi 1, D. Fixsen 2, D. Leisawitz 1, L. Mundy 2, R. Silverberg 1, J. Staguhn 2, A. Kogut 1, R. Lyon 1, J. Mather 1 The BENI Team: R. Lyon 1, M. Clampin 1, J. Herman 1, S. Rinehart 1, K. Carpenter 1, H. Ford 3, L. Petro 4, G. Vasudevan 5, R. Woodruff 5, J. Marzouk 6, P. Petrone 6 1: GSFC2: UMCP3: JHU 4: STScI 5: Lockheed-Martin 6: Sigma Space