1. Fundamental Understanding of the Universe: Dark Energy 2010 2001 Supernova Acceleration Probe: SNAP Development Configuration Launch Physics Discoveries Assembly Technology Physics Integration Engineering

2. SNAP Collaboration G. Aldering, C. Bebek, S. Deustua, W. Edwards, B. Frye, D. Groom, S. Holland, D. Kasen, R. Knop, R. Lafever, M. Levi, S. Loken, P. Nugent, S. Perlmutter, K. Robinson (Lawrence Berkeley National Laboratory) G. Commins, D. Curtis, G. Goldhaber, J. R. Graham, S. Harris, P. Harvey, H. Heetderks, A. Kim, M. Lampton, R. Lin, D. Pankow, C. Pennypacker, A. Spadafora, G. F. Smoot (UC Berkeley) C. Akerlof, D. Amidei, G. Bernstein, M. Campbell, D. Levin, S. McKee, M. Schubnell, G. Tarle, A. Tomasch (U. Michigan) P. Astier, J.F. Genat, D. Hardin, J.- M. Levy, R. Pain, K. Schamahneche (IN2P3) A. Baden, J. Goodman, G. Sullivan (U.Maryland) R. Ellis, M. Metzger (CalTech) D. Huterer (U.Chicago) A. Fruchter (STScI) L. Bergstrom, A. Goobar (U. Stockholm) C. Lidman (ESO) J. Rich (CEA/DAPNIA) A. Mourao (Inst. Superior Tecnico,Lisbon)

3. The Accelerating Universe: Science’s Breakthrough of the Year Redshift of spectral features measures the expansion of the universe. A magnitude vs. redshift plot provide a Hubble diagram measuring the expansion rate Ground-based work thus far has uncovered a major surprise:

4. Large statistics, ~2000 Sne Ia’s, distributed in redshift to z<1.7, with minimal selection bias and clean Ia ID. SNAP Baseline Sample

5. SNAP a simple dedicated experiment to study the dark energy —Dedicated instrument, essentially no moving parts —Mirror: 2 meter aperture sensitive to light from distant SN —Optical Photometry: with 1°x 1° billion pixel mosaic camera, high-resistivity, rad-tolerant p-type CCDs sensitive over 0.35-1  m —IR photometry: 10’x10’ FOV or larger, HgCdTe array (1-1.7  m) —Integral field optical and IR spectroscopy: 0.35-1.7  m, 2”x2” FOV Mission Design

6. Project History and Status SNAP project still in embryonic stage, conceived in March 1999 Project is being developed as a multi-agency partnership: —Team that produced current results was supported by DOE, NSF, and NASA. —Science review by SAGENAP of 260 page proposal March 2000: strong endorsement of science, recommendation for study funding. Entire session at Jan. meeting of the American Astronomical Society devoted to SNAP: 9 talks, 4 posters. Strong grass-roots support. Recent DOE/Science & R&D Review (Jan 2001): —“SNAP is a science-driven project with compelling scientific goals.” —“SNAP will have a unique ability to measure the variation in the equation of state of the universe.” —“We believe that it is not an overstatement to say that the Type Ia supernova measurements will uniquely address issues at the very heart of the field…” [Implications for particle physics]

7. Strategy within DOE Strategy for getting SNAP funded within DOE: Dark Energy a subject of the recent National Academies of Science Committee on the Physics of the Universe (looking at the intersection of physics and astronomy). One of eleven compelling questions: “What is the Nature of the Dark Energy?” SNAP reviewed by the NRC/”Committee on the Physics of the Universe” July 2001 as part of their Phase II review of projects. International collaboration is growing, currently 15 institutions. SNAP presented to HEPAP subpanel planning the future of HEP, in May 2001. APS/DPF held Snowmass meeting part of 20 year planning process for field —Dark Energy/SNAP teach-ins —“resource book” on SNAP science about to go to press

8. Conclusion SNAP: —Space observations of thousands of supernovae will provide the vital breakthrough in precision cosmology to characterize the dark energy —SNAP will measure the matter and energy densities with exquisite precision —SNAP will precisely determine the expansion rate of the universe as a function of time.