Observing Nitrogen Fluorescence Light with Owl Mission

1. Owl mission concepts • The OWL mission will: • Use the Earth's atmosphere as a vast calorimeter and observe nitrogen fluorescence light of giant air showers from ABOVE. • Determine arrival direction to better than 1° • Either two satellites observing same shower development: stereo OWL • Or one satellite (or Space Station attached payload) using fine timing of shower development to determine direction: mono OWL • Perform measurements of shower energy profile and determine depth of interaction in atmosphere, required for particle identification. • Monitor approximately 3 million km2 sr of atmosphere, with ~ 10% observing efficiency, to collect ~ 3000 events with energy >1020 eV per year.

2. EUSO Proposal • OWL concept proposed as EUSO as an ESA F2/F3 Free Flyer Mission • Science approved for Space Station deployment to be mounted as external payload on the Columbus module. A space of 4mx4m by one metric ton is reserved • Phase A study to be carried out by ESA to see if EUSO payload will be suitable for reserved space • ~$175 million for launched is approved if EUSO fits the space • US support for EUSO will come from a Mission of Opportunity proposal. Missions of Opportunity allow US participation in a non-NASA space mission of any size. NASA intends to solicit proposals for Missions of Opportunity with each future AO issued for UNEX, SMEX, and MIDEX investigations. • Next AO June, 2001.

3. EUSO – Current Status • Schedule reported by Arvind Parmar at GSFC on 11/9/00: • 1st Milestone is the Space Station Accommodation Study • Tim Stevenson (ESA) is official author • Dec. 7,8 Erice, Italy Review. Young,Pitalo/SOMTC and Takahashi/UAH will attend • Submit Accommodation Study to ESTEC on Jan. 22-26, 2001 • • Final decision on at Feb. 27, 2001 meeting of Science Program Committee • Phase A study - March 2001 to ≈ June 2002 • An ESA study contracted to industry (Italian??) • Scale of study is $ 0.75 M • Goals • Mission definition • Scientific payload definition • Identify group responsibilities • Phase B to run 18 months from Sept. 2002 - Mar. 2004 • Detailed design • Phases C-D, 3.5 years from March 2004 - Sept. 2007 • Launch nominally 2007

4. Co-Proposers outside ESA Member States ADAMS, J. – CHRISTL, M.J. NASA MSFC, Huntsville, USA ARISAKA, K. – CLINE, D.B. University of California, Los Angeles, USA EBISUZAKI, T. RIKEN, Saitama, Japan ISAAC, M.C.P. University of California, Berkeley, USA LOH, E.C. University of Utah & NSF, Arlington, USA LINSLEY, J. University of New Mexico, Albuquerque, USA SOKOLSKY, P. University of Utah, Salt Lake City, USA STREITMATTER,R.E. - NASA GSFC, Greenbelt, USA ORMES,J. - STECKER, F.W. TAJIMA, T. University of Texas, Austin, USA TAKAHASHI, Y. University of Alabama, Huntsville, USA WEILER, T. Vanderbilt University, Nashville, USA

5. Attached Payload Concept

6. EUSO Optical Design Double-Sided Curved Fresnel Lens • f/1.25 • 70 deg. Field of View • Back-cut losses • Lenses 1 cm thick

7. Accomplishments in Fresnel Lens Research • Development of accurate Fresnel lens computer and analytic models • Successful prototype fabrication • Single and Double-Sided • Planar and spherical substrates • Verification of computer models by testing the prototypes 52” Fresnel mandrel on Moore Predicted Image Actual Image Measuring Fresnel lens geometry Prototype OWL lens