1. Dwight Johns / RONCALLI update on O.W.L. project for: CROP summer 2002 by: Dwight Johns RONCALLI date: August 6, 2002

2. Dwight Johns / RONCALLI O.W.L. meaning  O rbiting W ide-angle L ight-collectors u OWL is an earth-orbiting system to study air showers caused by particles with energy equal to or greater than 10 19 eV

3. Dwight Johns / RONCALLI O.W.L. who? who? Laboratory for High Energy Astrophysics, NASA/Goddard Space Flight Center, Greenbelt, Maryland High Energy Astrophysics Institute, University of Utah Salt Lake City Dept. of Physics, University of Alabama, Huntsville Marshall Space Flight Center Huntsville, Alabama University of California, Los Angeles Washington University Columbia University Vanderbilt University

4. Dwight Johns / RONCALLI O.W.L. time frames u earliest reference: convention at University of Maryland set in Nov. of 1997 u NASA bulletin from Apr. 23, 2002: “A proposed space-based mission called OWL could detect the highest-energy cosmic rays...”

5. Dwight Johns / RONCALLI O.W.L.  extremely high energy- 10 20 e V  heavy particles- PROTONS  source- EXTRA GALACTIC u PARADOX !

6. Dwight Johns / RONCALLI O.W.L pair o’ Docs

7. Dwight Johns / RONCALLI O.W.L. paradox heavy particles cannot sustain such extreme high energy for the distances implied by being extra- galactic. SO... where do they originate ???

8. Dwight Johns / RONCALLI O.W.L. mission? u Use the Earth's atmosphere as a vast calorimeter u Observe fluorescence of giant air showers from above u Determine arrival direction to better than 1° u Observe same shower development with two satellites (stereo OWLs) u Perform measurements of shower energy profile and determine depth of interaction in atmosphere (required for particle identification) u Monitor approximately 3 million km 2 of atmosphere, with ~ 10 % observing efficiency, to collect estimated 3000 events with energy >10 20 eV per year. u Single photoelectron sensitivity u Identify acceleration mechanism for these particles

9. Dwight Johns / RONCALLI O.W.L. do you remember this? “Above a few times 10 19 eV, the number of cosmic rays was expected to drop off sharply, but observations showed an initial drop off (known as the ankle), and then the spectrum became more shallow, meaning there are a lot more particles at these energies than was expected...”

10. Dwight Johns / RONCALLI O.W.L. equipment & positioning

11. Dwight Johns / RONCALLI O.W.L. other interesting items

12. Dwight Johns / RONCALLI O.W.L. closing shots  extremely high energy- 10 20 e V u composition- protons  rare- (~1000 or so per year)  source- out of this world (galaxy too)  detection from ABOVE looking DOWN u still apparently in planning stage

13. Dwight Johns / RONCALLI O.W.L. online sources u http://spaceflightnow.com/news/n0204/28atmosphere u http://www.gsfc.nasa.gov/news-release/releases/2002 u http://owl.gsfc.nasa.gov/science.html