The Cosmic R A y Telescope for the Effects of Radiation

1. The Cosmic RAy Telescope for the Effects of Radiation

2. Presentation Goals Sources and Effects of Radiation in Space Designing and Testing a of a Space Craft Instrument Initial Results and Expected Goals of this Work

3. Energetic Particles in Space SEP’s GCR’s • Energetic particles can be, electrons, protons and heavier ions such as oxygen, carbon, and iron. • The particles are charged and have enough energy to break chemical bonds such as those that hold together DNA. • Damage to DNA is a major source of medical problems due to radiation exposure.

4. Solar Energetic ParticlesSEP’s SEP’s are mainly protons. Some SEP’s are accelerated during a solar flare. Others are created as a result interactions in the solar wind. SEP’s come in short bursts. Particle energies can vary from KeV to MeV(eV stands for electron volt) Solar Flare that accelerates charged particles to near light speeds Flare Movie: http://sohowww.nascom.nasa.gov/gallery/Movies/flares.html Webcam Movie: http://www.youtube.com/watch?v=vCFQZqSxWns

5. Galactic Cosmic Rays (GCR’s) Sources outside of the solar system • Supernovas can accelerate heavy ions particles to very high energies. • GCR’s are a mix of electrons and protons along with heavier elements. • GCR’s come from many different sources and so are constantly raining in from outside the solar system. Particle energies can vary from 10’s of MeV to GeV’s and higher

6. SEP’s and GCR’s are tied to the solar cycle SEP’s GCR’s SEP events happen more frequently during solar maximum But….. GCR’s are deflected more by the Suns magnetic field during solar maximum

7. Protection on Earth Quebec, Canada Aug. 19, 2009 http://www.spaceweather.com/ Atmosphere Absorbs High Energy Particles Earth’s Magnetic Field Traps Charged Particles http://radbelts.gsfc.nasa.gov/outreach/outreach.html

8. Effects of Ionizing Radiation • Ionizing radiation can cause cell damage • The damage is particularly harmful if DNA is broken apart • Top: • Images of cellular nuclei that have been bombarded by ionizing radiation • Green spots are places where DNA was split • Bottom: • Visualization of DNA strand breaks from an x-ray and a cosmic ray Image Credits: A. Cucinotta / NASA,JSC,SRAG

9. Electric Field Electric Field Incident Cosmic Ray CRaTER Electronics Step 1: Electrons freed from atoms by incident radiation Step 2: Electrons collected and measured. More electrons = more energy deposited Measuring Cosmic Rays • This ionization effect is used by instruments to measure the particles • Radiation ionizes atoms in our detector • Electric field accelerates electrons into our electronics • We measure the amount of energy deposited by each particle (LET) • How much energy is deposited? • Not all the particles energy is deposited • Low energy particles leave more energy then high energy particles

10. Measuring Cosmic Rays with CRaTER Detectors 1 & 2 Detector 3 & 4 Detectors 5 & 6 Particles from Deep Space Particles from the Moon TEP TEP Warning: The animator’s creative license has LRO pointing the wrong way. Don’t worry though…the spacecraft operators know which way to point it! Spacecraft Animation

11. Prototype Same electronics as we would use in flight, but easy to use (they plug into the wall!)

12. Protype Testing Need a source similar to the one we will measure, e.g. Brookhaven National Lab, where they can accelerate ions to very high energies Shadow of CRaTER prototype detector Image taken with Iron nuclei at Brookhaven National Lab

13. Data Rate: Entire Satellite: 100 Mbps : about the same as a wireless router…not bad! CRaTER: ~90 kbps (~0.1% of LRO rate!): better than dial-up connection, but not much! But what’s the real limitation? Power: $ Mass = Launch Costs: $ CRaTER: 6 Watts Payload: 98 Watts Payload: 190 lbs CRaTER: 13 lbs The Rest of LRO: 690 Watts The Rest of LRO: 2092 lbs Fuel: 1774 lbs

14. Engineering Model Testing Need sources similar to the one we will measure in space Radioactive Sources Cobalt-60 Source (gamma rays)

15. Engineering Model Testing Particle accelerators, e.g. Brookhaven National Lab Ion Beam

16. Flight Model

17. Flight Model Calibration

18. Flight Model Environmental Testing Make sure that instrument can survive in space environment Thermal – Large temperature gradients in space Vibration – Huge vibrations during launch Acoustic – Launch causes large sound waves

19. Integration with LRO Who are those masked men??

20. Testing of Entire Satellite

21. Launch! http://www.nasa.gov/mission_pages/LRO/launch/index.html

22. CRaTER Science Goals • Originally driven by exploration goals (measure energy deposited at different depths in the human body) • Exploration Enables Science! • High-data-rate and uniquely capable galactic cosmic ray (GCR) and solar energetic proton (SEP) science instrument

23. CRaTER Sees the Moon! When spacecraft is closer to the Moon, the moon shields more cosmic rays coming from deep space Altitude above the Moon CRaTER Count Rates

24. Periodic Table as Seen by CRaTER • Iron Ion Beam at Brookhaven National Labs • Iron factures in material placed in front of the detectorcreating smaller ions

25. Flight Data Why we do the experiment: Because this is what is really out there!

26. Two Detector Histograms Comparing Energy transfer to different detectors Detectors 1 & 2 • Particles deposit energy as they travel through material • Lower energy particles leave more energy Detector 3 & 4 Detectors 5 & 6 Particles from Deep Space TEP TEP • Each ion species leaves its owncharacteristic plot.

27. Keeping Track of CRaTERhttp://crater.bu.edu/monitor/ Time of Upload - no data is available when the spacecraft is out of communication Instrument Power Usage - CRaTER runs on the same power as 6 mini-Christmas lights Counts for Each Detector - 3 pairs of detectors separated by Tissue Equivalent Plastic (TEP) Total Counts - some detector counts are deemed noise by the instrument electronics. Instrument Temperature - instrument is warmed by the Sun but cools off in the Moon’s shadow; using electric current warms circuitry Dosimeter Reading - reading of medical dosimeter on board the instrument