In my previous post, I talked about how not all astronomers use photons. Well, neither do all astronomers look up from Earth or Earth orbit. A new telescope aims to look down at the Earth — precisely so that it can see the sky.
JEM–EUSO proposes fixing a downward looking camera on the space station. It would stare at Earth — primarily the oceans — and watch for ultra high energy cosmic rays (charged particles, typically protons) as they hit. It would work very much like the Pierre Auger Observatory in Argentina, which detects fluorescent showers of secondary particles caused by the cosmic rays colliding with atmospheric particles, followed by a final flash as the particles hit detectors on the Earth. Auger astronomers have detected the most energetic things in the universe, and asserted with bare bones statistics that they probably emanate from the supermassive black holes at the centers of galaxies. But some want better proof than that given by a few dozen high energy cosmic rays, and, for that, they need more hits.
Looking down from the space station, JEM–EUSO could monitor an area between 50 to 250 times as large as Pierre Auger. The 5-year mission goal would be to detect at least 1,000 particles with greater than 7×10e19 eV energies. Particles like that would be probes of energy regimes 10 million times bigger than those explored by the LHC. Maybe JEM–EUSO could even detect a few particles with 10e21 eV energies. Because then we could use my favorite prefix in the world, and talk about the Zev scale: Zettaelectronvolt particle physics. Yoshiyuki Takahashi, of University of Alabama Huntsville, and Mark Christl, of Marshall Space Flight Center gave a talk on JEM–EUSO on Saturday. They say it would take 20 years for Pierre Auger and its successor, Pierre Auger North (proposed for nearby southeastern Colorado), to do what JEM–EUSO could do.
The total cost? $220 million — and that includes the rocket ride that it needs. ESA and NASA were once enthusiastic. But then, with the space shuttle retirement, NASA couldn’t find a ride for EUSO. ESA also liked it but its transport vehicle, the ATV, can’t deal quite handle it. Thankfully, JAXA, the Japanese space agency, seems to like the idea. And it may have a rocket, the new H-IIB, to fly it up — if test flights later this year prove successful.
Takahashi says JAXA will make a final decision on JEM–EUSO in September, and it could launch sometime in 2013. It would be nice to get a real astrophysical experiment on the space station. Nobel prize winner Sam Ting seems to have found a way to get his $1.5 billion AMS up to the station on the shuttle’s last flight. Why can’t these guys fly a novel experiment that costs a fraction as much?
Image: JEM–EUSO