[meteorite-list] Versatile Instrument to Scout for Near-Earth Asteroids, Kuiper Belt Objects

[Ron Baalke]

http://www.jpl.nasa.gov/news/news.php?feature=5702

Versatile Instrument to Scout for Kuiper Belt Objects
Jet Propulsion Laboratory
March 3, 2016

At the Palomar Observatory near San Diego, astronomers are busy tinkering 
with a high-tech instrument that could discover a variety of objects both 
far from Earth and closer to home.

The Caltech HIgh-speed Multi-color camERA (CHIMERA) system is looking 
for objects in the Kuiper Belt, the band of icy bodies beyond the orbit 
of Neptune that includes Pluto. It can also detect near-Earth asteroids 
and exotic forms of stars. Scientists at NASA's Jet Propulsion Laboratory 
and the California Institute of Technology, both in Pasadena, are collaborating 
on this instrument.

"The Kuiper Belt is a pristine remnant of the formation of our solar system," 
said Gregg Hallinan, CHIMERA principal investigator at Caltech. "By studying 
it, we can learn a large amount about how our solar system formed and 
how it's continuing to evolve."

The wide-field telescope camera system allows scientists to monitor thousands 
of stars simultaneously to see if a Kuiper Belt object passes in front 
of any of them. Such an object would diminish a star's light for only 
one-tenth of a second while traveling by, meaning a camera has to be fast 
in order to capture it.

"Each of CHIMERA's cameras will be taking 40 frames per second, allowing 
us to measure the distinct diffraction pattern in the wavelengths of light 
to which they are sensitive," said Leon Harding, CHIMERA instrument scientist 
at JPL. "This high-speed imaging technique will enable us to find new 
Kuiper Belt objects far less massive in size than any other ground-based 
survey to date."

Hallinan's CHIMERA team at Caltech and JPL published a paper led by Harding 
describing the instrument this week in the Monthly Notices of the Royal 
Astronomical Society.

Astronomers are particularly interested in finding Kuiper Belt objects 
smaller than 0.6 miles (1 kilometer) in diameter. Since so few such objects 
have ever been found, scientists want to figure out how common they are, 
what they are made of and how they collide with other objects. The CHIMERA 
astronomers estimate that in the first 100 hours of CHIMERA data, they 
could find dozens of these small, distant objects.

Another scientific focus for CHIMERA is near-Earth asteroids, which the 
instrument can detect even if they are only about 30 feet (10 meters) 
across. Mike Shao of JPL, who leads the CHIMERA group's near-Earth asteroid 
research effort, predicts that by using CHIMERA on the Hale telescope 
at Palomar, they could find several near-Earth objects per night of telescope 
observation.

Transient or pulsing objects such as binary star systems, pulsing white 
dwarfs and brown dwarfs can also be seen with CHIMERA.

"What makes CHIMERA unique is that it does high-speed, wide-field, multicolor 
imaging from the ground, and can be used for a wide variety of scientific 
purposes," Hallinan said. "It's the most sensitive instrument of its kind."

CHIMERA uses detectors called electron multiplying charged-coupled devices 
(EMCCDs), making for an extremely high-sensitivity, low-noise camera system. 
One of the EMCCDs picks up near-infrared light, while the other picks 
up green and blue wavelengths, and the combination allows for a robust 
system of scanning perturbations in starlight. The detectors are capable 
of running at minus 148 degrees Fahrenheit (minus 100 degrees Celsius) 
in order to avoid noise when imaging fast objects.

"Not only can we image over a wide field, but in other modes we can also 
image objects rotating hundreds of times per second," Harding said.

One of the objects the CHIMERA team used in testing the instrument's imaging 
and timing abilities was the Crab Pulsar. This pulsar is the end result 
of a star whose mass collapsed at the end of its life. It weighs as much 
as our sun, but spins 32 times per second. The instrument focused on the 
pulsar for a 300-second exposure to produce a color image.

"Our camera can image the entire field of view at 40 frames per second," 
Hallinan said. "We zoomed in on the pulsar and imaged it very fast, then 
imaged the rest of the scene slowly to create an aesthetically-pleasing 
image."

Highlighting CHIMERA's versatility, the instrument also imaged the globular 
cluster M22, located in the constellation Sagittarius toward the busy 
center of our galaxy. A single 25-millisecond image captured more than 
1,000 stars. The team will be observing M22, and other fields like it, 
for 50 nights over three years, to look for signatures of Kuiper Belt 
objects.

Caltech manages JPL for NASA.


Media Contact

Elizabeth Landau
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-6425
Elizabeth.Landau at jpl.nasa.gov 

2016-059