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ATLAS Has First Light

by Louise Good

atlas dome on Mauna Loa

ATLAS software engineers Andrei Sherstyuk (foreground) and Larry Denneau Jr. inside the dome on Mauna Loa with the prototype Pathfinder telescope equipped with a Canon digital camera. This December 2013 photo shows Sherstyuk aligning the telescope mount with Earth’s rotation so that the telescope would accurately track the motion of the stars while Denneau concentrated his efforts on the dome control software. Photo by John Tonry.

ATLAS (Asteroid Terrestrial-impact Last Alert System) is now automatically scanning the sky with a prototype camera and telescope located on Mauna Loa on Hawai‘i island. It achieved first light on December 12 with a seven-inch Pathfinder telescope mounted in an existing dome. By 2016, ATLAS should have two observatories, one at the current location on Mauna Loa and the second possibly on Haleakalā. The two telescopes will search the entire sky that is visible from Hawai‘i. The goal of the project is to provide an early warning of asteroids that will hit Earth within days.

The camera used to achieve first light was an off-the-shelf Canon digital camera, but by the time you read this, it will have been replaced by a small scientific camera that will double the amount of sky and triple the sensitivity. Even with the first camera and the small telescope, ATLAS was able to observe hundreds of main-belt asteroids. These were not new finds, but the quality of the observations was good enough to be reported to the Minor Planet Center (MPC), the worldwide center for receipt and distribution of positional measurements of asteroids, comets, and small moons of the major planets.  

John Tonry, the head of the ATLAS project, is more than pleased with the progress so far. He says, “We must be at full productivity in two years, so the current situation puts us way ahead of schedule.” He gives a lot of the credit for the progress made so far to the project’s software engineers, Larry Denneau Jr. and Andrei Sherstyuk. Denneau predicts that even before the final telescope and camera are installed next year, ATLAS will find a hitherto unknown near-Earth asteroid.

DFM Engineering, the company building the ATLAS  telescopes, is making rapid progress. These wide-field telescopes will have a mirror to collect light and lenses to make exceedingly fine images over a 7.5-degree field of view. The mirrors have been ground, the lenses are being fabricated, and the mechanical parts are designed and about to be machined. The heart of the system is the CCD cameras, which will have 110-megapixel detectors housed in a cryostat (device for maintaining a very cold temperature, like a thermos) the size of a coffee can. The detectors and CCD controllers are being purchased, and the IfA is busily designing and building the cryostats. The telescope mounts are being built, and the domes are being acquired.

The job that ATLAS performs for NASA requires as much vigilance as possible, so ATLAS needs to run robotically, operating any time the sky is dark and clear enough. To that end, the team is installing a variety of equipment to determine whether conditions are safe for opening the domes, and they are in the process of writing the software that judges whether observations can take place and then carries them out. This equipment includes an all-sky infrared sensor that can detect clouds or rain, the usual temperature, humidity, and wind sensing equipment, and a fisheye camera that can image all the stars in the sky at once and determine the presence of clouds by whether known stars are not seen or are not as bright as they should be. The system will be smart enough to figure out that, for example, if the eastern part of the sky is cloudy, it should observe in the western part if that part is clear. Also, a plan is in the works to dramatically increase the bandwidth from Mauna Loa so that the observations can be downloaded almost immediately, thereby lowering the time between observing the sky and reporting detections of asteroids to a few minutes.

Compared with Pan-STARRS, which is trying to find dangerous asteroids years before they hit our planet, ATLAS is relatively simple, but still complicated. There is the software that controls the robotic telescope; image acquisition software to make the observations; reduction software to make the image into something scientifically useful; PHOTPIPE, software used by several observatories that compares the image with old images to see if the object has been observed before; and the Moving Object Pipeline Subsystem (MOPS), originally developed for Pan-STARRS, that actually detects the asteroids and sends notification to the MPC. It all has to work together.