April 09, 2013
A space-based infrared telescope designed to find Earth-threatening asteroids and objects like the one that exploded over the Russian Urals in February is about to enter system definition at Ball Aerospace.
The Sentinel spacecraft, led by the non-profit B612 Foundation, is designed to catalog 90% of the asteroids larger than 140 meters in Earth’s region of the Solar System. The craft will be placed in a Venus-following orbit, allowing it to view the night half of the sky every 20 days, and picking up objects that are currently often difficult, if not impossible, to see in advance from Earth.
During their passage through the Solar System, asteroids are detectable for up to five months. “We need to be able to see it when it’s close enough to be seen,” says Ball Aerospace Sentinel program manager John Troeltzsch. The spacecraft is designed to “systematically look at them when they are warm enough to detect,” he adds. During this period near Earth objects will rotate and re-radiate energy from the Sun that the Sentinel’s IR sensors will detect.
The systems definition phase will lead to a formal systems requirement assessment in the fall of this year, Troeltzsch says. This will clear the way for the start of the implementation phase leading to a preliminary design review in 2014, and a critical design review in 2015. Launch on a SpaceX Falcon 9 is planned for 2018, leading to the start of a 6.5-year long mission of data collection. Information on tracked objects will be transmitted to the Boulder, Colo.-headquartered Laboratory for Atmospheric and Space Physics, and then distributed for broader use via NASA’s Minor Planets Center in Cambridge, Mass.
Sentinel will “look like Kepler with a different telescope,” Troeltzsch says. Ball, which was NASA’s partner on both the Kepler and Spitzer Space Telescope missions, is working with Raytheon Vision Systems on the IR detector system. Ball also provided the large-format camera for Kepler and a cryogenically cooled instrument for Spitzer. Sentinel will scan in the 7- to 15-micron wavelength using a 0.5-meter IR telescope across a 5.5 by 2-deg. field of view. The IR array will consist of 16 detectors, and coverage will scan a 200-deg., full-angle field of regard.
Program architect Scott Hubbard says the B612 Foundation’s goal is to raise between $30 million and $40 million per year for the privately funded program. The overall fund raising target is $450 million to cover the final development and launch costs. “It’s a new way of venture philanthropy,” says Hubbard, who adds “without knowing where they [asteroids] are, we are essentially flying blind in a cosmic shooting gallery. NASA’s done a great job about detecting the big ones, but less than 1% of the 120-foot and above sized ones have been discovered.” Troeltzsch adds that the system also will detect “maybe 50%” of the even smaller, but still dangerous objects in the 40 to 140-meter size range.