Determining Near Earth Asteroids’ Properties from the California Desert
I recently asked our past winners of Planetary Society Shoemaker Near Earth Object (NEO) Grants for updates on what they have been up to. I'll be sharing several of their updates over a series of blog entries over the next few weeks. It is always gratifying and impressive to see what they are accomplishing, in part as a result of the grants provided by The Planetary Society and its members.
First a reminder that our Shoemaker NEO Grant Coordinator, Tim Spahr, was the guest on Planetary Radio about a month ago. Tim is the Director of the Minor Planet Center where all observational data about NEOs get submitted, as well as requests for more observations. On the show, he talks about what the Minor Planet Center does, and also about the importance of the Shoemaker NEO Grants, as well as some of the recent winners.
Back to our Shoemaker NEO Grant winner updates: we'll start with an update from Bob Stephens, a 2013 Shoemaker NEO Grant winner at the Center for Solar System Studies (CS3) in Landers, California. Bob focuses on characterizing the physical properties of asteroids using lightcurves, i.e., carefully measuring the brightness of the asteroid and how it varies with time, which can provide a wealth of useful information as he mentions below. Characterizing asteroids is crucial to not only the science of asteroids, but also for understanding near Earth asteroids better for purposes of determining how to perform deflection of dangerous asteroids.
The Shoemaker NEO Grant enabled purchase of a new Finger Lakes CCD camera for a 0.4 meter telescope (discussed below). The new camera enables precise measurements as well as greatly extending the nights of use of the telescope. Previously this telescope had to share a camera with another facility.
Finger Lakes Instruments Proline CCD Camera
A 2013 Planetary Society Shoemaker NEO Grant allowed the purchase of a Finger Lakes Instruments Proline CCD camera (black box “underneath” the white telescope) mounted on a 0.4-meter telescope at the Center for Solar Systems Studies. It takes images of asteroids every clear night.
Here is what Bob had to say:
Since the installation of a Finger Lakes Instruments Proline CCD camera on a 0.4-meter (16-inch) telescope at the Center for Solar System Studies (CS3) in late May, the telescope and camera have been remotely operated 51 nights. It was observing asteroids 78% of the available nights. CS3 specializes in obtaining lightcurves of asteroids in order to determine their physical properties such as rotational periods, pole orientations, shapes, and if they have satellites. Over this time period, eleven asteroids were observed with rotational periods ranging from 2.7 to 708 hours.
The most notable asteroid observed was the Potentially Hazardous Near Earth Object - 163249 2002 GT, whose closest approach was in late June. I participated in an international collaboration headed by Steve Chesley of JPL to study the asteroid which is a proposed target for the Deep Impact spacecraft in January 2020. In May and June, the asteroid was studied by radar at Arecibo, spectra were obtained from the IRTF telescope on Mauna Kea and the 200-inch at Palomar, and numerous lightcurves and color measurements were obtained from several telescopes around the world. Initial results will be announced at the Division for Planetary Sciences meeting in October.
Lightcurve of the Near Earth Asteroid 2002 GT
A lightcurve of the Near Earth Asteroid 2002 GT was obtained by Bob Stephens during a close approach to the Earth in June 2013 using a CCD camera provided by a Shoemaker NEO Grant.