Tim McLaughlin, Pine Park Engineering Corp; Roger L Mansfield, MITRE
Keywords: astrodynamics, instrumentation, sensors, modeling, small aperture, high etendue, wide field of view optical systems, cislunar space situational awareness, space domain awareness
Abstract:
Abstract. Using a Schmidt astrograph of 8″ (0.2m) aperture and f/2 focal ratio, the space object designated as 2020 SO was acquired and tracked just prior to its perigee of 2021 February 2. Acquisition occurred at approximately 283,800 km range (44.5 Earth radii) on February 1. This paper documents the detection, acquisition, tracking, metric and photometric data collection, and data reduction for seemingly-asteroidal object 2020 SO’s latest entry into cislunar space.
Motivation of Our Research. The International Astronomical Unions Minor Planet Center (MPC) reported, in electronic circular MPEC 2020-S78 dated 2020 September 19, that the Mt. Haleakala observatories Pan-STARRS2 and Pan-STARRS1, and the Catalina Sky Surveys Kuiper Observatory, had all tracked an apparently asteroidal object, now designated as 2020 SO.
Due to its low velocity relative to Earth, 2020 SO was thought maybe to be an artificial object. When it became possible to further investigate the orbit and ephemeris (e.g., via the JPL Horizons website), it was evident that the object had entered Earth’s cislunar regime on 2020 December 1 and would do so again on 2021 February 2 (see the Wikipedia entry for 2020 SO).
So, following its close passage on 2020 December 1, interest in object 2020 SO grew because a) its origin was uncertain, b) it had entered cislunar space quite close to Earth on that date, and c) it would enter cislunar space again two months later, close to Earth but not so close as before.
It had been determined, via reconstruction of the past trajectory, that 2020 SO is likely the Centaur rocket booster from the Surveyor 2 launch in 1966. Spectroscopic observations by NASA’s Infrared Telescope Facility in December 2020 indicated that 2020 SO’s spectrum is similar to that of stainless steel. The spectral evidence, together with trajectory reconstruction efforts, have led to a consensus that object 2020 SO likely originated from Earth in 1966.
That which enters cislunar space is of interest to the space community from the perspectives of both of SSA and SDA. How big, how expensive must an observatory be, to be useful for the surveillance of cislunar space?
To show that small, optically-fast but relatively-inexpensive telescopes can be advantageous for this purpose, we decided to attempt to track 2020 SO before (yet quite close to) its 2021 February 2 perigee. Our AMOS 2021 paper is about our success here.
Our Principal Finding. Small-aperture telescopes with optically-fast lens assemblies of high etendue can gainfully track faint cislunar objects, e.g., asteroids and man-made objects entering cislunar space, to include space probes just launched or flying by and satellites in multi-day orbits with distant apogees.
Date of Conference: September 14-17, 2021
Track: Non-Resolved Object Characterization