ADASSX

Space missions provide an opportunity to rapidly increase knowledge in a field by acquiring data that responds to a specific mission goal. Understanding the intersection of space-based and ground-based observation is critical to maximizing the scientific return of any mission. For example, the impact of the Gaia spacecraft extends to every corner of astronomy. This mission had a simple goal: produce a high-precision astrometric and photometric catalog of the sky, and its measurements have fed into many follow up observational studies. For asteroids, the ten-fold astrometric precision improvement enabled by Gaia’s data has profoundly affected the quality of asteroid orbits, in addition to yielding advantages in all other astronomy fields.

The NEO Surveyor 0.5m telescope at Sun-Earth L1 will observe simultaneously in two bands, NC1 (4-5.2µm) and NC2 (6-10µm). These two infrared observations will provide an astrometric position that is improved by the simultaneous two-band measurement of the asteroid and stars, and the object's diameter through modeling of the thermal flux. The mission design will take advantage of the fact that the near-Earth object population has an average albedo of much less than 50%, which means most of the Sun’s energy is absorbed, making these asteroids thermally bright.

NEO Surveyor is designed to discover and measure diameters of the near-Earth asteroid and comet population. It will not collect other physical characterization observations such as spectral type or geometric albedo, and is not optimized to obtain rotation rates for all objects detected. Therefore, this provides an opportunity for ground-based telescopes to expand the mission's scientific return by carrying out ground-based population studies.

We will present three possible ground-based studies that can be undertaken. First, since NEO Surveyor will detect asteroids via their thermal emission, the actual albedo of the asteroid will remain unknown without optical observations. As described in Masiero et al. (2024), the best estimate NEO Surveyor will be able to provide of a possible V-band magnitude is plus or minus two magnitudes. Therefore, the first opportunity for ground-based observers is to carry out a large ground-based campaign to collect optical observations of NEO Surveyor’s discoveries. Without an optical tracklet, additional characterization observations will be unlikely to succeed due to the large magnitude uncertainty.
The second possible ground-based observation campaign will be a geometric albedo study. Combining geometric albedos with NEO Surveyor diameters would uncover the real NEO albedo distribution. The third useful campaign will be a spectral type versus diameter study to determine the spectral type distribution of the NEO population as a function of size.