Optical observations of Didymos between DART and Hera with the NTT
- 1Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh, EH9 3HJ, UK
- 2Astronomical Institute of the Czech Academy of Sciences, Fričova 298, CZ-25165 Ondřejov, Czech Republic
- 3Physics Department, United States Naval Academy, 572C Holloway Road, Annapolis, MD 21402, USA
- 4Department of Astronomy and Planetary Science, Northern Arizona University, Flagstaff, AZ, USA
- 5Las Cumbres Observatory, Goleta, CA, USA
The binary asteroid system Didymos-Dimorphos is an important planetary defence mission target. In September 2022 the NASA DART mission successfully changed the orbit of Dimorphos around Didymos through kinetic impact. In late 2026 the ESA Hera mission will arrive to study the aftermath of the impact in situ. One of the base requirements of the DART mission was that the orbital period change be measured from ground-based observations. This goal was achieved in the first weeks post-impact (Thomas et al. 2023). However, extended studies have put into question the stability of the new orbit (Scheirich et al. 2024, Naidu et al. 2024, Pravec et al. 2024).
We will conduct observations of the Didymos-Dimorphos system in August 2024 with the European Southern Observatory’s 3.6m New Technology Telescope (NTT) in Chile. The goal of these observations is to monitor the orbit of the asteroid pair in the 'short-term', ahead of Hera’s arrival. The observations will be used to reveal whether the orbit is now stable and constrain the rate of change if it is still evolving. This will give us insights into ongoing processes in the system: the ejecta clearing timeline, possible reshaping of Dimorphos through the impact and subsequent landslides, and inform models of energy dissipation in the Didymos-Dimorphos system. We will also investigate whether there is any evidence of on-going mass loss from the system in the form of a tail, as was visible in the months immediately after the DART collision. The outputs of the observing campaign will provide critical input to Hera mission planning.
The main challenge of this campaign is the location of the asteroid system during the planned observations. The Didymos-Dimorphos pair will be crossing the Galactic plane. This means we expect extremely crowded star fields for observations of a quick-moving target. The unusual observing circumstances demand deployment of new difference image analysis (DIA) techniques, based on methods developed by e.g. Bramich et al. (2013), Hitchcock et al. (2021). The DIA methods need to be tailored to observations of fast moving targets with medium-sized telescopes, to allow construction of high-quality image templates within the limits of the awarded telescope time.
References:
- Thomas et al. 2023, Nature, 616, 448
- Bramich et al. 2013, MNRAS, 428, 2275
- Hitchcock et al. 2021, MNRAS, 504, 3561
- Scheirich et al. 2024, PSJ, 5, 17
- Naidu et al. 2024, PSJ, 5, 74
- Pravec et al. 2024 (Icarus, in review)
How to cite: Rozek, A., Snodgrass, C., Pravec, P., Knight, M., Thomas, C., Lister, T., Cannon, R. E., and Murphy, B.: Optical observations of Didymos between DART and Hera with the NTT, Europlanet Science Congress 2024, Berlin, Germany, 8–13 Sep 2024, EPSC2024-819, https://doi.org/10.5194/epsc2024-819, 2024.
