@article{27e252e5a1d64248acc4a4e60072a4a7,
title = "Near-earth asteroid (66391) Moshup (1999 KW4) observing campaign: Results from a global planetary defense characterization exercise",
abstract = "Hazards due to near-Earth objects (NEOs) continue to pose a threat to life on Earth. While our capability for discovering NEOs has steadily progressed over the last three decades, physical characterization of a representative population has lagged behind. To test the operational readiness of the global planetary defense capabilities, we conducted a community-led global planetary defense exercise, with support from the NASA's Planetary Defense Coordination Office (PDCO) and the International Asteroid Warning Network (IAWN), to test the operational readiness of global planetary defense capabilities. This campaign focused on the characterization (direct imaging, radar, spectroscopy) of the binary near-Earth asteroid (NEA) (66391) Moshup (formerly known as 1999 KW4) and its moon Squannit. We chose a binary system because roughly one in six large NEAs are binaries. An additional goal was to apply lessons learned from this campaign towards ground-based characterization campaign for binary NEA (65803) Didymos, the target of the PDCO's Double Asteroid Redirection Test (DART) and the European Space Agency's Hera missions. Spectral observations of Moshup from the NASA Infrared Telescope Facility (IRTF) show similarities to Q-type asteroids. Based on its spectral band parameters, the best meteorite analogs for Moshup are L chondrites. We did not detect a hydration feature at 3 μm, which suggests that the entire surface is anhydrous. We imaged the binary using the SPHERE instrument on the Very Large Telescope (VLT) and obtained resolved spectral measurements of Moshup similar to those obtained with the NASA IRTF. Squannit appears to have slightly redder spectral slope than Moshup. Radar observations Arecibo Observatory at 2380 MHz indicate a polarization ratio of ~0.4, which is higher than the average values for the S complex asteroids, which includes Q types. The visible extent of the components from the radar observations, taken as proxies for their radii, suggest Moshup and Squannit have diameters of 1500 ± 120 m and 480 ± 60 m, respectively. We constrain the system mass to 2.2 ± 0.5 × 1012 kg with a maximum range for bulk density between ~0.8 g/cm3 for a very low-mass system with spherical shapes up to 2.7 g/cm3 for very high-mass system where Moshup has a more ridged-ball shape. We note that the radar-derived parameters presented in the paper are for the purposes of this exercise and do not supersede those in Ostro et al. (2006). We assessed the impact risk of a hypothetical impactor based on Moshup's physical properties using the Probabilistic Asteroid Impact Risk (PAIR) model. We assessed three impact risk scenarios at different epochs as the state of knowledge of Moshup improved. For kilometer-scale impactors like Moshup, the risk is driven predominantly by the potential for global climatic effects (95–97% of cases across the epochs) with a few percent driven by local damage and a few tenths of a percent driven by tsunami.",
keywords = "Asteroids, Characterization, Meteorites, Radar, Spectroscopy",
author = "Vishnu Reddy and Kelley, {Michael S.} and Jessie Dotson and Landis, {Rob R.} and McGraw, {Lauren E.} and Marco Micheli and Moskovitz, {Nicholas A.} and Sanchez, {Juan A.} and Taylor, {Patrick A.} and Lorien Wheeler and Bauer, {James M.} and Brucker, {Melissa J.} and Maxime Devog{\`e}le and Emery, {Joshua P.} and Olivier Hainaut and Hickson, {Dylan C.} and Detlef Koschny and Larsen, {Jeffrey A.} and Marshall, {Sean E.} and Robert McMillan and Skiff, {Brian A.} and Venditti, {Flaviane C.F.} and Virkki, {Anne K.} and Bin Yang and Zambrano-Marin, {Luisa F.}",
note = "Funding Information: Building upon the lessons learned during the TC4 campaign, we conducted a dedicated characterization campaign in May 2019 with near-Earth asteroid (66391) Moshup as the target. Originally designated as 1999 KW4, the asteroid is a known binary (Pravec et al., 2006; Ostro et al., 2006), with the primary named Moshup, and its moon named Squannit (Minor Planet Circular 115,894). Moshup is a PHA that made a close pass by Earth in May 2019. Perigee was 0.035 au (5,300,000 km or about 14 lunar distances) on May 26. During its February 2019 meeting at the Vienna United Nations Office, IAWN announced its support for the Moshup observational campaign. We chose a binary NEA because they make up roughly one sixth of NEAs with diameters >200 m (Pravec et al., 2006), and because we wanted to apply any lessons learned here to the ground-based characterization of binary NEA (65803) Didymos, the target of the PDCO's Double Asteroid Redirection Test (DART) and European Space Agency's (ESA) Hera missions (See Rivkin et al., 2021; Michel et al., 2020; Zhang et al., 2021). As with Didymos, the heliocentric orbit of Moshup is already characterized extremely well, so the goal of the coordinated effort was to obtain the best possible physical characterization of the object in a short amount of time (i.e., days), using both ground-based and space-based assets. When an asteroid becomes relevant as a possible threat to our planet, knowing its actual size, shape, mineralogical and structural make-up, and possible binary nature becomes essential for any attempt to mitigate the consequences of a possible impact (Miles et al., 2018). Here, we present an overview of the campaign and summarize the operational results from the exercise. Our goal is not to publish the best science on Moshup based on the campaign data but to share information about our efforts to derive operationally relevant data products in a timely manner. Campaign participation was voluntary with 25 participants divided into working groups depending on the observational technique (spectroscopy, direct imaging, radar) or task at hand (hypothetical risk assessment). Photometric observations obtained as part of this campaign are presented in Scheirich et al. (2021) as the data from most of the photometric observers (except for Spacewatch) was not of sufficient quality (high photometric uncertainties) and quantity (observing runs <2 h). This is because short, isolated photometry runs for a binary asteroid cannot be decomposed into the primary and secondary lightcurves, independent of their data quality. The working groups provided derived target parameters (size, albedo, composition) which were inputs to our hypothetical risk assessment. We ran the model on different epochs depending on the inputs we received from the working groups.We thank Elizabeth Warner and Tony Farnham at the PDS Small Bodies Node for their support to maintain the campaign website. Parts of this research work was supported by NASA Near-Earth Object Observations Grant NNX17AJ19G (PI: Reddy). We thank the IRTF TAC for awarding time to this project, and to the IRTF TOs and MKSS staff for their support. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. Resolved imaging data presented in this paper were collected by Matias Jones at the European Southern Observatory under ESO program 103.200G. The Arecibo planetary radar is fully supported by NASA's Near-Earth Object Observations (NEOO) program through grant no. 80NSSC19K0523 (PI: Anne K. Virkki) awarded to the University of Central Florida (UCF). The Arecibo Observatory is a facility of National Science Foundation operated under cooperative agreement by UCF, Yang Enterprises, Inc. and Universidad Ana G. M{\'e}ndez. Part of this work was supported by NASA NEOO grant no. NNX13AQ46G awarded to Universities Space Research Association (PI: Patrick A. Taylor). Funding Information: We thank Elizabeth Warner and Tony Farnham at the PDS Small Bodies Node for their support to maintain the campaign website. Parts of this research work was supported by NASA Near-Earth Object Observations Grant NNX17AJ19G (PI: Reddy). We thank the IRTF TAC for awarding time to this project, and to the IRTF TOs and MKSS staff for their support. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. Resolved imaging data presented in this paper were collected by Matias Jones at the European Southern Observatory under ESO program 103.200G. The Arecibo planetary radar is fully supported by NASA's Near-Earth Object Observations (NEOO) program through grant no. 80NSSC19K0523 (PI: Anne K. Virkki) awarded to the University of Central Florida (UCF). The Arecibo Observatory is a facility of National Science Foundation operated under cooperative agreement by UCF, Yang Enterprises, Inc., and Universidad Ana G. M{\'e}ndez. Part of this work was supported by NASA NEOO grant no. NNX13AQ46G awarded to Universities Space Research Association (PI: Patrick A. Taylor). Publisher Copyright: {\textcopyright} 2021",
year = "2022",
month = mar,
day = "1",
doi = "10.1016/j.icarus.2021.114790",
language = "English (US)",
volume = "374",
journal = "Icarus",
issn = "0019-1035",
publisher = "Academic Press Inc.",
}