(192642) 1999 RD₃₂, provisional designation: 1999 RD₃₂, is an asteroid and suspected contact binary on an eccentric orbit, classified as a large near-Earth object and potentially hazardous asteroid of the Apollo group, approximately 5 kilometers (3 miles) in diameter. It was discovered on 8 September 1999, at a magnitude of 18, by astronomers of the LINEAR program using its 1-meter telescope at the Lincoln Laboratory's Experimental Test Site near Socorro, New Mexico, United States.^[3][2] The asteroid is likely of carbonaceous composition and has a rotation period of 17.08 hours.^{[4][lower-alpha 1]}

1999 RD₃₂ orbits the Sun at a distance of 0.6–4.7 AU once every 4 years and 4 months (1,571 days; semi-major axis of 2.64 AU). Its orbit has a high eccentricity of 0.77 and an inclination of 7° with respect to the ecliptic.^[1]

The asteroid's observation arc begins with a precovery taken at Palomar Observatory in January 1995.^[3] It is known that 1999 RD₃₂ passed 0.0093 AU (1,390,000 km; 860,000 mi) from Earth on 27 August 1969.^[10] During the 1969 close approach the asteroid reached about apparent magnitude 8.8.^[11] The similarly-sized 4179 Toutatis also reached that brightness in September 2004. It passed less than 0.007 AU (1,000,000 km; 650,000 mi) from asteroid 29 Amphitrite on 17 January 1939.^[1]

Arecibo radar observations on 5–6 March 2012 showed that 1999 RD₃₂ is approximately 5 kilometers (3 mi) in diameter^[5] and has an estimated albedo of only 0.04.^[5] Other sources calculate a smaller diameter of 1.63 kilometers based on a dated assumption, that the object is a stony rather than a carbonaceous asteroid.^[4] The two visible lobes suggest that 1999 RD₃₂ is a tight binary asteroid or contact binary.^[5] About 10–15% of near-Earth asteroids larger than 200 meters are expected to be contact binary asteroids with two lobes in mutual contact.^[12]

This minor planet was numbered by the Minor Planet Center on 13 November 2008.^[13] As of 2018, it has not been named.^[3]