Speaker
Description
The Chelyabinsk meteor entered Earth’s atmosphere on 15 February 2013, producing a shock wave that injured about 1,500 people and damaged thousands of buildings. Despite its relatively large size (~20 m), the progenitor asteroid approached Earth undetected. Its radiant was too close to the Sun for standard near-Earth asteroid (NEA) search programmes. In addition, it was very faint due to the high phase angle illumination geometry, and very fast moving.
We examine the potential for early detection of similar objects using current and upcoming infrared (IR) space initiatives, such as ESA’s planned NEOMIR mission. IR observations from space offer key advantages: (i) enhanced Sun-asteroid contrast (compared to visible wavelengths), (ii) small, fast-rotating object are (nearly) isothermal which make IR detections at high phase angles easier, (iii) immediate good-quality size estimation upon IR detection, and (iv) feasibility of observations near the Sun.
Our study evaluates the possibilities and limitations of detecting a Chelyabinsk-type object on a similar orbit, addressing challenges such as high zodiacal light background and fast apparent motion, requiring synthetic tracking techniques. Key questions include: optimal IR wavelengths for detection, best telescope placement in space, strategies for high-motion targets, and practical considerations when observing near the Sun.
We estimate that a 20-m object could be detected with a 0.5 m telescope in space, at mid-IR wavelengths, with a lead time of 5–10 days. The large uncertainty in the calculation of the detection lead-time is mainly related to uncertainties in the flux predictions for small, possibly fast-rotating asteroids seen under very extreme phase angles. However, technical challenges, including detector operations at high sky background, telescope straylight problems for observations close to the Sun, and fast orbit determination also must be overcome to achieve reliable early warning capabilities