UNC astronomers track roadster-driving ‘Starman’

College of Arts & Sciences

Last week’s launch of a sports car into space — it was a publicity stunt for a commercial rocket liftoff—has captivated sky watchers the world over, but perhaps none more than those who study the stars as their profession.
Having some fun after a productive observing night, astronomers from the University of North Carolina at Chapel Hill stationed in Chile tracked the Tesla roadster and its spacesuit-wearing mannequin using the SOAR telescope.
They made a time-lapse movie of the object (see below), known officially by its interplanetary ID as Starman 2018-017A, as it tumbled through space at nearly 8,000 mph. They recorded it in the early morning hours of Feb. 10, compressing 52 minutes of footage into a 24-second video. At the time of filming, it was already more than 660,000 miles from Earth, bound for an elliptical orbit around the sun, swinging by Mars on the way. Now that it is a week into its journey, only the largest telescopes on Earth are capable of detecting it.
By measuring periodic changes in the brightness of the car, the astronomers can report that the car  is likely rotating on its axis about 12.6 times per hour. (This observation is still being debated by experts on Twitter; it could be that the car is rotating at half that speed, based on the long side of the car and rocket stage being seen twice every time it spins.)
This graph shows changes in the car’s brightness as it rotates.“To make the light curve and measure the rotation period, we used the same techniques we use every day in our research of variable stars, but we’ve definitely never used them on a car,” said Erik Dennihy, a UNC graduate student who collected the data.
The images were collected using the imaging mode of the Goodman spectrograph, which was built at UNC and is …

Read More