The International Asteroid Warning Network (IAWN) led a cross-organizational analysis operation of the double asteroid 1999 KW4 as it made a close flyby near the Earth, spanning to a minimum radius of about 5.2 million kilometers on May 25th, 2019. The incredible abilities of the ESO’s Very Large Telescope, equipped with SPHERE, one of the few tools on Earth capable of capturing images sufficiently accurate to distinguish between two parts of an asteroid, have led to a discovery of double asteroid components. The two pieces are separated by approximately 2.6 kilometers.
The asteroid has a diameter of approximately 1.3 kilometers and does not pose any risk to the Earth. Because its trajectory is already known, researchers could foresee this fly-by and organize an observing operation. ESO brought its renown instrument, the Very Large Telescope (VLT) to the process, which has SPHERE aboard, which was constructed to identify exoplanets. Its incredible adaptive optics system can capture and deliver images as accurate and detailed as the telescope were in space. The observatory also has coronographs to eclipse the light coming from bright stars so it can observe and unveil dimmer orbiting exoplanets.
This time, the SPHERE instrument helped scientists describe the double asteroid, more specifically to measure whether the smaller meteor has an identical content as the more significant object. Diego Parraguez, who was managing the telescope said that the double asteroid was passing by the Earth at over 70,000 km/h, making the observations with the VLT a bit challenging, so he had to use the tool on it, SPHERE, to capture and observe the meteor.
Scientists used ESO’s SPHERE instrument to observe the double asteroid 1999 KW4
Even though 1999 KW4 is not posing a threat to Earth, it is incredibly similar to another binary asteroid system known as Didymos which could actually threaten our planet sometime in the faraway future. Didymos and its pair dubbed Didymoon are the focus of a future establishment of planetary defense experiments.NASA’s DART probe will collide with Didymoon in an effort to deflect its orbit around its bigger twin, in a test of the possibility of deviating asteroids. After the collision, ESA’s Hera mission will analyze the Didymos meteors in 2026 to collect significant data such as Didymoon’s mass, its surface characteristics, and the configuration of the DART cavity.
The successful realization of missions like this mainly depends on collaborations between companies, and recording Near-Earth Objects is a primary focus of the partnerships between ESO and ESA. This symbiotic collaboration had been continuing since their first favorable tracking of probable destructive NEO back in 2014.
The recent close rendezvous with 1999 KW4 will happen a month after Asteroid Day, an official United Nations day of information and education regarding asteroids, to be celebrated on June the 30th. To mark it, there will be various events being held across five continents, and ESO will be one of the essential astronomical organizations to participate. The ESO Supernova Planetarium & Visitor Center will accommodate a diverse spectrum of activities having asteroids as the central theme, and the broad public is invited to join the events.
Bo has over six years experience as a teacher, advocate and speaker. He has a B.S. from Cornell University, and a Ph.D. in Human rights from Harvard University Graduate School.