If humanity is to avoid the fate that befell the dinosaurs, the results of these analyses must be examined very carefully.
“The meteor that exploded over Chelyabinsk was a wake-up call,” says Zhu Qing-Yin of the University of California. He has performed chemical analyses of the fragments of the celestial stone which exploded over the Russian city in February 2013. “If humanity is to avoid the fate that befell the dinosaurs, the results of these analyses must be examined very carefully.” With a diameter of 15 to 20 meters, the asteroid exploded at an altitude of 30 - 50 kilometers above Chelyabinsk, releasing kinetic energy which was more than 30 times that generated by the Hiroshima bomb. Six cities in the immediate vicinity were shaken by the blast, injuring some 1,500 persons and damaging thousands of buildings as the blast had shattered all the windows.
Known as “near earth objects”, these asteroids have a diameter of between 5 and 500 meters and exist in large numbers in space. The problem is that only very few of them are known. For this reason, the European Space Agency ESA is developing an early warning system for these countless smaller asteroids in particular. Although they would not wipe out civilization on the earth unlike the asteroid that eradicated the dinosaurs 65 million years ago would have done, an object with a diameter of around 100 meters would destroy a city like Hamburg or Munich in the event of a direct impact.
This is why ESA has joined forces with NASA to develop and test suitable means of intercepting these asteroids. A preliminary step in this direction was the “AIDA” (Asteroid Impact & Deflection Assessment) project that ESA and NASA initiated in 2011 to defend our planet.
The Japanese space agency JAXA is already one step further, having launched an asteroid mission in 2014:. After traveling some 300 million kilometers, the “Hayabusa-2” space vehicle reached an asteroid known as “Ryugu” in June 2018, where it will be lowering the German-French probe “Mascot” on to the surface to collect information about the surface of the asteroid. This is decisive information required to design and execute an asteroid deflection maneuver.
Europe and the United States working hand in hand
The European part of the planned AIDA mission was known as AIM (Asteroid Impact Mission). In 2015, OHB System AG was commissioned by ESA to perform an AIM feasibility study. Together with his team, Marc Scheper, head of OHB’s department for space transfer, robotics and exploration studies and the project manager at the time, worked on the overall design of the mission and the probe, particularly the satellite platform. He was also responsible for the program structure, technology development, budgeting, scheduling and risk analysis. The concept for the related optical camera for collecting scientific data and for use for navigation purposes was developed at the OHB Optics and Science Space Center in Oberpfaffenhofen near Munich.
Unfortunately, however, nothing ever came of the mission after ESA postponed a decision on AIM in 2016. Originally it had been planned to send a probe on board a Soyuz launcher to the twin asteroid “Didymos” to ensure that the probe would reach it in a favorable constellation, namely in August 2022. The larger of these two asteroids is a giant with a diameter of 800 meters. Unofficially known as “Didymoon”, its smaller brother is only 170 meters and is the actual mission target.
“Regrettably, we can no longer achieve this deadline,” says Scheper. “However, the mission parameters still stand - a probe is to fly to the asteroid, observe and measure it and analyze its surface.” As the Americans still want to implement their part of the mission as planned and head for Didymos in 2020, the Europeans must revise their own plans. “The new mission is called HERA and aims to collect data on the composition of the asteroid,” Scheper explains. “HERA is to investigate the impact crater on the smaller of the two asteroids that the Americans will have left behind in 2022 with their DART mission.” According to scientific calculations, the impact should retard Didymoon by around half a millimeter per second and thus slightly enlarge its orbit. Using HERA, the Europeans want to observe whether Didymoon’s trajectory is modified as planned. If it is successful, this will mean that a suitable method for deflecting asteroids from collision courses with the earth will have been found.
“A small shove for mankind ...”
The decisive factor is to know what effects an impact has on the composition of the asteroid.
Asteroids, Scheper explains, cannot simply be destroyed. In order to know how to catapult them out of their trajectory with a “shove”, it is necessary to know all about their characteristics. “The decisive factor is to know what effects an impact has on the composition of the asteroid. We still do not know very much about these celestial bodies,” Scheper admits. “Only by knowing exactly what an asteroid is made up of will we be able to develop effective interception methods should such an object be on a direct trajectory for a collision with the earth one day. So, the motto is know your enemy!”
Thanks to the preliminary work conducted on the AIM study, OHB has already gained valuable knowledge in this area. For this reason, Scheper is confident that OHB also has a good chance of being awarded the HERA feasibility study. “The request for proposals has been received and we will be submitting our bid for the study by mid-July 2018. Given our experience and the skills that we gained with the AIM mission, we are very optimistic of being awarded the HERA study,” Scheper says.
Further observation systems crucial
The importance of the HERA project for the future of the Earth and of humanity as a whole is best illustrated by a few figures: experts believe that 90 percent of all very large asteroids capable of destroying civilization are known. However, only a small percentage of the smaller asteroids have been identified. At the same time, experts speak of giants with a diameter of up to 500 meters that are capable of wiping out entire regions. By comparison, the asteroid that exploded over Tunguska in Siberia on June 30, 1908 and felled every single tree over an area of 2,000 square kilometers, had a diameter of between 30 and 80 meters. Its explosive force is assumed to have been the equivalent of 1400 Hiroshima bombs.
“This means that it is crucial for us to install further observation systems,” says OHB project manager Scheper. ESA will soon be able to use the “Flyeye” telescope, which is being installed in Sicily solely for the purpose of observing near earth objects. OHB subsidiary OHB Italia is the prime contractor for the construction of this telescope. Christian Köberl, director of the Museum of Natural History in Vienna, which holds the world’s largest collection of asteroids, illustrates just how close smaller asteroids approach the earth almost daily: “You just have to gaze upwards. The moon is completely covered in craters. We do not see these craters as clearly on the earth because our planet has a very active geological surface. Yet, the earth is also being constantly bombarded. Although larger objects are very, very rare, the smaller ones can be seen almost daily.”