China plans to hit an asteroid with a Mach 26 projectile in planet defence test
Spacecraft to hit at 9km/s, equivalent to over 26 times the speed of sound near sea level and nearly 50 per cent faster than Nasa’s mission
It aims to directly alter an asteroid’s orbit relative to Earth, “or even break up its structure”, according to a team led by Li Mingtao, chief scientist for planetary defence at the China National Space Administration.
The spacecraft was expected to hit its target at more than 9km (5.6 miles) per second – compared with Dart’s 6.1km/s – during a close approach to within about 7 million km of Earth in 2029 or 2030, the paper said.
The paper is under peer review by the Chinese-language Journal of Deep Space Exploration.
The impact speed is equivalent to over 26 times the speed of sound near sea level.
In the meantime, a second spacecraft will be used to observe the asteroid before, during and after the collision, tracking changes in its orbit, shape and surface, while probing its interior. Unlike the European Space Agency’s Hera follow-up mission to Dart, however, it will do so as part of the same mission.
The Chinese mission was built around four goals: accurately striking the asteroid, successfully deflecting its orbit, precisely measuring the results and showing the impact left the Earth unharmed, the team added.
The target is a little-known near-Earth asteroid, dubbed 2015 XF261, which was first discovered in 2015. It is estimated to be just about 30 metres (98 feet) across, although its exact size remains uncertain.
The asteroid’s rotation and composition are not known, but it is most likely to be a solid rock or other high-strength body, which is very different from the 160-metre rubble-pile asteroid targeted by Dart.
According to the paper, the plan calls for two spacecraft to launch together before separating soon after leaving Earth. The impactor will head directly for the asteroid, while the observer will take a longer route that includes a gravity assist from Venus before rendezvousing with the target.
It will release a small probe before the collision to observe the impact in real time, then continue tracking how the asteroid’s orbit, shape, surface and ejecta evolve, with ground-based telescopes joining the campaign.
One major challenge would be simply finding the target, the researchers said.
The asteroid is extremely faint and has been observed only 74 times since its discovery. Scientists expect to learn much more about its size, shape and rotation only in the final months before impact.
Hitting it will be another challenge. The impactor will have to lock onto the tiny asteroid autonomously and strike it with extraordinary precision, as radio signals from Earth will take too long to guide the final approach, according to the paper.
After the collision, scientists must detect the tiny change in the asteroid’s orbit despite the cloud of debris kicked up by the impact, and then continue monitoring it to confirm the deflection worked as intended.
If successful, the effort would mark China’s first end-to-end demonstration of planetary defence, combining detection, deflection and post-impact verification in a single campaign, they said.
==========================================================
No comments:
Post a Comment