A Qinetiq-led consortium is one of three teams being awarded contracts to design a satellite mission to investigate and defect any asteroid threat to Earth.
The mission involves two spacecraft. First, an orbiter called Sancho will orbit the target asteroid, measuring its position, shape, mass and gravity field over the course of months. Using the captured data, an impactor spacecraft known as Hidalgo will then smash into the asteroid at a relative speed of 36,000kph, changing its course. Sancho will then monitor the deflection.
A particular threat ESA has identified is a 500m diameter asteroid known as 99942 Apophis that weighs 1000 million tonnes and is expected to pass within 30,000km of earth in 2029
Dr Sima Adhya, a space mission and system scientist on the project, said, ‘Over the next few months, the next stage will be to come up with the facts and the figures and the technical analysis of what we’re going to do. We will plan the orbit plan the route how to get there, what planets we’re going to go by, when we’re going to arrive, what sort of orbit we’re going to get into around it, design the spacecraft and say what instruments are going to be on them and say what we will actually do if we are chosen to fulfil the mission.’
Before any threat approaches earth, the system will need a test run.
‘We have identified two asteroids we’re going to test it on,” said Adhya. ‘The asteroids will be 50 million km away when we hit them and we’re planning to impact at a relative speed of 36,000kph.
‘We plan to move the asteroid by roughly 100m. There’s no way these test subjects could get on an earth trajectory, they’re so far away they’re completely safe. So what we’re trying to do is to prove that we can move a trajectory by a certain amount so that in the future if something was on an earth trajectory we could move it by the amount we want.’
The sheer distances involved provide technical challenges for the project.
Adhya said, ‘Part of the problem we know very little about the Apophis asteroid, and what we do know comes from observations from earth by telescope. We estimate its size between 100m and 500m, but there’s big difference. We don’t know its size, its mass, its density, whether its just one rock or whether it’s rubble piles held together by their own gravity. What’s hard about that is knowing how hard we need to hit it. As we have no idea of its density, obviously we won’t know how it will react to the impact, so there are quite a few questions we need to work on.
‘Basically, it’s very small and very far away.’