Exactly one year after its takeoff, the Lucy probe of NASA flew over the Earth this Sunday, October 16. A flyby at only 350 km altitude which required enormous precision… To take advantage of a maximum slingshot effect and accelerate in order to visit the Trojan asteroids of Jupiter before the end of the decade.
The mission will need further assistance in 2024.
Lucy ahead!
No way to miss. After an eventful year of flights with in particular the (successful) attempts to extend one of its two poorly deployed solar panels, the Lucy mission returned to square one on October 16. At 1:04 p.m. (Paris), the probe passed close, very close to the surface of the Earth: only 350 kilometers, closer than the orbit of the International Space Station!
But its speed is much greater, it did not stay very long in the vicinity. 24 hours later, it has already exceeded the distance of lunar orbit… It must be said that this approach was specifically designed to give it gravitational assistance, a maneuver which must be very precise but thanks to which a probe can save several hundred kilograms of fuel. Yesterday, Lucy accelerated almost 18,000 km/h…
In a game of bowling?
NASA teams have prepared this meeting with great caution. Indeed, overflights and gravitational assistance are maneuvers that are better and better documented and mastered. But with the Earth, there is an additional variable: that of the thousands of satellites and debris currently in orbit! Until the last days before the flyby, the teams of the American agency observed the possible approaches, reserving two “spots” to maneuver the probe in case, and to accelerate it if necessary by turning on its engines. It looks like they didn’t need it.
Another specificity is that most of the gravitational flybys in recent years have enabled the probes to direct their instruments towards the Earth, in order to calibrate and properly characterize them. But Lucy is designed to study the Trojan and Greek asteroids, hundreds of millions of kilometers from Jupiter (at its Lagrange Points L4 and L5). As a result, observing the Earth was not very representative… On the other hand, Lucy had to turn – if all went well – her optical instruments towards the Moon! Indeed its absence of atmosphere, its craters and the fact that it is particularly well documented make it a target of choice.
On the way to… Earth (again)
Lucy is now on an elliptical trajectory, but does not yet have enough energy to reach her future objectives: she will have to come back close to Earth in December 2024 to be able to rush towards the asteroids, with a real life-size test. , 25246 Donaldjohanson.
The latter is not in the “suburbs” of Jupiter, but it is on the way and it is of great interest to scientists. After her flyover, Lucy will head towards her other 8 or 9 objectives, including Eurybates. Don’t forget, even with a little equipment, you could also help NASA in this regard, on October 23…
Source : NASA
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