“Lucy”: NASA launches a probe into Jupiter’s swarm of Trojan asteroids | Science

About 10,000 trapped asteroids were cataloged by Jupiter, about 6,000 called Greek and 4,000 Trojans. These are considered geological fossils, parts that can contribute Answers about the formation of planets and the solar system. The NASA An investigation was launched there on Saturday. I baptized it like this Lucy, the name is no longer one-time abbreviations; Just the memory of this human whose remains were discovered in Ethiopia in 1974. A fantastically complete skeleton opened up new horizons for the study of human evolution, in much the same way this task is expected to perform in the origins of our planetary system. This name was given because of Lucy in the sky with diamonds, by the Beatles, was the song that was playing on camp radio at the time of discovery.

Lucy You will visit seven targets: six Trojans and an asteroid in the belt between the orbits of Mars and Jupiter. Well, eight if we have the recent discovery that one of them, Euribates, has, in turn, a small satellite known as Queta after Enriqueta Basilio, the first woman who lit an Olympic cauldron in Mexico during 1968. Asteroid belt main thing the probe will visit on its way to Jupiter is 52246 Donald Johansson, named as such specifically in honor of the discoverer of the small Australopithecus. Really cosmic coincidence.

The mission will last for 12 years. How do Lucy It will not orbit any asteroid, but will limit itself to studying them “in passing”, only for a fraction of that time will actually be able to image and analyze those remaining floating rocks of planetary origin.

The distance between the two groups of Jupiter-associated asteroids is enormous: 120 degrees in Jupiter’s orbit (60 in front and 60 behind) equals 1,500 million kilometers. The Lucy Trail would not allow visiting both squadrons in one pass. After exploring the four, you will return to Earth to gain momentum and repeat the path towards the “Trojans”.

What are Lagrange points?

This path has its interpretation in Lagrange points. Between the Earth and the Moon there is a point where the attractions of both bodies are equal. When a ship is launched towards our satellite, until we get there, everything is hill top, a constant battle against the force of gravity leads to a gradual loss of velocity. After that point, the path is decline The ship speeds up until it reaches its destination. If you think about it, this phenomenon is pure common sense.

What is not clear is that there are two other points where the same effect occurs: one on the other side of the Moon and one on the other side of the Earth. There, to put it simply, both attractions are also balanced by the effect of the centrifugal force of both objects revolving around each other.

And – even more surprisingly – there are still two other points of equilibrium. They are not aligned with the Earth and the Moon, but in their orbit, they are 60 degrees forward and many are behind the satellite: each one forms an equilateral triangle with the Earth and Moon. Things from the laws of celestial mechanics.

The discovery of these five intriguing points was the work of astronomer and mathematician Joseph-Louis Lagrange as a special case in his attempts to solve the more complex “three-body problem”. Therefore they are known as Lagrange points or, for brevity, L1, L2, and L3. The two at 60 degrees are L4 and L5.

Balance

Each pair of orbs defines its own balance point system. In the Earth-Moon system, for example, L1 is located a little more than 325,000 kilometers, but L1 of the Earth-Sun group is one and a half million kilometers from us. L2 is located somewhat at that distance, forever in the Earth’s shadow; L3 is farther away, on the opposite side of the Sun. This is a favorite of some science fiction novels, in which you put a default script Earth -2 We can never see it because it is hidden behind the glare of the sun.

Lagrange points on Earth (relative to the Sun or Moon) are very useful as a destination for certain space missions. The first three are unstable: any slight perturbation would be enough to throw the ship out of balance and throw it out of position. But using small debug motors, it is possible to install them in orbit around one of these points. It is in essence orbiting around a place where there is absolutely nothing there.

Earth-Moon L2, for example, was used to locate a Chinese communications satellite from which the signals of the rover that explored the Von Karman crater on the far side reverberated. For their part, the L points in the Earth-Sun system are much more desirable. On L1 there is, among others, the SOHO Solar Observatory; And L2 – the most common – hosted WMAP and Plank (for studying microwave background radiation), and Herschel (infrared astronomy) observatories and the James Webb Large Telescope will soon be sent there.

The same calculations can be made for the sun and other planets or for those planets and their satellites. There are Lagrangian points for the Sun, Mars, the Sun, Venus, etc. even for Pluto.

The most exciting case is the case of Jupiter Its points are L4 and L5. Unlike the other three, it is stable and over millions of years hundreds of asteroids have accumulated there, attracted by the planet’s massive gravitational pull. Since there are two groups (L4 ahead of the planet, 60 degrees ahead and L5 following at the same distance), it was decided to name them in memory of the heroes of the Trojan War. The advanced squadron are the “Greeks”: Achilles, Agamemnon, Ulysses, Ajax …; Rednecks, “Trojans”: Priam, Aeneas, LaConte … Because of an oversight before deciding to divide them into two camps, Hector, the Trojan hero par excellence, ended up in the group of the Greeks; and Patroclus, Achilles’ companion, the Trojan Horse. The error was never corrected, so both are considered “hackers”.

Rafael Clemente He is an industrial engineer and founder and first director of the Barcelona Science Museum (now known as CosmoCaixa). He is the author of “A Small Step To” [un] Man (The Dome Books).

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