Note4Students

From UPSC perspective, the following things are important :

Prelims level: Lagrange Points, Lucy Mission

Mains level: Not Much

The NASA has launched Lucy, the spacecraft on a 12-year cruise to look back into the origins of the solar system through Trojans.

Lucy will fly by eight Jupiter asteroids—seven Trojans and one main-belt asteroid — over the next 12 years.
It is NASA’s first single spacecraft mission in history to explore so many different asteroids.
Lucy will run on solar power out to 850 million kilometers away from the Sun.
This makes it the farthest-flung solar powered spacecraft ever, according to NASA.

Simply known as Trojans, they are a large group of asteroids that share Jupiter’s orbit around the Sun.
Thousands of such asteroids exist in a gravitationally stable space.
The swarms lead and follow the planet Jupiter along its orbit around the Sun.

Lucy’s Trojan destinations are trapped near Jupiter’s Lagrange (L) points, which are gravitationally stable locations — it is where the gravity from the Sun and from Jupiter cancel each other out.
This means their orbits are stable and the Trojans are trapped in the space between.
This also means that asteroids are as far away from Jupiter as they are from the Sun.
Jupiter’s leading and trailing Lagrangian points (L4 and L5) have been stable over the age of the solar system.
This means that their orbits have accumulated many, many asteroids.
It makes sense to call a Trojan a co-orbital object, which moves around one of the two stable Lagrangian points.

It took many a scientist to understand Trojans, and subsequently, name them so.
A German astro-photographer in 1906 made an important discovery: An asteroid with a particularly unusual orbit. As Jupiter moved, this asteroid remained ahead of Jupiter.
It was observed that the asteroid was nearly 60 degrees in front of Jupiter.

Students with engineering background would better understand who Lagrange was. Rest need not care.

This specific position of a peculiar behaviour was predicted by the Italian-French mathematician Joseph-Louis Lagrange over 100 years earlier.
Lagrange had argued that if a small celestial body is placed at one of two stable points in a planet’s orbit around the Sun (the L4 and L5), the asteroid would remain stationary from the planet’s perspective.
This is due to the combined gravitational forces of the planet and the Sun.
Thus, Lagrange’s prediction acquired credibility. More such asteroids were discovered over subsequent months in Jupiter’s Lagrange point L5.

It is the fossil of a hominin that lived 3.2 million years ago.
She is known to be one of the most famous pre-human fossil in history.
Nearly 40 per cent of the fossilised skeleton of this hominin was discovered in 1974 by a team of paleoanthropologists led by Donald Johanson.
The name was inspired from the famous Beatles song “Lucy in the Sky With Diamonds,” which Johanson’s team listened to at camp the night of their discovery.

Lagrange points are positions in space where objects sent there tend to stay put.
They are named after Italian-French mathematician Josephy-Louis Lagrange.
At Lagrange points, the gravitational pull of two large masses precisely equals the centripetal force required for a small object to move with them.
These points in space can be used by spacecraft to reduce the fuel consumption needed to remain in position.
There are five special points where a small mass can orbit in a constant pattern with two larger masses.

What is the Lucy Mission?

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