Questions tagged [lagrangian-points]

Lagrangian points (also Lagrange points, L-points, or libration points) are the five positions (L1 - L5) surrounding two celestial bodies where gravitational pull of the two large mass bodies provides the centripetal force required to orbit them. Such points are usually nominally unstable but somewhat periodic around celestial systems with stable orbits.

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Why are so many space telescopes placed in LEO instead of at Lagrange Points? And why do we hear about Hubble more than any Langrange-orbit telescope?

Here is the list of every space telescope launched by different space agencies - List of space telescopes. Most of the listed telescopes are placed in Lower Earth Orbit (about 95% of them). It's ...
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Why should the James Webb Space telescope stay in the unstable L2?

We all know that James Webb Space telescope is planned to be launched in 2018. It has been decided that the orbit of JWST will be elliptical around the Lagrange point L2, which has been declared as ...
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This orbit looks wrong near a Lagrange point. Is it?

On a completely unrelated forum, i came across the following graphic: The orbit seems wrong to me, especially the first curve. From the initial trajectory, I would expect the orbit to have been in a ...
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Is there a lot of space trash at the Earth-Moon Lagrange points?

Lagrange points are the points in a multi-body gravitational system in which the gravitational force and centrifugal force sum to zero. The image below from this Wikipedia article shows the 5 ...
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What does the Sun-Earth-Moon system look like from the Sun-Earth L-2 point?

The L-2 point of the Sun-Earth system is away from the Earth on the night-side of the Earth; i.e. it's always local midnight at the sub-satellite point. This is an attractive property for some ...
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Are there any (Lagrange) points in the Solar System in perpetual shade?

This answer mentioned thermal cycling made me think of this question: Are there any points in the solar system, such as Lagrange points, where a spacecraft could reside in perpetual shade, protected ...
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How deep is the force well of L4 and L5 Lagrangian Points of Earth-Sun set?

The Lagrangian Points are points in space, where the combination of gravitational pull of a set of two bodies and the centripetal force of orbiting one of them add up to zero. The special property of $...
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Why won't JWST deploy in LEO where it is potentially serviceable?

The James Webb Space Telescope will deploy (unfold mechanically) while on the way to L2. Couldn't it do so in LEO, where it is potentially serviceable? Starliner CST-100 and Dragon are planned to soon ...
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Are Lagrange points stable over a long period of time?

Do Lagrange points ever move or are they on the same spot as long as the solar system exists in it's current form with all it's planets in its current order?. They could move due to orbital objects ...
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Why would a mission to Sun-Earth L1 have an instantaneous launch window?

I was watching the webcast for Falcon 9 Flight 15 (launching DSCOVR) when they scrubbed their first launch attempt due to some issues during the terminal countdown. Before the scrub, the narrator ...
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How does orbital eccentricity affect positions of Lagrange points $L_4$ and $L_5$?

It is often said that the $L_4$ and $L_5$ points are "60 degrees ahead and behind" a planet like Jupiter. Clearly this is true only in the case of circular orbits. In more elliptical orbits, I assume ...
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Halo vs Lissajous orbit: Which station-keeping strategy to select and when?

I'm looking for a comprehensive pros and cons of the two most commonly used station-keeping types of orbits used at libration points, Lissajous and halo orbits. When would one select one over the ...
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Do we sufficiently understand mechanics of Lagrange point stationkeeping for EML2 rendezvous and assembly?

I've been watching some recorded videos from the April 22 - 24, 2014 Humans2Mars conference (videos and live streams, when available, are on the National Institute of Aerospace channel on Livestream), ...
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Ordering of the Lagrange points

Is there any basis for the ordering of the L-points? Specifically, is there any particular reason for choosing L1 as the first L-point?
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How many satellites can stay in a Lagrange point?

Lagrange points as I understand it are points in space between 2 objects where the gravitational pull between them is effectively equal. That makes station keeping at these points relatively easy. ...
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If something “falls off” the L2 or L1 point, where will it go?

The L1 and L2 points are thought to be unstable "saddle" points, meaning that there is stability in two directions of movement, but not in the other. That raises an obvious question - when a ...
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Could JWST stay at L2 “forever”?

Using only reaction wheels powered by solar panel and the sunshield as a sail (in continuous active attitude control) to generate thrust from solar photon pressure in the desired direction, could JWST ...
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Is this what station keeping maneuvers look like, or just glitches in data? (SOHO via Horizons)

I've been enjoying the JPL Horizons web interface and after I discovered the incredibly extensive database associated with SOHO (Solar and Heliospheric Observatory, also see sohowww.nascom.nasa.gov) ...
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Are there interstellar Lagrange points?

Is there for example some L1 like libration point where the Hill spheres of the Sun and of the Alpha+Beta Centauri meet? And are Lagrange points between stars inside of a binary system, like Alpha and ...
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How Many Martian Lagrange points are there? …And are they useful for satellites?

I know that the Sun-Earth system has 5 Lagrange points, and there are five more Earth-Moon associated Lagrange points; so ten in all that are in some way associated with the Earth. Since Mars has two ...
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Are some Halo Orbits actually Stable?

UPDATE: I found another reference! While I always enjoy a good video starring Jimmy and Linda Carter, this one has Dennis Wingo describing ISEE-3's original Halo orbit. He describes Sun-Earth $L_1$ as ...
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Reverse Lunar Space Elevator

The possibility of a space elevator from the lunar surface is discussed in this question. A lunar elevator for the purpose of return to Earth could be achieved at the L1 Lagrange Point between Earth ...
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Single-shot Blue Marble pictures

I was quite surprised to read in today's Earth Observatory Picture of the Day that the DSCOVR spacecraft, currently en route to the $L_1$ Lagrange point, will be the first spacecraft able to see the ...
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Can the James Webb Space Telescope basically manage its own orbit if necessary?

In this great answer I learned that the Mars rover Curiosity can be given some tasks and it will go ahead and manage the work and navigation by itself, to at least a certain limit. The James Webb ...
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Are there propellant-less ways to balance at an unstable orbital point?

A station situated somewhere like EML-2 is really at an unstable point. I've heard of crafts using rocket firing to maintain that position in response to small deviations. Could you do this without ...
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Low Energy Transfer within Earth-Moon system

Practical aspects of a total low energy transfer to the Moon have been seen in missions like GENESIS, which uses Weak stability Boundary legs of Earth and Sun to reach ESL-2. This four body model ...
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What are the sources of light at L2? How will the James Webb telescope be powered?

The James Webb space telescope will be positioned very close to L2. According to JPL, Webb will have a large solar-array to power itself. I don't understand how this works, since L2 is positioned "...
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What are reasons to put Gaia space telescope into L2 Lagrangian point of Sun-Earth system?

As I remember, Gaia (wiki, ESA) was planned to flight away from Earth, so it orbit is not LEO, and not GEO. It is located near 1.5 millions kilometers away from Earth, orbiting thousands kilometers ...
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What is the flight plan to get Gaia in orbit around the Sun–Earth $L_2$ Lagrangian point?

Gaia is a planned European Space Agency's (ESA) space observatory that will aim to chart a three-dimensional map of our Galaxy, the Milky Way. It is planned to operate around the Sun–Earth $L_2$ (SEL2)...
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What is the diameter of magnetopause 1.5 millions kilometers behind the Earth?

Earth has strong magnetic field, which changes concentration of charged particles from Sun near the planet. There is rather safe torus near the Earth (LEO non-polar orbits), and also there is long ...
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Aren't the mirrors of the James Webb Space Telescope too unprotected?

I've looked at the design of the James Webb Space Telescope and I got curious about something, some years ago, it seems that the international space station was hit by micro-meteorites. I'm wondering ...
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Stability of Lissajous orbits around Sun-Venus L1

How far is it from the Venus? Does Mercury gives too big perturbations for a stable Lissajous orbit?
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Can a whole planetary system have Lagrangian points?

Wikipedia says: The Lagrange points mark positions where the combined gravitational pull of the two large masses provides precisely the centripetal force required to orbit with them The major bulk ...
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For an EML-1 to Mars transfer orbit, would flying to the right or left of Earth be preferable?

If an L1 space station was used as a staging area for a mission to Mars, it looks like we would use the Oberth effect in a close flyby to Earth to make the burn. But I just realized - the idea, as ...
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Are there any man-made satellites at Lagrangian points?

There are 5 lagrangian points. Are there any man-made satellites at any of those points? Is there a reason for the presence or absence of satellites at these points?
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How to calculate libration amplitude of objects orbiting the $L_4$, $L_5$?

Is there a way to calculate the libration amplitude of a test object that orbits the $L_4$ or $L_5$ Lagrange points? By amplitude I mean the distance along the orbit between the two extremes of ...
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How does gravitational stability change with the distance from special places such as geostationary orbit and lagrange points?

How rapid do the attractive properties of GEO and lagrange points deteriorate with the distance from optimum? How "large" are such locations? At what distance would station keeping require, say, twice ...
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Where will objects end up, after losing stability at Lagrangian points?

The Lagrangian points are points of unstable balance (at least gravitationally; L4 and L5 are stable thanks to Coriolis force.), and that means an object not stabilized actively will fall out of them ...
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What plane will DSCOVR’s orbit be in?

According to the “NASA Earth Science Instruments” section of noaa.gov's DSCOVR page, DSCOVR will make unique space measurements from the first sun-Earth Lagrange point (L1). ... 1.5 million ...
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How could transfers between SEL1&2 and EML Lagrange points be utilized?

The Earth has 7 Lagrange points nearby since SEL1 and SEL2 (Sun-Earth Lagrange points 1 and 2, respectively) are only between 3 and 5 LD (lunar distances) away from the five EML (Earth-Moon Lagrange) ...
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How does the delta V to reach and orbit L4 and L5 compare to entering orbit around the Moon?

The L4 and L5 Lagrange points, 60 degrees in front of and behind the Moon in its orbit around Earth, orbit at the same speed as the Moon. But when a spacecraft flies to the Moon, the gravity of the ...
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Is the L2 Mars-Sun point protected from solar radiation?

To what extent is the L2 point protected in comparison to the surface, if at all? Since the L2 point might be in the umbra of Mars, it could be shielded against the sun. It would also be helpful if ...
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What, if any, libration points exist in systems of multiple orbiting bodies?

Are there libration points in a restricted 4-body problem (system of three orbiting bodies of significant mass, plus the libration point orbiting body)? If so, how many of them exist and where are ...
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Does any group have a serious proposal to build & maintain a station at L1?

To me, it's a no-brainer that the Earth-Moon L1 location is a strategic locale, sort of a forks of the Ohio in local space. I've seen some proposals to put some long-term station there, but has anyone ...
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Are large halo orbits around L₁'s and L₂'s preferred over small orbits for reasons other than geometry?

There have been many examples of the placement of satellites in orbits around Lagrange points, most have been sun-earth and earth-moon $L_1$ and $L_2$ due to their proximity to earth. In each case ...
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Is there a synchronous orbital height for Phobos?

My assumption is that any body in the solar system would have it's own specific geo-synchronous orbit height. But when I took a look at Phobos and calculated the GEO height based on the simple formula ...
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What is the required burn to keep a satellite at a Lagrangian point?

When a satellite reaches a Lagrangian point, it has a non-zero velocity $v_1$ because of the transfer orbit in which it had already been. What burn, say, $\Delta v$, one needs if the satellite is ...
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What determines the orbital speed around a massless Lagrangian point?

What value of M should I use to calculate the speed of a satellite orbiting a Lagrangian point where there exists no mass?
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Are there really just 5 Lagrange points?

In many online resources, like Wikipedia, five Lagrange points are specified. From my understanding, a Lagrange point is a point where the gravitational attractions of the two bodies (Sun and Earth, ...
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Does the Milky Way have a Lagrangian point? [closed]

About 2.5 million light years from the Milky Way is the Andromeda Galaxy. We have about 4 billion years before the two collide as they approach each other things are getting to get interesting. But ...