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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Can JWST come in for a pit stop? Is the fuel supply on JWST adequate for a transfer to an Earth Moon libration point to allow repairs?

The James Webb Space Telescope is generally considered unserviceable. This is primarily due to its location. Is it possible for the JWST to use a low energy heteroclinic transfer to reposition itself ...
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More advanced alternatives to Trajectory Optimization Tool?

I've been using Arrowstar's Trajectory Optimization Tool to plan interplanetary transfers, and it works well. The next thing I want to do is plan gravity assists from the Sun-Earth L2 Lagrange point ...
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Would it be practical to position a telescope like JWST at Sun-Earth L4 or L5?

During a discussion of Lagrange points I was asked why we didn't put JWST at SE L4 or L5 since they are less unstable than L2. I thought a bit and came to think that the Earth gravity driven Halo ...
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Porkchop plots/launch windows for Sun-Earth L2 to Mars transfers?

I've been using Earth-Mars launch windows, found with NASA's Trajectory Browser and EasyPorkchop, as launch windows from the Sun-Earth L2 Lagrange point to Mars, with the logic that since the L2 point ...
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Is there any software or other resources that can find optimal launch windows and gravity assist trajectories involving Lagrange points?

I've been using GMAT to make various trajectories involving the Sun-Earth L2 point. Earth-L2-Mars, Earth-L2-Earth flyby-Mars, etc. However, the main source of optimal launch windows I've been using is ...
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What is this figure I have obtained from this MATLAB code around Earth-Moon Lagrange point 2?

This is part of the code I used, where EM: Earth moon ...
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Has JWST done its first station keeping yet?

Has JWST done its first station keeping yet? The last burn I know about was the MCC2 burn on Jan24; more than 21 days ago; and that was a pretty long burn with a $\Delta v$ of 1.6 m/sec or 160 cm/sec, ...
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Which spacecraft have entered lunar orbit through L1?

I'm examining entering lunar orbit through the Earth-Moon L1 point with low-thrust propulsion. As part of this, I'm interested in all examples of spacecraft (both actually flown and ones that didn't ...
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Does the distance to L2 vary?

Discussion of Lagrange point L2 and the JWST seem to be dropping out of the news cycle, so I thought I should ask this question while the topic is still warm. The distance of L2 for the sun/earth two ...
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Code to generate Sun-Earth L2 halo orbits for given epoch?

I am working on a GMAT script out of personal interest (not part of a job) that involves a spacecraft orbiting the Sun-Earth L2 point. I have found some orbital state vectors for the spacecraft that ...
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Radio Telescope / DSN Node in L4 and/or L5

Deploying really big radio dishes in space seems to be possible and "frequently" done with SIGINT satellites in geosynchronous orbit (like the assumed specs of the Orion satellite class). ...
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Why does the hot side of the JWST vary so much?

Usually the a sensor is in the low $50s$, yesterday it was $38^\circ C$, and today it is $55^\circ C$. Was it a measuring/reporting anomaly or does it really change that much? Here is the link to ...
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Delta-v to hit the moon: is reaching Lunar L1 enough?

Lot of questions involve shooting things into the Sun. But there are no aliens on the Sun: they are on the Moon. I want to drop things on them, but since there's lot of them, I can just drop a ...
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How much margin does JWST have for station keeping in Halo orbit?

How much margin in $\frac{m}{s}$ does JWST have for station keeping in Halo orbit? JWST must always stay on the earth side of the L2 saddle since thrusters only point towards the sun. Also` solar ...
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Since L2 has no visible marker, how will James Webb's ground control determine its relative position and velocity for station keeping?

James Webb will be in a halo orbit, station keeping around the Sun-Earth L2 point. This means it needs to monitor its position with regard to L2, for periodic station keeping purposes. But L2 isn't an ...
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Parameters of the L2 insertion burn to be done tomorrow

What parameters control the impulse to be applied in the L2 insertion burn? What parameters control when/where it is to be performed? What velocity is the impulse applied to achieve? Is the vehicle ...
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Are L1 and L2 orbital periods always half the orbital period of the massive bodies?

Are L1 and L2 libration point orbital periods always half the orbital period of the massive bodies? The halo orbital period of JWST is a half a year. https://webb.nasa.gov/content/about/orbit.html The ...
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L2 for JWST - EM barycenter used in calculation?

I’ve been reading up on two and three body dynamics, wrt to L2 for the JWST. Are the calculations for this L2 based on the sun/earth masses and locations, or on the sun/(earth+moon barycenter) masses ...
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What are the characteristics of JWST's orbit around L2?

I'm particularly interested in the size of the elliptic, but also its eccentricity and whether it will be coplanar with Earth's ecliptic plane.
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How does gravity change beyond L2?

Why does gravity appear to increase again on the far side of L2 from earth as indicated on the gravitational contour diagram? One would expect gravity to continue to decrease as the distance from sun ...
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How is the moon's orbital motion accounted for in determining the best observation platform/location for JWST at L2?

The moon's periodic motion would appear to impose a perturbation to the otherwise equilibrium state of the solar/earth L2 point.
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What is the delta v required for insertion to sun-earth L2?

What is the delta v required to place a satellite in L2 from earth transfer orbit ( Like the James Webb Telescope )? Does orbits closer to L2 different delta v from orbits far from L2?
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Is L2 at a distance where the Earth totally eclipses the Sun?

What is the furthest from the Earth that still offers a total eclipse of the Sun? Is L2 inside that distance? (I assume so due the the halo orbit that is planned but perhaps there are numerous other ...
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How can back shield of JWST be 85-100 degrees Celsius hot if it will be in Earth's shadow?

I have heard, that back shield of James Webb space telescope will be as hot as 85-100 degrees of Celsius. But how can it be, if it will be in Earth's shadow in L2?
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Why are Jupiter's trojans even remotely stable?

The spacecraft Lucy is en route to explore Jupiter's trojan asteroids. Lucy is so named because the trojan asteroids are believed to be fossil remnants from the formation of the solar sytem. ...
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Why doesn't JWST use ion thrusters?

Since the L2 point is unstable, JWST needs engines to maintain its orbit. It uses mono-propellant engines which have given it a 5-year minimum lifespan. Why weren't ion engines used instead? Wouldn't ...
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The design of the halo orbit of the James Webb Space Telescope

As I feel a little less uncomfortable with "halo" orbits, with this question, I would like to explore the practical aspects, in particular those related to the design of the James Webb Space ...
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How to calculate the Lagrangian points positions?

I have two bodies, one rotates around another on orbit. For i.e. Earth and Sun or Moon and Earth. If we know masses, velocity, distance and keplerian elements of orbit, how can we find the positions ...
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How much mass can be put in an L4 or L5 and it still maintain reasonable stability?

Every explanation of Lagrange points I've seen refers to it as a sort of three-body solution, where one of the body's masses is taken to be comparatively negligible to make the solution work. However, ...
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What is the "mass" of a Lagrange point?

Of the five Lagrange points, L4 and L5, as stable points, can be orbited by asteroids, satellites, and any other useful or interesting object. Assuming two-body motion however, calculating orbits with ...
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Can mascons have Lagrange-like points? In principle? At the Moon?

Background Lagrange points are a mathematical consequence of the The Circular Restricted Three Body Problem (CR3BP or CRTBP); two massive bodies orbiting around their center of mass and a third ...
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In a 3D space defined by semimajor axis, eccentricity and inclination, what would be the shape of the space where SDP4 works better than SGP4?

@BillGray's answer to Why can't custom-made TLEs for the DSCOVR launch booster in orbit around Earth work with SDP4? is quite interesting and informative; I fail to do it justice by summarizing it as ...
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Earth-Sun decayed L1 to L4 transfer

Assume CR3BP (Circular Restricted 3-Body Problem) where a satellite occupies the Earth-Sun L1 point. The satellite dies, stops station-keeping, experiences a small perturbation (minimal effect on ...
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How do spacecraft reach Lagrange points?

As I understand, to reach a Lagrange point the spacecraft would need to slow down. Also, can spacecraft passing nearby Lagrange points get captured within the point?
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Why does it cost more to get to L4/5 than C3=0?

I was looking at Delta-V budgets and noticed that it costs 4.1 km/s to get from LEO to L4/5, but just 3.2 km/s for LEO to geocentric C3 = 0 (escape velocity). I find that counter-intuitive. Why does ...
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Spinning 16 Psyche at Mars L1 to envelop Mars with a magnetosheath?

16 Psyche is theorized to be the remnant iron core of an early small protoplanet that might have had it's surface and mantle stripped away through violent asteroid impacts. Some modeling of possible ...
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Travel time from lunar orbit (EML2) to Jupiter using skyhook only?

I am doing background research for a science fiction story, and hoping someone can help with this navigational question. Voyager 2 reached Jupiter from Earth in about 2 years. However (if I understand ...
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How is it possible to connect trajectories at a Poincare section using the "bisection" method?

When constructing a heteroclinic connection (a connection between two different periodic orbits at two different libration points), the stable and unstable manifolds of two different libration points ...
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How Moon and other planets affect Earth-Sun lagrange points locations?

We can calculate Earth-Sun Lagrange points based on Sun & earth mass/gravity. However moon and other planets must be affecting the location of these points. How this effect is analyzed and exact ...
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What does the term "libration point gateway" mean?

In the Circular Restricted Three Body Problem, natural paths exist between periodic orbits or the libration points that have negligible cost. These are commonly known as free transfers between ...
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When will DSCOVR appear too close to the Sun for reliable downlinking?

DSCOVR is in a Lissajous orbit about the Sun-Earth L2 point. That the orbit is called Lissajous rather than halo means that it's periods of horizontal libration and vertical libration are not equal. ...
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Who called the Lagrangian points as "Libration" points and and why was the terminology "Libration" used?

I am curious about the naming and why were the equilibrium solutions of the CR3BP called as Libration points? Who called them that and what is the history behind it?
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How should I understand these phrases in this paper on orbit transfers?

I am studying this article on orbital mechanics and can't understand the meaning of some terms related to mathematics (perhaps because my native language doesn't have such terms). I created the same ...
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What is the radiation level at the L2 Mars-Sun point?

This answer shows that the radiation levels at the L2 Mars-Sun point will be lower because it lies within Mars' solar umbra. So what will the level of radiation be at the L2 Mars-Sun point? Also, how ...
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For how long do the various earth-moon lagrangian points receive sunlight each month?

Every month the earth-moon lagrangian points must be in the shade of the moon for some time For L1 and L3 probably on new moons, for L2 probably on full moons, and for L4 and L5 maybe when the moon ...
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Fastest time to Sun Earth L2 (or L1)?

Of all the past, present or planned probes to SE-L2 (or L1*) which has or will take the shortest amount of time to arrive from leaving low earth orbit, or from passing that location if the probe doesn'...
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Do Lagrange points still exist if there is significant radiation pressure on the third body from the first?

From this answer: To obtain the distance to L1, find the smallest value of $r$ such that $$\frac{M_2}{r_1^2} + \frac{M_1}{R^2} - \frac{r_1(M_1+M_2)}{R^3} - \frac{M_1}{(R-r_1)^2} = 0.$$ To obtain the ...
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How likely will the James Webb Telescope encounter debris trapped at L2?

Do Lagrangian points collect micro-meteorites similar to how the Pacific trash vortex collects debris? I was wondering if the James Webb Telescope will have to clear its Lagrange point before ...
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How big would a collection of asteroids near the Moon's L4 point need to be to aggregate naturally into a "stepping stone" for space exploration?

Wouldn't it be useful to catch few meter sized near-Earth asteroids whenever opportunity knocks and "lock them up" at the L4 Langrangian point of our Moon ? Although at the L4 and L5 Lagrangian ...
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Would it be possible to Boost ISS to L1 or Lunar Orbit?

NASA and Russia plan to retire the ISS before 2030, and to launch a new lunar outpost to lunar orbit. This output could then be a gateway to future mission to Mars or the outer solar system. My ...
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