43
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Why are eclipses of the James Webb by the Earth or Moon not permitted during the mission?
From the JWST Mission Operations Concept Document
Some families of Lissajous orbits can result in the spacecraft crossing the line connecting the two bodies. In the Sun-Earth orbit, this can result ...
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23
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James Webb telescope; limits to propellant lifetime?
For some background see
this answer to Could JWST stay at L2 "forever"?
this answer to What happens to JWST after it runs out of propellant?.
From the 2nd linked answer (slightly edited):
...
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20
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What happens to JWST after it runs out of propellant?
This Northrop Grumman video (starting at 09:31) illustrates JWST's orbit in a non-rotating (normal) frame. It's really in an orbit around the Sun about 1% farther ...
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19
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Could JWST stay at L2 "forever"?
According to Wikipedia, the delta-v requirements to stay at L1 or L2 are about 30-100 m/s per year. That seems quite high, however, more likely is around 5-16 m/s. The sun shield has an area of about ...
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19
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Why are eclipses of the James Webb by the Earth or Moon not permitted during the mission?
tl;dr: despite having to drain its batteries to run its electronics heaters, it might survive a short eclipse, but since the mission can easily designed to be eclipse free it's simply good practice to ...
- 151k
18
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Why aren't energy and momentum (of a restricted three-body system) conserved, or are they?
In a two body system the total energy, the sum of kinetic energy and potential energy is constant for each body. If the total energy is constant for each body, the total energy for the whole system is ...
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17
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What is a near rectilinear halo orbit?
Halo orbit families exist near the L1, L2, and L3 librations points. This video focuses on the L1 and L2 halo families. There are northern and southern families at each of the libration points. The ...
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16
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How would you identify when an object in a Lissajous orbit needs station keeping?
Halo orbits and their cousins Lissajous orbits (like the one DSCOVR is in) around the Sun-Earth L1 and L2 have periods of about a half-year. They are not generally stable and they want to "unwind&...
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13
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James Webb telescope; limits to propellant lifetime?
The telescope trajectory changes direction for halo orbit insertion.
Image source: https://jwst-docs.stsci.edu/jwst-observatory-hardware/jwst-orbit
Such a large change of direction would require a ...
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12
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What is the required burn to keep a satellite at a Lagrangian point?
What is the required burn to keep a satellite at a Lagrangian point?
tl;dr: typical station keeping delta-v for a halo orbit around Sun-Earth L1 or L2 points are of the order of 2 to 4 meters/sec per ...
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12
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What is the difference between halo orbits and Lissajous orbits?
Halo orbits are a sub-class of Lissajous orbits.
So that image showing a simple circular-ish orbit is just showing a 1:1 Lissajous pattern.
These Lagrange-point orbits are really orbiting around the ...
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12
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How frequent are (or will be) JWST station keeping burns at L2?
How frequent are (or will be) JWST station keeping burns at L2?
21 or 42 days
I've heard mention of 'every 21 days' which at first look seems excessive but on second look may not be nuts if very ...
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11
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Why is a near rectilinear halo orbit proposed for LOP-G (formerly known as Deep Space Gateway?)
In fact, they are the preferred option among other staging orbits by analyzing multiple factors:
EARTH ACCESS:
A study considering NASA SLS and Orion performances was carried out. Since SLS places ...
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11
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How well is JWST doing on maintaining its Halo orbit?
Only partial:
Not directly answering since it seems ok:
Can only find up to 2022:
Orbit around L2 is maintained through regular station-keeping burns, which are scheduled every three
weeks. As of ...
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10
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Can the James Webb Space Telescope basically manage its own orbit if necessary?
I don't have too much time to research as I'm about to head off to work, but a quick investigation of the JWST doesn't show anything that could be used for Astrogation.
Curiosity can do its own ...
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9
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What sort of orbital elements are used to describe halo orbits?
tl;dr: For a given pair of bodies in circular orbits around their center of mass, there are two symmetric families ("Northern" and "Southern") of proper halo orbits associated with ...
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8
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Could JWST stay at L2 "forever"?
This paper by Heiligers et al. explores Earth-moon libration point orbits with the addition of solar sail thrusting. While it is of course not directly translateable to Sun-Earth L2 (JWST) the ...
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8
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Can the James Webb Space Telescope basically manage its own orbit if necessary?
Short answer is no--JWST does not manage its orbit corrections itself. Stationkeeping is done from the ground. During normal ops ,there are both medium-gain and high-gain antennas on the sun side, ...
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8
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How does a butterfly orbit move in 3D? Way to generate or visualize?
Sorry that I'm so late to this, but I worked with the butterfly family quite a lot when I was a student in Professor Howell's group so I feel compelled to answer! It looks like you found some good ...
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Why are eclipses of the James Webb by the Earth or Moon not permitted during the mission?
"Power and thermal" but no further details.
Earth and Moon eclipses
pose significant hazards to the power and thermal subsystems.
Source: LIBRATION ORBIT ECLIPSE AVOIDANCE MANEUVER STUDY
...
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8
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Would it be practical to position a telescope like JWST at Sun-Earth L4 or L5?
Surely a significant reason is that L4 and L5 are much farther away, roughly 150 million km vs 1.5 million. That makes things more difficult in a number of ways, but probably the biggest is that ...
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7
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How to best think of the State Transition Matrix, and how to use it to find periodic Halo orbits?
The State Transition Matrix (STM)
The STM is a linearization procedure of a dynamical system. It can be used for any non-linear dynamical system and is used to approximate the dynamics of a system ...
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7
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Why put X-ray telescope Spektr-RG/eROSITA all the way out at Sun-Earth L2?
eRosita is on its way to an elliptical orbit around L2 (with L2 in the centre of the ellipse).
(image source: https://www.slideshare.net/esaops/wilms, p. 19)
According to Merloni et al. (2012, https:/...
7
votes
Are there some three-body orbits that can't be escaped? Can we know without propagating forever?
There are really two questions here:
Do there exist $n$-body systems with long-term stability?
Can a third body (massive or not) be shown, a-priori, to be bounded or to escape—without resorting to ...
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7
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Nickname and citation for famous, historic three-body spacecraft trajectory design "manual"; something like "DoKaRoMo"?
You are likely looking for "KoLoMaRo".
http://www.cds.caltech.edu/~koon/book/KoLoMaRo_DMissionBk.pdf
Wang Sang Koon, Martin W. Lo, Jerrold E. Marsden and Shane D. Ross "Dynamical ...
7
votes
The design of the halo orbit of the James Webb Space Telescope
Has the JWST halo orbit been chosen from a stable halo "template", and in "broad terms", what were the trade-offs between JWST's scientific mission requirement, orbital life-time ...
- 151k
7
votes
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What are "transcritical, pitchfork, period-doubling, torus, and subharmonic bifurcations" in the context of three-body orbits? (e.g. butterflies)
I can attempt an answer by summarizing some of my favorite dissertations. Forgive some of the word vomit below, this is certainly not the most elegant or succinct explanation. I'll give a bit of a ...
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6
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Could JWST stay at L2 "forever"?
tl;dr: I think there could be room to do this. However, I don't think a conclusive answer can be had through analyses of magnitudes on envelope-backs. A real answer would only come from even more ...
- 151k
6
votes
Accepted
What is the period of halo/Lissajous orbits?
As the halo orbits grow out of plane, their orbital periods generally decrease. You can see a plot of the period (in days) of the L1 and L2 halo families at the Moon as a function of the closest ...
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6
votes
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What is the physical interpretation of the eigenvalues of the monodromy matrix and how are they associated with the invariant manifolds?
Eigenvalues and Eigenvectors
Before specifically addressing the monodromy matrix, it's important to make sure you have a physical understanding of what eigenvalues and eigenvectors represent in ...
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Only top scored, non community-wiki answers of a minimum length are eligible