# Questions tagged [gravity-assist]

Questions regarding the use of an object's gravity to change the velocity of a spaceship.

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### How to find the hyperbolic angle given the mean anomaly?

I'm modelling a hyperbolic gravity assist trajectory around Jupiter and trying to calculate the coordinates for each hour interval before/after passing periapsis. I've calculated $M_h = 0.0176$ is the ...
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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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### Are there any studies on Mars-Earth ballistic cyclers taking Mars-gravity assist into account?

In studies pertaining Earth-Mars cyclers, purely ballistic cyclers are usually relegated to many orbit solutions. For instance the classic Aldrin cycler, while elegant, can't achieve the desired turn-...
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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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### Is there a parameter that describes the angle between the spacecraft's position and the sun angle or direction of the Earth's motion?

I am trying to design an Earth flyby for gravity assist in GMAT, and I know from theory that the spacecraft should pass in front of a planet with regard to its heliocentric direction of motion in ...
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### Starting refueled in LEO, how much payload could a heat-protected Starship softly land on Mercury after a gravity assist from Venus?

This question may be a crucial follow-up to this one because in this answer it is calculated that the payload to Mercury without a gravity assist would probably be minimal, so if already a moderate ...
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### Which moon is best? (for gravity assists)

Inspired by my answer to Is a ballistic Jovian capture using the Galilean moons possible from interplanetary entry? in which I discovered that Callisto offers a stronger gravity assist than Ganymede ...
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### Is a ballistic Jovian capture using the Galilean moons possible from interplanetary entry?

While spacecraft like Galileo and Juno did use gravity assist to supplement their insertion burns, as answered here, is it possible to enter Jupiter's orbit without a capture burn?
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### Starship reentry velocity on return from Mars: What are the options

What are the reentry velocity options available to Starship on return from Mars? I assume the approach will be significantly faster than a Hohmann transfer orbit due to timing of transfer windows and ...
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### Which deep-space spacecraft flew closest by Earth during a gravitational assist?

The extremely cool NASA JPL video Triumph at Saturn (Part I) is really worth a watch and/or listen. (Don't forget Part II as well!) At about 26:30 it discusses ...
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### Is there any limit to how many times you can increase velocity by repeated sling shot manoeuvres?

I believe travelling to Alpha Centauri at ~10 km/s would take of the order of 100 000 years (10 km/s is the order of speed of probes currently leaving the solar system). That seems 1. rather a long ...
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### Why is there currently so little talk about a Venus gravity assist for a crewed Mars mission?

I just came across this video about manned Mars and Venus missions that were planned in the 1960s. They considered a Venus flyby the best way to get humans to Mars. Indeed, there are also modern ...
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### What is the maximal gravity assist boost achievable in the Milky Way galaxy using black holes?

This question on the world building site sparked my curiosity on whether we could see signs of an intergalactic civilization. The question itself effectively asks whether this is possible for our own ...
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### How will Juice substantially increase its inclination around Jupiter in January 2031?

The ESA video Juice’s Jovian odyssey linked below is quite interesting to watch. Around January of 2031 it substantially increases its inclination around Jupiter. Big inclination changes can be ...
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### How difficult to gravity assist brake on entry to Alpha Centauri system? [duplicate]

Say a generation ship arriving at Alpha Centauri A system wants to get into orbit (or land) on an exoplanet there. After decelerating for the 2nd half of the journey, their approach velocity is still ...
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### Did the spacecrafts Galileo or Juno use the Galilean moons for a gravity assist before entering Jovian orbit?

Galileo and Juno are the only two spacecraft to have entered orbit around Jupiter. Did either of them use one of the Galilean moons for a gravity brake before in order to enter a stable orbit around ...
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### Would the Oberth effect apply to a rocket powered playground swing?

Would the Oberth effect (as explained as an answer to a gravity assist maneuver) apply to an earthbound partial orbit simulator in a strong gravity field, i.e. a playground swing? Imagine a swing with ...
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### Would an astronaut experience a force during a gravity assist maneuver?

When an astronaut is inside of a ship accelerating (from engine burns), or decelerating (due to reentry) they experience a tug in a relative direction. Suppose an astronaut is in a space ship that is ...
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### Why is NASA proposing an EMEJ (MEGA) trajectory for Europa Clipper instead of EEJ?

A launch service request was recently put out for Europa Clipper to do a flyby of Mars on its way to Jupiter. How is that a better trajectory than an EEJ, similar to Juno? Launch Vehicle Performance: ...
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### Could artificial magnets orbiting the sun be used to accelerate spacecraft, like a magnetic "gravity" assist?

Say there's a powerful magnet in an orbit between those of Earth and Mars. Could a spacecraft traveling between those planets save propellant by performing a slingshot maneuver using its magnetic ...
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### Gravity assist from Jupiter if leaving Callisto?

If I spacecraft was leaving Callisto to return to Earth, would there by any situation where it would use a gravity assist from Jupiter to increase its velocity?
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### How do space agencies choose arrival dates to planets (i.e. Mercury) from a gravity assist (i.e. Venus)?

Assuming I was looking for arrival opportunities from 2020 to 2030, how can I calculate the possible arrival dates to Mercury given a departure date from a gravity assist from Venus?
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### Was the gravity assist at Jupiter the most dangerous part of the New Horizons mission?

In terms of success of the mission, was the Jupiter fly-by the time when problems with the flight path was most likely to happen? Was the odds of failure at that point ever studied? If so, what were ...
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### Is it more efficient to burn all needed fuel in an Oberth manoeuvre at once or burn a fraction of the fuel for each orbit?

I was looking into Parker Solar Probes trajectory and was wondering what would be the most optimal way to utilize a retrograde thrust at perihelion to reduce the number of needed gravity assists. I ...
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### Speed at aphelion is decreasing for Parker Solar Probe with each new orbit despite being closer to the Sun

Sorry for the really bad picture I am looking at some data from the Parker Solar Probe mission and I was looking at the speeds of PSP at perihelion and aphelion at each new, different, orbit (the ...
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### Effect of incoming velocity on change in velocity in a gravity assist

In a gravity assist does the incoming velocity of a space craft effect how much speed it gains. For example say a rocket was approaching Jupiter for a gravity assist with speed v and another rocket ...
1 vote
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### Why is the highest speed that Voyager 2 achieved from the Jupiter gravity assist not at perijove?

I plotted some data of the speed of Voyager 2 for various times (around the Jupiter flyby) and noticed that the highest speed that Voyager achieved was not at perijove and was wondering why this might ...
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### Where can I find the specific details of a gravity assist space mission?

0 I am writing a research essay where I need to know the specific details of a gravity assist mission such as Voyager 2's flyby of Jupiter for example (but any mission would work as long as it is a ...
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### What is the relationship between the periapsis altitude and the change in velocity in a gravity assist?

In a gravity assist maneuver if I were to decrease the distance from the rocket to the periapsis of the planet it is orbiting (I believe this is called the periapsis altitude but I may be wrong) it ...
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### Have space probe gone to unplanned destinations?

Reading this question about multiple gravity assists (Why is Voyager 1 faster than all other space probes?), it caused me to wonder if any probes have been redirected to additional (or alternate) ...
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### What do the shaded vertical lines in the animation of Gravity assists of space probes, mean?

Example Animations from Wikipedia — https://en.wikipedia.org/wiki/Gravity_assist#/media/File:Animation_of_Voyager_1_trajectory.gif https://en.wikipedia.org/wiki/File:...
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### Is a graviational slingshot around Mercury a feasible solution for space probes?

Our spacecraft have rarely visited Mercury, for reasons obvious to those who know orbital mechanics. The Mariner 10 visit to Mercury was revolutionary by using Venus for the novel slingshot maneuver, ...
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### Will Dragonfly flyby Jupiter en route to Saturn?

The table on the "Exploration of Jupiter" Wikipedia page suggests Dragonfly will be the first mission to the outer planets that will not use a gravity assist from Jupiter. Is there a source confirming ...
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### Why does Voyager 1 lose speed after the sudden gain in speed from gravity assist?

The Voyager 1 loses speed gradually after gaining speed from gravity assist. Is the external thrust is applied in the opposite direction to move closer to the planet, or does the spacecraft lose its ...
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### Rockoon on steroids

In typical rockoon a balloon is the lifting body to the upper atmosphere where a rocket is released and ignited. But I would like to ask about a variation to launch small payloads to space. Instead ...
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### How exactly did Jupiter change Ulysses orbital plane from nearly ecliptic to polar?

Ulysses spacecraft trajectory is truly amazing. Utilizing gravity assist from Jupiter it was sent into polar orbit around the Sun. I can understand gravity assist concept, I can also (intuitively) ...
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### Could we reverse gravitational slingshot a fast object to slow it down and capture it in an orbit?

I have heard of plans to capture an asteroid in an orbit around the earth, to have it close by so that we could study it more easily. Such objects can have very high velocities, (I assume) possibly ...
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### Free Return Transfer Problem

I'm trying to understand how a free-transfer return works. It makes sense to me conceptually, but putting numbers to it it is unclear. I'm not sure how to obtain information about the transfer ...
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### What is the fastest velocity to which something can be accellerated using a gravity assist [duplicate]

My understanding of gravity-assists (slingshot) is that they use some of a more-massive object's orbital energy to gain massive acceleration. What's the upper limit on how much velocity an object ...
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### STK Astrogator Earth Flyby

TLDR: How do you set up an EEV maneuver, specifically, how do you go from an earth orbit to a heliocentric orbit with a periapsis within Venus’s orbit in astrogator? I know the theory but astrogator ...
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### History of the planetary flyby for gravitational assist; first conception, mathematical demonstration, plan, and execution?

Planetary flybys for gravitational assists are a stable of deep space missions. When did the following things happen? First documented realization that gravitational assists in spaceflight were ...
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### Do you need to burn fuel between gravity assists?

If you are planning a mission to an outer planet with multiple gravity assists included, do you need to do some burns for corrections, between the slingshots, or the ideal trajectory is already ...
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### Were there any identified launch windows and gravity-assist trajectories that could put a probe on a "Grand Tour" trajectory around 1981?

For context, I am developing an alternate history that features a far more ambitious Voyager program than the one undertaken in real life. However, despite the increase in NASA funding provided in the ...
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### How to plot conic from Lambert solver

I am trying to solve for an optimal multi-gravity assist trajectory from Earth to Saturn using Matlab. I have already solved for the departure and arrival velocities from and to each planet using a ...
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### Gravity assist from Mercury

The Oberth effect states most energy can be gained when you have highest velocity in orbit. The interplanetary missions, generally involve ion propulsion along with gravity assist from planets such as ...
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### Can a "gravity assist" at a black hole accelerate light faster than the speed of light? [closed]

With the help of a gravity assist from a black hole, can light travel faster than its natural light speed?? Satellites use gravity assistance. In a similar way can light traveling near black hole ...
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### Gravitational keyhole for spacecraft flyby?

Is there a term for the area near a planet a spacecraft must pass through for a gravitational-assist flyby, or does 'gravitational keyhole' apply to gravitational assists as well as for asteroids?
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### Mangalyaan + Trident; is it possible? escape the solar system using a low cost booster

5 years ago, India launched the Mangalyaan spacecraft to Mars, on a budget that raised eyebrows at the time. It was probably the Mars mission launched with the least powerful rocket; a feat only made ...