Questions tagged [gravity-assist]

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

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What delta-v for launching Trojan asteroids or outer Jovian moon ice to crash into the earth's moon (using Jupiter gravity assist)?

Is it feasible to utilize Trojan asteroids or an outer moon of Jupiter as a water resource for Luna (earth's moon)? What would be the approximate delta-v requirements to mine ice from a Trojan ...
54 votes
3 answers
8k views

Why did Voyager 2 receive a gravitational slowdown (as opposed to a slingshot) at Neptune?

I was actually answering this question today regarding velocities of spacecraft, and it occurred to me I've never really looked at this graph in much detail before: Heliocentric velocity of Voyager 2 ...
2 votes
0 answers
74 views

How is the trajectory of a gravitational assist flyby mission computed?

Based on much research after posing my previous question, as well as the discussions with the rest of the community, I now (think I have) a deeper understanding of how mission planning works. Based on ...
3 votes
0 answers
121 views

Can a gravity assist be designed without using simulation?

Suppose a three body scenario with an artificial satellite, a planet (much massive than the satellite), and a sun (much massive than the planet). There is no other significant force on these three ...
0 votes
1 answer
203 views

What speed could you achieve by slingshotting around earth from moon?

Imagine Apollo 13 had fuel to burn engines on the way back to earth but instead used earths gravity to accelerate and the slingshot around earth
3 votes
1 answer
153 views

Can a ship's thrusters amplify a gravity assist?

If a ship successfully absorbs a planet's kinetic energy to increase its speed, can it add to that speed by firing its thrusters? Thank you very much.
7 votes
1 answer
529 views

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) ...
19 votes
2 answers
9k views

Why did Voyager 1 lose speed after the sudden gain in speed from gravity assist?

The Voyager 1 lost speed gradually after gaining speed from gravity assist. Is the external thrust applied in the opposite direction to move closer to the planet, or does the spacecraft lose its ...
5 votes
1 answer
2k views

Are there any studies about "ping pong" cyclers between gas giants?

Imagine arriving at Saturn, jettisoning your passenger cargo, and then utilizing the massive gravitational pull of the gas giant to slingshot back towards Jupiter. Due to the immense mass of these ...
5 votes
1 answer
587 views

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 ...
25 votes
5 answers
6k views

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 ...
9 votes
1 answer
265 views

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 ...
7 votes
4 answers
324 views

How to place a satellite in retrograde heliocentric orbit?

Imagine a mission which requires a retrograde heliocentric orbit. How could this be achieved? a direct launch would require ridiculous delta-v. There was a similar delta-v problem placing Ulysses in a ...
36 votes
5 answers
10k views

The dreaded apocalyptic asteroid approaches Earth but lands safely on the Moon at zero relative velocity

An asteroid approaches and the Moon 'catches' it in the same way that a sports player catches a ball - that is to say by matching the velocity of the hand to that of the ball. Could a lucky slingshot ...
3 votes
1 answer
356 views

Gravity assist (flyby/slingshot) from an asteroid?

Could a spacecraft perform a gravity assist maneuver in an asteroid? Has it ever been done? I tend to think that the asteroid would need to be quite massive for a "significant" change of ...
1 vote
0 answers
86 views

V infinity matching software for gravity assists?

Is their software someone has already written for hyperbolic velocity matching of porkchop plots to be used to figure out ballistic gravity assists? Doing this in single threaded python requires using ...
1 vote
3 answers
360 views

Why weren't super heavy lift launch vehicles used for deep space missions?

According to this PDF Cassini-HuygensPDF, we would need to launch 70 tons if we wanted to do a Saturn transfer orbit from a low earth orbit. It says that there are no vehicles in NASA’s stable even ...
6 votes
2 answers
238 views

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 ...
3 votes
0 answers
55 views

Does Juno have enough fuel to push itself into a more elliptical orbit reaching out to Himalia? [duplicate]

Does the Juno probe have enough fuel to push itself into a highly elliptical orbit around Jupiter so that its apojove would be at Himalia's orbital distance to study Himalia better? Would a gravity ...
5 votes
1 answer
763 views

Can Juno use Jupiter's gravity to alter its orbit so that it goes close to Himalia?

Himalia is the most massive and second largest non-Galilean moon of Jupiter. Yet, due to its distant orbit, we still don't have sharp images of it. Does Juno have enough fuel to alter its orbit with ...
2 votes
2 answers
399 views

For what reasons are gravity assists used? What objects can be visited without such measures?

I'm trying to understand if it is only fuel efficiency that makes us use gravity assist, or we don't have enough rocket fuel in an average spacecraft to reach farther ends of solar system. Also, is ...
2 votes
0 answers
51 views

Where to find detailed information about space mission like Voyager or Galileo

Is there any place aside from NASA-JPL web page, where there is only some general information about the missions, where one can find more in-depth detailed values? For instance, I am looking for the ...
4 votes
0 answers
105 views

How would I or who/what could help me find the trajectory of an "Extended Grand Tour" spacecraft, without having to take a long course on the subject?

(As forewarning, the most integral details of this question are bolded.) For context, I have been writing an alternate history involving the accelerated development of spaceflight technology for over ...
7 votes
1 answer
165 views

Could the Moon's gravitational anomalies be used constructively?

The moon has a habit of de-orbiting passive satellites in low orbit because it is not a homogeneous ball. Any orbit therefore passes through different sections with different surface gravities. This ...
3 votes
1 answer
158 views

Patching two Lambert's problem solutions together

I am following this paper on the implementation of a genetic algorithm to find a good MGA trajectory. The way they approach the problem is by solving the Lambert problem for each planetary transfer. ...
3 votes
1 answer
214 views

Does a Titan flyby guarantee that a spacecraft can escape Saturn?

Could a spacecraft orbiting Saturn, like Cassini, use a Titan gravity assist to leave the Saturn system (e.g. to bring a sample back to Earth), without using fuel other than to reach Titan?
2 votes
2 answers
379 views

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 ...
1 vote
3 answers
445 views

What is the maximum orbital speed beyond which the orbit around any large object in the Solar System becomes unstable?

How fast is too fast to stay in orbit around any particular large body in the Solar System?
5 votes
1 answer
397 views

What was the smallest intentional, acknowledged slingshot maneuver?

I'll keep it short but please read through! Gravitation's $1/r$ potential means everything in the solar system is pulling on everything all the time. Gravitational slingshot maneuvers are normally ...
5 votes
3 answers
1k views

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: ...
0 votes
1 answer
168 views

How to calculate the max mass and speed of an asteroid capturable by gravity assist?

After reading this question and the answers, I am wondering about the limits of slingshot method to capture an asteroid into a planet orbit. Is it possible to calculate if an asteroid can be captured ...
3 votes
1 answer
165 views

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-...
8 votes
1 answer
387 views

Venus gravity assist (and aerobraking) - How much delta-V can it add?

The Voyagers made a grand tour using the gravity assist of each planet. But Jupiter, with a 12 year orbital period, doesn't always line up to be useful for spacecrafts destined to further planets. ...
5 votes
1 answer
420 views

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 ...
3 votes
1 answer
290 views

Determining the spacecraft position vector with respect to ICRF frame for Venus flyby

For an interplanetary mission design to Saturn, I have considered doing multiple gravity assists starting with Venus. I am using the JPL Horizons ephemeris and ESA Lambert Solver. I have the velocity ...
3 votes
1 answer
211 views

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 ...
1 vote
0 answers
116 views

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 ...
2 votes
1 answer
207 views

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 ...
6 votes
2 answers
355 views

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?
4 votes
2 answers
561 views

Is it profitable to save fuel for the Oberth effect during a Jupiter gravity assist?

Probes to the outer Solar system use a Jupiter flyby for gravity assist, all six such missions thus far have. While flying near a gravity well one can enjoy the Oberth effect which multiplies the ...
4 votes
3 answers
262 views

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?
7 votes
1 answer
620 views

How can I look for the best date of launch for gravity assist?

I am new to astrodynamics, and I am trying to learn about gravity assists, but I don't understand how I can easily decide a launch date and arrival late for the planet in which I calculate the gravity ...
6 votes
2 answers
271 views

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 ...
5 votes
4 answers
428 views

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) ...
13 votes
1 answer
2k views

What does the BackFlip lunar cycler do in its pass by Earth?

This paper describes an Earth-moon cycler orbit. In this concept, a 180 degree "BackFlip" is used to modify a more simple cycler orbit. However, I can't figure out what cycler orbit it modifies, and ...
2 votes
1 answer
172 views

If Cassini's final flyby of Saturn's moon Titan is the 127th Titan flyby, why is it called "T-126"?

Cassini's final flyby of Titan in April 2017 sealed it's fate in September of that year. This is described further in answers to What force is bringing Cassini down into Saturn's atmosphere in another ...
28 votes
4 answers
13k views

Could the sun be used as a gravity assist outside the solar system (with current tech)?

I think I might have understood what this XKCD comic is trying to do. The diagram is proposing to use the Oberth effect at closest approach to the sun to escape the solar system! (image license: CC ...
9 votes
3 answers
10k views

How do we come up with the gravity assist (or slingshot) formula?

When you search up in google gravity assist formula, it comes up with the simplest version: Which means that: Final velocity = Initial velocity + 2 (velocity of the planet) Then if we do some more ...
8 votes
1 answer
165 views

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 ...
1 vote
2 answers
5k views

Can you use magnets to travel through space?

My thought process is that there is very little friction in space minus gravitational pull. Which could be a good thing if you wanted to go faster or slow down. The question is, is it possible to ...