# Questions tagged [delta-v]

Literal meaning is "change in velocity". The quantity has utility in rocketry as measure of the change in velocity that a reaction engine must produce to move into a given trajectory. The rocket equation establishes that the mass ratio of payload to initial mass is an exponential function of delta-v divided by the propellant velocity.

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### How could 99942 Apophis, in 2029, be captured and brought into a low Earth orbit?

I'm currently attempting to plan out a mission where, in 2029, during Apophis's close approach to Earth, a rocket is sent up to intercept Apophis and decelerate it, making it orbit the Earth. At it's ...
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### What Delta-V can I gain from very low thrust exit from EML-5 by gravity assist from Earth to Mars?

My vehicle can exit Earth - Moon L-5 point by very low thrust and enter Earth fly-by to Mars. I am not concerned about the time for this maneuver, but say at least 80 days. What Delta-V can be gained ...
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### Could an astronaut with a jump and a "jet pack" "jump" off of moon?

The initial naive question was: "Could an astronaut with a jump and a "jet pack" "jump" off of moon?" :) For fun let's assume the most beneficial circumstances: Gemini ...
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### What does ln mean in the Delta V equation?

I am working on a project for school and can't figure out what ln means in the Delta-V equation, as in Δv = VE * ln(ML / ME). I know that Δv is Delta V, VE is ...
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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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### Are there uses for these 'quasi iso-propic' supersynchronous transfer orbits?

In my answer to What are the benefits of supersynchronous transfer orbits? I stumbled upon an interesting outcome when considering the total $\Delta V$ cost from an inclined low altitude parking orbit ...
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### When is the supersynchronous orbit more efficient than a typical Hohmann transfer where inclination change and circularization are simultaneous?

The title essentially explains it all. Some GEO launch vehicles like Proton, which launches from Baikonur at a latitude of 46 degrees, launch into a supersynchronous orbit. So at what point is the ...
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### What are the benefits of supersynchronous transfer orbits?

Some satellites are injected into higher apogee than standard GTO apogee of 35 786 km. Next the satellite then has to increase its perigee ( usually 250 km ) to GEO altitude. Then the apogee has to be ...
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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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### What is the largest single burn plane change maneuver executed in LEO?

Below 2000 km in low Earth orbit (or close to it), what is the largest propulsive plane change from a single burn? Expecting an answer in degrees, a named mission and vehicle executing the burn itself....
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### How is delta-v calculated for an interstellar journey?

Just recently I have been learning about orbital mechanics and I came across the following article: https://blogs.scientificamerican.com/life-unbounded/why-chemical-rockets-and-interstellar-travel-...
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### What is the equation that relates delta v of a rocket to time taken to complete an orbit?

I wanted to see how the delta-v produced by a rocket affects the time it takes to complete a certain orbit. So what is the equation that relates these two quantities?
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### How much delta-v could be saved with a Hohmann-like transfer orbit to the aphelion of Mercury 's orbit instead of its perihelion?

I wrote "Hohmann-like" of course because Mercury's orbit is rather eccentric and has an inclination of 7 ⁰. From this factsheet I've learned that perihelion is at 46 million km and aphelion ...
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### How to convert bi-propellant fuel into Delta-v (for ex., for JWST)

The following news gave the details on the quantity of fuel embarked on JWST: NASA gives green light to fuel the James Webb Telescope. The Webb telescope’s spacecraft bus, built by Northrop Grumman, ...
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### Extended mission options for Juno?

Juno has been given several mission extensions, the last (and most exciting) of which involves close passes to three of the Galilean satellites, also allowing them to trim its orbit every time, and ...
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### Pure orbit inclination changing, why delta v differs between vector and numerical approach?

as said in the title I have different results between numerical en vector approach during inclination changing maneuver. The initial orbit : Perigee radius : 6700 km Eccentricity : 0.7 Inclination : ...
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### Does other orbital parameters change on plane alignment impulsive maneuver?

I work on small application to apply impulsive maneuver on an orbit. I want to align two orbits in the same plane. After the execution of the function, original orbit has the same inclination and ...
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### Why is "delta-v + $\sqrt{{v_E}^2 + C_3}$ where ${v_E}^2 =$11.19 km/s" the correct way to calculate total propulsive delta-v? Please show all work

There is one answer to What spacecraft has had the greatest total propulsive delta-v? and I can not understand how its numbers have been calculated. Response to comments does not seem forthcoming so I'...
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### What spacecraft has had the greatest total propulsive delta-v?

How fast is fuel escaping a rocket for it to reach the escape velocity 11 km/s? was an active and well-received discussion! It's always exciting when we first realize that a rocket can go much faster ...
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### Range of travel time between particular planets using the Interplanetary Transport Network/Interplanetary Superhighway?

I understand the Interplanetary Transport Network allows for travel at low speeds between different planets in the solar system using very little energy. Is there flexibility in how long it would take ...
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### Do lower pressure pressure-fed rockets get more Delta-V?

I was playing around with the math for getting a pressure-fed rocket to orbit and came across something that I haven't seen addressed anywhere. In a pressure-fed rocket, the chamber pressure of the ...
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### Minimum deltaV between two Orbits (re Jonathan McDowell tweet)

In this Tweet Jonathan McDowell estimates the required delta V between an object and a projectile. I have recalculated the ejection velocity of the Kosmos-2543 projectile. The delta-V between Kosmos-...
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### Why is it easier to escape the solar system than get to Mercury or the Sun?

It has been mentioned several times on this site that it is "easier" (less delta-v, and hence less fuel) to reach the escape velocity of the solar system, than to reach the planet Mercury or ...
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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 ...
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### Delta-v difference between Mars and Moon

Considering a simple Hohmann transfer, does it take less Delta-v and propellant to go to Mars than to the Moon
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