Delta-v budget
Encyclopedia
In the astrodynamics
and aerospace
industry, a delta-v budget (or velocity change budget) is the estimated delta-v
(or total velocity change) requirements for the various propulsive
tasks and orbital maneuver
s over one or more phases of a space mission.
Sample delta-v budget will enumerate various classes of maneuvers, delta-v per maneuver, number of maneuvers required over the time of the mission.
In the absence of an atmosphere, the delta-v is typically the same for changes in orbit in either direction; in particular, gaining and losing speed cost an equal effort.
Because the delta-v needed to achieve the mission usually varies with the relative position of the gravitating bodies, launch window
s are often calculated from porkchop plot
s that show delta-v plotted against the launch time.
of the vehicle. Minimising the delta-v budget as far as possible is usually very important to avoid the necessity for infeasibly big and expensive rockets.
The simplest budget can be calculated with Hohmann transfer, which moves from one circular orbit to another coplanar circular orbit via an elliptical transfer orbit. In some cases a bi-elliptic transfer
can give a lower delta-v.
A more complex transfer occurs when the orbits are not coplanar. In that case there is an additional delta-v necessary to change the plane of the orbit. The velocity of the vehicle needs substantial burns at the intersection of the two orbital planes and the delta-v is usually extremely high. However, these plane changes can be almost free in some cases if the gravity and mass of a planetary body is used to perform the deflection. In other cases, boosting up to a relatively high altitude apoapsis gives low speed before performing the plane change and this can give lower total delta-v.
The slingshot effect can be used in some cases to give a boost of speed/energy; if a vehicle goes past a planetary or lunar body, it is possible to pick up (or lose) much of that body's orbital speed relative to the Sun or a planet.
Another effect is the Oberth effect
- this can be used to greatly decrease the delta-v needed, as using propellant at low potential energy/high speed multiplies the effect of a burn. Thus for example the delta-v for a Hohmann transfer from Earth's orbital radius to Mars' orbital radius (to overcome the Sun's gravity) is many kilometres per second, but the incremental burn from LEO over and above the burn to overcome the Earth's gravity is far less if the burn is done close to the Earth than if the burn to reach a Mars transfer orbit is performed at Earth's orbit, but far away from Earth.
Because the slingshot effect and Oberth effect depend on the position and motion of bodies, the delta-v budget changes with launch time. These can be plotted on a porkchop plot
.
Course corrections usually also require some propellant budget. Propulsion systems never provide precisely the right propulsion in precisely the right direction at all times and navigation also introduces some uncertainty. Some propellant needs to be reserved to correct variations from the optimum trajectory.
can be surprisingly low. For the Ansari X Prize
altitude of 100 km, Space Ship One required a delta-v of roughly 1.4 km/s. To reach low earth orbit of the space station of 300 km, the delta-v is over six times higher about 9.4 km/s. Because of the exponential nature of the rocket equation the orbital rocket needs to be considerably bigger.
) are given in km/s units. This table assumes that the Oberth effect
is being used - this is possible with high thrust chemical propulsion but not with current electrical propulsion.
The return to LEO figures assume that a heat shield
and aerobraking
/aerocapture
is used to reduce the speed by up to 3.2 km/s. The heat shield increases the mass, possibly by 15%. Where a heat shield is not used the higher from LEO Delta-v figure applies, the extra propellant is likely to be heavier than a heat shield. LEO-Ken refers to a low Earth orbit with an inclination to the equator of 28 degrees, corresponding to a launch from Kennedy Space Center
. LEO-Eq is an equatorial orbit.
s) only produce a low thrust so the Oberth effect
cannot normally be used. This results in the journey having a higher delta-V and frequently a large increase in time. The high ISP of electrical thrusters may significantly reduce the cost of the flight but due to the extra time are not viable for humans (interplanetary flights are an exception). The delta-v is in km/s, normally accurate to 2 significant figures and will be the same in both directions unless say a heat shield is used.
According to Marsden and Ross, "The energy levels of the Sun-Earth and points differ from those of the Earth-Moon system by only 50 m/s (as measured by maneuver velocity)."
on Earths atmosphere (substantial reentry shields would be required). The orbital phasing can be problematic; once rendezvous has been achieved, low delta-v return windows can be fairly far apart (more than a year, often many years), depending on the body.
However, the delta-v to reach them is usually rather higher, over 3.8 km/s, which is still less than the delta-v to reach the moon's surface.
In general bodies that are much further away or closer to the Sun than the Earth have more frequent windows for travel, but usually have larger delta-v's.
Astrodynamics
Orbital mechanics or astrodynamics is the application of ballistics and celestial mechanics to the practical problems concerning the motion of rockets and other spacecraft. The motion of these objects is usually calculated from Newton's laws of motion and Newton's law of universal gravitation. It...
and aerospace
Aerospace
Aerospace comprises the atmosphere of Earth and surrounding space. Typically the term is used to refer to the industry that researches, designs, manufactures, operates, and maintains vehicles moving through air and space...
industry, a delta-v budget (or velocity change budget) is the estimated delta-v
Delta-v
In astrodynamics a Δv or delta-v is a scalar which takes units of speed. It is a measure of the amount of "effort" that is needed to change from one trajectory to another by making an orbital maneuver....
(or total velocity change) requirements for the various propulsive
Spacecraft propulsion
Spacecraft propulsion is any method used to accelerate spacecraft and artificial satellites. There are many different methods. Each method has drawbacks and advantages, and spacecraft propulsion is an active area of research. However, most spacecraft today are propelled by forcing a gas from the...
tasks and orbital maneuver
Orbital maneuver
In spaceflight, an orbital maneuver is the use of propulsion systems to change the orbit of a spacecraft.For spacecraft far from Earth—for example those in orbits around the Sun—an orbital maneuver is called a deep-space maneuver .-delta-v:...
s over one or more phases of a space mission.
Sample delta-v budget will enumerate various classes of maneuvers, delta-v per maneuver, number of maneuvers required over the time of the mission.
In the absence of an atmosphere, the delta-v is typically the same for changes in orbit in either direction; in particular, gaining and losing speed cost an equal effort.
Because the delta-v needed to achieve the mission usually varies with the relative position of the gravitating bodies, launch window
Launch window
Launch window is a term used in spaceflight to describe a time period in which a particular launch vehicle must be launched. If the rocket does not launch within the "window", it has to wait for the next window....
s are often calculated from porkchop plot
Porkchop plot
Porkchop plot is a chart that shows contours of equal characteristic energy against combinations of launch date and arrival date for a particular interplanetary flight....
s that show delta-v plotted against the launch time.
General principles
The rocket equation shows that the delta-v of a rocket is proportional to the logarithm of the mass ratioMass ratio
In aerospace engineering, mass ratio is a measure of the efficiency of a rocket. It describes how much more massive the vehicle is with propellant than without; that is, it is the ratio of the rocket's wet mass to its dry mass...
of the vehicle. Minimising the delta-v budget as far as possible is usually very important to avoid the necessity for infeasibly big and expensive rockets.
The simplest budget can be calculated with Hohmann transfer, which moves from one circular orbit to another coplanar circular orbit via an elliptical transfer orbit. In some cases a bi-elliptic transfer
Bi-elliptic transfer
In astronautics and aerospace engineering, the bi-elliptic transfer is an orbital maneuver that moves a spacecraft from one orbit to another and may, in certain situations, require less delta-v than a Hohmann transfer....
can give a lower delta-v.
A more complex transfer occurs when the orbits are not coplanar. In that case there is an additional delta-v necessary to change the plane of the orbit. The velocity of the vehicle needs substantial burns at the intersection of the two orbital planes and the delta-v is usually extremely high. However, these plane changes can be almost free in some cases if the gravity and mass of a planetary body is used to perform the deflection. In other cases, boosting up to a relatively high altitude apoapsis gives low speed before performing the plane change and this can give lower total delta-v.
The slingshot effect can be used in some cases to give a boost of speed/energy; if a vehicle goes past a planetary or lunar body, it is possible to pick up (or lose) much of that body's orbital speed relative to the Sun or a planet.
Another effect is the Oberth effect
Oberth effect
In astronautics, the Oberth effect is where the use of a rocket engine when travelling at high speed generates much more useful energy than one at low speed...
- this can be used to greatly decrease the delta-v needed, as using propellant at low potential energy/high speed multiplies the effect of a burn. Thus for example the delta-v for a Hohmann transfer from Earth's orbital radius to Mars' orbital radius (to overcome the Sun's gravity) is many kilometres per second, but the incremental burn from LEO over and above the burn to overcome the Earth's gravity is far less if the burn is done close to the Earth than if the burn to reach a Mars transfer orbit is performed at Earth's orbit, but far away from Earth.
Because the slingshot effect and Oberth effect depend on the position and motion of bodies, the delta-v budget changes with launch time. These can be plotted on a porkchop plot
Porkchop plot
Porkchop plot is a chart that shows contours of equal characteristic energy against combinations of launch date and arrival date for a particular interplanetary flight....
.
Course corrections usually also require some propellant budget. Propulsion systems never provide precisely the right propulsion in precisely the right direction at all times and navigation also introduces some uncertainty. Some propellant needs to be reserved to correct variations from the optimum trajectory.
Launch/landing
The delta-v requirements for sub-orbital spaceflightSub-orbital spaceflight
A sub-orbital space flight is a spaceflight in which the spacecraft reaches space, but its trajectory intersects the atmosphere or surface of the gravitating body from which it was launched, so that it does not complete one orbital revolution....
can be surprisingly low. For the Ansari X Prize
Ansari X Prize
The Ansari X Prize was a space competition in which the X Prize Foundation offered a US$10,000,000 prize for the first non-government organization to launch a reusable manned spacecraft into space twice within two weeks...
altitude of 100 km, Space Ship One required a delta-v of roughly 1.4 km/s. To reach low earth orbit of the space station of 300 km, the delta-v is over six times higher about 9.4 km/s. Because of the exponential nature of the rocket equation the orbital rocket needs to be considerably bigger.
- Launch to LEOLow Earth orbitA low Earth orbit is generally defined as an orbit within the locus extending from the Earth’s surface up to an altitude of 2,000 km...
— this not only requires an increase of velocity from 0 to 7.8 km/s, but also typically 1.5–2 km/s for atmospheric drag and gravity dragGravity dragIn astrodynamics and rocketry, gravity drag is a measure of the loss in the net performance of a rocket while it is thrusting in a gravitational field... - Re-entryRe-Entry"Re-Entry" was the second album released by UK R&B / Hip Hop collective Big Brovaz. After the album was delayed in May 2006, the band finally release the follow-up to "Nu Flow" on 9 April 2007...
from LEO — the delta-v required is the orbital maneuvering burn to lower perigee into the atmosphere, atmospheric drag takes care of the rest.
Stationkeeping
| Maneuver | Average delta-v per year [m/s] | Maximum per year [m/s] |
|---|---|---|
| Drag compensation in 400–500 km LEO | <25 | <100 |
| Drag compensation in 500–600 km LEO | < 5 | < 25 |
| Drag compensation in > 600 km LEO | < 7.5 | |
| Station-keeping in geostationary orbit Geostationary orbit A geostationary orbit is a geosynchronous orbit directly above the Earth's equator , with a period equal to the Earth's rotational period and an orbital eccentricity of approximately zero. An object in a geostationary orbit appears motionless, at a fixed position in the sky, to ground observers... |
50–55 | |
| Station-keeping in / | 30–100 | |
| Station-keeping in lunar orbit | 0–400 | |
| Attitude control (3-axis) | 2–6 | |
| Spin-up or despin | 5–10 | |
| Stage booster separation | 5–10 | |
| Momentum-wheel unloading | 2–6 |
Earth–Moon space High Thrust
Delta-v needed to move inside Earth–Moon system (speeds lower than escape velocityEscape velocity
In physics, escape velocity is the speed at which the kinetic energy plus the gravitational potential energy of an object is zero gravitational potential energy is negative since gravity is an attractive force and the potential is defined to be zero at infinity...
) are given in km/s units. This table assumes that the Oberth effect
Oberth effect
In astronautics, the Oberth effect is where the use of a rocket engine when travelling at high speed generates much more useful energy than one at low speed...
is being used - this is possible with high thrust chemical propulsion but not with current electrical propulsion.
The return to LEO figures assume that a heat shield
Heat shield
A heat shield is designed to shield a substance from absorbing excessive heat from an outside source by either dissipating, reflecting or simply absorbing the heat...
and aerobraking
Aerobraking
Aerobraking is a spaceflight maneuver that reduces the high point of an elliptical orbit by flying the vehicle through the atmosphere at the low point of the orbit . The resulting drag slows the spacecraft...
/aerocapture
Aerocapture
Aerocapture is a technique used to reduce velocity of a spacecraft, arriving at a celestial body with a hyperbolic trajectory, in order to bring it in an orbit with an eccentricity of less than 1. It uses the drag created by the atmosphere of the celestial body to decelerate. Only one pass in the...
is used to reduce the speed by up to 3.2 km/s. The heat shield increases the mass, possibly by 15%. Where a heat shield is not used the higher from LEO Delta-v figure applies, the extra propellant is likely to be heavier than a heat shield. LEO-Ken refers to a low Earth orbit with an inclination to the equator of 28 degrees, corresponding to a launch from Kennedy Space Center
Kennedy Space Center
The John F. Kennedy Space Center is the NASA installation that has been the launch site for every United States human space flight since 1968. Although such flights are currently on hiatus, KSC continues to manage and operate unmanned rocket launch facilities for America's civilian space program...
. LEO-Eq is an equatorial orbit.
| ∆V km/s From\To | LEO-Ken | LEO-Eq | GEO | EML-1 | EML-2 | EML-4/5 | LLO | Moon | C3=0 |
|---|---|---|---|---|---|---|---|---|---|
| Earth Earth Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets... |
9.3 - 10 | ||||||||
| Low Earth Orbit Low Earth orbit A low Earth orbit is generally defined as an orbit within the locus extending from the Earth’s surface up to an altitude of 2,000 km... (LEO-Ken) |
4.24 | 4.33 | 3.77 | 3.43 | 3.97 | 4.04 | 5.93 | 3.22 | |
| Low Earth Orbit Low Earth orbit A low Earth orbit is generally defined as an orbit within the locus extending from the Earth’s surface up to an altitude of 2,000 km... (LEO-Eq) |
4.24 | 3.90 | 3.77 | 3.43 | 3.99 | 4.04 | 5.93 | 3.22 | |
| Geostationary Orbit Geostationary orbit A geostationary orbit is a geosynchronous orbit directly above the Earth's equator , with a period equal to the Earth's rotational period and an orbital eccentricity of approximately zero. An object in a geostationary orbit appears motionless, at a fixed position in the sky, to ground observers... (GEO) |
2.06 | 1.63 | 1.38 | 1.47 | 1.71 | 2.05 | 3.92 | 1.30 | |
| Lagrangian point 1 Lagrangian point The Lagrangian points are the five positions in an orbital configuration where a small object affected only by gravity can theoretically be stationary relative to two larger objects... (EML-1) |
0.77 | 0.77 | 1.38 | 0.14 | 0.33 | 0.64 | 2.52 | 0.14 | |
| Lagrangian point 2 Lagrangian point The Lagrangian points are the five positions in an orbital configuration where a small object affected only by gravity can theoretically be stationary relative to two larger objects... (EML-2) |
0.33 | 0.33 | 1.47 | 0.14 | 0.34 | 0.64 | 2.52 | 0.14 | |
| Lagrangian point 4/5 Lagrangian point The Lagrangian points are the five positions in an orbital configuration where a small object affected only by gravity can theoretically be stationary relative to two larger objects... (EML-4/5) |
0.84 | 0.98 | 1.71 | 0.33 | 0.34 | 0.98 | 2.58 | 0.43 | |
| Low Lunar orbit Lunar orbit In astronomy, lunar orbit refers to the orbit of an object around the Moon.As used in the space program, this refers not to the orbit of the Moon about the Earth, but to orbits by various manned or unmanned spacecraft around the Moon... (LLO) |
1.31 | 1.31 | 2.05 | 0.64 | 0.65 | 0.98 | 1.87 | 1.40 | |
| Moon Moon The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more... (Moon) |
2.74 | 2.74 | 3.92 | 2.52 | 2.53 | 2.58 | 1.87 | 2.80 | |
| Earth Earth Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets... Escape velocity Escape velocity In physics, escape velocity is the speed at which the kinetic energy plus the gravitational potential energy of an object is zero gravitational potential energy is negative since gravity is an attractive force and the potential is defined to be zero at infinity... (C3=0) |
0.00 | 0.00 | 1.30 | 0.14 | 0.14 | 0.43 | 1.40 | 2.80 | |
Earth-Moon space Low Thrust
Current electric thrusters (alias ion thrusterIon thruster
An ion thruster is a form of electric propulsion used for spacecraft propulsion that creates thrust by accelerating ions. Ion thrusters are categorized by how they accelerate the ions, using either electrostatic or electromagnetic force. Electrostatic ion thrusters use the Coulomb force and...
s) only produce a low thrust so the Oberth effect
Oberth effect
In astronautics, the Oberth effect is where the use of a rocket engine when travelling at high speed generates much more useful energy than one at low speed...
cannot normally be used. This results in the journey having a higher delta-V and frequently a large increase in time. The high ISP of electrical thrusters may significantly reduce the cost of the flight but due to the extra time are not viable for humans (interplanetary flights are an exception). The delta-v is in km/s, normally accurate to 2 significant figures and will be the same in both directions unless say a heat shield is used.
| From | To | delta-v in km/s |
|---|---|---|
| Low Earth Orbit (LEO) | Earth-Moon Lagrange 1 (EML-1) | 7.0 |
| Low Earth Orbit (LEO) | Geostationary Earth Orbit (GEO) | 6.0 |
| Low Earth Orbit (LEO) | Low Lunar Orbit (LLO) | 8.0 |
| Low Earth Orbit (LEO) | Sun-Earth Lagrange 1 (SEL-1) | 7.4 |
| Low Earth Orbit (LEO) | Sun-Earth Lagrange 2 (SEL-2) | 7.4 |
| Earth-Moon Lagrange 1 (EML-1) | Low Lunar Orbit (LLO) | 0.60 - 0.80 |
| Earth-Moon Lagrange 1 (EML-1) | Geostationary Earth Orbit (GEO) | 1.4 - 1.75 |
| Earth-Moon Lagrange 1 (EML-1) | Sun-Earth Lagrange 2 (SEL-2) | 0.30 - 0.40 |
Interplanetary
The spacecraft is assumed to be using chemical propulsion and the Oberth Effect.| From | To | delta-v in km/s |
|---|---|---|
| LEO | Mars Mars Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance... Transfer Orbit |
4.3 |
| Earth Earth Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets... Escape velocity Escape velocity In physics, escape velocity is the speed at which the kinetic energy plus the gravitational potential energy of an object is zero gravitational potential energy is negative since gravity is an attractive force and the potential is defined to be zero at infinity... (C3=0) |
Mars Mars Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance... Transfer Orbit Hohmann transfer orbit In orbital mechanics, the Hohmann transfer orbit is an elliptical orbit used to transfer between two circular orbits, typically both in the same plane.... |
0.6 |
| Mars Mars Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance... Transfer Orbit Hohmann transfer orbit In orbital mechanics, the Hohmann transfer orbit is an elliptical orbit used to transfer between two circular orbits, typically both in the same plane.... |
Mars Mars Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance... Capture Orbit |
0.9 |
| Mars Mars Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance... Capture Orbit |
Deimos Deimos (moon) Deimos is the smaller and outer of Mars's two moons . It is named after Deimos, a figure representing dread in Greek Mythology. Its systematic designation is '.-Discovery:Deimos was discovered by Asaph Hall, Sr... Transfer Orbit Hohmann transfer orbit In orbital mechanics, the Hohmann transfer orbit is an elliptical orbit used to transfer between two circular orbits, typically both in the same plane.... |
0.2 |
| Deimos Deimos (moon) Deimos is the smaller and outer of Mars's two moons . It is named after Deimos, a figure representing dread in Greek Mythology. Its systematic designation is '.-Discovery:Deimos was discovered by Asaph Hall, Sr... Transfer Orbit Hohmann transfer orbit In orbital mechanics, the Hohmann transfer orbit is an elliptical orbit used to transfer between two circular orbits, typically both in the same plane.... |
Deimos Deimos (moon) Deimos is the smaller and outer of Mars's two moons . It is named after Deimos, a figure representing dread in Greek Mythology. Its systematic designation is '.-Discovery:Deimos was discovered by Asaph Hall, Sr... surface |
0.7 |
| Deimos Deimos (moon) Deimos is the smaller and outer of Mars's two moons . It is named after Deimos, a figure representing dread in Greek Mythology. Its systematic designation is '.-Discovery:Deimos was discovered by Asaph Hall, Sr... Transfer Orbit Hohmann transfer orbit In orbital mechanics, the Hohmann transfer orbit is an elliptical orbit used to transfer between two circular orbits, typically both in the same plane.... |
Phobos Phobos (moon) Phobos is the larger and closer of the two natural satellites of Mars. Both moons were discovered in 1877. With a mean radius of , Phobos is 7.24 times as massive as Deimos... Transfer Orbit Hohmann transfer orbit In orbital mechanics, the Hohmann transfer orbit is an elliptical orbit used to transfer between two circular orbits, typically both in the same plane.... |
0.3 |
| Phobos Phobos (moon) Phobos is the larger and closer of the two natural satellites of Mars. Both moons were discovered in 1877. With a mean radius of , Phobos is 7.24 times as massive as Deimos... Transfer Orbit Hohmann transfer orbit In orbital mechanics, the Hohmann transfer orbit is an elliptical orbit used to transfer between two circular orbits, typically both in the same plane.... |
Phobos Phobos (moon) Phobos is the larger and closer of the two natural satellites of Mars. Both moons were discovered in 1877. With a mean radius of , Phobos is 7.24 times as massive as Deimos... surface |
0.5 |
| Mars Mars Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance... Capture Orbit |
Low Mars Mars Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance... Orbit Orbit In physics, an orbit is the gravitationally curved path of an object around a point in space, for example the orbit of a planet around the center of a star system, such as the Solar System... |
1.4 |
| Low Mars Mars Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance... Orbit Orbit In physics, an orbit is the gravitationally curved path of an object around a point in space, for example the orbit of a planet around the center of a star system, such as the Solar System... |
Mars Mars Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance... surface |
4.1 |
| EML2 | Mars Mars Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance... Transfer Orbit |
<1.0 |
| Mars Mars Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance... Transfer Orbit |
Low Mars Mars Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance... Orbit |
2.7 |
| Earth Earth Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets... Escape velocity Escape velocity In physics, escape velocity is the speed at which the kinetic energy plus the gravitational potential energy of an object is zero gravitational potential energy is negative since gravity is an attractive force and the potential is defined to be zero at infinity... (C3=0) |
Closest NEO Near-Earth object A near-Earth object is a Solar System object whose orbit brings it into close proximity with the Earth. All NEOs have a perihelion distance less than 1.3 AU. They include a few thousand near-Earth asteroids , near-Earth comets, a number of solar-orbiting spacecraft, and meteoroids large enough to... Asteroids |
0.8 - 2.0 |
According to Marsden and Ross, "The energy levels of the Sun-Earth and points differ from those of the Earth-Moon system by only 50 m/s (as measured by maneuver velocity)."
Delta-vs between Earth, Moon and Mars
Near earth object
Near earth objects are asteroids that are within the orbit of Mars. The delta-v to return from them are usually quite small, sometimes as low as 60m/s, using aerobrakingAerobraking
Aerobraking is a spaceflight maneuver that reduces the high point of an elliptical orbit by flying the vehicle through the atmosphere at the low point of the orbit . The resulting drag slows the spacecraft...
on Earths atmosphere (substantial reentry shields would be required). The orbital phasing can be problematic; once rendezvous has been achieved, low delta-v return windows can be fairly far apart (more than a year, often many years), depending on the body.
However, the delta-v to reach them is usually rather higher, over 3.8 km/s, which is still less than the delta-v to reach the moon's surface.
In general bodies that are much further away or closer to the Sun than the Earth have more frequent windows for travel, but usually have larger delta-v's.
See also
- Bi-elliptic transferBi-elliptic transferIn astronautics and aerospace engineering, the bi-elliptic transfer is an orbital maneuver that moves a spacecraft from one orbit to another and may, in certain situations, require less delta-v than a Hohmann transfer....
- Gravity assist
- Hohmann transfer
- The Oberth effect
- Tsiolkovsky rocket equationTsiolkovsky rocket equationThe Tsiolkovsky rocket equation, or ideal rocket equation is an equation that is useful for considering vehicles that follow the basic principle of a rocket: where a device that can apply acceleration to itself by expelling part of its mass with high speed and moving due to the conservation of...
- Pork-chop plot
- Synodic period