ATRONOMY – ORBITAL MECHANIC (52) CALCULATOR
Deorbit Burn
A precise tool.
What is the Deorbit Burn & How does it work?
A deorbit burn is a retroβgrade impulse applied to a spacecraft in a circular orbit to lower its perigee into the denser layers of a planetβs atmosphere. By reducing the orbital energy, the spacecraft will intersect the atmosphere and experience drag that ultimately leads to reβentry and landing or disposal. For a circular starting orbit with radius rβ and a desired perigee radius rβ, the required change in velocity (Ξv) can be derived from visβviva equations. The burn is performed opposite to the direction of motion, turning the circular orbit into an ellipse whose perigee is at rβ. This Ξv is independent of the spacecraftβs mass, but it determines how much propellant must be expended. Once Ξv is known, the propellant mass follows from the Tsiolkovsky rocket equation, which relates Ξv, the specific impulse Iββ, and the initial mass mβ. The result tells mission planners the amount of fuel needed to safely deorbit the vehicle.
\Delta v = \sqrt{\frac{\mu}{r_1}}\left(\sqrt{\frac{2 r_2}{r_1+r_2}}-1\right)
\Delta v = required deorbit burn deltaβv, \mu = Earthβs gravitational parameter, r_1 = initial orbital radius, r_2 = target perigee radius
Parameters
Result
β
Frequently Asked Questions
What is a deorbit burn?
A deorbit burn is a maneuver where a spacecraft fires its engines in the opposite direction of its motion to lower its orbit and eventually re-enter the atmosphere.
How does the radius of the starting orbit affect the deorbit burn?
The larger the starting orbit’s radius, the more Ξv is required to achieve the desired perigee radius and initiate re-entry.
What factors determine the effectiveness of a deorbit burn?
The effectiveness depends on the spacecraft’s mass, the altitude of the orbit, and the duration and force of the engine burn.
Can a deorbit burn be performed in any orbit type?
A deorbit burn is typically performed in a circular orbit to simplify calculations and ensure even energy distribution.
What happens if the deorbit burn is too small?
If the deorbit burn is insufficient, the spacecraft may not reach the desired perigee altitude and could require additional burns or remain in orbit longer than intended.
How long does it take for a spacecraft to re-enter after a successful deorbit burn?
The time to re-entry depends on factors like atmospheric density, spacecraft design, and the altitude of the perigee. It can range from minutes to hours.
Is there any risk associated with performing a deorbit burn?
Yes, there is a risk of engine failure or miscalculating the Ξv needed, which could result in either too much or too little orbital change.
Results are for informational purposes only and do not constitute professional advice.