# How much G force is applied when correcting an orbit around Earth?

How much g force is applied to a satellite to correct a decaying orbit if done each orbit? How long does it take to correct an orbit on the average?

I understand there are variables as in which orbit and the weight of the satellite. Maybe using the least and most wieght burn and g-force.

Is solar power electromagnetic propusion possible? The Orbital Mass Accelerator Engine Theory

• obviously it depends on how long is the burn and how big is the correction. In principle, a spacecraft can experience unlimited G force, for an extremely short burn. Apr 26, 2018 at 19:09
• In principle, as @user3715778 says, it could be almost anything -- a hugely violent, but very brief accelleration every few orbits, or a gentle nudge equal to the drag force experienced, but going on all the time (this is used by so-called "drag free" satellites). A reasonable question might be what is the most delta-V per orbit needed to maintain LEO for a known satellite. The lower limit is zero for satellites in high enough orbits. Apr 26, 2018 at 20:23

In practice, the g force applied for orbital corrections is very small. The satellite operator has plenty of time to make the correction, and if you are capable of accelerating the satellite at more than a small fraction of a g, it suggests that you brought too much mass along in the form of a rarely used, over-powered engine.

For the ISS in particular, acceleration during reboost ranges from 0.008 m/s^2 to 0.0185 m/s^2, that is, 1/1200 g to 1/500 g, depending on whether the reboost is done by the Zvezda module or a docked Progress supply ship. Correction burns are typically done once or twice a month, and take several minutes to execute.

A hypothetical 4.4 ton satellite in LEO using a single R-4D hypergolic thruster producing 440N for reboost would accelerate at 0.1 m/s^2 or 1/100 g.

In geosynchronous orbit, some satellites are using efficient electric thrusters with even lower thrust. The USAF's AEHF communications satellites mass about 6 tons, and use Hall-effect thrusters which produce 270 milliNewtons (!) of thrust. This yields only about 0.00004 m/s^2 acceleration, or 4 micro-g. In this case, the maneuvering isn't to reboost from drag losses, but to correct for any other causes of drift - measurement errors from the last time the satellite was maneuvered, solar wind, thermal radiation effects, etc.

Using a very strong engine for high accelaration in a very short time requires additional mass for the rocket engine and the structure. Therefore additional fuel is necessary to accelerate the heavy engine itself. This method is inefficient.

To raise a circular orbit, the most efficient method is a Hohmann transfer using two short burns. But the Hohmann transfer is a mathematical theory based on two instantaneous velocity changes. In reality instantaneous velocity changes are impossible.

Using a very long continous small thrust needs more fuel and may be used with ion thrusters.

A practical method (without ion thrusters) would use short burns, but not too short as well as too long.

• That is exactly how the OMA would work. Thanks
– Muze
Apr 27, 2018 at 10:14
• Your first paragraph undermines your second; splitting the Hohmann into multiple burns at perigee and apogee is more efficient if it lets you use a significantly smaller engine. Apr 27, 2018 at 15:43