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Answer(s) to What types of propulsion are used to adjust an orbit? lead me to wonder if electric propulsion has ever been used for a proper TCM or "trajectory correction maneuver" in deep space. I am sure that the long propulsive periods (months or years) have had integrated fine tunings as their progress has been monitored,

but here I'm asking about a "burn" or maneuver using an ion engine that was implemented strictly as a calculated correction to a trajectory; it was perhaps listed as an option on the mission plan but it was uncertain if it would be needed or if so how much (how long) would be needed until that point in the trajectory arrived.

Question: Has ion propulsion ever been used in a deep space trajectory correction maneuver proper?

A specific example is necessary for a "yes" answer, but I suspect the answer might be "no" or "not really in a separate TCM as they are currently recognized, but definitely integrated into long propulsive burns".

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The latter: not really in a separate TCM, but integrated into long propulsive burns ... which may be updated after anomalies occur.

TCMs are small maneuvers (possibly as small as 5-10 m/s) and used to correct differences between the mission design and the flight (e.g. launch errors, thruster misalignment errors, etc.). Optimization of TCMs include the exact placement in the trajectory, their duration, the rotation of the vehicle during the maneuver, etc. Overall, a TCM is typically quite short (single digit seconds, maybe up to a few dozen seconds). Insertion maneuvers (to insert a spacecraft around a celestial body as an interplanetary trajectory) are however quite long and require lots more fuel (typically several minutes long).

Low thrust trajectories require a very different mission design to high thrust trajectories. Instead of being able to rely on a high thrust (e.g. 1500 Newton) burn that can create a large force within milliseconds of activation, a low thrust trajectories follow a continuous optimization of the trajectory. Therefore, if a TCM-like maneuver is needed, the trajectory would be fully re-optimized from when the trajectory deviation is noticed and the full profile of the trajectory will be impacted. An example of how mission designers can plan for this is laid out in "A Monte Carlo Approach to Measuring Trajectory Performance Subject to Missed Thrust" by Laipert and Imken (2014), open-access on NASA NTRS.

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DS1 was a JPL technology-demonstration mission launched in 1998. It used an ion-propulsion system (IPS) for trajectory shaping and used both IPS and RCS for TCMs. DS1 flew by asteroid 9969 Braille on July 29, 1999 and comet 19P/Borrelly on Sept 22, 2001.

This link points to a collection of reports about Deep Space 1 AutoNav. Several IPS TCMs were used on the approach to asteroid Braille. The reports' page 25 describes one on 6/14/99 (m/d/y) and page 30 on 7/23/99. Page 117 describes one on 9/11/01 (!) to target comet Borrelly.

So, yes, ion propulsion has been used for deep-space TCMs.

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    $\begingroup$ Interesting find! Is it known how long these burns were? The premise of my answer (and my experience) is that thrusting arcs for low thrust are not considered TCMs because of their duration. This distinction changes how one would fly the mission in terms of OD. For TCM, it's fair to stop the tracking during the maneuver, pick it after, and rebuild the maneuver with OD. For a thrust arc, you need to model the maneuver in the OD filter or your results won't be good at all. $\endgroup$
    – ChrisR
    Commented Nov 28, 2021 at 21:54
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    $\begingroup$ In that report, the paragraph immediately before the cited 6/14/99 says the first IPS TCM was 1.5 m/s. Don't know about the others. You're right about modeling the TCM. Onboard DS1, the ACS and IPS subsystems provided delta-v information to AutoNav which was collected in a "nongrav-history file" (report p13 section 2.4.5.2). $\endgroup$
    – Bob Werner
    Commented Nov 29, 2021 at 0:07
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Yes it has on the Dawn mission to be exact. The ion drive uses an energized xenon atoms to propel it (It has three).

Dawn mission NASA

it was launched in 2007 and is still active today

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LISA-Pathfinder uses Colloid/FEEP thruster for keeping exact position on it's trajectory around Sun/Earth-L1.

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    $\begingroup$ Welcome to Space! Yep, while the Sun-Earth Lagrange point orbits are in resonance with Earth it's definitely a heliocentric orbit and therefore counts as "deep space". I totally forgot about that, thanks! $\endgroup$
    – uhoh
    Commented Nov 29, 2021 at 22:56

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