# How much could “sublimator operation” have possibly contributed to Apollo 11's “sizable downrange miss”?

This answer to the question Apollo-11 delta-v “due to residual pressure in the docking tunnel pushing the spacecraft apart” detected as it happened? Was it corrected? quotes from the Apollo 11 Mission Report; MSC-00171. Here is a longer quote from Section 7.8 LUNAR ORBIT NAVIGATION:

The coordinates obtained from the landmark tracking during revolution 12 deviated from the best preflight estimate of the center of the landing site ellipse by 0.097 degree north , 0.0147 degree east , and 0.038 mile below . These errors are attributed to the R2 potential model deficiencies. The large difference in latitude resulted from an error in the spacecraft state vector estimate of the orbit plane ; these were the data used to generate the sighting angles. The difference in longitude could also have been caused by an error in the estimated state vector or from tracking the wrong landmark .

The third problem area was the large number of trajectory perturbation in revolutions 11 through 13 because of uncoupled attitude maneuvers, such as hot firing tests of the lunar module thrusters, undocking impulse, station-keeping activity, sublimator operation and possibly tunnel and cabin venting. The net effect of these perturbations was a sizeable downrange miss.

A comparison between the lunar landing point coordinates generated from various data sources is presented in table 5-IV. The difference, or miss distance , was 0.0444 degree south and 0.2199 degree east, or approximately 4440 and 21 990 feet, respectively. The miss in latitude was caused by neglecting the two-revolution orbit plane propagation error , and the miss in longitude resulted from the trajectory perturbations during revolutions 11 through 13.

Question: How much could "sublimator operation" (second paragraph) have possibly caused a trajectory perturbation large enough to even be considered as a contributing factor to Apollo 11's trajectory error and "sizable downrange miss"?

Sublimation of water at least, is the conversion of solid ice to gas in a low vapor pressure environment such as space or a home freezer. It removes heat and is used to cool space suit coolant; see How have space suits dissipated the heat removed from astronauts? Roughly how much thrust and delta-v could this have possibly produced? Is it anywhere near large enough to have made a difference?

• Note that the operation of the LM sublimator did put Apollo 13 off course during the trans-Earth return phase, requiring midcourse corrections to keep the spacecraft in the proper reentry corridor and apparently puzzling controllers on the ground -- the LM, of course, wasn't normally present for trans-Earth flight. – Russell Borogove Jul 22 at 19:32
• @RussellBorogove if there is a source with some numbers or a calculation, that might make for a good answer. (I thought it was just the missing moon rocks, but all I know is what I learned in the movie) – uhoh Jul 22 at 23:43
• I think "missing moon rocks" was easier to explain than sublimator thrust. They also changed an amp-hour constraint to an amp constraint, Shepard's out-of-practice-ness due to being off flight status for years while struggling with Menière's disease to an ear infection, etc., etc. – Russell Borogove Jul 22 at 23:48