After the recent micro-meteoroid impact into a 2.5 inch thick cockpit window of the space shuttle Discovery during STS-120, I’ve checked what I had on micro-meteoroid research conducted by unmanned spacecraft. It seems NASA launched the Pegasus series
Satellites, which consisted of vast detector panels deployed from the large Saturn IV stages on Saturn I test flights. These unmanned spacecrafty provided vital data on micrometeoroid density in low earth orbit for design and development of the Apollo manned spacecraft.
I found photo in attachment showing Meteoroid Technology Satellite (MTS).
MTS was launched in August 1972, although the image seems to show a large spacecraft, it was only 0.7 meters wide... Can anyone acknowledge if the image shows the MTS?
From NASA-GSFC: The objectives of the Meteoroid Technology Satellite were to measure the meteoroid penetration rates in the bumper-protected target, and to obtain data on meteoroid velocity and flux distribution. MTS was launched in August 1972, although the image seems to show a large spacecraft, it was only 0.7 meters wide...

Additional missions carrying useful meteoride detectors were the 1966-1967 Lunar orbiters. Beside the develop-film-and-read-out imaging system, they carried two engineering experiments. One was a simple radiation detector to monitor radiation exposure that could fog the film (find out why the images were all suddenly washed out if a major radiation storm happened). The other was a ring of meteoride penetration tubes (maybe 2 rings) surrounding the spacecraft on it's engineering bus section. They confirmed (with a very low number of penetrations on the detectors for 5 spacecraft, generally a few months to a year each for 3 or 4 of the 5 missions (one died early)) that the micrometeoride rate was very low in lunar orbit, and was consistent with rates seen on the Pegasus spacecraft (after corrections for gravitational focussing and energy adding at Earth)

Surveyor 3 hardware returned to earth was checked microscopically for impact pits. I don't think <recall> that any were found.

The Pioneer 10 and 11 spacecraft carried similar penetration tubes outwards, providing data starting at Earth's orbit, again consistent with Pegasus/Lunar orbiter data.

Many earlier missions carried piezoelectric plates to record acoustic impulses from impacts, or other schemes to detect meteororids.. they tended to provide wildly discordant results so that a review in the 60's before the Pegasus results were in <i think> decided all such experiments were invalid, and had produced corrupted data (from thermal flexure and popping of the detector plate, etc.) This included the Mariner 4 meteoroid instrument.

Modern instruments are time-of-flight plasma detectors. Meteoroid hits a target plate <may be sensed, piezoelectrically> then vaporized ions from the impact reach a detector a foot or three away, heavier ions arriving later (travelling slower) than lighter ions. The cooincidence between a piezo event on the plate and the ions reaching the detector confirm this was a "good, controlled" event, giving scientifically useful data.

I have no modern knowledge of such instrument use in low earth orbit for meteoroid and debris monitoring.

Indeed, on this Pioneer remembrance coin, the asteroid-meteoroid detector scan is labeled at the 10 o'clock position