Recently, there have several posts related to dust and the ever popular blast crater myth. With that in mind, I decided that to post a small review of mine and other people findings about this topic.

An excellent reference about lunar dust transport can be found in following report that I refer to quite often.

NASA Contractor Report 4404
Lunar Dust Transport and Potential Interactions with Power System Components
Cynthia M. Katzan and Jonathan L. Edwards
Contract NAS3-25266
November 1991

Based on the astronaut's observations, it was noted that the dust could reach as high as 37 m (115 ft). These observations were made primarily during Apollo 11, 12 and 14. After this time, NASA changed the flight paths, so that the Lunar Module (LM) hovered less, thereby generating less dust and giving the astronauts a better view of the landing site.

While the astronauts could see dust as high 37 m, an examination of the Surveyor III hardware showed that most of the vehicle was covered with dust. Most of the dust comes from the landing site when the descent engine was close to the lunar surface. Some of the accumulated dust occurs because the LM flew over and to the north of the Surveyor III vehicle. You can see the flight path here.

http://home.pacifier.com/~garyn/maps.html

We know that some of the dust does come from the fly over because; surfaces that are protected (face away) from the dust ejected by the landing site are also covered with dust. Using this flight path, at its closest point, the LM was 67 m (208 ft) above the vehicle.

Examination of the dust particles on the surfaces of the Surveyor III also only shows particles of a certain size or less and using these data and projectile trajectory equations, it can be shown that the LM could move or eject dust to about 1 kilometer. Furthermore, these data show that the ejection angle is very tiny, less than ONE degree, more like 0.1 degree. In other words, when the dust it ejected out of the landing site, it is very close to the lunar surface; hence another reason why the footpads which have a several inch high lip, have no dust on them.

Using the photographic data returned by the early missions, it was possible to measure the depth and diameter of the amount of lunar dust ejected by the descent at the landing locations. The amount of erosion was about 10 cm deep (3.9 inches) and 220 cm (86.6 inches or 7.2 feet) in diameter. Finding the volume and calculating the mass ejected shows that 650 kg (1436 lbs) of materials was ejected from underneath the LM.

Finally my favorite topic, the blast crater. The hoaxers love to point out that the combustion temperature of the LM descent fuels is around 5000 F and therefore love to say that there should be plenty of melted rock. Unfortunately for their point of view (lack of understanding), the actual temperature of the exhaust as it leaves the descent engine is 2800F. Of course the exhaust gasses cool of after that. It is important to note that some of the lunar materials will not melt at a temperature of 2800F. Using some very simple and extremely conservative (over predicts) heat transfer analysis methods, only about 1.5 mm of the surface can potentially be removed by melting.

P.S. For you heat transfer folks, I used the semi-infinite solid method.