Soviet Luna Missions Options

[PhilHorzempa]

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I thought that it was time to start up a discussion of what we know, or
would like to know, about the Soviet Luna Missions.

To start off, I have heard many a reference to the landing system utilized
by the early landers, such as Luna 9. However, I have yet to find a report,
or even a diagram, that shows the sequence of events, or such details as
the air bags. If such references do not exist, I hope that some of the UMSF
community have Russian contacts that could lead us to the source material
before it ends up in the dust bin of history.

In addition, I heard of an effort several years ago to obtain ALL of the imagery
from Lunakhods 1 and 2. Does anyone know if that effort was able to
secure that data?

Also, as far as Lunas 15, 18 and 23, the sample-return missions that didn't
quite make it home, are there any official reports "out there" that detail what
actually occurred to those missions? Or will we have to wait for the
high-resolution images from the LRO to determine their fates?


Another Phil

[John Whitehead]

Regarding the Luna 16, 20, and 24 sample returns, does anyone have solid verifiable information about the mass or physical size of the upper part that launched off the moon? I have seen conflicting information that the earth entry capsule (the sphere at the top) was anywhere between 1 foot and 3 feet in diameter. Anything more accurate and verifiable would be much appreciated. Has anyone been to the NPO Lavochkin Museum where the sample return capsules are (or were) on display?

Below is some information about how the Luna ascent vehicles worked:

It was functionally very simple engineering, tailored to the particular physical situation. The moon's small size (compared to Mars) permitted a direct return. Not going into lunar orbit meant no circularization (orbit insertion) burn, and the fact that the target (earth) was gravitationally large and nearby meant no midcourse corrections either. No need for any engine restarts or staging. A single propulsive burn from the 1-stage ascent vehicle was simply timed (both moment of launch relative to the calendar, and burn duration).

Guidance consisted of flying a vertical trajectory off the moon. The vernier engines were controlled by a local vertical sensor, a pendulum! Site selection was limited to the east side of the moon, where a vertical ascent reduced the geocentric velocity compared to the moon's, so it was effectively just a deorbit burn with respect to the earth. Velocity would have been less than lunar escape velocity, since the earth was sitting there pulling it home. The return stage had a transmitter that could be switched on and off by commands from earth, and the resulting signals received on earth were used to predict the landing point accurately enough to go out and find it.

All this is explained in a paper by Boris Girshovich, presented at the National Space Society's 26th International Space Development Conference, Dallas Texas 2007May25-28. See isdc.nss.org/2007/index.html.

Also I found an online paper in the Electronic Journal of the Astronomical Society of the Atlantic, Vol. 7, Nr. 1, Jan 1996, by Andrew J. LePage. He points out that the return capusle was essentially just falling almost straight toward earth, and notes that they had to land near 56 degrees east longitude on the moon, in order to make the simplified return scheme work. The ascent vehicle is said to be 520 kg total, roughly 300 kg of which would have to be expended propellant. The sample return capsule is described as 40 kg total and 50 cm in diameter, which suggests that the "3 feet" diameter noted by the Girshovich paper is a typo.

John W.