Target of N-1 launches and nature of 7K-L1S spacecraft

Sven Grahn

Table of contents

Summary of N-1 launches
Target of N-1 launches
Nature of L-1 spacecraft

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Summary of N-1 launches

The table below shows the available information about the N-1 launches, their launch date and time, payload and fate. Very little has been reported from Russian sources about the intended missions for these launches. More specifically, were they aimed at the Moon. The published launch times make it possible to determine whether or not a particular launch was aimed at the Moon.

Date	Spacecraft	Launcher	Time of launch	Comments
21.02.69	7K-L1S no.3	11A52 No.3L	09:18:07 UT	Fire in the tail of rocket; exploded after 70 sec of flight.
03.07.69	7K-L1S no.5	11A52 No.5L	20:18:32 UT	LOX pump was disabled; Rocket exploded on launch pad right away after launch
26.06.71	Mock-up LOK+ mock-up LK	11A52 No.6L	23:15:07.5 UT	Blown up after 51 sec
23.11.72	Mock-up LOK+ mock-up LK	11A52 No.7L	06:11:52 UT	Fire in the propulsion system;exploded after 107 sec

The launch on June 26, 1971 is sometimes said to have occured on June 27. It indeed did take place on June 27, Moscow Time.

A method to calculate the launch time (expressed in fractions of a day, UT) has been developed. It is a very simplistic method and does not take into account the detailed astrodynamics near the Moon. It is based on the simple assumption that the Moon (at the time of arrival) must be close to the orbital plane of the low parking orbit (before trans-lunar injection). Using a function of Launch time v.s. Age of the Moon that fits well with the Zond flights and assuming that the flight time to the Moon for the N-1 launches would be roughly the same (3.3 days) we can derive a hypothetical launch time based on the age of the Moon at the day of launch. This time is called "Launch time to reach the Moon" below. The difference column shows the difference between actual and hypothetical launch time. Only for 3L and 5L is this difference small enough to say with certainty that the target was the Moon. The two other flights were not aimed at the moon (unless TLI occured on a southbound leg of the parking orbit, which is improbable).

Target of N-1 launches

N-1	Date	Launch time	Age at launch	Launch time to reach moon	Difference	Comments
3L	21.02.69	09:18:07 UT	4.73	7:23 UT	115 min	Target = MOON
5L	03.07.69	20:18:32 UT	18.76	18:48 UT	90 min	Target = MOON
6L	26.06.71	23:15:07 UT	4.05	6:50 UT	985 min	-
7L	23.11.72	06:11:52 UT	17.22	17:34 UT	-682 min	-

In the figure below the N-1 launch attempts have been plotted together with the Zond Age/launch-time curve. The dashed line fits the 3L and 5L launches. A conclusion could be that the N-1 lunar launches would have used a longer flight time to the Moon and/or a different trajectory near the Moon than the Zond flights.

Nature of the 7K-L1S spacecraft

Only 3L and 5L carried the L-3S payload which consisted of the Zond-type vehicle 7K-L1S. The "S" designation stands for "Sputnik" according to Mr Oleg Sokolev, who worked on these missions. This means that they were intended for lunar orbit! The 7K-L1S was very similar to the L1 spacraft, but it had the DOK (attitude control and propulsion unit used on top of the LOK) and its guidance and control subsystem was more similar to that of the LOK. If the 3L and 5L flights had been successful, the missions could not so neatly have been concealed as Zond flights. They would not have been mixed up with the Proton-launched Zond series because the fact that they entered lunar orbit pointed to a larger launch vehicle.