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Monday, March 18, 2013

Reading List: Rockets and People. Vol. 4

Chertok, Boris E. Rockets and People. Vol. 4. Washington: National Aeronautics and Space Administration, [1999] 2011. ISBN 978-1-4700-1437-7 NASA SP-2011-4110.
This is the fourth and final book of the author's autobiographical history of the Soviet missile and space program. Boris Chertok was a survivor, living through the Bolshevik revolution, the Russian civil war, Stalin's purges of the 1930s, World War II, all of the postwar conflict between chief designers and their bureaux and rival politicians, and the collapse of the Soviet Union. Born in Poland in 1912, he died in 2011 in Moscow. As he says in this volume, “I was born in the Russian Empire, grew up in Soviet Russia, achieved a great deal in the Soviet Union, and continue to work in Russia.” After retiring from the RKK Energia organisation in 1992 at the age of 80, he wrote this work between 1994 and 1999. Originally published in Russian in 1999, this annotated English translation was prepared by the NASA History Office under the direction of Asif A. Siddiqi, author of Challenge to Apollo (April 2008), the definitive Western history of the Soviet space program.

This work covers the Soviet manned lunar program and the development of long-duration space stations and orbital rendezvous, docking, and assembly. As always, Chertok was there, and participated in design and testing, was present for launches and in the control centre during flights, and all too often participated in accident investigations.

In retrospect, the Soviet manned lunar program seems almost bizarre. It did not begin in earnest until two years after NASA's Apollo program was underway, and while the Gemini and Apollo programs were a step-by-step process of developing and proving the technologies and operational experience for lunar missions, the Soviet program was a chaotic bag of elements seemingly driven more by the rivalries of the various chief designers than a coherent plan for getting to the Moon. First of all, there were two manned lunar programs, each using entirely different hardware and mission profiles. The Zond program used a modified Soyuz spacecraft launched on a Proton booster, intended to send two cosmonauts on a circumlunar mission. They would simply loop around the Moon and return to Earth without going into orbit. A total of eight of these missions were launched unmanned, and only one completed a flight which would have been safe for cosmonauts on board. After Apollo 8 accomplished a much more ambitious lunar orbital mission in December 1968, a Zond flight would simply demonstrate how far behind the Soviets were, and the program was cancelled in 1970.

The N1-L3 manned lunar landing program was even more curious. In the Apollo program, the choice of mission mode and determination of mass required for the lunar craft came first, and the specifications of the booster rocket followed from that. Work on Korolev's N1 heavy lifter did not get underway until 1965—four years after the Saturn V, and it was envisioned as a general purpose booster for a variety of military and civil space missions. Korolev wanted to use very high thrust kerosene engines on the first stage and hydrogen engines on the upper stages as did the Saturn V, but he was involved in a feud with Valentin Glushko, who championed the use of hypergolic, high boiling point, toxic propellants and refused to work on the engines Korolev requested. Hydrogen propellant technology in the Soviet Union was in its infancy at the time, and Korolev realised that waiting for it to mature would add years to the schedule.

In need of engines, Korolev approached Nikolai Kuznetsov, a celebrated designer of jet turbine engines, but who had no previous experience at all with rocket engines. Kuznetsov's engines were much smaller than Korolev desired, and to obtain the required thrust, required thirty engines on the first stage alone, each with its own turbomachinery and plumbing. Instead of gimballing the engines to change the thrust vector, pairs of engines on opposite sides of the stage were throttled up and down. The gargantuan scale of the lower stages of the N-1 meant they were too large to transport on the Soviet rail network, so fabrication of the rocket was done in a huge assembly hall adjacent to the launch site. A small city had to be built to accommodate the work force.

All Soviet rockets since the R-2 in 1949 had used “integral tanks”: the walls of the propellant tanks were load-bearing and formed the skin of the rocket. The scale of the N1 was such that load-bearing tanks would have required a wall thickness which exceeded the capability of Soviet welding technology at the time, forcing a design with an external load-bearing shell and separate propellant tanks within it. This increased the complexity of the rocket and added dead weight to the design. (NASA's contractors had great difficulty welding the integral tanks of the Saturn V, but NASA simply kept throwing money at the problem until they figured out how to do it.)

The result was a rocket which was simultaneously huge, crude, and bewilderingly complicated. There was neither money in the budget nor time in the schedule to build a test stand to permit ground firings of the first stage. The first time those thirty engines fired up would be on the launch pad. Further, Kuznetsov's engines were not reusable. After every firing, they had to be torn down and overhauled, and hence were essentially a new and untested engine every time they fired. The Saturn V engines, by contrast, while expended in each flight, could be and were individually test fired, then ground tested together installed on the flight stage before being stacked into a launch vehicle.

The weight and less efficient fuel of the N-1 made its performance anæmic. While it had almost 50% more thrust at liftoff than the Saturn V, its payload to low Earth orbit was 25% less. This meant that performing a manned lunar landing mission in a single launch was just barely possible. The architecture would have launched two cosmonauts in a lunar orbital ship. After entering orbit around the Moon, one would spacewalk to the separate lunar landing craft (an internal docking tunnel as used in Apollo would have been too heavy) and descend to the Moon. Fuel constraints meant the cosmonaut only had ten to fifteen seconds to choose a landing spot. After the footprints, flag, and grabbing a few rocks, it was back to the lander to take off to rejoin the orbiter. Then it took another spacewalk to get back inside. Everybody involved at the time was acutely aware how marginal and risky this was, but given that the N-1 design was already frozen and changing it or re-architecting the mission to two or three launches would push out the landing date four or five years, it was the only option that would not forfeit the Moon race to the Americans.

They didn't even get close. In each of its test flights, the N-1 did not even get to the point of second stage ignition (although in its last flight it got within seven seconds of that milestone). On the second test flight the engines cut off shortly after liftoff and the vehicle fell back onto the launch pad, completely obliterating it in the largest artificial non-nuclear explosion known to this date: the equivalent of 7 kilotons of TNT. After four consecutive launch failures, having lost the Moon race, with no other mission requiring its capabilities, and the military opposing an expensive program for which they had no use, work on the N-1 was suspended in 1974 and the program officially cancelled in 1976.

When I read Challenge to Apollo, what struck me was the irony that the Apollo program was the very model of a centrally-planned state-directed effort along Soviet lines, while the Soviet Moon program was full of the kind of squabbling, turf wars, and duplicative competitive efforts which Marxists decry as flaws of the free market. What astounded me in reading this book is that the Soviets were acutely aware of this in 1968. In chapter 9, Chertok recounts a Central Committee meeting in which Minister of Defence Dmitriy Ustinov remarked:

…the Americans have borrowed our basic method of operation—plan-based management and networked schedules. They have passed us in management and planning methods—they announce a launch preparation schedule in advance and strictly adhere to it. In essence, they have put into effect the principle of democratic centralism—free discussion followed by the strictest discipline during implementation.

In addition to the Moon program, there is extensive coverage of the development of automated rendezvous and docking and the long duration orbital station programs (Almaz, Salyut, and Mir). There is also an enlightening discussion, building on Chertok's career focus on control systems, of the challenges in integrating humans and automated systems into the decision loop and coping with off-nominal situations in real time.

I could go on and on, but there is so much to learn from this narrative, I'll just urge you to read it. Even if you are not particularly interested in space, there is much experience and wisdom to be gained from it which are applicable to all kinds of large complex systems, as well as insight into how things were done in the Soviet Union. It's best to read Volume 1 (May 2012), Volume 2 (August 2012), and Volume 3 (December 2012) first, as they will introduce you to the cast of characters and the events which set the stage for those chronicled here.

As with all NASA publications, the work is in the public domain, and an online edition in PDF, EPUB, and MOBI formats is available.

A commercial Kindle edition is available which is much better produced than the Kindle editions of the first three volumes. If you have a suitable application on your reading device for one of the electronic book formats provided by NASA, I'd opt for it. They're free.

The original Russian edition is available online.

Posted at March 18, 2013 23:35