What exactly was the name of the first Soviet nuclear test? As it turns out, it is not a simple question. In the United States, the test was designated Joe-1, but its actual name was not known for quite a while. As the Soviet Union started opening up the history of its nuclear program, the name of the device tested on 29 August 1949 quickly entered public domain - RDS-1.

The test itself did not in fact have a name - unlike the United States, the Soviet Union did not name its tests, at least not in the early years of the nuclear program. Rather, they were known as tests of a certain device (изделие, izdeliye). Moreover, the first test, being unique, was referred to simply as a "test of the first exemplar of an atomic bomb." No designation, no RDS-1, nothing of the kind. In an interesting footnote, Stalin didn't actually approve the decision to go ahead with the test. The decision was made by the Special Committee at its meeting on 26 August 1949, three days before the test. Stalin apparently was not among those present. The Committee approved the draft decision of the Council of Ministers prepared by Kurchatov and forwarded it to Stalin for signature. But he never signed it (see document notes here and here).

Even though the test did not have a designation, the "first exemplar of an atomic bomb" that was tested did have a name - RDS-1. But even the participants of the Soviet atomic project could not agree on the meaning of that acronym. One version that is cited probably most often is that RDS stands for "Reaktivnyy Dvigatel Stalina" or "Stalin's Rocket Engine." A variation of that is "Reaktivnyy Dvigatel Spetsialnyy" ("Special Rocket Engine"). Some suggested "Rossiya Delayet Sama" or "Russia Does It Herself" (which would have been rather ironic name for what was essentially a copy of the U.S. Trinity device).

Documents, however, tell a slightly different story. It was indeed a "reaktivnyy dvigatel" - this is how the bomb was referred to in the early documents of the atomic project. The earliest I can find is the decision to establish the KB-11 design bureau (Soviet counterpart to Los Alamos), dated April 9, 1946. KB-11 was established with a specific purpose of designing and manufacturing of "experimental specimen of rocket engines" ("опытных образцов реактивных двигателей"). At the time the Soviet program was still considering a possibility of pursuing uranium as well as plutonium path to the bomb. At its May 18, 1946 meeting the Special Committee discussed two "rocket engine" variants. A month later, on 21 June 1946, the Council of Ministers approves a plan of work for KB-11 that explicitly says that the design bureau will build a "Rocket Engine S (RDS for short) in two variants - with heavy fuel (S-1) and light fuel (S-2)." Here is the paragraph:

From this point forward, "rocket engine," which clearly stands for "atomic bomb," almost disappears from the documents as it is replaced first by "S-1 and S-2 variants of RDS" and almost immediately after that - by RDS-1 and RDS-2. (To make things a bit more complicated, the RDS-2 in 1946--a uranium gun-type bomb--is not the RDS-2 that was tested in the second Soviet test in 1951. The uranium bomb project was terminated in 1948. Here is a very good guide to the evolution of early bomb designations.)

Now, we cannot be certain that S in "Rocket Engine S" does not stand for "Stalin" or for "special." So, in the end, RDS-1 may have been a "Stalin's rocket engine." But it is more likely that it was a fairly random choice of a letter that would specify that it is not some rocket engine, but a very specific one (the atomic bomb) and that this "engine" exists in two versions - S-1 and S-2. At least that is the way I read it.

What is certain is that RDS was never meant to be "Russia does it herself." Another name that didn't exist is "First Lightning" ("Первая молния"). This is the name that many sources claim the Soviet Union gave to its first nuclear test. It has made its way to Wikipedia and from there -- to numerous popular and academic works. The only problem is that you never see that name in the documents of the time or in memoirs of the participants of the Soviet nuclear project. It did appear, however, in some U.S. publications back in the 1980s. The origin of that was a bit of a puzzle until Vitaly Fedchenko, a colleague from SIPRI, found what appears to be a perfectly reasonable explanation. "First lightning" was the title of one of the chapters in the biography of Kurchatov published in the Soviet Union in 1968. The chapter about the fission bomb was called "First lightning," the one about the thermonuclear device - "Second lightning." These were very short chapters - not much can be said about the program back then. And, of course, the name of the device was off-limits, so the author just created a metaphor for that. It clearly caught on, but that name was never used in the nuclear project and should not be used to describe the first Soviet nuclear test.