His life had a remarkable trajectory. He was an astrophysicist working on Soviet unmanned space flights to Mars when he was arrested in a clampdown on the democratic movement in 1972. At his trial he described his pride in reading about the Mars 2 space probe, even if it was from a prison-issue Pravda in his cell. He was sentenced to five years' imprisonment, for "agitational propaganda", and when he got out was exiled - on no legal grounds whatsoever - to the tiny town of Tarusa in the Moscow region, where the authorities surveilled and harassed him daily and urged him to leave the Soviet Union.
He left in October 1977, and ended up in Munich, where he made the running with publications that brought Soviet political prisoners right into the centre of the western human rights movement - at a time when the KGB had finally crushed human rights journals inside the country.
For 13 years Lyubarsky's output was enormous. There was a bilingual news brief twice monthly; a yearbook of political prisoners complete with case details and family contacts; and a monthly journal called My Country and the World with analytical pieces from international contributors. All this was possible only because his prodigious contacts trusted him.
After 1991 and the collapse of the Soviet Union, Kronid Lyubarsky went back to Moscow and became Deputy Editor of the prestigious New Times. Under him the weekly journal turned radical and always opposed the war against Chechnya.
Lyubarsky never became a human rights "celebrity". For a start his temperament was unsuited to it and he was basically too busy; moreover his work demanded that he was anonymous and in the background. But the impact of this rigorous, rational figure at the heart of the movement was enormous.
It was state censorship and the Soviet invasion of Czechoslovakia in 1968 which propelled him to human rights work, like a number of scientists of his generation. At his trial he put it like this: "For a scientist it is natural to strive to find out things for oneself.
"For me and people of my generation this idea is all the simpler in that we were reared in a peculiar era - an era when `the essence of all philosophy' was contained in chapter 4 of The Short History of the All Union Communist Party (Bolsheviks) and nowhere else. And that kind of upbringing bears its fruit. I will never take anyone at his word. Not later and not now."
In the Sixties and Seventies, when the personal risks were enormous, Lyubarsky helped to edit the first Soviet human rights journal, A Chronicle of Current Events (which ran from 1968 to 1981). It began as an effort to monitor what happened to the handful of people who protested against the Czech invasion, but became a compendium of political imprisonment throughout the 15 republics of the union, before it was finally crushed in 1981.
Lyubarsky also co- distributed political prisoners' aid, and was a member of Amnesty International in Moscow. In recent years he edited a new Human Rights Bulletin which is the most interesting and authoritative publication of its kind in Russia today.
Not long ago some of the Moscow media started referring to 30 October as "Political Prisoners' Day". This gave Lyubarsky wry gratification: it was the anniversary of his own trial, which he and other prisoners had turned into the first countrywide hunger strike in the 1970s, and made a yearly tradition.
In 1975, when the Nobel Peace Prize Committee awarded Andrei Sakharov the Peace prize, Kronid Lyubarsky wrote to him from Vladimir prison: "Keep healthy, for God's sake, and may your fortress of a spirit never fail. We are all proud of you and send our love. We shall yet see the sky lit up for you." We did, and I think we shall yet see a salute to Kronid Lyubarsky.
Kronid Arkadievich Lyubarsky, scientist and human rights campaigner: born Pskov, Soviet Union 4 April 1935; married 1959 Galina Salova (one daughter); died Indonesia 23 May 1996.