Here’s the wikipedia entry. The editors have chosen to render his last name phonetically, instead of using the Russian “ë”. I don’t care how the wiki is spelled, but just as a matter of practice, which would be the preferred way when rendering his name in English?
The scientific way is Transliteration where each Kyrillic letter is mapped (according to an universal standard) to one latin letter. This makes the system
a) indepent of the target language (an english and a german transliteration are the same) and
b) reversable: you can transfer back to cyrillic using the same universal table.
c) Hi Opal!
In common use, however, people use Transscriptionwhich
This system is dependent on the target language, that is, a German and an English transcription of the name will look different. (This also relates to Arabic: a transliteration eliminates dialects on both sides).
For historical people, certain transcriptions have became standard, though, because they have become popular under that name in the west.
To my knowledge, wikipedia uses the scientific standard of transliteration, along with the commonly known name. You would have to look at their specific guidelines to be certain, though.
Transcription is a matter of taste, and, I guess, geography.
As an American Russianist, I’ve always used the ALA-LC system, and so would write the name Sergei Pavlovich Korolev. The “yo” spelling shows the palatalized vowel better, but looks British to me.
Wikipedia has an article on the different transliteration systems: http://en.wikipedia.org/wiki/Romanization_of_Russian
Note that the spelling might be different if Korolev were considered a Ukrainian.