Usually questions about space-whales are a steaming pile of pseudoscientific twaddle, however, this question confines itself to something sensible. The OP may congratulate himself.
For the sake of scientific sanity, it is assumed that space-whales are otherwise whale-like creatures created by extremely advanced alien technological civilizations. Basically they are cyborg marine mammals equipped with environmental protection systems to enable them to survive in space, and a propulsion system for easy travel around the galaxy.
The core question is essentially whether dying or dead whales "beaching" themselves on alien planets can be a source of life dissemination. Basically, panspermia by dead space-whales. So the question is would this work?
Could life on a planet be initiated by the cells and tissues from a dead whale? The simple answer is no. Possibly the DNA from those cells might form the precursors to life on the planet, but this should be regarded as extremely improbable. So no.
What is more probable to be a source of life on a planet is the microbiota carried by the space-whale's body. If microbes could become established in the planet's environment they could colonize the planet. However, there are caveats about the fact that these micro-organisms will be well adapted to the environment and ecology of the space-whale's body this will make it improbable, but not impossible, for dead space-whales to be the vectors for spreading life to otherwise lifeless planets.
Possible, highly improbable.
May life even grow inside the corpse without ever needing to go out?
Sadly, no, even ten thousand ton dead space-whales don't last forever. Their tissues will either run out or break down to the point where the viable existence for any organisms living inside a dead space-whale will run out. Eventually the outside environment will break in, and the space-whale won't be anymore. So, for a short time, yes, but not in the long run.
3Wouldn't it be Japanese space-whale-hunters? – dot_Sp0T – 2016-12-07T11:28:21.567
25Am I the only one, thinking about the Hitchhikers Guide? – Alexander von Wernherr – 2016-12-07T11:51:04.207
2
@AlexandervonWernherr Nope! Was just about to post this: At the risk of being too noobish, is the space whale a reference to Douglas Adams' space whale
– Thom Blair III – 2016-12-07T11:56:39.6606@AlexandervonWernherr I wish whoever clipped that from the movie had left in the next sentence: "Curiously enough, the only thing that went through the mind of the bowl of petunias as it fell was Oh no, not again. Many people have speculated that if we knew exactly why the bowl of petunias had thought that we would know a lot more about the nature of the universe than we do now." – Thom Blair III – 2016-12-07T11:58:59.363
5In fact from the books we know why the bowl of petunias says that, it implies reincarnation. – Goufalite – 2016-12-07T12:56:04.940
10,000 tons of charbroiled seafood (is (space!) whale meat seafood?) – Serban Tanasa – 2016-12-07T13:05:38.370
@SerbanTanasa Speafood? – Thom Blair III – 2016-12-07T13:06:31.597
1I think it's most likely possible if it's a Sperm Space Whale: Panspermwhalia! – Thom Blair III – 2016-12-07T13:13:40.280
1As we have exactly one data point for life evolving on a planet, and while most of us agree that it evolved from simpler forms it's still debated how it made the first step from non-life to life, it's pretty hard to answer this question with any scientific accuracy. Of course, it helps, if bacteria are already present, if they are not completely incinerated during the atmospheric entry. – vsz – 2016-12-07T16:05:52.667
Wouldn't the whale be incinerated on entry? – TruthOf42 – 2016-12-07T16:53:14.577
How comes nobody talked about cress eggs sandwich, and the absence of mayonnaise ? – Antzi – 2016-12-08T07:13:06.417
Does the spacewhale have internal bacterial (and maybe even macroscopic) symbiotic flora (like Earth animals do) or is this species 100% sterile? – Agent_L – 2016-12-08T14:47:57.180
I've been reading to much Hitchhikers... Not the Only one, @AlexandervonWernherr – Dan Brown – 2016-12-08T17:06:17.833