With the Radiation Absorption skill up to 17%, even when there was barely any light from the stars, Ning's body still improve quite a bit.
With this, the next 30 years he was going to spend on top of the ship was more akin to spending about 250 years in the stars. It wasn't much, but it was something.
Also, because he was moving so fast, in the next 30 years, he would go nearly 15 lightyears away from where he had started.
Which was a lot higher distance than the mere 4 lightyears he had spent nearly 20,000 years flying through space last time.
So, he would also be hit by more radiation in general because of the distance. As such, Ning was at least going to have his body improve by quite a significant amount.
Ning was still being bombarded by the interstellar wind, but this time around, he didn't need to worry about trying to speed himself up every time he was slowed down over the course of the many years.