I dont know if this is good place to write about that but, I just wanted to ask about become a beta tester of SE. Is this still valid?
Unfortunately, beta tester group is closed, and people can't apply to join anymore. It was closed approximately one year ago, and other beta testers that got beta later even if it was closed were mostly translators. The other people that got it were given beta because admins decided to give it to certain people due to their accomplishments or other things.
Considering your skill with Space Engine, maybe you could ask Doc? Your screenshots would look great with beta, but it's up to admins to decide.
Also, you should consider translating SE to get beta.