I got the twelve glowing scrap and went back to the dying astronaut, but I wasn't able to interact with her anymore. Is that supposed to happen? Either way, I stopped playing after that. I liked the pressure of having to run through these arenas and get as many kills as possible before dying or running out of time. But arenas 1 and 2 are so samey and repetitive that it's hard to remember where I went last time. Its good there are more boss nanobots than needed to get the twelve glowing scrap. Otherwise I never would have found the last few. The speed powerup felt really weak. It either doesn't work or the speed increase is so small to not be noticeable. The shooting mechanic was strange, but I kind of liked it. I got down the rhythm of pressing and releasing to get max fire rate while dodging enemy shots. I wish it had some charging sound effects to help indicate when the shot is ready.
Overall, good job. Great visuals and gameplay, even if it could have used a bit more polish.