I found the second time on the asteroid gun a lot easier? Second time I got it on my first go, but the first took me a few goes to just survive, and then a lot more goes to get the achievement.
In other news, a second run through the game on hard with a maxed suit really is ridiculously easy. I'm going for the "get grabbed 10 times by a lurker" achievement, and even their long grab attack only knocks one bar off my health.
I'm looking forward to starting on Impossible (once I've finished maxing out my guns for the achievement) because at the moment I'm basically invincible.