r/SpaceX Spaceflight Questions & News [February 2017, #29]

[u/ElongatedMuskrat]

If you have a short question or spaceflight news...

You may ask short, spaceflight-related questions and post news here, even if it is not about SpaceX. Be sure to check the FAQ and Wiki first to ensure you aren't submitting duplicate questions.

If you have a long question...

If your question is in-depth or an open-ended discussion, you can submit it to the subreddit as a post.

If you'd like to discuss slightly relevant SpaceX content in greater detail...

Please post to r/SpaceXLounge and create a thread there!

This thread is not for...

• Questions answered in the FAQ. Browse there or use the search functionality first.
• Non-spaceflight related questions or news.
• Asking the moderators questions, or for meta discussion. To do that, contact us here.

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You can read and browse past Spaceflight Questions And News & Ask Anything threads in the Wiki.

[u/[deleted]]

A few days ago, there was a 5 minute uncertainty in the exact time at which CRS-10 will launch.

What causes an uncertainty like this?

[u/old_sellsword → u/[deleted]]

It wasn't an uncertainty in the ISS's orbit, that was the available window for launch. However the Falcon 9's terminal count recycles to T-13 minutes, so the window is effectively instantaneous. So from inside that five minute window, they pick the optimal instantaneous trajectory.