HN Theater @HNTheaterMonth

They don’t reach the stations orbital velocity immediately after launch though. What they do is launch into a lower orbit behind the station. Lower orbits have a shorter orbital period, so they gradually catch up and raise their orbit as they get closer.

If the went into a ballistic trajectory directly at the station, there is a risk of debris from the launch, such as paint flecks, scraps of metal, etc hitting the station. Also a lower initial target orbit makes various abort scenarios easier. Then of course another poster has pointed out they need time to check and validate all the vehicles systems.

Generally in space it’s best to avoid doing anything in a rush if you can avoid it. In recent years the Russians moved to a 6 hour launch to rendezvous window which is pretty quick really. This is what made it possible to capture footage of the launch from the station.

https://youtu.be/ouBfzCgXHgk

⬐ sandworm101

Technically they do reach the stations velocity. In fact they exceed it. The lower orbit is slightly faster. Total energy is lower, but they are moving faster than the station.

A counterintuitive part of spaceflight is that often you have to first accellerate in order to slow down.

⬐ vermontdevil

Makes sense. Get up to a higher speed and it’s easier to do a controlled slow down. Than having to speed up after getting into orbit near another orbiting body.

⬐ JshWright

That's not really it. "Speeding up" and "slowing down" are equally easy (or hard). They're both acceleration, just in a different direction.

The reason it's going faster is because it's lower. The lower an orbit, the faster the thing is moving. In order to slow down, you have to accelerate twice (I'm using the term "accelerate" here to refer to "going faster in the direction you're already going").

The first acceleration raises the far side of your orbit. You then have to "climb" up to that new higher orbit. Once there, you accelerate again to raise the low side of the orbit (otherwise you'd pick up all that speed again then "falling" back down to the lower altitude).

At the end, you're in a new, higher, orbit, going slower than when you started.

⬐ None

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⬐ drivingmenuts

I swear that looked like movie FX. All it needed was some sort of display with a circle around the target and ranging, etc. information constantly updating.

Very cool!

⬐ modzu

faker than the moon landing!

⬐ None

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⬐ gardaani

Previous comments: https://news.ycombinator.com/item?id=18518302

⬐ jdnier

This is just breathtaking. The music makes it feel overly cinematic, but it's real—no CGI.