Thread by @MaryRobinette

Who wants to watch people launch into space today?

As you watch them walking in their spacesuits, the reason that they are bent over a little is because the suits are designed to be "comfortable" in something close to a fetal position.

I have been told that comfortable is relative.

We're twenty-seven minutes away from launch, so that gives us time to talk about a couple of historic aspects of this flight.

This is scheduled to be the last flight of the Soyuz-FG, which was designed to be a bridge between the Soyuz-U and the next generation Soyuz 2.

The Soyuz-U has all analog controls and the Soyuz 2 is digital.

The Soyuz-U first flew in 1973 and has the highest launch rate per year, with 47 flights in 1979. Its problem is that it can't roll onto the right azimuth after launch.

They solved that problem with the Soyuz-U by LITERALLY ROTATING THE LAUNCH PAD. So then all the Soyuz-U has to do after launch is pitch over to be on the correct course.

The Soyuz-FG has the same analog controls, but with many of the Soyuz 2 engines and systems. It also needs to rotating launch pad to get on the correct course.

The Soyuz 2 will be able to rotate itself, so it no longer needs the special launch pad, Site No. 1/5.

Site No. 1/5 is where Sputnik launched and where Yuri Gargarin launched in 1961.

Today's flight is the final one for the Soyuz-FG and is scheduled to be the last launch from Site No. 1/5.

Dr. Jessica Ulrika Meir from NASA is Swedish-American, with dual citizenship, so this launch will make her the first Swedish woman into space.

Hazza Al Mansouri (هَزَّاع ٱلْمَنْصُوْرِي) will be the first United Arab Emirates astronaut into space. He's been trained through Roscosmos in Star City.

Ooo! They just put in the launch key. Yes, a literal key, just like the key to a car. Take a look!

facebook.com/ESAAlexGerst/p…

The umbilicals are separating. We're less than a 15 seconds
away from launch.

LIFT-OFF!

Boosters separated. Everything is nominal.

(By the way, the NASA commentator is PAO (Public Affairs Officer) Gary Jordan, who hosts the really fantastic HOUSTON WE HAVE A PODCAST, which I highly recommend to anyone who writes SF or just likes space.)

nasa.gov/johnson/HWHAP

Yay! The second stage has separated and we're on to the third stage.

They should dock with the ISS in about six hours. It only takes eight to ten minutes to get into space, but docking is a lot more complicated.

The length of time from launch to docking at the ISS varies a lot. The fastest time was just under four hours the longest was three days.

Usually, you've got two variants. 6 hours, like today, or 2 days.

To dock with the ISS:
1. Fire the Soyuz's rockets parallel to Earth to get into an insertion orbit.
2. Fire twice for a Hohmann transfer. Once to boost farther into space, the second to maintain that new orbit.

3. Correction burns to get to an orbit every 86 minutes, which is 4 minutes faster than the ISS.
4. Another Hohmann transfer as they pass the ISS, which puts them in front.
5. A u-turn in space!
6. Slow-down to let ISS catch up.
7. Then it's just docking, which is... simple?