Space Station Reboost: The Inside Story

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Recommends user12102 · 2020-02 · Space Exploration Stack Exchange · on “Does the speed of ISS slow down at the time of a spacewalk or does it become stationary?”

Not necessary! Astronauts are in orbit around the Earth, traveling at the same speed as their space ships. This is true whether they are inside or outside of the space ship. So if they go outside, they travel along side it without any need to slow down. Of course since they are in circular orbits around the center of the Earth, if they wait 20 minutes they will gently return to the ship because the orbits of the astronaut and the ship will intersect in two places. (for more on that 20 minutes, see How to estimate which astronaut ends up furthest from the ISS after one orbit? [LINK] ) That's because each orbit is in a different plane that passes through the center of the Earth. Here are some

Cites Russell Borogove · 2015-09 · Space Exploration Stack Exchange · on “When the ISS accelerates, do the astronauts feel it?”

If you watch these videos: ATV boost [this video] Zvezda boost [LINK] ...you can see that the acceleration is quite gentle, but definite. The astronauts do need to hang on to something if they don't want to drift to the back of whatever room they're in. The first video was a reboost performed with the ATV [LINK] service ship, as described in this article [LINK] . Depending on what numbers you look at, acceleration during an ATV boost is something like 0.0035-0.005 m/s 2 -- about 1/3000 or 1/2000 of a g. So an ounce or two of force (~30 grams-g-force, or 300 N) is enough to keep an astronaut in place -- easily done with a pinky finger. You can see in the first video that the astronauts can throw t

Cites Rory Alsop · 2019-03 · Space Exploration Stack Exchange · on “What is the orbital boost acceleration of the ISS?”

If you follow the link in this superb answer [LINK] by @TildalWave [LINK] to the NASA blogs [LINK] , you can get info on every boost. His example from the blogs is: ISS Daily Summary Report – 05/06/15 ISS Reboost: This morning, the ISS performed a reboost using 58P thrusters to set up phasing requirements for 41S landing scheduled on May 13. Burn duration was 12 minutes, 17 seconds with a Delta-V of 1.34 meters/second. And definitely worth reading the blog linked to [LINK] in the comments there. @Uhoh pointed out two awesome YouTube clips linked from that blog demonstrating the effect of the boost burn on people and items inside the ISS: Expedition 29 crew [this video] and Expedition 22 Commander

Cites user12102 · 2019-03 · Space Exploration Stack Exchange · on “ISS location identification; estimate size and direction of astronaut acceleration puzzler”

note: This question addresses the same video and phenomenon described in this answer [LINK] (which I found after posting this) but here I'm asking for an analysis of the trajectories of the test masses (the astronauts) based on known ISS structure, not accelerations read from sentences in blogposts. The NASA Johnson YouTube video Space Station Reboost: The Inside Story [this video] shows Expedition 29 Flight Engineer Satoshi Furukawa in orbit around the Earth, inside the ISS during a propulsive orbit-boosting maneuver. From the camera's perspective Furukawa appears to be accelerating away from the camera, but it's really the ISS changing velocity. Furukawa's position changes substantially during

Cites user12102 · 2019-10 · Space Exploration Stack Exchange · on “Forces experienced during transfer orbit”

During the impulse, I imagine the astronauts would feel the forces of acceleration (just like a car accelerating), but that only lasts for a small time. What happens to the feeling of weightlessness during this time? They don't have a feeling of weightlessness during this time. When the ship accelerates during a propulsive maneuver they would drift to the "bottom" of the spacecraft where the engine is located and then experience a small force. If they land feet first, it will feel like they are standing on an extremely low gravity body. If they are seated, they'll feel like they are sitting on one. When the burn ends, they will regain their sensation of weightlessness. You can see what a ver

Cites user12102 · 2021-04 · Space Exploration Stack Exchange · on “Do standard procedures for securing the ISS before an orbital boost burn include making sure that at least large objects are securely "strapped down"?”

In discussions on previous posts it was debated whether ISS crew would need to "batten down the hatches" and confirm all objects were "lashed to the deck" before an orbital boost burn. My thinking is that for the heavier objects the force necessary to restrain against the continuous air circulation (a mere breeze) would be much less than the force necessary to restrain against a 0.02 g acceleration This is clearly seen in the two videos below, where as soon as the engines start, a several kg camera+lens and say a 65 kg astronaut immediately start accelerating towards the back of the bus station. After 01:36 in the 2nd video there Demonstration of Acceleration Inside the International Space S

Cites user12102 · 2021-04 · Space Exploration Stack Exchange · on “What do ISS astronauts do while the ISS gets reboosted?”

[LINK] above: holding on. below: letting go, and immediately accelerating towards the back of the station. [LINK] [LINK] I’m going to let go now and here I go drifting back toward you again so the acceleration applies to me to. tl;dr They would have to hold on with a force of about 1.3 Newtons to keep in place. Background They strap everything down first (it was suggested that good station hygiene means everything is probably already strapped down, so there should be no separate effort to "batten down the hatches" and confirm all objects were "lashed to the deck" before they say " Let's light this candle! [LINK] " and begin a period of ~0.002 g acceleration, a significant departure from norm