Questions tagged [attitude]
Questions on ascertaining, predicting, and controlling spatial orientation and rotation of spacecraft, and on forces that affect spatial orientation.
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How is a rocket stabilized during the initial, slow speed, portion of launch?
Let's say we're at T+0, just as the rocket starts to move, what keeps it upright as it clears the tower and gains speed?
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Why did the Space Shuttle fly upside-down normally
After reading this answer I found out that the space shuttle normally spent its time upside-down. Why is that? I'd guess it has to do with shielding from the sun, but I can't back that up with ...
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Does a satellite naturally turn in phase with its orbit, always facing Earth?
Assume you want a satellite to constantly point its radio dish towards Earth while orbiting it, or its solar panels towards the Sun if it is instead orbiting it. Is any of the following true about ...
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Why does the ISS rotate exactly once per orbit?
Looking at the HDEV experiment, one can see that the orientation of the ISS is always the same with respect to the Earth. This means that the ISS must rotate exactly once per orbit (like the Moon ...
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Can you turn in space without propulsion?
Say an astronaut is floating perfectly still inside their spaceship. Can they rotate themselves by stretching out their arms and twisting one way, then pulling in their arms to their sides and ...
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Falcon 9: engines stabilize spin
On CRS-16, the landing Falcon 9 booster entered a spin rotation due to a stalling grid fin hydraulic pump.
According to Musk, the engines stabilized the spin. How is this possible? The main engines ...
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Are the computers on Pioneer 10 & 11 still running?
So, I have been wondering.
Pioneer 10 and 11 went silent because there wasn't enough power left to operate the antenna.
But what happened after that? Was there still enough power to keep the computers ...
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How do astronauts turn in space?
A recent question back in Physics asks whether there is a way for an astronaut to rotate when in microgravity and without touching anything else, while still conserving angular momentum.
One way to ...
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Did the designers of Voyager neglect the angular momentum of the tape recorders?
I have heard many times that the designers of the Voyager spacecraft neglected to account for the angular momentum of the tape recorders (on which data was stored). To compensate for it after launch, ...
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Optimal placement of 4 reaction wheels?
What is the optimal orientation to place 4 reaction wheels, such that complete 3 axis control can be maintained at all times?
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Did Sputnik 1 have attitude control?
The (currently only) answer to Why did Sputnik 1 have four antennas? discusses how Sputnik 1 had four antennas in order to ensure that the Earth would never be in the null of any of its antennas.
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When Mir's attitude control computer failed, why did the station immediately start rotating?
Re-reading Linenger's Off the Planet and encountered a question from long ago that I never had found an answer to.
During Mir's troubled old age, the attitude control computer would fail frequently. ...
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Why does NASA intentionally spin space probes?
In several NASA animations of missions, I've noticed that the spacecraft is rotating while traveling in deep space. This was true of Curiosity when that video came out. Now the Juno mission ...
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How does a single SRB control attitude?
The Ares I-X was a test flight from the Constellation program for crewed Ares I-launched Orion capsules.
If liquid fueled rocket motors can gimbal, how do solid rocket motor-propelled spacecraft ...
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How does astronaut activity from within affect a spacecraft?
Can physical activity from within a space craft affect it somehow? For example if somebody on the ISS performs repairs involving a lot of hammering, would it perhaps affect the station's orientation a ...
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Passive attitude stabilization with magnets - are there studies based on actual flight data?
Specifically with the small satellite and cubesat people, there is an rather 'old' idea around: Passive attitude stabilization based on permanent magnets.
Schematic of the Earth magnetic field lines ...
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Do any spacecraft use GNSS for attitude determination?
In principle, by placing a GNSS-receiver on all extremities of a spacecraft (or aircraft, for that matter), one can determine the orientation of the satellite. Google lists some studies, but have ...
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What are quaternions and how are they used to represent spacecraft dynamics?
The title says it all. Quaternions are widely used to represent the orientation of a spacecraft. Why is that, and how do quaternions compare to other alternatives?
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How did the attitude system of the uncrewed Soyuz 7K-OK No.1 fail on the launch pad in 1966, killing ground staff as LES was activated?
Wikipedia has a stub article on the loss of the Soyuz 7K-OK No.1 test flight in 1966-12-14, but this part doesn't make sense to me:
However, once the Soyuz rocket's engines ignited, they did not ...
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What control engineering techniques are used for the landing maneuvers of Falcon 9-R?
Which are the main control theories behind the landing maneuvers of the Falcon 9? For the hovering part, as it approaches the landing surface, I guess the inverted pendulum control approaches would do ...
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Why does the Psyche Spacecraft use cold gas thrusters?
In a recent article on SpaceNews they write
[There exist] nitrogen cold-gas thrusters that orient the spacecraft.
This seems like an odd choice for me, considering it is a multi year mission that ...
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What is the math behind Magnetorquers?
I'm trying to better understand the mathematics behind how torque rods work. I know that even if you have 3 axis of magnetic torquers, in effect there is only 2 axis of control, and I'm trying to ...
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How often must the ISS desaturate its control moment gyros?
I understand ISS uses control moment gyros as the primary attitude control system. As the article states, CMGs eventually get "saturated", a state in which they can no longer absorb momentum. This can ...
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What factors determine whether a spacecraft/probe/satellite uses gyroscopes or propellant thrusters to rotate?
Say I'm designing a probe or satellite. To control its attitude, I can add some gyros, or I can put thrusters on each corner, or I can add both and pick one in flight according to the situation. How ...
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How powerful are reaction control wheels?
Most (ok, all) of my space exploration experience has been from Kerbal Space Program which has reaction control wheels with greatly exaggerated performance.
I'm aware of real life missions (notably ...
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What is the minimum number of RCS thrusters capable of stabilizing a satellite against an arbitrary rotation?
In case of a very specific rotation, even one suffices, but it must be located just right for that specific axis of rotation, and if you want to rotate the satellite, it can do so in that specific ...
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How do Voyager 1's Trajectory Control Thrusters differ from its Attitude Control Thrusters?
There are several popular news items about the recent test of Voyager 1's Trajectory Control Thrusters to see if they can be used for attitude control to facilitate communication with Earth. The ...
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Did any rockets use differential throttling instead of gimbal?
It seems the standard approach to control of rockets during launch is either vernier thrusters, or gimbals on the main engines. Sure that works, and is quite efficient, but I wonder about a simpler ...
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How to tell a satellite is tumbling and out of control?
I've just read North Korea’s “successful” satellite in orbit, but tumbling and useless. How can we tell a satellite is tumbling or not? It's so far away!
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What is so difficult about the ISS zero propellant maneuver?
Nazareth Bedrossian (from Draper Laboratory) et al. describe the ZPM in this paper. What I want to know is:
Why is planning and executing the maneuver so difficult it had not been done before 2007?
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Does this kill vehicle contain momentum wheels? Watch how it moves!
This comment below this answer about 'spacecraft' or at least 'craft' that can maneuver near the surface of low gravity bodies links to this video about Lockeed Martin's Multiple Kill Vehicle.
If I ...
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How is gyroless operation possible?
I was reading recently about the near-loss of the Solar and Heliospheric Observatory (SOHO) spacecraft back in 1998, in this Wikipedia article. This article mentions that
Only one gyro remained ...
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What kind of thrusters will the James Webb Space Telescope use for station keeping?
Question is fairly self-explanatory, but I couldn't find an answer on Google. I would expect ion thrusters because of their efficiency.
Thanks!
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How does the space station rotate, if at all?
I know the station's solar panels rotate to track the sun (and also rotate to be in-line with the station for lower drag on night passes), but how does the station itself rotate? I imagine it has to ...
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Does ISS stop rotation for docking?
A question from 3 years ago got an answer that would be a great answer to a different question (and concluded with a comment that more would be posted later.) Let me re-ask, making the question ...
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How does desaturation of the reaction wheels work?
I'm having a little trouble understanding the 'principle' behind the desaturation process. The aim of desaturation is to reduce the the speed of the Reaction Wheel. My understanding is that I can't ...
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Why did New Horizons have to be spin-balanced to grams-level precision? (With quarters!)
This story about receiving a roll of Space-Themed Florida State commemorative quarters from the Governor of Florida mentions that the New Horizons spacecraft had to be "spin-balanced" to ...
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SpaceX's ITS - why gimbal only the inner cluster?
Does anyone know the reason why, in SpaceX's newly-announced ITS launch vehicle, only the inner cluster gimbals, and not the whole engine system?
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How can a yo-yo de-spin maneuver reverse the rotation?
I just read about yo-yo de-spin as a measure to reduce the spin of objects. The basic idea is simple and makes sense, but then I read this:
As an example of yo-yo de-spin, on the Dawn Mission […] ...
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Xenon vs Hydrazine, "Should I Stay or Should I go?" Dawn mission decisions
edit 2: There seems to have been some announcement/extension by NASA (20-Oct-2017), possibly this will shed more light on the issues in this question.
edit 1: Several months have passed since this ...
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How are the Voyagers' thrusters configured in a novel way to minimize accelerations along Earth-spacecraft axis?
I've just read in Eshleman et al 1977 Radio Science Investigations with Voyager that the voyagers have:
...a novel attitude-control thruster configuration that minimizes accelerations along the ...
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Using a fidget spinner to rotate in outer space
There is a question How do astronauts turn in space?, and related questions here and on physics.stackexchange, that detail how astronauts might maneuver by spinning their upper and lower body ...
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How could aerodynamic forces break up the Challenger orbiter?
Wikipedia's explanation of the sequence of events:
The O-ring failure caused a breach in the SRB joint it sealed, allowing pressurized hot gas from within the solid rocket motor to reach the ...
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Why are spin-stabilized rockets stable?
Spinning rigid bodies are stable about their axes of smallest and largest moments of inertia. When there are energy dissipation modes, such as bending and propellant slosh, only the largest moment of ...
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Why does the ISS always point the same side towards the Earth?
I recently got into a twitter discussion over the ISS attitude. The point of the discussion is the attitude that the ISS mantains while orbiting around the Earth.
From my reminescences of Oribital ...
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What sensors or combination of sensors do rockets use during takeoff for their orientation?
I know that after using up rockets and before reaching final orbit, satellites use Earth, Sun, Star trackers to find the absolute position depending on the application and orbit. After that, they use ...
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What are the numbers on the Soyuz docking cam?
This morning I was watching another video of Soyuz docking to the ISS (Expedition 45/Visiting Crew Docks to the Space Station).
The commentator noted that the two quantities $\rho$ and $\dot\rho$ in ...
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At what RPM does a desaturated reaction wheel run?
A plenty has been written and said about reaction wheels on this site, but there's still one thing I'm curious about: what's the "nominal/rest" speed of a reaction wheel? Say, we've just finished the ...
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Electromagnetic Propulsion Technology
I read this article: Astronauts Test Electromagnetic Propulsion Technology Aboard ISS
And here is a video: RINGS on a Reduced Gravity Flight.
Looks like they tested the "rotate mechanism".
How ...
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How often do reaction wheels require desaturation, normally?
I'm sure the answer to this question is, "it depends" but I'm hoping for a ballpark number here.
Let's assume you design a smallish satellite to point at the earth while orbiting. You have the ...
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