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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New Horizons - Orientation in space

How does the New Horizons probe know it's close to Pluto and turn its science instruments towards Pluto and other targets of its observations during the flyby?
SRudrabhatla's user avatar
2 votes
1 answer
2k views

How can I compute the attitude of a satellite given its yaw, pitch, roll, and velocity?

How can I compute the attitude of a satellite given its yaw, pitch, roll, and velocity? Yaw, Pitch, and Roll are given with respect to the velocity vector (A vector whose origin is the satellite's ...
user10638's user avatar
2 votes
1 answer
662 views

Dual Spin satellite control using momentum exchange

When the stability of dual spin satellite with rotor along z axis an additional equation for the relative motion between the rotor and satellite is added to Euler's equation. Similarly on introducing ...
Astroynamicist's user avatar
5 votes
3 answers
2k views

How does New Horizons control its attitude?

I used NASA's eyes tool to see what's going at the time of New Horizon's closest approach to Pluto. I realized that in the programmed sequence, New Horizons is rotated on its axis by more than 90° ...
joe's user avatar
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Why are two frames of reference needed for attitude determination?

I am trying to understand the global workings of attitude determination, specifically in space, but I don't understand why two reference frames are needed to establish that? Let's say you have a ...
ohiliouh's user avatar
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8 votes
3 answers
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Does the second stage of the Falcon 9 have RCS thrusters?

This video (a tour of the SpaceX factory by Elon Musk) suggests that the second stage of Falcon 9 has Draco thrusters as a Reaction Control System (RCS) (at 2:14), but I don't recall ever seeing them ...
Hobbes's user avatar
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7 votes
1 answer
113 views

Rotation speed of Progress M-27M

On launch date, when first reports of Progress M-27M mishap were received, it was reported (and seen in the released onboard video) that the ship was rotating around its barycenter at an approximate ...
Claudio's user avatar
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Why do upper stages spin before deploying satellites?

I saw the Ariane 6 animation, and I noticed, that the upper stage spins before deploying the satellites. Why are they doing this? Is it necessary or is it possible to successfully deploy a satellite ...
zbarni's user avatar
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11 votes
2 answers
2k views

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 ...
Federico's user avatar
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6 votes
1 answer
2k views

What auxiliary engines do the Falcon 9 first stage have?

Looking at the launches and animations for the Falcon 9, you can clearly see some rockets firing at the top/side of the stage to maneuver it clear of the second stage and orient it correctly for ...
neelsg's user avatar
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1 answer
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What is a "Y-Thomson spin"?

I am new in the field of Spacecraft Attitude Dynamics and Control, and came across the terminology "Y-Thomson spin". What is it? Where can I read more about this attitude control mode?
Christo's user avatar
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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 ...
KonstantinosV's user avatar
13 votes
1 answer
5k views

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!
Peter's user avatar
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5 answers
5k views

Can a free falling astronaut change his spin and orientation?

Imagine that an astronaut during an EVA is cut loose from the space station and falls away from it in a tumbling way. Without any foreign object or air to interact with, could he stop tumbling and ...
LocalFluff's user avatar
11 votes
3 answers
2k views

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 ...
AlanSE's user avatar
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10 votes
2 answers
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AOCS for very small satellites (micro, nano, pico, femto)

What does a typical Attitude and Orbit Control System (AOCS) look like for a very small satellite? How does such a satellite control its attitude and orbit? Are there any means of propulsion at this ...
user avatar
2 votes
1 answer
167 views

Can spacecraft magnetometers be used in orbits of planets other than Earth?

My lecture slides on spacecraft magnetometers for use in attitude sensing only mention the use in the context of Earth orbits, but leave it open to interpretation if they can be used for attitude ...
MikeFoxtrot's user avatar
13 votes
1 answer
687 views

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 ...
Nickolai's user avatar
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4 votes
3 answers
423 views

Is there an existing method of automatic thruster alignment?

Does any mission have a propulsion system such that thrusters are aligned automatically, in order to only give delta-v, but without changing angular momentum? If so, how is this done? That is to say, ...
charlesCroode's user avatar
9 votes
2 answers
1k views

Can the reaction wheels also be used to store energy?

My understanding is that the parts of a typical flywheel energy storage are pretty much the same as the parts of a typical reaction wheel subsystem -- both have a flywheel, electric motor/generator, ...
David Cary's user avatar
41 votes
6 answers
21k views

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 ...
LocalFluff's user avatar
17 votes
2 answers
2k views

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 ...
Dan Hulme's user avatar
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14 votes
3 answers
2k views

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? ...
Deer Hunter's user avatar
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7 votes
1 answer
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What is "forward rotation" of a spacecraft?

According to ISRO's Mars Orbiter Mission (MOM): Forward rotation of the spacecraft has been completed successfully. What kind of maneuver is that and what is its purpose?
Hash's user avatar
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27 votes
3 answers
13k views

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 ...
E.P.'s user avatar
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8 votes
3 answers
2k views

How does a launch vehicle control its trajectory during the first stage?

It appears during most launches that the only engines working are the main first stage engines. It was my understanding that these engines are fixed in place and cannot turn the rocket, but I must be ...
Stu's user avatar
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4 votes
1 answer
194 views

What pattern is made by the satellites of ESA's Swarm Mission?

Swarm satellites, like in this article, are satellites being released at the same time. Do they enter different orbits? If so, how do they power themselves to get into unique orbits?
Stu's user avatar
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13 votes
2 answers
999 views

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 ...
E.P.'s user avatar
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11 votes
1 answer
799 views

ISS attitude during docking

The ISS is using the Control Moment Gyroscopes to maintain its attitude (the Cupola pointing towards Earth). That means the ISS is slowly rotating with respect to distant stars. What happens during ...
mpv's user avatar
  • 3,022
21 votes
1 answer
5k views

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 ...
AlanSE's user avatar
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17 votes
2 answers
11k views

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 ...
PearsonArtPhoto's user avatar
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7 votes
1 answer
304 views

Have Magnetorquers been used anywhere outside of the Earth?

On Earth, small satellites often include Magnetorquers. A magnetorquer allows the satellite to re-orient itself without using fuel in a way more permanent than magnets. While not every planet has a ...
PearsonArtPhoto's user avatar
  • 121k
8 votes
2 answers
1k views

Could Magnetorquers be used on the ISS?

The way that the ISS manages it's attitude now is to use a set of reaction wheels for primary control, and occasionally firing small thrusters to allow the wheels to despin themselves. This isn't ...
PearsonArtPhoto's user avatar
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9 votes
1 answer
303 views

Why would Kepler’s pointing problems be minimized if aimed within the ecliptic?

Having read a few articles on the suggested new uses for the crippled Kepler space observatory with only two out of four functioning reaction wheels, several ideas suggest that Kepler’s pointing ...
TildalWave's user avatar
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11 votes
1 answer
2k views

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 ...
innocent-world's user avatar
19 votes
5 answers
4k views

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 ...
s-m-e's user avatar
  • 6,571
10 votes
1 answer
2k views

Would magnetic torquers placed in a polar satellite work?

Would magnetic torquers placed in a polar satellite keep the satellite stable? If it would work, would it be very efficient?
Hash's user avatar
  • 18k
8 votes
1 answer
2k views

How is spin stability used in spacecraft?

I understand the basic concept inasmuch that the gyroscopic effect is used and that the rigid body is given an initial spin around an axis of maximum mass moment of inertia (MMOI). However, can ...
TopGun's user avatar
  • 83
20 votes
3 answers
3k views

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 ...
coleopterist's user avatar
  • 6,043
19 votes
2 answers
2k views

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 ...
gerrit's user avatar
  • 11.6k
17 votes
2 answers
6k views

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 ...
user avatar
24 votes
2 answers
3k views

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?
PearsonArtPhoto's user avatar
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