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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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What does Starship use for attitude control thrusters?

What does Starship currently use for attitude control thrusters? The attitude of ITF-3 Starship appeared out of control from engine shut-down, on through re-entry. According to How does the Falcon 9 ...
Woody's user avatar
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1 answer
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What could cause a satellite to tumble during operation?

Detumbling is a common problem and challenge for satellite operators during Launch and Early Orbit Phase (LEOP), with a common cause being a tip-off rate induced during separation with the launch ...
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Creating an animation short and need orientation info

I'm creating a short film celebrating Voyager 1's progress out of our Solar home. I would like to be as accurate as possible. Question: What is the craft's normal orientation as it travels? Is the ...
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Modeling Spacecraft Jitter from Reaction Wheel Imbalances

I am working on a project trying to model a satellite's pointing error caused by jitter from the reaction wheels. I have found a couple of papers (Paper 1 and Paper 2) which implement the simple model ...
Sam's user avatar
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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 ...
Hans's user avatar
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How often does a CubeSat leverage its ADCS?

I'm wondering how often an Earth observation-focused CubeSat (6U - 27U) would leverage its onboard Attitude Determination and Control System (ADCS). Would it be employing its ADCS to optimize every ...
spacegr33q's user avatar
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736 views

Spacecraft attitude: rotation between ECI, LVLH, and Body frames

I'm starting to study spacecraft attitude control and I'm quite confused about the attitude representation in different frames. By reading a bunch of textbooks and papers, I understood that I can ...
Chicca's user avatar
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How do I simulate a magnetometer and get an attitude?

I consider that I have a single magnetometer (i don't know if I need more), how can I model that sensor? This was my idea: Consider a random unit length vector $\textbf{m}$ which is the magnetic field ...
Hamzalihi's user avatar
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Orbital Angular Momentum on STK

I want to allign my satellite with the orbital angular momentum vector. Thus, I've computed this vector in a Fixed Coordinate System using the cross product (r x v) between position vector and ...
Frank's user avatar
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1 answer
290 views

How can I determine a rotation matrix from unit vectors?

I want to determine the rotation matrix from which compute the Euler Angles to rotate my spacecraft in order to point in a specific direction. For example, i want the z body axis of the spacecraft to ...
Frank's user avatar
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GN&C free / open source softwares suggestions

I am looking for a GN&C software free (and open source if possible) capable to compute the attitude and control including hardware profiles, example: RWs (reaction wheels) profiles I know 42 does ...
Pietro De Marchi's user avatar
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Does the ISS keep pointing prograde for most of the time?

I know the solar panels rotate independently, so theoretically there should be no need for keeping the station pointing prograde. It would also be problematic for docking maneuvers. But on the other ...
Mister Smith's user avatar
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1k views

Determine Yaw, Pitch, Roll from two vectors

I need to find the roll, pitch an yaw rotation to point a satellite to a precise point on Earth. I know the satellite position and velocity in ECEF coordinates, the position of the site on Earth (also ...
Frank's user avatar
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What happens when an RCS thruster fails to fire?

Let's imagine a UDMH/N2O4 thruster (like on a Soyuz) has an issue where the oxidizer valve/line freezes solid, blocking the flow. What happens with the fuel? The propellants are pressure fed with a ...
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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 ...
RAD6000's user avatar
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How do satellites ensure they are orientated towards the Earth to allow of clear connections? [duplicate]

As the title says, How do satellites ensure they are orientated towards the Earth to allow of clear connections, whilst having their solar panels face the sun? I understand reaction wheels are ...
Connor's user avatar
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What do/will "quantum gyroscopes using nitro­gen-vacancy centers in diamond" for space applications actually look like, and how do they work?

The NASA page ELaNa 41 Mission has a section labeled QubeSat - University of California, Berkeley which says: QubeSat is a technology demonstration mission. It will test and character­ize the effects ...
uhoh's user avatar
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what is the difference between inertial pointing and nadir pointing?

I want to know, what is the difference between inertial pointing and nadir pointing for a satellite?
u1997's user avatar
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Is there any more information available on JWST's "aft momentum flap"

I gather that the James Web Space Telescope (JWST) has just deployed its "aft momentum flap". However I cannot find much other information. It is described as the "aft" momentum ...
Roger Wood's user avatar
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How can the proposed LUVOIR space telescope slew to different directions while keeping the sunshade in a fixed orientation? What compensates?

In this answer to Why does JWST have such a big Blind Spot? I mention that it moves as a rigid body; in order to change the direction the telescope is pointing the whole spacecraft slews, including ...
uhoh's user avatar
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Modeling satellite attitude for propagation of orbit

I recently obtained good results with a high-precision numerical orbital propagator using a constant effective area for drag and radiation pressure. I have now become interested in checking if the ...
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Why exactly did SOLRAD 1 have a magnet? Why weren't its interactions with Earth's magnetic field anticipated?

Wikipedia's SOLRAD_1; Scientific results says: The satellite communicated results in real-time, which meant that data could only be received when there was a tracking station within range – either ...
uhoh's user avatar
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5 votes
0 answers
119 views

What are the contingency plans for lost ISS attitude control?

Apparently the Russians had a mishap with their new ISS module. The module fired its thrusters after docking and caused attitude control loss The Russian "Nauka" module linked to the space ...
Machavity's user avatar
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How (the heck) can thrusters alone stabilize New Horizons well enough to take high magnification 30 second long exposures in order to see +21 m objs?

Wikipedia's Long Range Reconnaissance Imager says that LORRI is a: ...telescope aboard the New Horizons spacecraft for imaging. LORRI has been used to image Jupiter, its moons, Pluto and its moons, ...
uhoh's user avatar
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What is this block of long, skinny rectangles in this New Horizons trajectory/operations simulation?

This answer to What do all these vectors point to in this New Horizons trajectory/operations simulation? begins: The software is definitely AGI's STK (notice the font and the states at the left top ...
uhoh's user avatar
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2 votes
0 answers
189 views

What's the farthest an ISS astronaut gets from the station's center of mass during routine activities? At 0.5°/s what centrifugal effects are there?

This answer to Are there really “Dead End” signs on the outside of the International Space Station? won't be helpful here since for the purposes of this question spacewalks aren't part of routine ...
uhoh's user avatar
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6 votes
1 answer
906 views

Do astronauts aboard ISS notice a change in ISS orientation?

The ISS was rotated by Nauka today. As far as I understand, this took quite some time, i.e. the ISS was not simply rotated by 45 degrees within a few seconds. I know that the ISS usually rotates once ...
DarkDust's user avatar
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4 votes
3 answers
453 views

Did the ISS just turn upside-down? Nauka docking attitude maneuvers; did the cupola near pointing zenith and therefore show only black sky w/ stars?

This answer to Is the ISS going to yaw and assume the XPOP attitude for Nauka docking? contains lots of information on the attitude trajectory in yaw-pitch-roll space, but from those I can't envision ...
uhoh's user avatar
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Why aren't ISS attitude control thrusters a "tool" picked up by robotic arms?

Since ISS is an evolving structure which center of mass flucuates in position depending on added or removed modules, could Canadarm or latest European robotic arm be used to manipulate attitude ...
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347 views

Is the ISS going to yaw and assume the XPOP attitude for Nauka docking?

I noticed this in the launch of Nauka MLM to the ISS. (Previously I had assumed it would dock in a similar manner to Progress or Soyuz, that is coming from behind and underneath - this says the ...
blobbymcblobby's user avatar
4 votes
0 answers
125 views

How to reduce fuel consumption in an attitude-control PID

I've programmed a spaceship with thrusters, and an attitude control system with a PID controller for each axis. Although my spaceship movement is visually fine, my ship rotates to the target attitude ...
Innovine's user avatar
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1 vote
0 answers
220 views

Calculating body frame X vector's look direction in GEO (NED) frame from roll, pitch and yaw data, is this correct?

I have roll, pitch and yaw angle values for a LEO satellite. Satellite orbit frame and spacecraft body frame are defined as LVLH. The satellite position and velocity are given in ECI/GEI frame. I have ...
Ceren's user avatar
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328 views

Dragon RCS: Four controlled degrees of freedom... or six?

Would Dragon's RCS clusters allow it to translate cleanly left-right and backward-forward, like a crab? Or are they meant only for roll/pitch/yaw control + longitudinal (up/down) translation, like an ...
user avatar
2 votes
0 answers
38 views

Dragon launch escape: roll control?

Dragon’s four superdraco pods are positioned well for pitch and yaw control, but not for roll control. So I’m wondering how they’ll control for roll during launch escape—or if they’ll even control for ...
user avatar
2 votes
1 answer
487 views

How do grid fins actually work? Which aerodynamic mechanism(s) produce the torque on the spacecraft?

I’m trying to model the steering force that grid fins exert on a falcon 9. I know these things are not just grid-shaped fins but actually grids of fins. And each of those fins will experience drag and ...
user avatar
3 votes
1 answer
121 views

Attitude determination with phototransistors and magnetometer

This was originally in Engineering Stack Exchange but someone suggested posting it here. This is for a University Engineering project. The project is the design of small satellite which would be ...
Fraser Curry's user avatar
2 votes
1 answer
202 views

Attitude control with cold gas thrusters

Consider the cold gas thrusters on a Falcon 9. There are two thruster pods on stage 1 and two on stage 2. Each pod has four orifices to fire along the x, y, and z axes of the scacecraft. By varying ...
user avatar
10 votes
4 answers
2k views

Most accurate attitude determination system in spacecraft?

It seems that IMUs suffer from integration errors that build up over time, so they are not the most accurate means of determining the attitude of your spacecraft. So what then would be the most ...
user avatar
3 votes
0 answers
117 views

Why are Hubble's magnetorquers angled?

Watching a video on how Hubble attitude control works I saw one portion on magnetorquers. It has four for redundancy but they are angled in a way that looks awkward from a packaging viewpoint, so what ...
Pilothead's user avatar
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6 votes
2 answers
677 views

Solid state thrust vectoring

Usually thrust vectoring for the whole rocket is done by changing the orientation of individual engine(s) by hydraulic/electric actuators. So in this system the engine simply moves and with it the ...
Kozuch's user avatar
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1 vote
2 answers
217 views

Are bicomplex numbers including tessarines ever used in spaceflight (as an alternative to quaternions)?

The answer to What are quaternions and how are they used to represent spacecraft dynamics? gives us a thorough overview of the topic and is worth a good read. I saw the HNQ Why are quaternions more ...
uhoh's user avatar
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6 votes
1 answer
381 views

Displaying spacecraft attitude from rotation matrix or quaternion?

Navigation and guidance systems generally use rotation matrices or quaternions to uniquely specify 3D rotations. But these are not the least bit intuitive, so we like to convert them to Euler angle ...
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0 votes
0 answers
79 views

Design a cold gas ACS nozzle

I have the total thrust required to be F=16.9 KN. I am using nitrogen gas, and the stored temperature in the nitrogen gas cylinder is 155 bars with a temperature of 325k. How would I design the nozzle ...
letsflybaby's user avatar
4 votes
1 answer
986 views

How powerful do cold gas thrusters normally get?

Modern rockets like the Falcon 9 use cold gas thrusters for steering on landing approach when the engines are dead. Cold gas thrusters are common in smaller satellites and spacecraft, which way a ...
user avatar
11 votes
2 answers
2k views

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 ...
StefanH's user avatar
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8 votes
1 answer
140 views

How does Hayabusa2's return capsule orient and stabilize after separation and before and during reentry?

How does Hayabusa2's return capsule orient and stabilize after separation and before and during reentry? Have it some onboard system like RCS or reaction wheels, or does it rotate around longitudinal ...
Peter Nazarenko's user avatar
5 votes
1 answer
70 views

Attitude and orbit detection systems for solar sails

When a solar sailing craft is successfully getting force from solar photon pressure, that force applies a small torque to the craft because the center of pressure is never perfectly aligned with the ...
BobTheAverage's user avatar
9 votes
3 answers
440 views

Would this Starship design alternative be viable?

Considering Starship's atmospheric entry, belly dive and "bellyflop", latest iteration displays four aerodynamic surfaces, two aft fins and two canard fins. Soon, this configuration will be ...
user avatar
4 votes
0 answers
2k views

How do Falcon-9's cold gas thruster maneuvers account for the center of mass changes due to "floating fuel shifts"?

The Art of Engineering video How SpaceX Lands Rockets with Astonishing Accuracy after 07:19 explains: Cold Gas Thrusters The falcon 9 is equipped with a total of ...
uhoh's user avatar
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1 vote
2 answers
999 views

pitch, yaw and roll

Imagine a spacecraft in space, which is required to dock with other. Presume that it needs to "pitch" by X degrees, "yaw" by Y degrees, and "roll" by Z degrees (although &...
Niranjan's user avatar
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