Questions tagged [flight-control]

Systems and software used to control a space craft's trajectory.

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Please explain a way of calculation of Lagrange multiplier in algorithm of low thrust transfer

In David Vallado's book 'Fundamental of Astrodynamics and Applications', chapter 6.7. ("Continuous-Thrust Transfers") there is an algorithm #47: Low Thrust Transfer. In this algorithm a ...
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Will JWST be handed over from Arianespace/ESA/CNES to NASA at some point the way Cape Canaveral handed over missions to Houston?

Will JWST be handed over from Arianespace/ESA/CNES to NASA at some point the way Cape Canaveral handed over missions to Houston? JWST has its own propulsion and communication system. Presumably the ...
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Identifying attitude control mode in GNC software?

Launch vehicles will generally have multiple multiple attitude control modes. At launch, the engine-gimballing thrust-vectoring system is in charge. In orbit, the reaction control system is (at least ...
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Exact condition for hold-down release?

I've read the space-shuttle hold-down clamps would be released once all engines registered 90% of nominal thrust. But would this be sufficient condition to open the hold-down clamps and release the ...
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Space missions that employed separate flight software development teams?

A recent question "Back up plan to use LOX-RP1 for Apollo mission" has an answer stating Another example is that some spacecraft have a backup flight software system written by a group of ...
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How was it commanded to Ingenuity to fly to 10 ft and land again?

Since Mars is multiple light minutes away from Earth, Ingenuity can't be controlled remotely like any drone. Was there a command given to Ingenuity to at a certain time rise to 10 feet and then land ...
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How did the pilot lockout on Vostok 1 work?

The entire mission would be controlled by either automatic systems or by ground control. This was because medical staff and spacecraft engineers were unsure how a human might react to weightlessness, ...
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During space shuttle reentry, why was the sign of GALR based on mach number rather than directly on alpha?

(My apologies if this should go in Aviation.SE instead - I'm not quite certain where questions regarding the behaviour of the shuttle's flight controls during reentry should go.) For flight in ...
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Trim controls for Apollo RCS systems?

Did any of the Apollo-era spacecraft have any method of trimming the RCS jets? Due to variable mass placement (fuel tanks and sublimators emptying, astronauts moving, item stowage, location of moon ...
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Trying to modify a JPL guidance algorithm for the Mars Sky Crane and Mars 2020

I've been trying to implement a modification to the JPL guidance law that was used (or very similar to what was used) for the powered descent portion of the MSL mission and I'm struggling to figure ...
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What are the implications of North Korean black and white patterns on missiles?

Black and white patterns on rockets were originally intended as roll patterns. They helped as a visual back-up for acceleration sensors measuring the roll, as discussed in this previous question What ...
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Can ten (or more) rockets be used together to launch one massive object?

With computer flight controls where they are today, what would stop us from building a relatively large space station on earth, but then using 10 or 20 or even 100 falcon heavy or Starship or SLS ...
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Is steam a good gas to use for a small RCS thruster on a small rocket?

Is steam a reasonable tradeoff from other hot/cryogenic gases in order to have safety and have it easily obtainable? Thanks
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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 ...
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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 ...
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Efficiency in Space Capsule Docking Process

I'm watching the first operational Crew Dragon Capsule proceed through the regimented, and VERY careful International Space Station (ISS) docking process, which was turned on after pausing another ...
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Can the grid fins affect the rotation of the Falcon 9 descent?

Can the grid fins control the rotation of the Falcon 9 on descent? How would they have to be positioned to stop the rotation? If used to rotate the ship, then how they would they have to be positioned ...
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Rocket Engine - Actuator in Loop Simulations

For Actuator-In-Loop simulations, why are the rocket engine nozzles along with the thrust vector control assembly (including the actuators) kept inverted on a platform like in the attached image or as ...
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Knowing when to stop burning

Navigating in orbit usually relies on firing engines for some amount of time to achieve a specific velocity. This answer, for example, mentions "closed-loop guidance" for the ISS boosting. ...
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How do Falcon 9 grid fins deploy?

Is it aerodynamic drag that flaps the grid fins open? Or is there a controlled mechanism for it? Pictures show the grid fins connect through a small link to something inside the rotating trunnion arm--...
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Who or what performs the throttle up?

During a Falcon 9 launch you hear the commands 'throttle up' and 'throttle down'. Who or what performs 'throttle up' and 'throttle down' (i.e. astronaut or computer)?
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How did omission of command to Huygens lander not get caught by anybody at ESA nor anybody at JPL? Procedures in place to avoid in future?

In this answer to Prior to putting spacecraft on a trajectory going a significant fraction of the speed of light, would some things need to be tested on Earth? I wrote: As far as communications is ...
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How does “space weather” cause reaction wheel failure?

Failure of reaction wheels often causes premature mission ending or failure to achieve the goal because spacecrafts are no longer able to maintain orientation and have to rely on chemical propellants. ...
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Why were hot-stick downmoding to CSS, and the ability to use CSS for some control axes but not others, disabled during space-shuttle powered flight?

During ascent, if need be, a space shuttle’s flight controls could be switched from the normal, automatic control mode over to manual1 control (known as control-stick steering, or CSS), allowing the ...
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High altitude stage separation

Normally, at high altitude above Earth's surface, there are stage separation of a rocket. If we consider unmanned rockets, at high altitudes, how does human operators of a rocket who are here on Earth ...
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Could the Apollo Lunar Module be flown to a landing without the LEM Guidance Computer?

Inspired by answers to Could the lunar module have moved to a different spot? question but not talking about that specific relaunch scenario: Could the LEM stack (descent configuration) be flown ...
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Control torque to a Reaction wheel that compensates for friction - need help understanding a working code

Reaction wheel in a s/c is driven by controller torque. However, since there is friction torque in RW, less than the reqd momentum change is achieved. Hence the control torque must be increased by ...
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How do single-nozzle staged combustion rockets control roll?

Related: How do single engine rockets control roll? While many single-nozzle motors are gas generators & can deflect the pump exhaust asymmetrically to produce a torque, staged combustion motors ...
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Time scale separation and cascading control loops

The typical approach to designing flight control systems is to design an inner control loop to stabilize vehicle attitude and angular rates, while an outer loop tracks vehicle position. The reason ...
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Would astronauts have been able to save the CST-100 mission?

The Boeing CST-100 Starliner failed an unmanned test because the timer on the spacecraft was off by 11 hours. This caused the spacecraft computer to think it was ahead in mission timing by 11 hours, ...
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16 votes
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Why are there advertisements in the Russian ISS flight control room?

I found a photograph of the Russian ISS flight control room: Source: NASA https://commons.wikimedia.org/wiki/File:Russian_ISS_Flight_Control_Room.jpg Below the large screen are several ...
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How to filter a white noise or random noise in Matlab Simulink?

I am working on a sun-synchronous satellite Simulink model wich determines its attitude from a Sun sensor and a star sensor whom measure the sun and star direction in the satellite body reference ...
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Did a flight controller ever answer Flight with a no-go?

OK, all flight controllers, I'm going around the horn Retro? Go FIDO? Go Guidance? Go Control? Go TELCOM? Go GNC? Go EECOM? Go Surgeon? Go Are there any recorded instances of a No-Go?
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Can a spacecraft use an accelerometer to determine its orientation?

I know that almost every spacecraft uses a gyroscope to determine its orientation, but I don't know if an accelerometer could also be used in addition to a magnetometer to calculate it. I have been ...
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4 votes
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How do small, spin stabilized launchers follow a rhumb line?

This concise answer to What exactly is rhumb-line control in the context of a launch trajectory? explains the concept in the context of the SS-520 nanosatellite launch vehicle (which "doesn't exist"). ...
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What exactly is rhumb-line control in the context of a launch trajectory?

The conference paper SS-520 Nano satellite launcher and its flight result SSC18-IX-03 from the 32nd Annual AIAA/USU Conference on Small Satellites linked in this answer describes the use of rhumb-line ...
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Where are these historical IBM + Apollo related locations within NASA? What do these computers do?

In the Fortune Magazine video IBM's Moonshot: Past and Future with the notes BM’s John Kelly reflects on Apollo 11’s historic mission and looks forward to what future technology will accomplish. ...
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Apollo CSM RCS maximum number of simultaneously active engines?

Reading the RCS subsystem manual, it seems like each RCS quad of the Apollo SM consisted of four hypergolic engines. Am I correct in saying that all four engines of each of the four quads could be ...
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7 votes
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Apollo CSM mass, inertia and RCS parameters?

Is there a document specifying the total mass, the 3-by-3 inertia tensor of the Apollo CSM assembly, as well as the geometry of the service module and command module RCS assemblies (in other words, ...
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Satellite mission design/performance requirements to attitude/orbit control design specifications

Are there any good sources that discuss: the steps involved in deriving attitude/orbit control design specifications, from satellite mission design/performance requirements?
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What are the top most used satellite control system, flight dynamics solution at the moment ? Approx costs?

I am looking for a list of top most used satellite control systems, flight dynamics solutions by space agencies, private companies etc. the moment? How much do they cost approx for use by 1 person? Is ...
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Analyzing Amateur Rocket Stability and Range Safety

I am working with a university bunch of other university students on building a very large amateur rocket. Our objective with this rocket is just to go very high, with no significant payload or ...
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2 answers
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Among Quantitative Feedback Theory and H infinity, which one is preferred for robust control of satellites esp. small satellites? And why?

I am interested in designing a robust controller for a small satellite with antenna, sloshing propellant and flexible panels on board. I am mostly interested in achieving arcsec precision pointing ...
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11 votes
5 answers
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Is it possible to navigate space travel with no computer?

From launch to land could a person travel in space with only mechanical devices like a sextant? With enough experience what would be the minimum devices needed? Which vehicle currently would be easier ...
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Why would someone use Modified Rodrigues Parameters over Quaternions for spacecraft attitude estimation? And vice versa?

I see quite some papers on spacecraft attitude determination and control, that rely on quaternions. While some others rely on MRPs. The advantage that I see so far is that... for quaternions, the ...
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Avionics Systems on board Falcon 9 (Reusable)

What kind of control systems are active and how do they function on board a Falcon 9 booster while it's landing ?
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How can a rocket go straight up after ignition? [duplicate]

We have seen during rocket launches that the rocket goes straight up after the launch clamps have disconnected. What ensures that it doesn't tilt because of the uneven mass distribution? How does a ...
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Machine Learning and Classical Navigation, Guidance and Control in Space Exploration

Due to the increasing availability of large quantities of data and computational power, machine learning (ML) is providing increasingly better results in various fields. Much research has been done on ...
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4 votes
4 answers
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Using what technology one can keep a spacecraft truly non rotating

Inspired by the question I thought maybe a photon thruster can be used for precisely giving thrust to maintain spacecraft attitude. But soon I realized that for high precision attitude control, one ...
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An program that automatically generates a rocket guidance system?

This is for a liquid propelled rocket that launches from earth. It could also perhaps be used for orbital maneuvers and landing on the Moon (not mars or earth). The inputs for such a program would ...
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