# Questions tagged [calculation]

How to calculate things directly related to Space Exploration as defined in the help center, or how the calculations have been done in the past or will be done in the future.

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### Calculating rocket nozzle throat area

I'm trying to calculate a rocket nozzle throat area, $A_t$. My propellant is KNDX. I am trying to do this according to the following equations, taken from this reference: where $P_t$ is and $T_t$ ...
213 views

### How to calculate the time to reach a given true anomaly? [closed]

I'm looking for a general formula or procedure calculate time to reach any given true anomaly.
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### What are the energy requirements to reach Earth orbit and Mars orbit assuming no efficiency losses?

Suppose some magic propulsion method exists which directly converts electricity into kinetic energy. And its efficiency is 100%. And its weight is 0. What is a way to calculate the energy requirements ...
178 views

### What exactly the orbit accuracy requirement in KSP missions and contracts, and how is it mathematically defined and implemented? [closed]

When playing e.g. the Rosetta mission in Kerbal Space Program (KSP), one of the things one can achieve is called Orbit Accuracy. Unfortunately, after searching KSP's forums and Wiki I still can not ...
94 views

### Making sense of rocket engine thrust calculation [closed]

Recently I've been trying to design a hypothetical rocket engine using the mass flow rate, exit mach, temperature, and pressure calculations provided by NASA's own website. I've come to know quite ...
66 views

### How to calculate degrees above/below horizon? (For KiNET-X rocket getting to an altitude of over 200 miles.)

I live near Detroit, Michigan, USA. Let's say I'm viewing from 42.34768° N, 83.47610° W, altitude 718 feet (219 meters) above MSL (mean sea level.) (No, these are not my exact coordinates.) I've ...
24 views

### Apogee estimate starting from simplified one-dimensional numerical simulations

I asked a question on pen and paper apogee estimation and got an answer from @tom-spilker that called my attention: He said that he quickly estimated an inclined launch apogee from the results of a 1-...
576 views

### Calculating mass expelled from cold gas thrusters

Consider a cold gas thruster rated at 1 lbf per firing. The thruster is on-off: there is no throttling, so when it fires it's at a constant full thrust. Assume the gas is nitrogen, and that it has a ...
111 views

### What is the relation between chamber pressure and expansion ratio?

I've always assumed that the expansion ratio of an engine equaled the pressure inside the engine over the atmospheric pressure, but I'm not sure this is right, could someone check me on this?
226 views

### What is the EXACT time that the sun will rise, at the Apollo 11 landing site, in Feb 2173

So this was only supposed to be a fun little easter egg in my sci-fi novel for any eagle-eyed reader who decided to run the numbers, but I've driven myself quite literally - to distraction for the ...
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### Finding the mass flow rate of a blowdown system?

This is a rather amateur question I will admit but how does one find the mass flow rate of an engine with a given tank pressure? Is it really as simple as calculating the cross-section of all plumbing,...
52 views

### Pointing accuracy and relevant manoeuvers CUBESAT

How do you calculate or determine the pointng accuracy of your CUBESAT in sunlit-part and eclipse-part modes? Also how do you determine the maximum roll/pitch/yaw angles and slew rate required in ...
666 views

### Accuracy of converting from TLE/Orbital Elements to Cartesian if used for other propagator?

Say that I wanted to propagate a real-life satellite based on an initial position in space. However, the only source of data I can get is from a tracking website like CelesTrak or Space-Track, where ...
165 views

### Where can I learn to calculate the physics of an ion thruster?

I am trying to build an ion thruster, but I don’t know where to start learning the actual numbers behind one. I know how they work on a basic level, but not much more. Basically I want to be able to ...
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### Ion Lifter Thrust Calculation Problem

I've recently started building an ion lifter. I tried calculating the thrust the lifter produces but I came to a value that is way to high for such a small lifter. I'm using a 40kV at 1800mA AC ...
136 views

### How do you calculate the percentage of light-speed a ship with a certain delta-v can achieve, accounting for relativistic effects?

I was doing some back-of-a-postage-stamp calculations on high-isp interstellar spacecraft earlier and realised something. If I design a spaceship which according to the rocket equation has a very high ...
1k views

### Moment of Inertia of rocket

I am trying to model a rocket launch, and am trying to calculate its moment of inertia at each instant. I am assuming a two-stage rocket with a liquid fuel tank, plus a payload (nosecone-shaped for ...
162 views

### Orbit Elliptical Fitting

Question: Given a set of XYZ (3D) coordinates in the Earth-fixed frame, after converting them to the inertial frame, how do I perform orbit fitting in the least-squares sense (meaning minimising all ...
294 views

### Are hyperbolic trigonometric functions used to calculate hyperbolic orbits?

The following comment is really intriguing! I would say, "Yes, The equations for going from Mean Anomaly to Eccentric Anomaly to True Anomaly are indeed different for hyperbolic orbits than for ...
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### How to calculate the amount of lunar regolith needed to reduce solar radiation in an area on earth by 0.2% or 0.5%

I am working on a climate change that doubles as a lunar infrastructure project. I am wondering if anyone could direct me to resources or help me answer the question of how much regolith scattered ...
1k views

### How to calculate position of GPS Satellite with transmitted ephemeris data?

How can I calculate the position of a satellite using the ephemeris data transmitted by each satellite? I will then use positions generated from each GPS satellite's self-reported ephemeris to ...
206 views

### How to satellite-to-site range given site coordinates and satellite ephemeris?

How can I calculate the distance of a position on earth to a satellite (for example a GPS satellite)? The satellites position is exactly known by its ephemeris data. In a related question I've asked ...
59 views

### Are there any equations out there that can calculate the burnup of an asteroid depending on angle?

Are there any equations that can calculate the burnup of an asteroid depending on the angle? I want to be able to calculate the magnitude of an asteroid impact with the angle being the changeable ...
148 views

### Calculate Date of Spring Equinox, possibly using JPL's Horizons website?

I'm familiar with orbit ephemerides and the ways to use those to plot orbits and positions. However, in all the charts I find, I can't seem to find a way to determine when an equinox on another planet ...
163 views

### Calculation of V1 (orbital speed) during ascent

I am studying instrumentation of NASA's Orion spacecraft, and there is a readout for V1 (I am assuming this is the "first orbital velocity", for circular orbit), and it seems to be in small decimals. ...
235 views

### How to calculate angle in elliptic orbit?

I would like calculate angle in elliptic orbit ZCP at any time, where: Z (position of periapsis), C (center of ellipse), P (current position of planet). I find topic, where is picture (in accepted ...
133 views

### Can a solar mirror increase an ion engine 's output?

Could an ideal size solar sail work as a parabolic mirror to increase the out put of an ion engine? Would the extra weight encumber the ion engine nullifying the increases sunlight on the ion engine? ...
1k views

### Calculations Apollo astronauts were trained to do by hand if loss of guidance computer and/or data & coms link to Earth?

This answer to the question is it possible to navigate space travel with no computer? currently contains the line Yes, as long as you don't care where you end up but I am not so sure this is true. ...
268 views

### What was NASA's “LUROVA” Operational Thermal Computer Model analog or digital? How were capacitors used?

@GremlinWrangler's answer links to Apollo Rover Lessons Learned Applying Experiences on the Apollo Lunar Rover Project to Rovers for Future Space Exploration by Ronald A. Creel, Space and Thermal ...
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### How to make satellite ground track on map?

I want to make satellite ground track using matlab. I already had a position of satellite(ECI) by solving Kepler equation. And I know convert ECI to ECEF using rotation determinant. Then I convert ...
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### How can I calculate the orbital elements from two position vectors and a time difference?

I have two position vectors for my satellite, and I know that the satellite reaches these two positions 15 minutes apart. I know I can find the inclination using linear algebra and my position ...
231 views

### What is this perturbation effect called, and what would be an analytical expression for the resulting eccentricity oscillations?

In this answer I've generated some oscillations of eccentricity by being somewhat naughty and propagating a TLE for +/-250 days from epoch. I believe it's okay for the purposes of demonstrating gross ...
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### How can I calculate Mean anomaly from True longitude?

So, I have - TLE data - Reference frame: QMOD - Type: Osculating - Semimajor axis - Eccentricity - Asceding node - ...
555 views

### different ways to calculate satellite height

I found 2 formulas for calculating height. First is: height = magnitude(satillate_position_vector) - Earth_radius Second is: ...
2k views

### What are the energy-to-mass ratios of some fuels/oxidizers, when including the oxidizer?

Energy-to-weight ratio is an important parameter. We would like it to be high so we don't have to carry around much fuel. Maybe you've heard some of the numbers for common fuels. Hydrogen is about ...
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### Help with Cartesian State Vectors → Keplerian Orbit Elements C#

EDIT I am currently attempting to try the standard Cartesian State Vectors to Keplerian Orbit Elements conversion but i am having problems getting my head around the formulas and the use of vectors. ...
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### How to get true anomaly from time?

An exercise that was left unsolved from last year's class gives me this equation : $$t-t_{p} = \sqrt{\frac{a^3}{\mu}}*(\arcsin(X) - e*X)$$ where : $$X = \frac{\sqrt{1-e^2}*\sin(v)}{1+e*\cos(v)}.$$...
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### Calculating the planets and moons based on Newtons's gravitational force

I am trying to understand how to calculate the orbits of solar system bodies in an n-body framework, based on the pair-wise gravitational interaction between the objects. At present, I am considering ...
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### How big is a human's space bubble?

How big is a human's (space) bubble - in other words: how far could we (as mankind) transport a human being from Earth in such a way that the being would be still alive? (Let's not consider returning.)...
612 views

### Distinction between spacecraft data and telemetry - difference in spacecraft resource use?

What is the distinction (if any) between spacecraft data and spacecraft telemetry? Do these terms tend to represent different kinds of information? While each case is different, in what ways do they ...
1k views

### How were Frenet frames and Gram–Schmidt orthonormalization used in spacecraft orbit calculations?

I haven't seen the film Hidden Figures yet, but I have read and listened to some dialogue clips in this NPR Review. In it they mention a Frenet frame and the Gram–Schmidt process for ...
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### What is the correct thrust curve for a solid rocket with a simple circular hole, and why?

Going to wikipedia's article on solid-fuel rockets, I come across some graphs of thrust curves for certain bore-hole geometry. Right now I'm interested in the simplest bore-hole: a circular hole right ...
936 views

### What formulas do I use to calculate the gravity and drag forces on an object ascending from Earth's surface?

I'm trying to model a slingshot launch to space, literally, and I'm using 2 basic formulas. Simplifying my model, a object with a (really big) initial velocity is launched from Earth's surface on the ...
2k views

### "Pythagorean Three Body Problem" - need some points from an accurate solution for comparison

note: if you up-vote (or even if you don't), don't forget to scroll down and see the excellent answer as well - it's beautiful! The Pythagorean Three Body Problem also know as Burrau's problem is a ...
366 views

### attitude determination TRIAD - how are orbital reference frame vectors constructed?

I am trying to fully understand the TRIAD algorithm for attitude determination of a satellite. https://en.wikipedia.org/wiki/Triad_method So so far I know that the vectors $\vec{r}_1$ and $\vec{r}_2$...
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### A more accurate way of solar sail calculation?

From the Wikipedia article on solar sails: The force on a sail and the actual acceleration of the craft vary by the inverse square of distance from the Sun (unless extremely close to the Sun) This ...
610 views

### A constant parameter in a three body system?

In a two body system, there are a lot of orbital parameters not changing over time, like eccentricity or the orbital plane. A constant parameter can be a combination of two or more, like even though ...