Questions tagged [orbit]
Questions regarding the mechanics or attributes of objects falling 'around' other objects, thereby orbiting them.
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Distribution of satellites by inclination
What is the distribution of Earth orbiting satellites by inclination? In other words, what inclinations are more or less popular? I work with Earth observation myself, where many satellites are Sun-...
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0answers
27 views
Computing the local orbital frame vector directions and angles of gyroscope direction in the satellite
In the context of the study of a cubesat (little satellite), I am asked to define the local orbital frame and compute the local orbital frame vector directions as a function of time (...
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2answers
127 views
How to get experiments to space?
How would a person get an experiment done in space? What is the chain of command on something like that?
I would like to drop some inflated balloons from space to reenter the atmosphere to see which ...
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1answer
58 views
How low does OSIRIS REx's record-setting orbiting around Bennu go?
This OSIRISREx tweet says:
It's official! I'm in orbit around #asteroid Bennu -- now the smallest body ever orbited by a spacecraft. My snug path around the asteroid also sets a new record for the ...
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0answers
59 views
What is typical lifetime of GTO rocket stages before reentry?
Most of geostationary satellites are launched at geostationary transfer orbit (GTO) first by rocket's upper stage. Than satellites separate and circularize the orbit by own propulsion. The upper ...
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2answers
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How far have astronauts been in space?
I just listened to a podcast where it was said that astronauts have only been at most 400 miles from Earth (except for the moon of course in the '60s/'70s). Is this true?
I know that the ISS orbits ...
5
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1answer
82 views
At what altitude do the effects of atmospheric drag completely disappear?
The spate of K-questions got me thinking: At what point does atmospheric drag disappear1 with the pressure from sunlight, solar wind, or other forces becoming overwhelmingly dominant? I'm guessing it'...
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1answer
195 views
Deviation of semi-major axis
If I calculate the semi-major axis of Molniya-1T with
$a = \sqrt[3]{\dfrac{GM}{n^2}}$ with $n=3.18683728\text{ }d^{-1}$, I get another apoapsis ($a=19505.7$ km) as noted at Heavens Above:
apogee ...
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1answer
51 views
Which orbit around Earth has the least perturbation?
Which orbit around Earth would have the least amount of perturbation from the moon, Sun etc.? Does an orbit exist where in either direction of travel that the perturbation would be the same?
The ...
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4answers
355 views
What could a High Earth Orbit be used for in practice?
I was perusing wikipedia and saw this awesome infographic:
Original location of infograhpic: Wikipedia
Then it hit me, in all the time I've been browsing space articles and such...
I've never ...
3
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0answers
29 views
How close will the cubesats be when numerous of them are launched simultaneously?
Checking the onboard video of PSLV C43 gives a feel like the CubeSats are released in very proximity.
Does this mean that these CubeSats will be orbiting in such very close proximity through out ...
5
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2answers
99 views
What are the advantages of a Molniya orbit over a tundra orbit?
As I understand them, Molniya orbits and tundra orbits are very similar: they are both intended to provide satellite coverage over large latitudes and provide a large apogee dwell time over the large ...
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1answer
126 views
What is the darkest orbit around Earth?
What orbits around Earth has the least and most sun light exposure?
I wondered: When taking pictures either of Earth or otherwise with various telescopes in orbit, does it help to be in Earth's ...
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6answers
601 views
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 ...
4
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1answer
110 views
What orbits are popular?
So the two I can think of are the ISS orbit and GEO. Are there any other orbits that consistently have 10+ launches a year?
For this question, when I say matching orbit, I mean eccentricity, ...
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1answer
157 views
Why was Dawn placed into an orbit that would only be stable for “decades”
Last year NASA put Dawn into an orbit around Ceres that Ars Technica said "would remain stable for decades" so as to not contaminate Ceres.
Decades are pretty small on the cosmic scale though. Why ...
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2answers
2k views
Question on giant satellite orbit
So here's a strange question that came up in a class tonight. It is axiomatic that satellites in the same orbit travel at the same speed.
But is there some size of satellite whose mass is so great ...
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0answers
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What would astronauts see if they were in an Earth Moon L1 Lissajous orbit?
Would they be moving fast enough that the change of their position relative to the Earth and the Moon would be perceptible? Or would that change be too slow to notice moment by moment?
I take it as ...
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What forces and motion would astronauts experience in a spacecraft in Earth-Moon L1 & L2 Lissajous orbit?
What is the maximum velocity they would experience? Would they be aware of the movement based on the positions of the Earth, Moon, or stars, or would it be too slow to notice? Would they feel any G ...
10
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1answer
218 views
What did Karman's original “Karman line” calculations look like?
Looking for the atmospheric parameters (density for example) and vehicle parameters (CL for example) as well as formulae that were used in the original calculation. Primary sources strongly preferred,...
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2answers
423 views
How would the International Space Station be maintained unmanned?
Russia's lunch to the ISS failed and the crew may have to leave it unmanned. How would the ISS run without a crew? Could some one else take it over or squat in it?
https://www.npr.org/2018/10/11/...
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1answer
230 views
Why are 22N and 440N liquid engines quite common?
One can often spot that liquid apogee engines are 440 N and attitude control systems are 22 N.
Is there a reason why the thrusts are proportional? If the engines are scaled for reducing development ...
8
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1answer
210 views
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 ...
3
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2answers
182 views
Name for point in a satellite's orbit around a planet when the satellite is furthest from the sun
When a satellite is orbiting a planet (which itself is orbiting the sun) there are periodic points when the satellite is closest to and farthest from the sun, once where it is interposed between the ...
10
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1answer
236 views
Why do GPS satellites have increasing eccentricity over time?
When comparing GPS, Beidou, Galileo, GLONASS, and potentially other GNSS, we can see that the eccentricities of GPS spacecraft are increasing with time (i.e. apogees increasing and perigees decreasing)...
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2answers
212 views
What is the shape of a space elevator?
When we think of a space elevator, we might usually think of a purely vertical tower, sticking perpendicular to the surface of the Earth, extending way past the geostationary belt, to the end-mass.
...
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0answers
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Aerobraking on Mars
I am looking for a calculator or formulas that can be used to calculate the aerobraking on Mars mission. I have found some data on previous Mars flights where aerobraking was used and all my current ...
4
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1answer
138 views
How to determine an orbit of a satellite for a collision detection?
I'm trying to validate an collision detector , and for that I'm starting from a pair of initial conditions for a satellite.After that I will use an RK method to integrate . How can I determine a pair ...
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2answers
120 views
Onboard propagator in satellites SGP or J2
The Earth orbit propagator SGP4 (simplified general perturbation) was developed by NORAD to allow users to generate short-term prediction of satellite positions using two line element sets (TLEs) ...
43
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5answers
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Where does space begin on planets without atmospheres?
On Earth the Karman Line is used as the boundary of space, and I believe it is defined as the height where you would have to go faster than orbital speed in order to obtain aerodynamic lift. Therefore ...
2
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1answer
53 views
The appropriate reference frame for the interplanetary missions
In the JPL Horizons there are Earth mean equator and ecliptic reference planes. The ecliptic is an apparent path of the Sun's ...
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0answers
62 views
What is optimum data interval algorithm for Orbit Determination?
I am trying to find Optimum data interval algorithm for orbit determination. Because in Leo, Geo orbit updates the measurement data can be different so that I want to implement an optimum data ...
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1answer
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Would we be able to see a Space craft transit in Lunar orbit?
If a Apollo type Moon mission happened today would we be able to see it transit in Lunar orbit? I know we can't see the Landing sites of the Apollo but could we see the Command Module and its shadow ...
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1answer
604 views
Elliptical orbits transformed to “equivalent” circular orbit
I'm trying to transform Mars' elliptical orbit into its circular "equivalent". I understand that if the semi-major axis is used as the radius, and the mean angular rate and period are kept the same, ...
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0answers
181 views
How can I calculate Mean anomaly from True longitude?
So, I have
- TLE data
- Reference frame: QMOD
- Type: Osculating
- Semimajor axis
- Eccentricity
- Asceding node
- ...
5
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3answers
274 views
Is a sun-blocking orbit possible?
Is it possible for an orbital "sun shade satellite" to have a geosynchronous equatorial orbit such that it is in an approximately straight line between the Sun and a fixed point on the Earth's ...
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1answer
109 views
What attitude have past and modern manned spacecraft maintain(ed) relative to Earth?
I hope this question is not too broad. It is inspired by another question.
We know that ISS keeps its nadir pointing to Earth's surface.
What about other manned spacecraft?
Do/did they have ...
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0answers
166 views
Outlier detection algorithm for orbit determination, how do different ones compare?
I have been reading about outlier detection algorithm for improving determinations based on realistic data.
Outlier exclusion is an important tool in any analysis of realistic noisy data. There are ...
2
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2answers
196 views
Is it possible to orbit a black-hole AT the event horizon? [closed]
https://en.wikipedia.org/wiki/Black_hole#Innermost_stable_circular_orbit_(ISCO)
ISCO is apparently the current theoretical limit for orbiting black holes (as sourced by wikipedia).
Original Question:...
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1answer
90 views
Drag-only and gravity-only satellite orbit propagation, need help understanding the results
I'm trying to propagate the orbit of an Earth satellite. I've tried my calculation with gravity only (no drag), and also with drag only (no gravity).
The gravity-only calculations work fine and ...
5
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1answer
413 views
How do I determine the ground-track period of a LEO satellite?
I was analyzing a LEO satellite with polar orbit for work purposes. I am relatively new to the field of Satellite orbits. I know that TLE can give information about the current & future orbits ...
5
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1answer
97 views
How is stability of Geosynchronous Orbits (GSO) affected by Earth’s mass?
I'm researching stable orbits slightly beyond GSO and I need to find out how close to GSO I could place an object without risking collision. If the Earth was homogeneous the altitude should be the ...
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0answers
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Need help with calculating state vectors from Orbital Elements - C#
I have been working on a project where I want to visualize the orbits in the solar system with the help of Unity Engine.
I have been using different guides and similar questions on this forum to ...
5
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2answers
477 views
What is hyperbolic eccentric anomaly F?
I have no idea what this is and have been searching on the net but all I get is eccentric anomaly. The equation that relates hyperbolic eccentric anomaly F to its true anomaly $\theta$ is exactly the ...
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1answer
7k views
What is the farthest artificial satellite in orbit in our solar system?
When did we send the farthest satellite and what is its role and name ?
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1answer
96 views
How can I look for the best date of launch for gravity assist?
I am new to astrodynamics, and I am trying to learn about gravity assists, but I don't understand how I can easily decide a launch date and arrival late for the planet in which I calculate the gravity ...
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1answer
123 views
What orbit is this?
Can this orbit exist around the Earth and the Moon if the weight and speed of the satellite is ideal? I have added a picture below with the orbit drawn.
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1answer
176 views
Can you operate a satellite in the disposal “graveyard” region
The NASA safety standards allocate the region between 2,500km to 18,833km altitude for the disposal of LEO satellites.
Most satellites, as far as I understand, will either operate in LEO (so well ...
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6answers
2k views
Why do satellites appear to move faster when overhead and slower closer to the horizon?
I've been watching man-made satellites with the naked eye using the "Heavens Above" mobile app. They seem to move incredibly slowly near the horizon, but when they go overhead, they look like they ...
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2answers
108 views
Orbits that allows observation of a polar region
If a mission is only interested in a single polar region of a planet, what kind of orbit would be most fitted for the satellite.
The first things that comes to mind is a polar orbit, but then it ...
