Questions tagged [orbit]
Questions regarding the mechanics or attributes of objects falling 'around' other objects, thereby orbiting them.
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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 ...
4
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1answer
102 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, ...
4
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1answer
153 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 ...
13
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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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0answers
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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 ...
6
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1answer
136 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,...
7
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2answers
338 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/...
4
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1answer
172 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 ...
7
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1answer
152 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
172 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
199 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
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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.
...
2
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0answers
34 views
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
121 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 ...
3
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2answers
88 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) ...
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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
48 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
56 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 ...
3
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1answer
71 views
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 ...
5
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1answer
574 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, ...
0
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0answers
127 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
votes
3answers
247 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 ...
4
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1answer
99 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 ...
5
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0answers
149 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
133 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
65 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 ...
4
votes
1answer
269 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
votes
1answer
94 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
votes
2answers
331 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 ...
28
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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 ?
4
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1answer
93 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
122 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
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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 ...
13
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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 ...
4
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2answers
104 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 ...
6
votes
2answers
414 views
Satellite altitude as a function of time?
In order to obtain a more accurate radiation estimate in this question, I am trying to approximate and/or determine the altitude of a satellite as a function of time. The satellite has an apogee of ...
8
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1answer
377 views
Propagation of pressure waves in Low Earth orbit
So in a Wikipedia article about space debris i read that----
At higher altitudes, where air drag is less significant, orbital decay takes longer. Slight atmospheric drag, lunar perturbations, ...
4
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1answer
140 views
What living organisms adapt to 0 gravity?
Other than humans are there any other organisms with a brain that learn how to maneuver or act normal in 0 gravity? I saw a video of cats and pigeons at 0 gravity freak out but in time could they ...
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0answers
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Is the Earth's orbit regulated? [duplicate]
Does somebody or some organization regulate the Earth's orbit? For example, could I send my project there by my own? Or do I have to ask someone for permission?
3
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2answers
149 views
Do all rigid bodies of radius r have at least one stable orbit with perihelion p such that 2r > p > r?
In reading about the TESS mission, I was ultimately led to this NASA commentary from 2006, discussing how lumpy Earth's moon is. One of the points made is that there exist only 4 orbital inclinations ...
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1answer
3k views
What is the biggest piece of space junk?
What is the biggest of space junk in orbit? What was it used for and is there a picture?
Source: Wikipedia
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3answers
2k views
Teleporting an object into geosynchronous orbit
Assuming that a method was found to teleport objects, and at huge range, if an object was teleported from the surface to a location at the correct height (wikipedia says about 42,164 km from earth's ...
9
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1answer
184 views
Why is the LEO/MEO boundary at 2,000 km?
Differentiating Medium Earth Orbits from High Earth Orbits at the geosynchronous altitude makes intuitive sense. Is there some meaningful difference between orbits above vs. below 2,000 km, or is the ...
6
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1answer
105 views
Why is Nodal precession affected by the rotational period of the planet?
The $J_2$ term in Nodal Precession equation has the rotational period of the planet. I understand that the oblateness of the sphere with an equatorial bulge induces a torque on the orbit of a ...
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2answers
82 views
Stationary Inter-planetary Satellite?
Is there a way to place a satellite in-between two planetary bodies such that the force from each gravitational pull is effectively nullified? In other words, is there any type of situation that would ...
2
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1answer
57 views
Plotting error values between simulated and JPL data
I'm attempting to compare values between my simulated data for the solar system and the official JPL data, to find errors for the position, velocity, inclination and azimuth.
The simulated data was ...
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1answer
357 views
How to calculate a transfer orbit
I'm starting to study by myself orbital mechanics, but I don't understand well how can be calculated the transfer orbit. If I have for example a route Earth-Jupiter, how can I calculate it?
I've read ...
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1answer
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Small aircraft launchers
I have read that Stratolaunch carrier from ALTAIR project has a 117 m wingspan, it will weight in at over 540,000 kg including the fully fueled launch vehicle and will require a runway at least 3,700 ...
