Questions tagged [orbit]
Questions regarding the mechanics or attributes of objects falling 'around' other objects, thereby orbiting them.
504
questions
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1answer
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Does Tianwen-1 have a near-repeat ground track orbit in order to scan the same general area on each of its low altitude passes?
Though it's not as easy1 to get details on Chinese missions in English, it seems that Tianwen-1 is in a 12,000 x 256 km highly eccentric orbit around Mars, with its hi res cameras able to resolve 0.5 ...
4
votes
1answer
126 views
Precision in the space navigation [duplicate]
I am curious about the precision NASA and other agencies have in the space navigation.
Are they always accurate to the meter in position they aim for; in mission like the recent rover landing on the ...
33
votes
2answers
5k views
What are ISS orbit's sudden falls?
In current (2021) graph from heavens above (https://www.heavens-above.com/IssHeight.aspx) there are sudden falls - more than 1km in many cases and then after other sudden changes, the graphs return on ...
3
votes
2answers
67 views
How to find ECI coordinates for a circular orbit
Suppose a satellite is orbiting Earth in a circular orbit, of which I know the inclination $i$, the right ascension of the ascending node $\Omega$, the semi-major axis $a$ (or orbit radius given that ...
3
votes
1answer
64 views
Rocket engine with lowest Isp to reach orbit
Which engine with the lowest possible specific impulse has reached orbit propelling a given rocket? There is a page at Wikipedia that compares orbital engines but some engines are missing Isp value ...
4
votes
1answer
159 views
What is the Best position of an object in geostationary orbit relative to the launch site for rendezvous using GTO?
So let's say we have a space station or spacecraft in GEO, and I want to get another spacecraft to it from earth's surface on a direct geostationary transfer orbit, i.e. no waiting about in LEO for ...
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3answers
95 views
Orbital launches
In the 1950s, many US rockets were capable of reaching the lower limit of LEO altitude. Despite this, no one thought of making the launch vehicle / its payload orbit around earth, even for one ...
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2answers
177 views
How many time-zone does the ISS cross through during one orbit?
A recent non-answer to an unrelated question stated that the ISS crosses 16 time zones during New Year's Eve, which is obviously incorrect, the actual answer being "around 200".
But this ...
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3answers
4k views
Are all satellites of all planets in the same plane?
I'm aware of the fact that all planets are almost in the same plane as the Sun and the Earth(ecliptic) plane except Mercury and Pluto(which are more tilted). Are all satellites of all the planets also ...
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2answers
145 views
Does it count as orbital flight if one reentered the atmosphere due to its drag after about 1 revolution?
Imagine a spacecraft entered an orbit around the Earth whose perigee is low enough into the atmosphere so that it reenters and lands after a revolution, without having to perform a reentry burn. While ...
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vote
1answer
56 views
How did the Kepler Telescope establish its orbit after third stage burn? (Follow Up)
note: This is a follow-up question based on a discussion under this answer.
The Kepler Telescope was (is) in a heliocentric Earth trailing orbit, but I want to figure out how it was able to reach this ...
3
votes
1answer
38 views
Apsis suffix for object orbiting an exoplanet
Is there already an agreed upon apsis suffix for an object orbiting an exoplanet? I don't think it's super likely that there is, as I don't think any moons have been discovered (or at least not at a ...
2
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2answers
123 views
What's the fastest orbital period for a spacecraft?
I'm not asking about velocity, I'm talking about overall speed. Shortest time from perigee to perigee. This orbit would be a low, circular orbit, but I can't really find any specifics on any world ...
3
votes
3answers
206 views
How to plot this orbit?
I have these data for some orbits, without any explanation about meaning of each datum:
...
2
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1answer
128 views
How many spacecraft orbiting the sun?
How many spacecraft have been sent in a heliocentric orbit in all history?
By this, I mean spacecraft sent to stay in heliocentric orbit.
The satellites orbiting planets or moons don't count.
Related ...
3
votes
1answer
111 views
Leaving the ISS orbit
Working on a project of sorts and I can't wrap my head around this at all., have a question regarding leaving the ISS orbit. If, let us say as an example, an astronaut jumped out of a capsule which ...
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0answers
40 views
Using the Clohessy-Wiltshire equation, what would be the expression for ' r '?
I'm looking for an expression for r. The difficulty I'm facing is simplifying the C-W equation
0
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1answer
55 views
When B is directly below A, as shown, what's B’s velocity (in vector notation) relative to A?
Spacecraft A and B are in coplanar circular orbits around the Earth. The orbital radii are as shown in the figure.
(Not looking to use C-W equation. Just the equation describing relative velocity ...
5
votes
1answer
146 views
(U.S.) What paperwork do civilians need to send items into orbit or beyond?
Are civilians allowed to send objects into orbit, or even leave orbit, like send something to the moon or deep-space? If they can what kind of paperwork/waivers/licenses etc. need to be obtained ...
3
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0answers
50 views
Further understanding of a de-orbit burn problem worked on in 2018 [duplicate]
I'm having trouble understanding exactly how calculations in this answer to Calculating a de-orbit burn, is this problem written correctly? were performed.
It’s been a while, but now I’m working on ...
1
vote
2answers
428 views
When and where on Planet Mars are the Sun's rays the most blueshifted?
Let's say for a moment that the spin of a planet causes the Sun's rays to be blue-shifted in the morning.
As far as I know, redshift occurs in steps of like 2.6 km/s or something like that. We can't ...
2
votes
2answers
53 views
General Delta V Calculation for Two-Body-Problem
Problem: Given two orbits (e.g. in the 5 keplerian elements excluding true anomaly) A and B calculate the $\Delta v$ necessary to perform a transfer from A to B using instantaneous burns.
Simple ...
2
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1answer
58 views
Orbit lifetime of a Nano-Satellite in 350 Km Orbit
I was trying to write a very simple program to calculate orbit life time of a nano-satellite.
I got the atmosphere density as function of altitude from this site.
...
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2answers
74 views
How to determine the delta V required in order for the satellite at pt. A to hit the earth at pt. B?
I'm confused about how would I go about obtaining delta-v in this case. I'm aware of orbital transfers such as bi-elliptical but that is not the answer to this. Kindly help
3
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1answer
60 views
How to get ISS trajectory information after spaceflight.nasa.gov has been taken offline?
The nasa spaceflight website states that it will soon shut down.
I don't know how long this disclaimer has been there so maybe this is nothing to worry about...
In any case, which different ways do ...
5
votes
2answers
150 views
Do I have enough info to find the true anomaly of an orbit?
For a personal coding project, I'm trying to model orbits of satellites around the Earth. I take in some values from a user and use them to determine the shape of the orbit. I want to model the ...
17
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2answers
1k views
Highest apogee of a Soviet/Russian crewed spacecraft?
I wonder which Soviet/Russian crewed spaceflight reached the highest apogee and how high. For America, the highest apogee ever reached is 1,368 kilometers (~ 850 mi) by Gemini 11 (except that America ...
3
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0answers
50 views
Lagrange coefficients orbit acceleration
I have an initial position, velocity and acceleration (in x,y,z coordinates) for a certain orbit, and I need to compute the next position, velocity and acceleration after a certain time interval (I ...
5
votes
1answer
123 views
Are satellites whose orbits go below 100 km perigee considered having multiple spaceflights?
The International Aviation Federation (FAI) considers the space border at 100 km (330,000 ft) above sea level. So if an orbiting body goes below that altitude and continues its orbit without ...
2
votes
2answers
68 views
How were the boundaries of LEO and MEO (or all geocentric orbits) determined?
From my understanding:
Low Earth Orbit is from 100 - 1240 miles.
Medium Earth Orbit is from 1240 - 22246 miles.
High Earth Orbit is from 22246 and above.
What ...
1
vote
1answer
90 views
Does the Earth's orbiting the Sun influence spacecraft in Earth's orbit?
As I try to comprehend how spacecraft are able to stay in orbit around the Earth I began to think about why the Earth's own orbit around the Sun does not influence spacecraft in Earth's orbit.
I came ...
3
votes
1answer
137 views
Map showing which part of geostationary orbit is allocated to which country?
This article (google translated version) says that part of the geostationary orbit is allocated to Hungary (they are talking about 4°W).
Is there a map, which shows me which part of the orbit is ...
1
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1answer
139 views
Error in Propagating equatorial orbit using GMAT
I propagated an orbit with semi-major axis of 7000km and the rest of the keplerian orbital elements 0 on GMAT. Since the orbit is circular and in the Equatorial plane, it should not change over time. ...
1
vote
1answer
101 views
Keplers equation: written in change in eccentric anomaly
I am reviewing the "Fortran Astrodynamics Toolkit (can be found here) and even more specifically at the two body propagation method implemented in this Kepler module for elliptical and circular ...
4
votes
1answer
148 views
Why can't I just use dot product angles to get satellite vision of a point on Earth?
Right now I'm using MATLAB and can easily get the ECEF coordinates of the satellite and the point on the Earth. Since ECEF is cartesian, why can't I just rearrange:
$$
r_{es}\cdot r_{ps} = \|r_{es}\| ...
5
votes
2answers
292 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 ...
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0answers
30 views
Benefit of Universal Variable formulation for elliptical only cases
I have been reading, and understand that for robust systems dealing with all types of orbits in a two body system universal variables approach has been favored. My question is, if I am strictly ...
10
votes
2answers
236 views
Why do many Mars missions launch now, if the Hohmann transfer orbit is the most propellant-saving one?
The Hohmann transfer orbit is the most propellant-saving transfer orbit to Mars. When using this kind of transfer, the rover/rocket/etc. starts from Earth when Earth and Mars are in conjunction.
But ...
23
votes
9answers
10k views
If someone built a vacuum tunnel through the atmosphere, could you have an orbit with a sea level perigee?
This is something I've been thinking about for a while now. My initial estimates for the structure were based on people's estimates for an O'Neil cylinder, but assuming you can make the structure a ...
5
votes
1answer
929 views
Would a sniper bullet fired on Ceres reach orbital or even escape velocity?
What would happen if you fired a sniper bullet horizontally from the top of Ahuna Mons, the highest mountain of Ceres? Once I read somewhere that if you fired a bullet on the Moon in the correct angle,...
2
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0answers
51 views
What is the preferred orbital trajectory for a rover/lander to land on a body?
With the new perseverance rover about to launch to mars, I have a question about landers and rover orbital trajectories. Do the landers/rovers circularize their orbit before landing on the body or do ...
4
votes
2answers
212 views
What is the maximum apogee a Space Shuttle could have reached?
What is the maximum apogee a Space Shuttle (and which one of the five space-flying Shuttles?) ever reached and what is the maximum one it could have reached? A Space Shuttle never exceeded the apogee ...
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7answers
3k views
Why are all space initiatives designed to get to space overnight when in Nature all extreme feats are achieved in a gradual process
Is the current design paradigm of space engineers still too anti-naturalistic?
Why not design Space Cruisers first large & slow but steady into outer orbit, over months rather than in a day? I ...
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vote
0answers
83 views
Keplerian to cartesian elements issue
I am trying to convert between keplerian orbital elements to cartesian position and velocity but something is going wrong. The issue is that I (as a check) compute some keplerian orbital elements with ...
2
votes
1answer
110 views
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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0answers
49 views
Compute eccentricity and angular momentum vectors of a binary
I having some trouble finding the direction vectors (in 3D) of the eccentricity and angular momentum of a binary. The issue is that the binary has only been described in Keplerian orbital elements and ...
20
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2answers
2k views
Escaping moons conflict with what I understand of gravity
I have known that the Earth's Moon, let's call it Luna (tip of the hat to The Expanse), has been slowly but surely increasing it's distance from the Earth by a small measure each year.
This week I ...
3
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0answers
88 views
How low would a full revolution around Titan and Triton be possible?
A lowest circular orbit to remain stable around the Earth is possible at an altitude of about 95 mi (155 km) while the lowest perigee for a stable elliptical orbit around the Earth would be around 55 ...
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0answers
37 views
How did Osiris-Rex enter orbit around asteroid Bennu?
Bennu became the smallest and probably least massive celestial body orbited by a probe. Its surface gravity is 6 micro-g (= 6 millionths the gravity of Earth) according to Wikipedia. How did a probe ...
2
votes
2answers
119 views
Simulating engine burn with scipy ode solve
I'm using ODE solver to calculate complex trajectories.
A simplified setup is like this:
...
