Questions tagged [orbit]
Questions regarding the mechanics or attributes of objects falling 'around' other objects, thereby orbiting them.
431
questions
2
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1answer
122 views
Space and Newton laws
I've read some articles which explain that we can't totally rely on Newtonian gravity concepts for understanding the motion of objects in space.
My question is how the use of relativity helps us to ...
2
votes
1answer
43 views
Geocentric latitude and longitude of sub-satellite point
I was trying to derive the expressions for the geocentric latitude and longitude of the sub-satellite point using Keplerian elements. The final equations connecting the combination of the Keplerian ...
4
votes
1answer
225 views
Why don't spacecraft get left behind once in deep space?
On earth, I know that if I throw a tennis ball straight up while in a car, it comes straight back down thanks to Newton's first law. The ball, the air in the car, and myself are all moving at a speed, ...
2
votes
1answer
84 views
How to identify an object in orbit last night?
I saw an object last night (November 24, 2019) in the sky that was rather unusual and am curious about what it might have been. It had the luminosity and speed of movement across the sky (generally ...
1
vote
1answer
104 views
Could we reverse gravitational slingshot a fast object to slow it down and capture it in an orbit?
I have heard of plans to capture an asteroid in an orbit around the earth, to have it close by so that we could study it more easily.
Such objects can have very high velocities, (I assume) possibly ...
33
votes
4answers
6k views
How did the USSR track Gagarin's Vostok-1 orbital flight? Was tracking capability an issue in the choice of orbit?
For the USA's Mercury flights, a number of tracking stations were installed around the globe. John Glenn's first orbital flight was tracked with them, plus a number of ships.
(Tracking stations used ...
1
vote
0answers
52 views
Earth Rotational Vector and Orbital Inclination
I'm doing a project regarding orbital launches and i'm kinda confused about how to calculate orbital inclination from launch sites. I've simplified my model so I can ignore fuel and the rocket ...
2
votes
3answers
208 views
What is the gravitational acceleration of the Sun?
What is the gravitational acceleration of the Sun?
I've seen numbers such as 274 m/s2, but that doesn't make sense to me seeing that relatively weak sources of spacecraft thrust such as Electric ...
1
vote
1answer
77 views
How to calculate 𝛥𝑣 that required to change orbit with same radius but different inclination?
How could I calculate the total 𝛥𝑣 required to change the inclination of a Geostationary orbit to another circular orbit with an inclination of 30° and the same radius? (The sidereal day is used for ...
4
votes
2answers
234 views
What information can I get if an elliptical orbit intersecting a circular orbit of radius 𝑟 and velocity of ellipse is equal to velocity of circular?
How can I approach solving the question below?
Consider an elliptical orbit intersecting a circular orbit of radius $r$ as shown below. If $v_{ellipse} = v_{circular} = v $, find:
True ...
2
votes
2answers
480 views
Velocity of a rocket needed to get to Mars
At 2:16 in this video, Don Pettit says he used the Rocket Equation to determine the velocity of the rocket needed to travel to Mars, which was 16 km/s. I am not sure as how he did it though, and was ...
19
votes
4answers
4k views
How does a Spacecraft change its orbit?
I am a high school student. I saw the latest Indian spacecraft "CHANDRYAANN 2", which was in orbit around the Earth for 14 days.....
I am so curious to know how a spacecraft changes its orbit. I ...
7
votes
2answers
142 views
Do satellites in orbit undergo translational motion or rotational motion, when initially they are not given any additional spin?
Regarding the proposed duplicate: Thought the proposed duplicate has a similar titIe, I have read those answers and this question requires a different answer.
We know satellites orbit around Earth, ...
3
votes
0answers
37 views
When will ISS return to approximately the same projected location on Earth's surface?
The ISS sailed over my country, Sri Lanka on the eve of yesterday (14th October), and there was some news coverage on the event. While the reporting wasn't particularly scientific or even factual (I'm ...
0
votes
1answer
38 views
How to deteremine the angle between Sun and 2 probes?
I have the orbital position and velocity and the orbital parameter of 2 spacecraft at LEO, how to define the angle between Sun - Probe 2 - Probe 1 in ECI frame (If you imagine at a point sun then ...
-1
votes
1answer
72 views
Issue with SGP4 modelling from scratch in MATLAB
I am trying to develop the code from this source , this research paper and from this too as same as bibliography of that aforementioned source.
So, here as you can see at page 14, they have defined ...
1
vote
0answers
19 views
Velocity Vector Transformation for Point Ahead Angle and Doppler Shift Calculation for Inter-Satellite Link
So, I have the Radial and Tangential Velocity Vector (like in Figure 1) and also the Cartesian coordinate of 3D velocity vector. For reference, you can see in this link. Where, $o_{dot}$ vector matrix ...
0
votes
2answers
115 views
How does the orbit of the Voyager and New Horizons probes manage to get into interstellar space?
I understand that every probe launched has been launched into an orbit. The further you want to go into the solar system, the faster it needs to be moving. And everything orbits the sun until it finds ...
4
votes
2answers
174 views
What is the closest distance SpaceX's Tesla Roadster (Starman) will ever be to Mars?
Elon Musk's own personal Tesla Roadster launched on the Falcon Heavy in November 2018 and unfortunately overshot the orbit of Mars. This short animation shows the trajectory of SpaceX's Roadster. It ...
3
votes
2answers
147 views
When calculating the future orbit of an artificial Earth satellite, is the Moon's gravity significant or insignificant?
Imagine a mathematician is plotting the future orbit of a satellite to be launched and put in orbit around the Earth.
When they are making their calculation, is the moon so far away and the ...
1
vote
2answers
106 views
Do satellites inject into a Hohmann transfer orbit in Low Earth Orbit or in Solar orbit?
Lets say we have a satellite wanting to go to Mars. Do satellites such as MAVEN inject into a Hohmann transfer orbit while in Earth's orbit, or do they go out of Earth's Sphere of Influence into solar ...
7
votes
1answer
170 views
Where in orbit was Michael Collins when the LM landed?
In the NPR podcast On Apollo 11 Anniversary, A Former Crew Member Reflects On The Lunar Trip Scott Simon interviews Michael Collins. Near the beginning is this exchange:
SIMON: We asked the man who ...
12
votes
1answer
347 views
A spacecraft is travelling at X units per hour. But relative to what exactly? Does it depend on orbit? How?
If I am walking, the ground is stationary, and I move X units/hour relative to the ground.
If I am in low-earth orbit, then I am still moving X units/hour relative to the ground, only its a much ...
4
votes
1answer
133 views
Can a Space Telescope orbit so it was always in the shadow of the Earth?
Imagine you have a space telescope that had temperature sensitive instruments. (Like the Spitzer Space Telescope).
In order to maintain a cool temperature - you want it always to orbit in the shadow ...
4
votes
1answer
671 views
Why does the eccentricity vector equation always equal -1?
This is the eccentricity vector equation,
$$e=\frac{1}{\mu}[(v^2-{\mu \over r})r-(r \cdot v)v]$$
$$e=|e|$$
Now this equation is written differently from many different sources but they essentially ...
2
votes
0answers
116 views
Orbiting clock visible with the naked eye
Does anyone remember from the 1980s or possibly early '90s in the UK news a (serious) story about contructing a huge orbiting clock so that people would be able to look up at the sky to read the time ...
1
vote
0answers
32 views
Tools for testing look angle generator?
I'm looking for a software test tool with a specific capability:
Given the lat/long/altitude of a point on the ground and the az/el/range from that spot to a point in space, generate a TLE for a ...
7
votes
5answers
3k views
How could a satellite follow earth around the sun while staying outside of earth's orbit?
I'm wondering if its possible for a satellite to follow earth around the sun while staying outside of its orbit. I wondering for the sake of space based solar infrastructure or just something ...
3
votes
2answers
269 views
Why was the Energia’s payload capacity to lunar orbit greater than its payload capacity to geosynchronous orbit?
The Energia rocket, developed in the 1970s and 1980s to launch the Soviet Buran space shuttle, had the second-highest payload capacity (100 tonnes to LEO) of any rocket ever flown (and the highest-...
3
votes
1answer
118 views
Tiny orbital body detection
What technology would be required to detect a coconut-sized sphere in Earth orbit, at the average altitude of communications satellites?
2
votes
0answers
32 views
Special Case Constellation Analysis Approach: Walker Constellation with Circular (e = 0) orbit in LEO
I am familiar with the general approach to propagate orbits using orbital parameters, and how to account for basic J2 perturbations. I am looking to perform some analysis on large walker ...
1
vote
1answer
96 views
PIR application as a sun sensor
Is there any history or merit to using a PIR (Pyroelectric ("Passive") InfraRed Sensor) as a sun sensor for determining the attitude or position of a Satellite?
2
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0answers
115 views
Recalculate Orbital Elements after a ΔV
I would like to write a program able to simulate a keplerian orbite given an initial position and velocity (r0, v0) and able to manage accelerations in different directions.
To simulate the orbit, I ...
0
votes
2answers
134 views
How many stages needed for a launch ? How to plan a launch
I am looking on how to find out how many stages are needed to reach a certain orbit. I come across equations to compute the height reach by a stage of a certain time. On the other hand I don't find ...
5
votes
1answer
752 views
How precise must a satellite's orbit be?
I was thinking about the question on solid upper-stages and my feeling that a liquid upper-stage would allow a more precise orbit. But... how precise does an orbit actually have to be? I guess I mean ...
5
votes
1answer
114 views
Reference to understand the notation of orbital charts
To address various orbital evolutions of spacecrafts, some particular orbital charts are taken into account. For example, the following is used to depict how a chaser reaches a target:
The only thing ...
4
votes
1answer
94 views
How would off-apsis burn effect the angle and position of new apoapsis
Let's say you have an elliptical orbit, if you burn prograde at the periapsis, you extend the apoapsis by some factor(according to vis-viva equation). But if you burn prograde on somewhere during the ...
1
vote
1answer
109 views
On the dynamics of two connected objects located at different circular orbits
I'm just thinking about the qualitative and quantitative implications of a hypothetical orbital problem, but what I ended up does not make sense as it should.
In particular, assume that two objects ...
28
votes
6answers
9k views
Do simulator games use a realistic trajectory to get into orbit?
In videogames (such as KSP or Spaceflight simulator) people put rockets in orbit with the following procedure:
Turn on the engines and move vertically for a bit.
Start a roll program to turn the ...
3
votes
4answers
176 views
Could we build a sunlight regulator to orbit the sun and help with global warming? [duplicate]
like less sunlight around the poles would be good.
if we put it in orbit close to the sun we may not need it to be that large.
we can keep it in good position with RF cavity thrusters and mini ...
2
votes
0answers
25 views
Where will BioSentinel be relative to Earth while running experiments?
The Space.com article In 2020, NASA Will Send Living Things to Deep Space for First Time Since Apollo describes (among other things) the BioSentinel spacecraft, and links to a NASA BioSentinel fact ...
0
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0answers
133 views
ECI to LVLH transformation [duplicate]
I am working on a transformation of ECI coordinates to LVLH (Local Vertical Local Horizontal) coordinates in order to calculate satellite maneuvers. Does anybody know how should I approach the problem?...
7
votes
2answers
1k views
Have any humans orbited the Earth in anything other than a prograde orbit?
As per the title, have any humans been launched into an orbit around the Earth which is anything other than prograde? E.g. retrograde or polar.
22
votes
3answers
4k views
Why use a retrograde orbit?
I've been looking around and saw
on What is the highest inclination orbit ever attained from a Cape Canaveral launch? a question about launching into retrograde orbit. Of course, due to range safety ...
5
votes
1answer
70 views
Trouble deriving rectangular components of acceleration of satellite in orbit around Earth with J2 consideration
I am trying to derive the rectangular components of acceleration for a satellite in orbit, with Earth oblateness in consideration, in order to use the RK4 method to find the updated position and ...
6
votes
3answers
449 views
How much of a rocket's energy is used to achieve altitude vs horizontal velocity?
Given how it is significantly easier to achieve suborbital spaceflight, I was wondering about how a rocket spends its energy budget. If you magically could launch a rocket from 0 km/s but from an ...
3
votes
1answer
158 views
Have there been any spacecraft with an ecliptic Earth orbit?
Have any spacecraft (manned or unmanned) orbited the Earth in the same plane as the Sun?
(Please read the question carefully. It is not an orbit centered around the Sun, nor an equatorial orbit.)
8
votes
1answer
847 views
How to calculate density of unknown planet?
Having approached an unknown planet, a
spaceship went in a low circular orbit. Would
astronauts be able to determine the average
density of the planets using only a watch
2
votes
1answer
275 views
Argument of Perigee for a circular orbit
For a perfectly circular orbit (e=0), how is the argument of perigee defined??
Thanks.
4
votes
2answers
240 views
Where can I find examples of orbital state vectors?
I'm currently trying to write a program that can calculate orbital trajectories. The goal is to take any orbital state vector (position, velocity) and convert it into Keplerian orbital elements, or ...
