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Questions tagged [frames]

The tag has no usage guidance.

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0answers
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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 (...
3
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0answers
71 views

Determining the spacecraft position vector with respect to ICRF frame for Venus flyby

For an interplanetary mission design to Saturn, I have considered doing multiple gravity assists starting with Venus. I am using the JPL Horizons ephemeris and ESA Lambert Solver. I have the ...
4
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1answer
81 views

What's the best way to understand different relative coordinate systems?

I've been reading a lot about the different coordinate systems: Topocentric (From a local observer on the surface, not the center) Geocentric (From the center of a celestial body) Perifocal (From the ...
1
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0answers
50 views

How to define a body-centered ICRF/J2000 frame in SPICE?

I am trying to define a reference frame in SPICE that is Centered on a particular body, for example Mars, and with axes parallel to J2000/ICRF After going through the required reading for reference ...
2
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0answers
130 views

Conversion of GCRF to ITRF

I have to convert the $[r,v,a]$ vector from GCRF frame to the ITRF frame (and vice versa), complying with the precession, nutation and polar motion. How to calculate the ...
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 ...
7
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1answer
223 views

Using of the coordinate systems in orbit propagation

For the orbit propagation in ECI coordinate system, considering the effects of zonal harmonics and Sun/Moon perturbations the following procedure was formed: Convert the state vector to ECEF ...
6
votes
1answer
100 views

How to calculate the speed of rotation of a given point on the Earth's WGS84 ellipsoid, about its axis?

Launches often happen near the equator in order to take advantage of Earth's rotation speed. This is why more launches are towards the East than towards the West. How can one calculate the speed of ...
4
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1answer
387 views

What is the difference between GCRS and J2000 frames?

What is the difference between GCRS and J2000 frames? Which is commonly used worldwide in satellite communications? I've read a statement here, that ...
3
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1answer
117 views

Reference frames - why do I need to convert to Geocentric Equatorial State Vector to solve equation of motion?

I am asking this question in relation to an example shown in the 'Orbital Mechanics for Engineering Students' book by Howard Curtis (third edition) pp659 example 12.1. The example is demonstrating ...
4
votes
3answers
716 views

SGP4 TEME frame to J2000 conversion

I've got familiar with the SGP4 model. The problem which I faced is that, the results are in TEME frame. How to convert the TEME to J2000? Would be glad also, if you suggest a method in ...
3
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1answer
137 views

Satellite Positions in ICRF

For a project I need precise satellite positions in ICRF. After doing some searching I was not able to determine any online resource which provides such time series. In detail I am interested in the ...
3
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2answers
596 views

Satellite Velocities: Relative or Absolute?

Are the reported satellite velocities, such as for the ISS at 17,450 mph relative to the surface of the earth, which is turning, or to some fixed point without the rotational velocity. In other words,...
1
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1answer
223 views

Is this an ECI frame?

I am reading a document on satellite attitude control and the Kalman Filter and it mentions that the satellite is tumbling through free space in a reference frame that has the Sun vector of constant ...
6
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2answers
2k views

In “spacecraft talk” is nadir just a fancy word for “down”?

Assume the approximation that the Earth is spherically symmetric — without higher order gravitational multipoles, and other effects that might be related to gravity from other bodies or the ...