Questions tagged [two-line-elements]
Set of values carefully prepared to be used together with a simplified perturbations model (most often SGP4) to predict satellite positions with a moderate level of accuracy for times near the epoch contained within the TLE.
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Determine orbit type from TLE
I was wondering if, and how, one can tell from the values in a TLE whether an orbit is LEO, MEO, HEO, or GEO. I'd like to do this in code eventually, so any formulas or threshold values would be much ...
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Will the new "TLE format" be orbitally-mechanically better than traditional TLEs?
Celetrak's A New Way to Obtain GP Data (aka TLEs) by Dr. T.S. Kelso 2020 May 27 explains the arrival a new infoblob format that in several ways is "better" than the ancient TLE, and contains ...
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TLE filtering techniques to remove the mean motion/eccentricity/inclination outliers
I am working on a TLE filtering code to prepare the TLE series for orbit propagation. I am using a sliding window approach with meadian+ n*mad or IQR to detect the outliers in those orbital elements ...
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TLE on path to be deprecated - what is 9 digit?
The TLE format will soon run out of numbers. The US Space Force is implementing an Alpha 5 scheme where the first byte of the NORAD_ID will be a letter giving nearly 400,000 numbers. After that a 9-...
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How to get semi-major axis from TLE?
This should be fairly straightforward, but, how do I get the semi-major axis (a) from at TLE.
For example if I have the TLE:
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Get dates when a satellite has performed maneuver from historical TLE data (python)?
I have been recently acquainted with orbital mechanics and am trying to do some analysis on the subject. Since I don't have subject matter expertise, I am at a crossroads with trying to decide that ...
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Second derivative of mean motion as indicator of deorbit
I noticed that the second derivative of mean motion (SDMM) is non-zero for only a small percentage of the NORAD catalog. All those objects I checked have reentered since the TLEs I was using were ...
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Why did the frequency of TLEs for the Hubble Space Telescope drop by a factor of 3 in 2009?
I noticed that the TLEs for the Hubble Space Telescope (HST) are posted almost twice a day. Then I looked back in time and saw that this rate varies quite a lot!
The plot shows the time interval ...
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Where can I find a satellite/space debris database with object masses
The title pretty much says it all. As far as I can tell the default method by which space debris objects are tracked/stored in a database is using two line element sets. However these have no way to ...
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Obtain archived TLE data
Now I'm achieving the up-to-date TLE from the celestrak.com and tle.info
However, for some analysis in the past, I need old TLE files, to make my calculations more accurate.
Is there a way to obtain ...
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How would blockchain be integrated into spaceflight? Have any methods been proposed yet?
Blockchain offers a way of keeping track of information such that its authenticity can be verified and it can not easily be falsified.
In a space environment with an increasing number of both active ...
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Why is the NORAD Catalog number of SpaceX's Starlink's "Darksat" both 71130 and 44972?
@BowlOfRed's answer to Which of the recently launched Starlink satellites is the coated one? links to Celestrak's supplemental table for Starlink. https://celestrak.org/NORAD/elements/supplemental/...
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How do two-line element sets handle rev numbers > 99,999?
In a two-line element set (TLE), five characters in line 2 -- columns 64-68 -- are for the rev number. (https://en.wikipedia.org/wiki/Two-line_element_set)
But some satellites have been around the ...
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What would be a "big picture" understanding of how the orbits of Earth satellites are monitored?
In preparation for another question, I typed "keeping track of satellites in orbit" into a search engine, and found a website called keeptrack.space which has a ...
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How can I plot a satellite TLE from its orbital parameters using python and skyfield? [closed]
I have a function that uses TLEs (Two-line elements) from Celestrak to plot the visibility of a satellite in Python. Is there a method with skyfield or poliastro to plot a TLE from given orbital ...
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Are SpaceBEEs actually hard to track?
The IEEE News article FCC Accuses Stealthy Startup of Launching Rogue Satellites focuses mostly on the intrigue addressed in the question What checks are supposed to be carried out to prevent illegal ...
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How does the SpaceBEEs' experimental passive radar reflector work?
My Question: What is the nature of the "experimental passive radar reflector developed by the U.S. Navy’s Space and Naval Warfare Systems Command"? How does it work, and why does it work for ...
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What is "OBJECT BS"?
I checked 2018-099 in Celestrak's satcat again for the question Where can I find the TLE of ExseedSat 1, India's first ever private LEO satellite? and noticed that ...
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What caused so many objects in Earth orbit to "go NEA"? (no elements availabe)
T. S. Kelso tweeted the following, is this a case of lost and found? How can so many substantial objects become lost like this? The list of 23 objects "formerly known as Prince NEA" all seem ...
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Why are there some NORAD catalog IDs larger than 80000 in space-track?
I was trying to find the international designator for the Starlink-2 constellation launch. Not finding anything in Celestrak I looked in Space-Track.
The following space-track.org query builder setup ...
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Generating TLEs with STK Using SGP4 Propagator;
STK has two methods for generating TLEs; Trajectory Sampling method and Single Point method.
I have read the differences both of them at http://help.agi.com/stk/index.htm#stk/tools-10.htm
but I am ...
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Why does 2018-099 (SpaceX, December 2018) still have a dozen unidentified payloads?
According to today's Raw SATCAT Data from Celestrak, the launch designated 2018-099 (SpaceX, December 2018) still has twelve unidentified payload objects!
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How can I "debounce" these TDRS satellite inclinations? (reconstruct the zero-crossings)
The plot below is from the question Why do the geosynchronous TDRS satellites have this distribution of inclinations?, and the explanation says
Inclination and mean motion (rev/day) for TDRS ...
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Distance between GRACE-FO 1 and 2
I calculated the distance between the two satellites by propagating some TLEs with the SGP4. Here’s the result:
the solid lines are for TLEs 19197.90524586 (GRACE-FO 1) / 19197.90551489 (GRACE-FO 2) ...
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How to correctly make a fake, counter-propagating TLE?
In this answer I have said:
Do not make FAKE TLEs!
I would now like to make a fake TLE.
Specifically I'd like to generate a counter-propagating "twin" of an orbit by flipping inclination by 180° ...
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Are there publicly-available non-amateur sources of TLEs other than Space-Track?
As an amateur satellite tracker, and sometime reentry analyst, I am always anxious to get the newest tracking data for low-orbiting spacecraft. I have had to rely exclusively on Space-Track for the ...
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How frequent do TLEs of LEO satellites change?
I was doing some MATLAB simulations on LEO satellites using TLEs obtained from n2yo websites and I observed that n2yo was displaying a different TLE for the same satellite after a few days. I don't ...
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Is TESS really lost? What does Celestrak mean exactly?
From this answer to the question What artificial satellite has the farthest orbit around the Earth?:
I found the following "far out" spacecraft:
TESS (Transiting Exoplanet Survey Satellite)...
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Has a TLE ever been issued for a spacecraft trajectory not bound to Earth orbit?
This excellent answer to the question Why has no TLE been published for the DSCOVR satellite and the Falcon 9 R/B? suggests that to the best of the writer's knowledge TLEs are only issued for ...
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Elevation and Azimuth of satellite in different location
I know the Elevation and Azimuth of the a specific GPS satellite (I have the RINEX files of the station in a specific Location 4.4801,-73.3433; in order to calculate this), but I want to know the ...
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Has IBEX "gone dark"?
I'm having a difficult time finding information on the Interstellar Boundary Explorer's (IBEX) orbit.
Unless I've made some kind of error, the TLE's have stopped at TLE epoch ...
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CSpOC’s identical TLEs
Identical TLEs are often published by CSpOC at https://www.space-track.org/.
For example, here’s the first line of the three newest TLEs for IRNSS-1H:
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Who released pre-launch TLE data for the Space Shuttle?
The question Pre-launch TLEs for NASA launches asks:
I was curious if the United States is on the verge of launching maned flights to the ISS, will anyone release Pre-Launch TLE data like was done ...
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Pre-launch TLEs for NASA launches
I was curious if the United States is on the verge of launching maned flights to the ISS, will anyone release Pre-Launch TLE data like was done back when the shuttle was flying.
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TLE/SGP4 state vector accuracy assessment
I’m using the Planet Labs state vectors downloadable from http://ephemerides.planet-labs.com/planet.states or http://ephemerides.planet-labs.com/planet_YYYYMMDD.states to assess the TLEs/SGP4 accuracy ...
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Can the deactivated satellites also be tracked through TLE?
TLE is used to track whether the satellites are in orbit or not. However, is it possible that a particular satellite is deactivated, decommissioned or deorbited yet its TLE is being updated regularly?
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What does it mean to ask for a date beyond epoch time?
I am fairly new to this industry. As I am playing around with a library on Python, ephem, I have encountered an error saying that:
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Why the PRN obtained from Android is different from calculated by TLE
I want to use TLE data to calculate the azimuth and elevation of every GPS satellites at user's location.
In order to verify the correctness of TLE calculation, I wrote an Android app that can be ...
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Why Celestrak has Archived TLEs for most space stations from Russia and the US, but not Tiangong-1, Tiangong-2 or Skylab?
Thinking about this question, I wanted to look at historical data. Then I noticed that while Celestrak does provide Archived TLE data for Salyut 7, Mir, Kvant-1, Kvant-2, Kristallm, Spektr, Priroda, ...
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How does the ISS Transit Finder website get the position of the ISS so accurately?
The recent Petapixel article How to Shoot the ISS Flying Across the Face of the Moon gives a lot of detailed, helpful advice for photographing transits of the ISS across the disk of the Moon.
For ...
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Does this electronics box, or any other non-spacecraft released by astronauts have a TLE?
According to Space.com's 02-Feb-2018 article Cosmonauts Break Russian Spacewalk Record During Space Station Antenna Repair:
The cosmonauts spent the day replacing an electronics box for a high-gain ...
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Converting TLEs into the input data for SGP4
At face value this seems like a trivial question the TLE's are the input to SGP4, but my question is a little more specific.
Given a TLE, the values are in specific units (eg. argument of perigee is ...
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Has NORAD ever experienced a catastrophic event and "lost track of" a bunch of objects?
NORAD tracks satellites for several very important reasons. From time to time an object might become temporarily mis-identified or otherwise confused with another object, these things usually get ...
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How can I plot a precessing orbital plane of an artificial satellite on a polar plot from a TLE in Python?
How can I plot the orbital plane of an artificial satellite on a polar plot from a TLE in Python?
Very new to all of this. As I understand it I need to extract TLE's from Space-track.org. Then use ...
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It's been over two weeks now, will the real Humanity Star please stand up?
edit: This must be some kind of record! (cf. ISRO's PSLV-C37 with 104 satellites - after 56 hours only six TLEs, which factor is greatest challenge? This time its only six total!)
At the end of ...
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PSLV-C39/IRNSS-1H TLE accuracy
The TLEs accuracy for PSLV-C39/IRNSS-1H seems low when compared to that of the other LEO satellites (ISS, HST, Tiangong, Sfera 2, ...). Look, for example, at the following graph that shows the radius ...
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Why are Keplerian elements used in TLEs instead of Cartesian state vectors?
Propagating a state vector seems easier, you just account for the gravity, change the velocity and update the position.
It also allows to easily apply perturbations, etc.
Additionally, the ...
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What happens when the 3-letter suffix space of a SATCAT ID gets exhausted?
The ISS' SATCAT ID is 1998-067A.
The CubeSats and other objects released from the space station are considered its sub-units, thus using different suffixes: 1998-067C, etc.
The same principle applies ...
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Calculate ground track from CCSDS OEM
Are there open source solutions (preferable Python) to calculate the ground track of a spacecraft (i.e. in latitute/longitude) from CCSDS OEM (orbit ephemeris message) format (which is a dataset of ...
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Recreating the eccentricity value of TLE
I cannot confirm the eccentricity value of a TLE using corresponding position and velocity vectors.
Let me go through an example, ISS, to explain the situation.
Using this TLE for ISS,
1 25544U ...
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