# Tag Info

1

I can't answer you fully why Celestrak is wrong, but the correct number is 44972. It seems like this was updated in the other source. New objects are around 45000 right now, they shouldn't be much larger than that.

0

Partial answer only; I took a small chunk of TLEs from that time frame and plotted rev number versus epoch day number and there is a bimodal distribution separated by about 24,500 revs. In other words about half of the TLEs are near your 18,000 and the other half are near your 42,600. But I don't know why there are two groups, nor am I certain what happens ...

4

Here is a simulation to predict the reentry date. The simulation includes the Newtonian and the relativistic accelerations of all the planets, Sun and Moon. The Earth's gravity field is modeled with the SGG-UGM-1 gravity model (computed using EGM2008 derived gravity anomaly and GOCE observation data) truncated to the degree and order 15 (to save the running ...

0

Here is a theoretical physicist's answer to this problem (see below for what I mean by this). This should be adequate to get a handle on the relative positions of satellites when they are distant from each other, and when the time after some known position & velocity of the satellites is not too long. The theoretical physicist's approach First of all ...

1

Read the file using Python Python has a library, py5 that can read and write these types of files. There are good introductions and instructions in https://www.christopherlovell.co.uk/blog/2016/04/27/h5py-intro.html and https://stackoverflow.com/questions/28170623/how-to-read-hdf5-files-in-python Sample code import h5py import pandas as pd f = h5py....

3

My bet would be on needles of the Project West Ford experiment, launched 9 May 1963. a ring of 480,000,000 copper dipole antennas (needles which were 1.78 centimetres long [...] was placed in orbit to facilitate global radio communication. Fifty years later, in 2013, some of the dipoles which had not deployed correctly still remained in clumps, ...

3

I looked more carefully at my source, which is plots using STK, and here is a recent closely zoomed in plot. Note that for some reason it uses a different perigee and apogee on a regular basis, which seems a bit odd, to say the least... I'm using the classical orbital parameters, mean of epoch. I switched this from the "Apogee Altitude" to the "Apogee ...

3

They are some weird processing artifacts. Here is the correct plot for KMS-4 (ID 41332) obtained from the TLEs downloaded from www.space-track.org and processed with the CSpOC library (downloadable from the same link): the shape is incredibly smooth and there are no evident secondary perturbations (surely there are several small components of perturbations,...

10

A starting point for checking orbital stability is the Sphere of Influence for short term stability (or rather, to select a suitable frame a reference in the patched conic approximation), and the Hill sphere for more long term stability (satellites). $$r_{SOI} \approx a\left(\frac{m_{satellite}}{m_{parent}}\right)^{2/5}$$ For a reference spacecraft, I'm ...

2

The language here tends to get in the way a bit. Generally “reaction wheels” are used for pointing: you turn them, then stop turning them once the satellite is pointing as desired. They’re not meant to spin rapidly to soak up a bunch of angular momentum. If you just need to control pointing, a reaction wheel system isn’t going to be able to absorb the ...

Top 50 recent answers are included