Talk:Molniya orbit/GA1

GA Review

Article (edit | visual edit | history) · Article talk (edit | history) · Watch

Reviewer: Annette Maon (talk · contribs) 17:25, 27 July 2018 (UTC)[reply]

On initial reading nothing most of the text looks reasonable. There is a discrepancy between the orbital parameter at the start of the article and in the middle that might come from different sources. The definition of Molniya orbit is not accurate enough to make the statements false and both sets of orbital parameters satisfy the technical requirements of Molniya orbits, however, the discrepancy may be confusing to the user. A particular concern is the fact that the argument of perigee is specified as 270 degrees (which corresponds to the desired situation of a fast perigee pass in the southern hemisphere and a long apogee duration over the northern hemisphere). At the same time an argument of perigee of 280 is quoted later with support from the "Kolyuka, Yu. F.; Ivanov, N.M.;" citation (section 2: EVOLUTION OF THE “MOLNIA” TYPE ORBITS).

Additional comments: The figures are far from the text that refers to them and do not clearly demonstrate the concepts that the text tries to convey. A short video clip that demonstrates the orbit (including both 3D view from above the pole and a ground track on a Mercator projection map cold significantly improve both readability and the quality of the article. If the author can not find such a video as a reference already out there, it should be easy to generate one with tools like GMAT.

Figure 1 contains 4 separate images and should be split into 4 separate figures (with corresponding references).

The ground track in one of the Figure 1 images clearly shows that a Molniya orbit goes over both hemispheres. It would be good to mention in the caption that while the lines in the southern hemisphere look longer, the satellite travels faster in the southern hemisphere and spends more time in the Northern Hemisphere (over Russia and then over canada 12 hours later).

Formating Keplerian orbital elements as lists rather than Prose should make the article more readable.

A list of satellites (and families of satellites) that use Molniya orbits (in the past and the present) would enhance the article and may help resolve the ambiguity between the difference sources by fleshing out the different possible orbits that can still be considered Molniya. The raw data for such a list can be produced by submitting an appropriate query at https://www.space-track.org/

"a sub-satellite point of 63.4 degrees north" only happens once per orbit when the satellite passes through apogee. The current text may create the false impression that the satellite spends all of the time (instead of much of the time) at high latitudes.

It would be good to address the issue raised in the talk pages about the fact that molniya apogees are so high that the satellite can be seen from almost half of the Earth for a long period. It would be good to cover the following topics in the article discusion:

 How do "low elevation angles" degrade communication performance and when does that become unacceptable 
 How much time does a Molniya satellite spend above some elevation.
    One way to do this is with color codes distribution graphs of percentage time vs. elevation for several different latitudes.
 Provide a link to an article disussing the advantages and disadvantages of GEO satellites (which have fixed position) vs. Molniya orbits.

The claim that "Molniya orbits require considerably [emphasis addded] less launch energy than geostationary orbits" is not supported by the reference provided in Russian (even after passing it through google translate). It is true (common sense) that more launch energy is required to launch into an inclination lower than the latitude of a launch site (whether it is in Russia or in Florida) but an English reference to this concept would be useful and in and case the word "considerably" is somewhat of an exaggeration.

 — Preceding unsigned comment added by Annette Maon (talk • contribs) 18:08, 27 July 2018 (UTC)[reply]

Thanks Annette, I'm working on a SpaceTrack list of Molniya orbits, but it's not trivial to find their operational orbital parameters (before they've decayed). Do you have much experiance in these queries? Spacepine (talk) 00:04, 30 July 2018 (UTC)[reply]

A few months ago I managed to write a few Queries that returned molniya orbits from https://www.space-track.org/ I believe their database also includes at least some historical data for orbits that have already decayed. As a reviewer I will be happy to comment and make suggestions but I can not get the data myself or write it up without compromising my neutrality as a reviewer. Annette Maon (talk) 12:56, 5 October 2018 (UTC)[reply]

Hi all. This appears to have stalled. Is there any way I can help get it moving again? AIRcorn (talk) 22:17, 22 January 2019 (UTC)[reply]