Talk:Molniya orbit/GA2

GA Review

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Reviewer: Bryanrutherford0 (talk · contribs) 19:39, 8 April 2019 (UTC)

I'll review this one. The first review should be up in the next few days. -Bryanrutherford0 (talk) 19:39, 8 April 2019 (UTC)

GA review (see here for what the criteria are, and here for what they are not)

1. It is reasonably well written.

   a (prose, spelling, and grammar): b (MoS for lead, layout, word choice, fiction, and lists):

   I've done some copyediting, and the article is now at an appropriate prose standard. It complies with the indicated sections of MoS.

2. It is factually accurate and verifiable.

   a (reference section): b (citations to reliable sources): c (OR): d (copyvio and plagiarism):

   The article has citations for its claims, as well as a "References" section in accordance with MoS. I'm not seeing any issues with plagiarism of online sources.

   I have some concerns about the orbital dynamics equations included in the "Properties" section. Equations 1 & 2 make no sense as written, since their left sides are changes ($\Delta \omega$ and $\Delta \Omega$), not rates of change (such as $d\omega /dt$ and $d\Omega /dt$). I'm guessing from text in the "Orbital period" section that they are meant to give rates of change in radians per orbit? The units need to be spelled out, and the left sides changed to something like $d\omega /d\Theta$.

   More fundamentally, Kidder et al. give much, much more complicated formulae for the time rates of change of these quantities (equations A2 and A3 in their article); are these "angle per orbit" formulae in the other cited source, the Wertz & Larson? I guess I'll need to sit down with pen and paper for a bit and figure out whether I think the two sets of formulae come to the same thing.

   I've used the formulas from SMAD, and clarified that they only account for the first order oblateness of the earth (other sources may go further). I reckon extra detail can go in Orbital perturbation analysis if needed. --Spacepine (talk) 04:44, 12 April 2019 (UTC)

   Now that I've had a chance to dig through the sources, I have a number of issues. First, although Anatoly Zak appears to be a published expert on Russian spaceflight topics, his website, "Russianspaceweb.com", appears to be self-published without any sort of editorial oversight, and it doesn't appear to me to reach Wikipedia's standards for reliable sources. If you can find a place where the same author has had the same content published *in a magazine or journal with editorial oversight*, then that should work fine, but I don't think a Good Article can cite Russianspaceweb.com. The same goes for Braeunig.us, another apparently self-published enthusiast site (albeit a very thorough and professional one); I think its claims in the first sentence of the "History" section can be covered by the Martin source. This also goes for Astronautix.com.

   Astronautix is gone, but left Russianspaceweb for now in hope I can dig up a different source in the next few days --Spacepine (talk) 11:03, 16 April 2019 (UTC)

   Found alternative to Russianspaceweb source --Spacepine (talk) 09:29, 17 April 2019 (UTC)

   Second, the Ilčev citation (GSMO Theory) in the lead section doesn't appear to support the claim that GSO satellites can only observe latitudes below 81°; another citation will be needed for that sentence. The GSMO theory book does support the earlier ideas in that paragraph, and I like its assertion that the Molniya orbit functions as sort of part-time, nearly geostationary orbit for high latitudes; that would do well paraphrased and added to that second lead paragraph.

   Got ref, added summary--Spacepine (talk) 11:03, 16 April 2019 (UTC)

   Great; now that that's supported, let's move that detail (and the citation) to the first paragraph of the section "Uses", and leave a less specific claim (without a citation) in the lead, without the numbers (e.g. "unable to view the highest latitudes at all"). -Bryanrutherford0 (talk) 22:05, 18 April 2019 (UTC)

   Done --Spacepine (talk) 12:27, 19 April 2019 (UTC)

   Third, the Hendricx citation ("A History of Soviet/Russian Meteorological Satellites") doesn't appear to support the claims about the launch date of the first Molniya satellite in the second paragraph of "History"; I see the date "23 April 1965" in the Martin source, but then the Kolyuka et al. source says in its abstract that the first Molniya satellite was inserted into orbit in 1964, contradicting the article's current claim. This needs to be cleared up. Incidentally, the "as of 2018" also needs to be updated (if the claim is still true).

   The keyword was first successful Molniya satellite - the one launched in 1964 reached orbit, but comms antenna didn't unfurl. Clarified and added source --Spacepine (talk) 11:03, 16 April 2019 (UTC)

   Fourth, the "Geek Times" source redirects to a Russian-language blog post at habr.com; this is, again, not a reliable source.

   Removed--Spacepine (talk) 11:03, 16 April 2019 (UTC)

   More generally, a lot of the citations need cleanup to ensure that they all have dates, links (wherever possible), journals, publishers, and all the various parameters filled in. All the ISBNs should be hyphenated properly (you can figure it out here).

   Okay, I think I've done it. How does it look now? --Spacepine (talk) 09:29, 17 April 2019 (UTC)

   Great progress! Minor detail, but please get all the authors' names into Last, First format (I'd just use the |last= |first= parameters in the citation templates). -Bryanrutherford0 (talk) 22:12, 18 April 2019 (UTC)

   Done. Any good cite tool recommendations? It gets super fiddly and boring to do by hand --Spacepine (talk) 12:48, 19 April 2019 (UTC)

3. It is broad in its coverage.

   a (major aspects): b (focused):

   Some issues regarding content: has anyone ever used or considered using a Molniya orbit to achieve satellite coverage of the high southern latitudes? Either way, it should be pointed out that, although the Soviet/Russian and American uses have focused on the north, it could just as easily be used for communication and observation in the far south, and either any southern applications should be described, or it should be explained why the orbit has not been used in the southern hemisphere (presumably because all the major space powers have been in the northern hemisphere, along with most of the land, people, etc.). This content could go in the "Uses" section, probably under a subheading before the subheading about the use of constellations of three Molniya satellites (so as not to separate that text from its diagrams).

   Added southern hemisphere section. Couldn't find any actual sources saying that "there is nothing because theres more landmass in the north", so I left it implied. --Spacepine (talk) 05:30, 12 April 2019 (UTC)

   Yes, that looks good. -Bryanrutherford0 (talk) 17:52, 14 April 2019 (UTC)

   Next, the "Properties" section should have a subheading regarding the argument of perigee, explaining briefly why it must be 270° (to put the apogee as far north as possible), and pointing out that this would be different (90°) for a Molniya orbit meant to create coverage of the high southern latitudes. The section on eccentricity should also specify the semi-major axis, as well as the resulting perigee and apogee elevations. Then, purely in terms of layout and ease of reading, the summary of orbital properties at the beginning of that section should probably follow the same sequence as the subheadings (argument of perigee, inclination, period, eccentricity and semi-major axis), which build logically from one to the next and should be kept in their current order. The introduction to the "Properties" section should also include a wikilink to the topic Frozen orbit, of which these calculations are a good example.

   Done --Spacepine (talk) 06:08, 12 April 2019 (UTC)

   Yes, that's much better. -Bryanrutherford0 (talk) 17:52, 14 April 2019 (UTC)

   The section on "Eccentricity" should include a number for how high the perigee needs to be to keep the satellite functionally above the atmosphere (I'm seeing the figure "500 km" used in some of the sources), with a citation. -Bryanrutherford0 (talk) 22:05, 18 April 2019 (UTC)

   Done --Spacepine (talk) 12:31, 19 April 2019 (UTC)

4. It follows the neutral point of view policy.

   Fair representation without bias:

   The article takes an appropriately neutral tone, and it includes examples of various states' uses of Molniya orbits in satellite constellations (not only Soviet/Russian uses).

5. It is stable.

   No edit wars, etc.:

6. It is illustrated by images and other media, where possible and appropriate.

   a (images are tagged and non-free content have fair use rationales): b (appropriate use with suitable captions):

   The images are generally relevant and appear to have good licenses, if the ones that claim to be the original work of the submitting users can be trusted. I notice that Figure 5 is not mentioned anywhere in the text of the article; it should either be called out at an appropriate point in the text, or else it may not need to be included. It could go well with with a discussion of a question raised by the previous reviewer: "How do 'low elevation angles' degrade communication performance and when does that become unacceptable?" In that case, the figure and the accompanying discussion would probably go in the "Uses" section, and all the figures would need to be renumbered accordingly.

   Added ref to figure 5. Fig isn't strictly needed, but adds some context to other pics. Added a short sentence explaining low elevation angle claims. Any further details could probably go in a short article on satellite communications (a quick geez doesn't reveal anything that fills that niche). --Spacepine (talk) 06:54, 12 April 2019 (UTC)

   Yes, that's an improvement. -Bryanrutherford0 (talk) 17:52, 14 April 2019 (UTC)

7. Overall:

   Pass/Fail:

   An important topic, and lots of good material here! I've noted some pieces that need to be added to achieve broad coverage, along with some concerns I have about the orbital physics in the "Properties" section. I still need to look more deeply through the sources. With some work, this should be able to reach GA. -Bryanrutherford0 (talk) 15:56, 11 April 2019 (UTC)

   Okay, it's pretty much there. I need to look more deeply through the sources and make sure everything's in order there; I'll have time to do that in the next two days, and if no problems come up, then this will be ready to be promoted. -Bryanrutherford0 (talk) 17:52, 14 April 2019 (UTC)

   I think that's all I have to say! Only a few more relatively small things, and it'll be done. -Bryanrutherford0 (talk) 22:12, 18 April 2019 (UTC)

   Sweet, thanks! --Spacepine (talk) 12:50, 19 April 2019 (UTC)

   This article is approved for GA. Thanks to the nominator for being so responsive! -Bryanrutherford0 (talk) 13:05, 19 April 2019 (UTC)

   Thanks for all the advice and copyediting --Spacepine (talk) 13:11, 19 April 2019 (UTC)