Talk:Geostationary orbit/GA1

GA Review

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Reviewer: Amitchell125 (talk · contribs) 07:41, 21 September 2019 (UTC)

Looks interesting! I'm happy to review the article. Amitchell125 (talk) 07:41, 21 September 2019 (UTC)

Assessment

Good Article review progress box Criteria: 1a. prose () 1b. MoS () 2a. ref layout () 2b. cites WP:RS () 2c. no WP:OR () 2d. no WP:CV () 3a. broadness () 3b. focus () 4. neutral () 5. stable () 6a. free or tagged images () 6b. pics relevant () Note: this represents where the article stands relative to the Good Article criteria. Criteria marked are unassessed

Sorry for the delay. Now looking in detail at each section, and working my way down the article.. Amitchell125 (talk) 07:13, 28 September 2019 (UTC)

No rush - I nominated this for GA review when I had more time. I should be able to respond as you work down the sections, but it may take a few days in some cases. --Spacepine (talk) 12:35, 28 September 2019 (UTC)

Lead section

• I would consider removing the link to Earth, as it's a commonly understood word.
• Link satellite.
• There should not be a capital letter at the start of Navigation satellites.
• Copy-edit to Earth's rotation - 'to the Earth's rotation'.

Done. Feel free to just change minor gramatical errors like these. --Spacepine (talk) 12:35, 28 September 2019 (UTC)

Will do, but if I edit too much I am no longer an independent reviewer (according to some Wikipedians). Amitchell125 (talk) 15:39, 28 September 2019 (UTC)

Ah, I understand. Whatever you feel comfortable with --Spacepine (talk) 13:06, 29 September 2019 (UTC)

• The idea that the orbit is circular is in the lead but not discussed in the main article; geosynchronous equatorial orbit or its abbreviation as an alternative name is also not given in the main article.

That the orbit is circular is covered in the Properties section (eccentricity=0 means circular), and I don't think there's anything more to say about the geosync equ / GEO name. --Spacepine (talk) 12:35, 28 September 2019 (UTC)

Didn't spot the eccentricity fact (and I have a physics background), so I would suggest that you add a bit there, something like: 'Eccentricity: 0 (i.e., the orbit is circular)'. Regarding the GEO bit, not everything in the lead section has to be present in the main text as well, but imo the alternative name is significant enough to include in the main text (see MOS:LEADNO for where I am coming from). Amitchell125 (talk) 15:39, 28 September 2019

I see, spelled it out. GEO edit to come --Spacepine (talk) 07:01, 29 September 2019 (UTC)

• Consider including the bold alternative terms in the lead section.

Clarke Orbit and co have historical significance as names, but little scientific useage so I'd prefer to remove the bolding than place them in the lede. --Spacepine (talk) 12:35, 28 September 2019 (UTC)

Agreed. Amitchell125 (talk) 15:39, 28 September 2019 (UTC)

• Some of the text in the third paragraph is not represented in the main article.

Which part? --Spacepine (talk) 12:35, 28 September 2019 (UTC)

... but can be pointed permanently at the position in the sky where the satellites are located. - I think it rather strange that one of the main reasons why GEOs are so useful is not spelt out to the reader. Amitchell125 (talk) 15:39, 28 September 2019 (UTC)

Spelt it out in text --Spacepine (talk) 07:01, 29 September 2019 (UTC)

• Page number needed for reference 1 (arianespace).

Done --Spacepine (talk) 12:35, 28 September 2019 (UTC)

• Most of the above list are quite minor points (and some are not essential for GA), but more importantly, the lead section does not summarise the whole article adequately as it contains little of the 'Implementation', 'Retired Satellites' and 'Properties' sections.

I've added an extra paragraph. I kept it quite brief, didn't want to get too technical. Let me know your thoughts.--Spacepine (talk) 12:35, 28 September 2019 (UTC)

The lead section does look better now. It may possibly need a bit of tweaking at a later stage, if I see something I should have spotted earlier. Thanks for your prompt work so far, Spacepine. Amitchell125 (talk) 15:39, 28 September 2019 (UTC)

History

• Amend link to Science fiction in science fiction author.
• HF radios - link 'HF' to High frequency and replace HF with 'high frequency'.
• undersea cable - link to Submarine communications cable.
• Link - rocket; Spin-stabilisation; Arthur C. Clarke; also President John F. Kennedy; 'Balewa' should be Abubakar Tafawa Balewa.
• Please explain (in the article) the phrase produced a flattened waveform. Is a citation needed here?
• Link Delta_(rocket_family)#Delta_D.
• To increase the size of some of the very short paragraphs in this section, combine the two paragraphs beginning By 1961… and They lost…, and also combine the last 3 paragraphs into one.
• At least one image would be useful for this section, e.g. from c:Category:Syncom_satellites.
• Add a url to reference 2 (Smith) (Google Books [1]).
• The second sentence requires reference 4 (Clarke) as a citation, because of the position of reference 3 in the section.
• I couldn't find anything about so early communication satellites were placed in a low Earth orbit in ref 8 (Caltech), if I am right, a citation is needed here.
• It looks like a citation is needed for The first satellite placed in a geostationary orbit was Syncom 3, which was launched by a Delta D rocket in 1963. With its increased bandwidth,… (not in reference 9 (Vartabarian)).
• US President Kennedy to phone Nigerian PM Balewa - I would include the date this happened, mentioned in the source.
• As far as I can tell, refs 13 and 14 are specific to two countries only - the article's text is not. Consider keeping the citations, but amending the text, giving the US and Australia as examples.

Rearranged and added new references to cover concerns, including some minor rewording. --Spacepine (talk) 12:55, 29 September 2019 (UTC)

Sorry, was referring to the whole history section --Spacepine (talk) 01:35, 30 September 2019 (UTC)

Uses

• The image does not come from a verified source.

- sorted that out. Amitchell125 (talk) 12:05, 1 October 2019 (UTC)

• The 'citation needed' tag needs to be sorted.

Sorted --Sp

• extending 81° - a general reader might needed this to be clarified.

Done --Sp

• and stationary position in the sky, eliminating the need for movable ground - c/e.

Done --Sp

• latency becomes significant — about 250ms - improve the prose by replacing the dash with text.

Done --Sp

• Short paragraphs - combine paragraphs 1, 2 & 3.
• Link - atmospheric refraction; thermal emission (Thermal radiation); infrared images (Thermographic camera); oceanography; cyclone; meteorological prediction models (Numerical weather prediction; volcanic ash;

Done --Sp

• 0.5 and 4 square kilometres - convert to sq. miles, using 'between 0.5 and 4 square kilometres (0.19 and 1.5 sq mi)'.

I don't really want to, it's not neccesary in scientific articles (MOS:CONVERSIONS) --Sp

Happy with that.

• Citation(s) needed for the latency paragraph, down to cosine rule formula.

Done --Sp

• These satellites typically captures images in the visual and infrared spectrum with a spatial resolution between 0.5 and 4 square kilometres. - citation needed.

Covered in BOM reference --Sp

• Reference 32 (Nature) could be used to expand why the data from weather satellites is not much used for models. Use/quote reference 33 (WMO) to explain more about the uses of satellites in generating models, e.g. when it says "NOAA feeds data collected from these instruments into NWP models and uses the data to generate dozens of additional products, including measurements of clouds, vegetation, ocean colour, and land and sea surface temperatures". What do you think?

Expanded it out a bit --Sp

• Aren't references 32 and 34 identical in their content? - one can go.

Yep --Sp

• ~5m to ~1m - as not all readers will be familiar with this symbol, it might be better to replace the symbol with 'around' (or something similar).

Done --Sp

• The punctuation in the navigation list does not have a consistent style (personally, I would end each line with a semi-colon).

Done --Sp

• Main article: GNSS augmentation § Satellite-based augmentation system - as the link is only to a section within an article, it would imo make sense to replace this with '
  Further information: GNSS augmentation
  '.

Done --Spacepine (talk) 12:18, 1 October 2019 (UTC)

Implementation

• Unlink Earth in the caption; also unlink latitude (as it is already linked further up in the text).
• Link both apogee and perigee to Apsis.

Done--Sp

• Link longitude, radio frequencies (Radio frequency), inclination change (Orbital inclination change).

Done --Sp

• The requirement to space these satellites apart to avoid harmful radio-frequency interference during operations means that - c/e (using brackets, commas, or dashes), e.g. 'The requirement to space these satellites apart, to avoid harmful radio-frequency interference during operations, means that...'.

Done --Sp

• Remove all 3 subsection titles, so that the section has three paragraphs.

I think there are separate concerns for each section, and the statite one is especially removed from the other two. Why do you think launch and orbit allocation should be combined? --Sp

Apologies, I meant four paragraphs - nothing should be combined. --Am

• A statite, a hypothetical satellite that uses a solar sail to modify its orbit, could theoretically hold itself in a geostationary "orbit" with different altitude and/or inclination from the "traditional" equatorial geostationary orbit. I understand what is written, but the prose should be improved to help the sentence make better sense.

Ooft, yeah fixed --Sp

• Reference 41 (EUMETSAT) doesn't specifically refer to 'inclination change', but the article does. Also, why not include some information not in the article that the reference provides, i.e about launching towards the east, the suitability of launching GEOs from Kourou, the stabilisation of its spin rate?

Done, didnt include Kourou or spin rate thing because I think that Meteosat specific. A list of geostationary launch sites might have to be a future project. --Sp

• Reference 42 (Farber et al) - page number required.

Done --Sp

• orbital "slots" - neither source referred to in the article uses this term. I'm not sure why quote marks are used here, or where the word comes from.

Looks like it was used in quotation marks in the patent. Removed quotation marks but left the term, it's descriptive. --Sp

Fine by me. --Am

• 'augment' (relating to an augmentation system) is a specific technical term that does not have a Wikipedia link or a definition in Wiki dictionary. Consider placing it in quotes (so linking it to references 35/36), or explaining the term in a separate note

In laypersons terms it means "to improve" though, which isn't wrong. --Sp

Agreed, and the technical (as opposed to colloquial) meaning of the term is now evident from the 'Further information' line above the text, so everything is fine. --Am

• Reference 37 (Geoscience Australia) doesn't seem to verify the sentence.

It describes it as reaching sevel decimetre (10cm) precision. The 5m is from earlier non augmented position calculations --Sp

many thanks

• The 'Statite proposal' subsection needs to be copy-edited so that it reflects what the patent abstract describes.

Ooft, yeah, rewritten --Spacepine (talk) 13:02, 2 October 2019 (UTC)

Retired satellites

• Not sure why both words in the title are in capitals.

No reason. Fixed --Sp

• (minor point) Resize the image to make it thumb-sized (it's presumably no more important than the others in the article). Consider reducing the amount of text in the caption: 'A computer-generated image of space debris. Two debris fields are shown: around the space occupied by GEOs, and in low Earth orbit.'

Done --Sp

• orbits are mostly synchronous - is 'synchronous' the right word? Consider keeping the physics simple by replacing the phrase with 'GEOs orbit the Earth at the same speed'.

Reworded --Sp

• An explanation for what causes satellites to move from the correct orbital distance from Earth would be useful, as it would explain properly why thrusters are needed.

Explained later in Properties. Reworded a bit --Sp

• Link transponders with Transponder (satellite communications).

Done --Sp

• and, by stopping N–S station keeping, needs to be copy-edited.

Reworded --Sp

• Link eccentric orbits (Orbital eccentricity), meteoroid.

Done --Sp

• Comma after Earth; remove semi-colon after inoperable.

Done --Sp

• Reference 51a discusses ExoAnalytic Solutions' ability to detect small objects - perhaps their important role should be mentioned.

I think that's beyond the scope of this article, might belong in Space Debris --Spacepine (talk) 02:04, 30 September 2019 (UTC)

Agreed. --AM125

Properties

• The listed properties could be in a table as shown below (only a suggestion - your call, table can be modified in any way):

Cells center-aligned, table centered

Property	value
Inclination	0°
Period	1436 minutes (one sidereal day)
Eccentricity	0
Argument of perigee	undefined
Semi-major axis	42,164 km

I'd like to keep the formatting consistent with Molniya Orbit and it's not really a exhaustive list of all orbital properties (which I think a table implies), just highlighting the ones that are important for identifying/understanding geostationary orbits in the same order that they're explained in subheadings.

Happy with that. Amitchell125 (talk) 11:20, 30 September 2019 (UTC)

Oh, source to come for those earlier subsections. Should be covered in Space Mission Analysis and Design just have to dig up a page number --Spacepine (talk) 02:10, 30 September 2019 (UTC)

Done --Sp

• Citation needed for first equation (suggestion - this).

Done --Sp

• very close to 35,786 km (22,236 mi) Conversions should say 'miles' here, not 'mi' - '35,786 kilometres (22,236.39 miles)'. Same thing for 3.07 km/s (1.91 mi/s).

Done --Sp

• To correct for this orbital perturbation... - just 'To correct for this...'?

Reworded --Sp

• There are two stable… - consider amending to 'There are two stable equilibrium points…'.

Reworded --Sp

• Link flattening of the Earth at its poles (Equatorial_bulge#On_Earth).

Done --Sp

• It's a colon after 'small forces on satellites'; also, hyphenate station keeping.

Added the colon, why hyphenate? --Sp

Hyphenate to improve the prose, also see the link (Orbital station-keeping). --Am

Ah yep, done --Spacepine (talk) 10:37, 3 October 2019 (UTC)

• Remove To calculate the geostationary orbit altitude, one begins with this equivalence - it's self-evident.

Replaced with your version --Sp

• The derivation section lacks citations and may in fact need to be replaced with a more polished version.

Replaced. Added extra link to formula for object moving around a circle. Trying to keep it easy to understand at a ~year 10 level --Spacepine (talk) 11:13, 3 October 2019 (UTC)

Notes

• Note (b) needs to be copy-edited so that it stands alone as a well-written sentence.

Done--Sp

References

• Author-link George Smith.

Done --Sp

• Reference 3 - op. cit, p. x - a full citation is needed here for GA (the text in the paragraph cannot be verified until this is done).

It's from the Complete Venus Equilateral introduction, included link to google book, but can't find page number --Spacepine (talk) 10:29, 3 October 2019 (UTC)

The quotation is reproduced here (Arthur C. Clarke by Neil McAleer, registration is required to access the book on the Internet Archive), it's worth citing McAleer instead. --Am

Thanks! -Sp

• Reference 18 (Freeman) - is this (http://www.biruni.tn/gw_2009_4_3/thumbs/contents-table/102/TM.1022955.pdf) it? - if so, please clarify the volume and page number.

Replaced with SMAD ref --Sp

External links/templates/further reading

• Template:Orbits is not hidden, and Template:Arthur C. Clarke is - consider hiding both templates.

Done --Sp

• How about adding… ...id=rzw4wOHDpjQC&printsec=frontcover&dq=physics+of+geostationary+orbits&hl=en&sa=X&ved=0ahUKEwjp0f_er_jkAhXOVhUIHfIRAv4Q6AEIUjAG#v=onepage&q&f=false this and this to the Further reading section?

Done--Spacepine (talk) 10:35, 3 October 2019 (UTC)

Think that's it

I think that's it. Let me know if I missed anything!

The one small thing left was geostationary orbit vs geosynchronous equatorial orbit as an alternative name. They're used interchangeably in references, but I can't find anything discussing that fact (although I haven't looked that hard yet). People have opinions all over the talk page if you want to wade into the mud of it. Even if there is a source discussing the merits of one term over the other (they quite clearly mean the same thing in industry), I'm not sure where it would fit into the article. Any suggestions? --Spacepine (talk) 11:40, 3 October 2019 (UTC)

I would cite something heavyweight, such as A Dictionary of Astronomy, page 187, (here), which defines both terms clearly and correctly. I would then add a note in the lead section, mentioning that both terms are used in references when referring to geostationary orbits. Consider using a source like this one, which states "The terms geosynchronous and geostationary are often used interchangeably".

Reference 1 would be better placed in the main text, alongside the text it refers to. Many editors avoid including citations in the lead section altogether, or are advised to by others. Amitchell125 (talk) 12:28, 3 October 2019 (UTC)

Done! Added a bit on terminology in the History section. Thanks again for all your work --Spacepine (talk) 02:38, 4 October 2019 (UTC)

You're welcome, Spacepine. Amitchell125 (talk) 06:34, 4 October 2019 (UTC)

It's close now. I'll do one final check for minor c/e points (if there are any) before passing. Amitchell125 (talk) 13:36, 3 October 2019 (UTC)

GA

Passing now, congratulations and thanks for all your efforts. Amitchell125 (talk) 14:13, 3 October 2019 (UTC)

Thanks for your help! --Spacepine (talk) 21:30, 3 October 2019 (UTC)