"but its mass constitutes an insignificant fraction of the belt's total" This seems a tad unnecessary. Isn't the main belt comprised of enough asteroids that no one asteroid would ever constitute a significant fraction of the total?
- Well, 1 Ceres and 4 Vesta account for a third and a tenth of the mass of the asteroid belt respectively, so the really big ones can constitute a significant fraction. Ida isn't one of them. Wronkiew wanted this sentence left in because it gives some perspective on Ida's size compared to other asteroids. I agree, but it could be made clearer- I'll have a think on how to do that. Reyk YO! 00:39, 17 April 2009 (UTC)[reply]
- By my calculations, Ida makes up 0.001% of the belt's mass, but since you're the second to recommend against the comparison, I removed it. Wronkiew (talk) 01:07, 17 April 2009 (UTC)[reply]
"Ida was named by Moritz von Kuffner" This is the only mention of Kuffner. Who was he and why was he the one who got to name the asteroid instead of Palisa?
- I'm working on this one, but it's going to take some time to come up with additional sources. Wronkiew (talk) 01:25, 17 April 2009 (UTC)[reply]
- Added more detail on von Kuffner. Palisa's reasons for letting von Kuffner name his asteroids is probably lost to history. Wronkiew (talk) 06:10, 17 April 2009 (UTC)[reply]
"Ida's reflection spectra was measured on 16 September 1980 by astronomers David J. Tholen and Edward F. Tedesco as part of the eight-color asteroid survey (ECAS). This led to the classification of Ida and other members of the Koronis family as S-type asteroids"
"reflection spectra" is redlinked and no explanation is given. I know what a spectrum is, but many people won't.
- Linked to a section of Astronomical spectroscopy that describes it. Wronkiew (talk) 04:18, 18 April 2009 (UTC)[reply]
Spectrum = singular, spectra = plural, yes?
- Fixed by Reyk. Wronkiew (talk) 16:51, 17 April 2009 (UTC)[reply]
It's totally unclear how the first sentence "led to" the second sentence. What about the spectra led to the S-type classification?
- Reworded. Wronkiew (talk) 16:51, 17 April 2009 (UTC)[reply]
Who classified it as such?
- This is attributed in the inline note. Wronkiew (talk) 16:51, 17 April 2009 (UTC)[reply]
"Many observations of Ida were made in early 1993 by the US Naval Observatory in Flagstaff and the Oak Ridge Observatory, prior to the Galileo flyby" Yikes, not very good use of the comma there. "prior to the Galileo flyby" needs to be worked into the sentence better or dropped completely. Also, what Galileo flyby? The sentence is written as though the reader should already know what it is. I don't.
- I removed the "prior to" clause, as it was repetitive. The flyby was introduced in the lead. Wronkiew (talk) 04:18, 18 April 2009 (UTC)[reply]
"These improved the measurement of Ida's orbit around the Sun and reduced the uncertainty of its position during the flyby to within 60 km (37 mi)" Alright, what was the uncertainty before these observations?
- 78km- now in the article. Reyk YO! 05:50, 17 April 2009 (UTC)[reply]
"The decision to attempt an Ida flyby was delayed until the consequences of the loss of 34 kg (75 lb) of propellant, the amount needed to change Galileo's trajectory, could be evaluated" Not clear what's going on here. Who lost the propellant?
- The loss refers to burning 34kg of propellant in order to change the course of Galileo. I've used the word "consumption". Reyk YO! 01:04, 17 April 2009 (UTC)[reply]
- So let me get this straight: In the process of changing the trajectory of the satellite, it would consume 34 kg of propellant. Because this would significantly alter its total mass, it would have an affect on later parts of the mission, yes? --Cryptic C62 · Talk 01:41, 17 April 2009 (UTC)[reply]
- Reworded. Wronkiew (talk) 05:41, 18 April 2009 (UTC)[reply]
- Ah, much better. --Cryptic C62 · Talk 04:56, 19 April 2009 (UTC)[reply]
"it flew by Ida on 28 August 1993 at a relative speed of 12,400 m/s (28,000 mph)" Relative to Ida, correct? Then what was its absolute speed?
- The sentence now more clearly says the speed was relative to Ida. Absolute speed? Albert Einstein would have fits if he heard you talking like that. ;) Do you mean the speed relative to the Earth? The sun? Reyk YO! 01:04, 17 April 2009 (UTC)[reply]
"Because Ida has a short rotation period, the probe imaged about 95% of the its surface during the flyby" It isn't entirely clear how the rotation period affects the surface imaging. Perhaps you should include how long the entire flyby lasted.
- It now reads "95% of the surface came into view of the probe". Reyk YO! 00:54, 17 April 2009 (UTC)[reply]
- Erm, that doesn't really help. The way I see it, how much of the surface gets imaged depends on two variables: How quickly the asteroid rotates and how long the spacecraft approaches/images. This will not be clear to everyone unless you include some sort of time frame.--Cryptic C62 · Talk 01:41, 17 April 2009 (UTC)[reply]
- The details would be unnecessarily distracting, so I removed the part about its rotation. Wronkiew (talk) 06:17, 18 April 2009 (UTC)[reply]
"Ida's relatively large surface exhibits a diverse range of geological features." Should be past tense, yes? We can't be entirely certain that the surface hasn't changed since Galileo.
- I have reworded this sentence. Reyk YO! 00:54, 17 April 2009 (UTC)[reply]
What is stony-iron?
"and that the asteroid contained mostly core material" What is "core material"?
- Reworded. Wronkiew (talk) 06:42, 17 April 2009 (UTC)[reply]
- Still confusing. What do you mean by "from the core"? Did it start at the center and work its way out? Or did it come from the core material of some other object? --Cryptic C62 · Talk 18:27, 17 April 2009 (UTC)[reply]
- The two sentences comparing stony-irons to OC meteorites aren't vital to understanding the discoveries made by Galileo, so I removed them. Wronkiew (talk) 06:45, 18 April 2009 (UTC)[reply]
"Calculating Dactyl's orbit around Ida enabled a rough measurement of Ida's density"
- Who calculated this orbit? When? How?
- This is completely described in the inline reference. Wronkiew (talk) 06:42, 17 April 2009 (UTC)[reply]
- Perhaps "estimate" instead of "measurement"?
- Done. Wronkiew (talk) 06:42, 17 April 2009 (UTC)[reply]
- Statement include the actual estimate, if possible.
- I added a number for the upper bound. Wronkiew (talk) 06:42, 17 April 2009 (UTC)[reply]
- Is "enabled" the right word here?
- Removed. Wronkiew (talk) 06:42, 17 April 2009 (UTC)[reply]
"This low density ruled out the presence of significant quantities of metal, and indicates a non-stony-iron composition" Switches from past to present tense.
- Amended "ruled" to "rules". Reyk YO! 05:34, 17 April 2009 (UTC)[reply]
"The Galileo images also led to the discovery of a space weathering process active on Ida" Reads awkwardly. Suggestion: "The Galileo images also led to the discovery of an active space weathering process taking place on Ida"
- Done, though I edited your version a bit. Wronkiew (talk) 17:56, 17 April 2009 (UTC)[reply]
- Looks good, but now I've noticed something else: "The Galileo images also led to the discovery of an active space weathering process on Ida, which causes older regions to become more red in color" This sentence reads as though the "which" refers to the discovery, not the process. Here's an idea: "The Galileo images also led to the discovery that space weathering was taking place on Ida, a process which causes older regions to become more red in color over time." or something like that. --Cryptic C62 · Talk 04:56, 19 April 2009 (UTC)[reply]
"Space weathering changes the appearance of Ida's surface over time, with older regions becoming more red in color" I thought this was going to be a brief generic explanation of space weathering, but then it mentioned Ida. It should either serve as a standalone explanation or the relevant details (more red over time) should be merged into the previous sentence.
- Done, good idea. Wronkiew (talk) 06:54, 18 April 2009 (UTC)[reply]
"The same process affected both Ida and its moon, although Dactyl showed a lesser change. " So what does this mean? Is Dactyl younger than Ida? This just seems like an important but somewhat dead-end statement.
- Sorry, not enough information in the sources to say for sure what causes it. Wronkiew (talk) 06:54, 18 April 2009 (UTC)[reply]
- Alright, fair enough. I was just curious to see if the sources made any conclusions, but if not, then that's fine. --Cryptic C62 · Talk 04:56, 19 April 2009 (UTC)[reply]
"The color change revealed another detail about Ida's composition" This may be confusing for some readers since the previous sentence also dealt with Dactyl's color change.
- Reworded for flow. Wronkiew (talk) 06:54, 18 April 2009 (UTC)[reply]
"S-types are the most numerous kind in the inner part of the asteroid belt. OC meteorites are, likewise, the most common type found on the Earth's surface" Both of these statements should make it explicitly clear what "kind" and "type" refer to.
"Ida's mass is between 3.65 and 4.99 x 1016 kg, a measurement derived from the poorly constrained orbit of its satellite"
- Again, consider replacing "measurement" with "estimate".
- Removed text. Wronkiew (talk) 04:20, 22 April 2009 (UTC)[reply]
- "poorly constrained orbit" is ambiguous. Is Ida a bad parent that can't seem to properly constrain its child Dactyl? Or were there loose mathematical constraints on Dactyl's orbit?
- Agreed. The discussion of Dactyl's orbit also isn't very relevant in this section. Wronkiew (talk) 04:20, 22 April 2009 (UTC)[reply]
- Wouldn't the mass/density also depend on the apparent size of the asteroid?
- The density would, but not the mass. Wronkiew (talk) 04:20, 22 April 2009 (UTC)[reply]
"This field is so weak that an astronaut standing on its surface could leap from one end of Ida to the other.[39] An object moving in excess of 20 m/s (70 ft/s) could escape the asteroid entirely" Consider merging these two sentences together, as they are making essentially the same point.
- Done. Wronkiew (talk) 07:00, 18 April 2009 (UTC)[reply]
"Ida's weak gravity coupled with its short rotational period produces some counterintuitive effects" This is true, but somewhat confusing. It might help to include the phrase "trajectories of projectiles" as it appears in the source.
- I don't have a better way to explain it, and it isn't vital information, so I removed the two sentences about projectile trajectories. Wronkiew (talk) 08:09, 18 April 2009 (UTC)[reply]
"Ida is a distinctly elongated asteroid, with an irregular surface,[41]" Ref 41, Bottke et al, doesn't really seem to be an appropriate reference for this statement. The ref seems to be a very broad overview of several satellites, not a presentation of new information: "We briefly review their characteristics below" Surely a claim as simple as this one can be attributed to a primary source.
- Found a somewhat better source. Reyk YO! 22:02, 17 April 2009 (UTC)[reply]
- ...then why not use it? Bottke et al is still the ref for "with an irregular surface." --Cryptic C62 · Talk 22:50, 20 April 2009 (UTC)[reply]
- Ah, right. I thought you meant the source for "elongated". Fixed. Reyk YO! 00:17, 22 April 2009 (UTC)[reply]
"Whilst steep slopes tilting up to about 50° are present on Ida, the slope rarely exceeds 35°" These two claims seem to contradict each other. Suggest rewording the second clause to "the slope is generally less than 35°." or some such.
- I've expanded it a bit so that, hopefully, it is more clear that the 35 degrees is the rule and 50 degrees the exception. Reyk YO! 22:02, 17 April 2009 (UTC)[reply]
"Besides craters, other features are evident, such as grooves, ridges, and protrusions." A sentence like this should ideally come right after the bit about craters, not at the end of the paragraph. Assuming you keep the paragraph at all, that is.
- We're keeping the paragraph. Like you said, it explains terms which are used later in the section. Wronkiew (talk) 04:54, 22 April 2009 (UTC)[reply]
- Erm, perhaps I wasn't clear. "the bit about craters" refers to "Ida's surface appears heavily cratered and uniformly gray, although minor color variations mark newly formed or uncovered areas. Cratering has reached the saturation point, meaning that on average new impacts erase evidence of previous ones, leaving the total crater count unchanged." I wasn't suggesting to remove it from the paragraph altogether, I was suggesting to just move it up a few sentences. --Cryptic C62 · Talk 17:47, 22 April 2009 (UTC)[reply]
- I see now. Done. Wronkiew (talk) 01:26, 24 April 2009 (UTC)[reply]
"The surface is covered in a blanket" The surface of what? :)
- Of Ida. Duh ;). Fixed. Reyk YO! 00:17, 22 April 2009 (UTC)[reply]
Caption: "Galileo mosaic recorded 3.5 minutes before its closest approach" Uh... what? Might be less confusing if you nix the technical details and just say something like "Image of Ida's surface taken by Galileo."
- I reworded it to make it clear that this is a mosaic of images. Wronkiew (talk) 04:54, 22 April 2009 (UTC)[reply]
"The material for this layer originates from the many impact craters" This sentence is written as though the craters intentionally donated material for the regolith project. Perhaps "The material in this layer originated from the many impact craters" or some such.
- Reworded. Wronkiew (talk) 05:50, 22 April 2009 (UTC)[reply]
"Regolith can be moved over the surface of the asteroid by geological processes. One observed by Galileo was the downslope movement of debris." Yikes, needs some serious reordering. How about "Geological processes and Ida's own gravity can cause the regolith to move across the surface of the asteroid." or something?
- Reworded. Wronkiew (talk) 05:50, 22 April 2009 (UTC)[reply]
- I think you've cut too much out, because now the reader is given no clue as to why/how the regolith moves. --Cryptic C62 · Talk 17:47, 22 April 2009 (UTC)[reply]
- I restored the detail that it moves downslope. Wronkiew (talk) 04:09, 23 April 2009 (UTC)[reply]
"The appearance of this substance changes over time through a process called space weathering" Which substance? Silicate? Or olivine? Or pyroxene?
"The older regolith appears more red in color compared to freshly exposed regolith" It isn't entirely clear that this is connected to space weathering. Consider merging with the previous sentence.
- Clarified. Wronkiew (talk) 05:50, 22 April 2009 (UTC)[reply]
"Impact event" is used several times. It should be linked or explained at some point, as its meaning might not be clear to non-nerds. --Cryptic C62 · Talk
- Wikilinked, good idea. I don't think an explanation is necessary, as the term is not used in an introductory section. Wronkiew (talk) 01:22, 24 April 2009 (UTC)[reply]
The introductory paragraph of "Surface features" does not have any references. I see that the information is repeated later on in the subsections. Is this paragraph even necessary then? It may be confusing for some readers that terms like "regolith" and "ejecta block" are linked and well-defined here but not later on.
- Yes, it's just a summary of and introduction to the material in the section. If there's anything controversial there, I can add a reference to it. We didn't reference anything in the lead, either. Wronkiew (talk) 04:54, 22 April 2009 (UTC)[reply]
- Well, if we're going to treat this paragraph as a lead, then we'll follow WP:LEAD, which specifically states that information introduced here must also be present in the main body. "Saturation point" appears here but not in the crater section. Ida's color ("uniformly gray") is mentioned here but not later. "ejecta blocks" are explained in detail here, but not later. Either cite the new information in this paragraph, or make sure to include/cite everything in the main body. --Cryptic C62 · Talk 17:47, 22 April 2009 (UTC)[reply]
- I waffled on the "uniformly gray" sentence and added an inline citation for it. Inline citations are not required for every piece of new information. In the two other cases that you brought up, these definitions could be considered "subject-specific common knowledge", and are well covered by the sources in the references section. If you think either of these definitions are controversial or contain original research, I can add more inline citations. Wronkiew (talk) 16:39, 23 April 2009 (UTC)[reply]
- Alright, I'll buy the "subject-specific common knowledge", I had forgotten about that exception. However, "saturation point" should still be mentioned in the Crater section. --Cryptic C62 · Talk 00:01, 25 April 2009 (UTC)[reply]
- Moved it to the crater section and added a ref. Wronkiew (talk) 21:37, 25 April 2009 (UTC)[reply]
"Most of them are located within the craters Lascaux and Mammoth, but were not produced there." I skimmed through the source you've cited for this statement and found this statement: "The blocks that lie within or near the rims of craters Lascaux and Mammoth were likely mobilized in the low-velocity tail portion of the excavation flow that formed those craters." The inclusion of the word "likely" in this statement makes me think that "but were not produced there." is a bit too strong. You're more familiar with the material than I am, but my instinct tells me that "but were not necessarily produced there" would be a better choice.
- You're right. Done. Wronkiew (talk) 21:03, 25 April 2009 (UTC)[reply]
"This area attracts debris due to Ida's odd gravitational field." Perhaps "irregular" instead of "odd"?
- Done. Wronkiew (talk) 21:03, 25 April 2009 (UTC)[reply]
"Some blocks may have been ejected from the young crater Azzura on its opposite side" Eh? Whose opposite side?
- Clarified. Wronkiew (talk) 21:06, 25 April 2009 (UTC)[reply]
"The asteroid appears to be split into two halves, each featuring slightly different geology, connected by a "waist"... If [the waist] formed from impact craters, then the two halves may share the same geology" These two statements seem to contradict one another.
- Not really contradictory, more an indication that several interpretations exist about Ida's geology. I removed this and some other speculative material in the section. Wronkiew (talk) 21:26, 25 April 2009 (UTC)[reply]
- Well, I didn't think the material had to be deleted, it just needed to be clarified that the two ideas are both speculative. --Cryptic C62 · Talk 22:18, 25 April 2009 (UTC)[reply]
The two sections of the asteroid that are separated by the waist are Regions 1 and 2, yes? This isn't made explicitly clear in the Structures section. Also, it might be useful to have some sort of simple comparison between the two, such as noting which of the two is larger.
- The main difference between them seems to be the crater size distribution. I noted that the "regions" refer to the two halves of Ida. Wronkiew (talk) 05:40, 27 April 2009 (UTC)[reply]
"One is a prominent 40 km (25 mi) ridge named Townsend Dorsum that stretches 150 degrees around Ida's surface.[26][52]" Ref 52 adequately covers this material, but Ref 26 (Chapman p. 707) does not. I read through that page, but didn't find any mention of Townsend Dorsum. It only vaguely alludes to "the prominent ridge". Was this just a superfluous reference, or did you mean to cite a difference page?
- Only one prominent ridge on the asteroid, but the extra ref was superfluous. Wronkiew (talk) 05:40, 27 April 2009 (UTC)[reply]
"Ida's Region 2 features several sets of grooves, usually about 100 m (330 ft) deep and up to 4 km (2.5 mi) long" The use of "usually" implies that these grooves are not permanent. Also, what defines a "set" of grooves?
- Replaced "usually". The relevant dictionary definitions of "set" are sufficient to describe the arrangement of grooves, and I don't think we need to repeat that definition here. Wronkiew (talk) 06:29, 27 April 2009 (UTC)[reply]
- Alright, I was just wondering if there was a more specific definition that the reader should be aware of. --Cryptic C62 · Talk 14:27, 27 April 2009 (UTC)[reply]
"for example a set opposite the large indentation Vienna Regio" I don't think "the large indentation" is necessary, as you introduced Vienna Regio just a few sentences earlier.
- Removed the duplicate information. Wronkiew (talk) 05:40, 27 April 2009 (UTC)[reply]
Caption: "Asymmetric 1.5 km (0.93 mi) crater Fingal at 13.2°S, 39.9°E" What measurement does 1.5 km refer do? Diameter? Depth?
- Clarified. Wronkiew (talk) 05:40, 27 April 2009 (UTC)[reply]
"leaving the total crater count unchanged" Not necessarily true. Consider replacing "unchanged" with "approximately the same".
- Done. Wronkiew (talk) 06:29, 27 April 2009 (UTC)[reply]
"It is covered with craters of all sizes and stages of degradation" Is there something to which we could wikilink "stages of degradation"?
- Stage of degradation is a descriptive rather than a technical term. A possible link is to Erosion, but that doesn't describe the erosion of asteroid craters better than this article does. Wronkiew (talk) 06:29, 27 April 2009 (UTC)[reply]
"The major craters are named after caves and lava tubes on Earth" Is this true for all craters? Or just craters on Ida?
- Clarified. Wronkiew (talk) 06:29, 27 April 2009 (UTC)[reply]
Infobox: "Alternate name[note 1] A910 CD; 1988 DB1[2]" Note 1 doesn't seem to work. Ref 2 says it's just A910 CD; 1988 DB1, no subscript.
- The subscript is standard notation for provisional designations. However, a provisional designation from 1988 doesn't make any sense for this object. Without any other source to corroborate the alternate designation or any explanation in the JPL database, I think we may have misinterpreted the data. I've removed it until another source can be found. That also takes care of the strange note, which was a standard part of the infobox. Wronkiew (talk) 05:41, 28 April 2009 (UTC)[reply]
"The craters are simple in structure, bowl-shaped with no flat bottoms and no central peaks" That comma should be replaced with either a colon or "and".
"The composition of Ida's interior has not been directly analyzed, but is assumed to be similar to OC material based on observed surface color changes and its measured density" Whose measured density? Ida's? Or the interior's?
- In this case, it doesn't matter. As explained in this section, Ida's density is even throughout its extent. Wronkiew (talk) 16:55, 28 April 2009 (UTC)[reply]
- Well, I'd say it does matter. To someone who assumes that "it" refers to the interior, the notion that the interior's density has been measured conflicts with the notion that the interior has not been directly analyzed. --Cryptic C62 · Talk 03:22, 29 April 2009 (UTC)[reply]
- Fixed. Wronkiew (talk) 04:23, 30 April 2009 (UTC)[reply]
"and the asteroid's spin indicates an even density" Perhaps "consistent" rather than "even" ? "Even" implies that the density is a multiple of 2.
- Done. Wronkiew (talk) 04:23, 30 April 2009 (UTC)[reply]
"The range of stable orbits for Dactyl correspond to a bulk density between 2.27 and 3.10 g/cm3 for Ida" Does Dactyl's generally stable orbit vary within a certain range? Or is its exact orbit not known?
- Removed the information about Dactyl's orbit. This is already covered in more detail elsewhere. Wronkiew (talk) 04:23, 30 April 2009 (UTC)[reply]
"The grain density of Ida's chondritic material would range from 3.48 to 3.64 g/cm3" The use of "would" implies that these values are derived from the previous sentence, but the next sentence discusses the discrepancy between the two sets of values.
- Rewritten. Wronkiew (talk) 04:23, 30 April 2009 (UTC)[reply]
"The mineral content appears to be homogeneous throughout its extent. Galileo found minimal variations on the surface, and the asteroid's spin indicates a consistent density" minimal variations of what?
- Minimal variations in mineral content. I don't think it needs to be re-stated. Wronkiew (talk) 04:44, 1 May 2009 (UTC)[reply]
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