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Archive 1

Fastest relative to what

What does it mean to be the "fastest" object when something is in space?

That is, speed relative to what? — Preceding unsigned comment added by 93.34.50.240 (talk) 08:40, 17 August 2012 (UTC)

Speed is measured relative to the inertial frame of reference of the moving object. For earth bound objects (including those in orbit around the Earth) that is the Earth itself. So you time the object between two points relative to the Earth. We tend to use the surface of the earth for convenience, but for accuracy and for use in space, the center of gravity of the Earth is the actual reference.
For a spacecraft, like Solar Probe, in the solar system, the inertial frame of reference is the Sun. So you use the time between two points relative to the center of the Sun. For Solar Probe, this is especially appropriate, since it will be "skimming" the surface of the Sun, so to speak. — Preceding unsigned comment added by Alan.A.Mick (talk • contribs) 02:03, 13 October 2013 (UTC)

Please update if this is the correct link. http://spacenews.com/41380solar-probe-plus-nasas-mission-to-the-fires-of-hell-trading-atlas-5-for/

BenjaminJMeyer (talk) 08:30, 2 January 2015 (UTC)

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Relativistic effects?

I know relativity is needed to explain long term precession of Mercury. I'm curious if relativistic corrections are needed for a mission like that? Tom Ruen (talk) 19:45, 22 November 2017 (UTC)

I see the question here [1] Tom Ruen (talk) 19:46, 22 November 2017 (UTC)

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Materials, and spacecraft design

Of what materials is the Parker Solar Probe to be constructed? MaynardClark (talk) 17:59, 21 August 2017 (UTC)

Various different materials. I don't have to whole list. But that, as well as a description of the spacecraft and the instruments, should really be added to this page. Fcrary (talk) 18:03, 21 August 2017 (UTC)

Yes please. What propulsion does it have ? (any ion thrusters?)
What attitude control (thruster jets only, or also reaction wheels ?)
Does it have a steerable high gain antenna for communications ? When will it be out of contact ? Rod57 (talk) 10:09, 3 April 2018 (UTC)
In the March 2008 Mission Engineering Study Report it says
"Propulsion Hydrazine monopropellant 190 m/s ΔV
Attitude control Reaction wheels and thrusters
Telecommunications • Dual-frequency X-band and Ka-band through articulated HGA"
Rod57 (talk) 10:36, 3 April 2018 (UTC)

Can we have details on the design of SACS (Solar Array Cooling System)? What I have read so far is that it uses one gallon of water and there's a pump (not heat pipes). But how is the water kept from freezing when the spacecraft is far away from the Sun? Is it stored in a heated reservoir and the system is bled (possibly purging some filler gas?) once the probe gets close enough to the Sun for water not to freeze? Or perhaps it's naturally kept above freezing point at all times as it circulates in the exposed solar panels? And how is thermal expansion (of water) compensated for?

Remove Voyager 2 plot?

There is currently a sidebar diagram showing Voyager 2 info, with the following caption: 

   Plot of Voyager 2's heliocentric velocity against its distance from the Sun, illustrating the use of gravity assist to accelerate the spacecraft by Jupiter, Saturn and Uranus.[23] Using the same technique but with Venus, Parker Solar Probe will decelerate to lower its orbit.

This isn't really useful in this article; it feels like someone threw it in because it's available and somewhat related. Plus, Section 2 is really unbalanced at this point, with the sidebar being far taller than the body text.

Second flyby of Venus on December 22, 2019. The velocity decreases by 2.9 km/s to 26 km/s on December 26 (red circle), then the spacecraft enters a new orbit closer to the Sun.

Would it be appropriate to remove the diagram? -- Dan Griscom (talk) 13:04, 11 August 2018 (UTC)

I replaced the chart with a PSP flyby chart.―― Phoenix7777 (talk) 04:08, 13 August 2018 (UTC)
Great stuff. Could you perhaps try a version showing two Venus gravity slingshots and several intervening orbits? — JFG talk 15:27, 13 August 2018 (UTC)
I created a chart for a whole mission of PSP. See #Planned timeline.―― Phoenix7777 (talk) 12:26, 14 August 2018 (UTC)

Costs

How much did that probe cost? — Preceding unsigned comment added by 78.49.247.38 (talk) 09:19, 15 August 2018 (UTC)

I added it. (US$1.5 billion). Cheers, Rowan Forest (talk) 01:01, 16 August 2018 (UTC)

That "Error" in the table.

@Mfb: Re:your edit, FYI that was caused by a change in column heading. It was originally perihelion distance, and was accurate for the launch orbit. (But of course, the spacecraft was nowhere near perihelion; it launched from 1.0 AU, not 0.278.) I changed the column heading to "perihelion" to help untangle the frequent confusion in various sources between distance-from-Sun-center and altitude-above-Sun-surface. I thought using "perihelion" for the former and "altitude" for the latter and avoiding the ambiguous word "distance" entirely was the way to go.

Then someone changed it back to "distance" and that resulted in the mess you dealt with. 209.209.238.189 (talk) 01:09, 18 August 2018 (UTC)

Ah, I didn't check the page history. I just saw it in that state and fixed the value that was wrong. --mfb (talk) 01:28, 18 August 2018 (UTC)
I changed the header to "Distance from Sun" because this table documents several events other than perihelions, namely the launch and the Venus flybys, and we may add other events later, e.g. some of the aphelions. I failed to correct the value, thanks mfb. We should now fill in the missing distances according to the predicted dates for gravity assist maneuvers at Venus. I don't think there's any case for listing the "altitude from Sun surface" metric; that's best reserved for the article text, when discussing "how close" the probe will pass such "surface". — JFG talk 04:23, 18 August 2018 (UTC)
@Mfb: You're not obliged to check edit history every freaking time. As you say, fixing what's wrong is the important thing. I just thought I answer the "WTF?" subtext I heard in your edit comment.
@JFG: I'm not trying to make a big deal about it; it's just that a heck of a lot of the non-technical reports about the probe quote altitude and it can be very confusing. I wish there were a simple word like "altitude" that unambiguously meant distance-between-centers-of-mass. Another hard-to-untangle datum is the final perihelion; an awful lot of design documents quote 9.5 R☉. But maybe now it's 9.86 R☉? That's why I added the note about the fact that it's not determined yet.
What I do wonder is why you removed the "bold=completed" convention from the table. Too much work to keep up to date in the future? 209.209.238.189 (talk) 10:37, 18 August 2018 (UTC)
Bold was just unnecessary; readers know the current date. — JFG talk 14:29, 18 August 2018 (UTC)
My downloaded data from HORIZONS says the last three perihelion is 6.863, 6.862, 6.864 million km center to center. So it is 9.86 R☉.―― Phoenix7777 (talk) 11:46, 18 August 2018 (UTC)

Storage card, not memory card.

The third paragraph which begins "A memory card containing the names of over 1.1 million people..." seems incorrect. It should be "A data storage card containing the names of over 1.1 million people..."

In cyber technology memory is a volatile data container (does not retain data when powered off) whereas storage is a nonvolatile data container (retains data even when powered off). I presume the device is in fact a storage card sans confirmation, but very strongly believe my presumption is accurate - no even partially competent circuit or systems engineer would entrust such data to a volatile device, nor have any technical or economic reason to do so.

Please comment if you disagree or have additional perspective. Otherwise I'll make the change in about a week. Cheers! --H Bruce Campbell (talk) 16:52, 18 August 2018 (UTC)

We know what a memory card is, and it's non-volatile. The term "memory" does not imply volatile storage; ever hear of flash memory? (Or core memory, read-only memory, drum memory, etc.) Wikipedia has a whole article on different types of non-volatile memory. Nor does "storage" imply the non-volatile; the term "volatile storage" I used in my second sentence is also common in the field.
It's quite obvious that the storage medium is non-volatile; that's implied by "card" (meaning removable/transportable) and the fact that there would be little point otherwise. "Data storage" does not make that implication stronger, and given that it makes the phrasing more labored and awkward, I oppose the change. 209.209.238.189 (talk) 12:56, 19 August 2018 (UTC)
I could quibble about how, technically, a "memory card" can mean a circuit board populated with volatile memory chips... But that's irrelevant. As you say, it can also mean non-volatile memory.
A more important point (to me) is that the NASA and APL press releases consistently call this thing a "memory card." Debating whether or not they are using the term correctly doesn't matter. The Wikipedia article needs to go with the sources, not the editors' interpretations and opinions. Fcrary (talk) 19:25, 19 August 2018 (UTC)
I defer to the valid element of Fcrary's point - I'll make no change at this time. But I defer very reluctantly, and in spirit only partially, because:
I disagree with 209.209.238.189 because in my experience in the history and evolution of these technology sectors memory and storage are strictly defining terms. Yes misuse is common, but it's in the long evolutionary process of being corrected by more broad acceptance and use of the correct terms. That is, in cyber technology the correct term for a volatile data container is memory, and for a non-volatile container storage. Frequent misuse isn't justification for continued misuse - 'can mean' can be cited to try to justify any erroneous rhetoric, but it's an empty and counterproductive justification which perpetuates chaotic and confusing communication.
The industry is slowly advancing the proper terms into more popular and disciplined use - fabrication firms particularly are increasingly more rigorous about this (in spite of Toshiba's lingering corporate division name mistake, which in my estimation is rooted in a combination of a translation error from long ago and the earlier much weaker rhetorical discipline, but will ultimately be corrected too). And in my view the process should be supported. I don't suggest Wikipedia should be the primary force behind this long process of language refinement, but neither should it resist and thus oppose productive change.
And therein lies a significant challenge since, as 209.209.238.189 cites, numerous Wikipedia references are conflicted and confused about the terminology and thus adding potholes to the road to clean and clear rhetoric which technologists and the industry are advancing. And though a daunting challenge, in my view Wikipedia should join the global process toward clean and clear terminology - numerous Wikipedia pages need an enlightened process of patient but clearly focused change to contribute, or at least be in line with, the process of change to popular use of the correct terminology.
People frequently referred to dolphins as fish. And not so long ago... A process of enlightened language refinement largely eliminated that misuse. The same terminology refinement process is slowly occurring with memory and storage technology, and in my view Wikipedia should rationally support or at least not oppose this productive evolution. In time we'll look back in wonder that anyone ever referred to storage as memory or memory as storage, just as we now perceive it as remarkably ignorant that people frequently referred to sea mammals as fish in earlier times.
And this is no small matter as AI, leading to ASI (evolved Strong AI), are storage intensive and, in my view, soon to become storage insatiable technologies. And will very likely swiftly become key defining features of life on this planet. --H Bruce Campbell (talk) 16:44, 26 August 2018 (UTC)
That's why I like sticking to the terms and names used in the source material. If we do so, your concern will automatically be taken care of. Once people (i.e. the source material) adopt consistent terminology, then accepting their usage will be consistent. On the other hand, it's quite possible people will adopt some completely different, but consistent terminology. However, until then, we are linking to the article on Memory card and it doesn't seem to say anything about terminology or volatile versus nonvolatile storage. That might be the right place to note the issue about terminology and consistent usage. Fcrary (talk) 19:10, 26 August 2018 (UTC)
Thanks Fcrary. We might differ in some modest measure but I respect your perspective, and especially agree that the Memory card article is the most suitable place to consider the matter further. If time permits... --H Bruce Campbell (talk) 07:59, 27 August 2018 (UTC)

Users of satellites on Earth have to deal seasonally with sun transit, when the satellite passes between the sun and the receiver, causing the satellite signal to be overwhelmed by the unmodulated but powerful output of the sun. How will Parker's signal be detected against this solar output? I am wondering if these close passes or the transmission time will occur when the probe is actually "beside" the sun, and not in front of it, that is, it is about to slip around the far side of the sun. GBC (talk) 17:54, 8 August 2018 (UTC)

The spacecraft has an elliptical orbit. Presumably, science data will be recorded near perihelion, and transmitted when it's farther away. Its aphelion remains outside the orbit of Venus, which is ample distance. 209.209.238.189 (talk) 08:49, 11 August 2018 (UTC)
A small point, but I understand that after the 7th Venus flyby, the aphelion will be slightly INSIDE the orbit of Venus. Anyway, I have seen a site--if I find it again, maybe I'll provide it-- showing the parts of the orbits where close solar observation will take place, and the parts where date will be transmitted to Earth. Uporządnicki (talk) 17:31, 24 October 2018 (UTC)
It's not useful for the article, but this is correct according to some of my colleagues who work on the project. Downlink of data and uplink of commands happen away from periapsis. I'm not sure if that's entirely due to solar noise; there may be thermal constraints involved in pointing an antenna at Earth. Around periapsis, they don't have any communications for a multi-day period (I think something like two weeks.) If someone can find a reference to this, it would be good to add to the article. Unfortunately, all I've got is a personal communication. Fcrary (talk) 20:33, 24 October 2018 (UTC)
This article https://www.researchgate.net/publication/301998540_SOLAR_PROBE_PLUS_MISSION_DESIGN_OVERVIEW_AND_MISSION_PROFILE goes into the question quite a bit. Basically, it says that the portion of each orbit closer to the Sun than 0.25 AU will be devoted to observation--the science phase. Once outside that portion of the orbit, the probe will be transmitting data to Earth. The article also goes into a fair bit of detail about some further considerations. While the angle--as measured from Earth--between the Sun and the probe is too small, communication will be limited or not possible. Furthermore, the probe needs to keep its heat shield pointed to the Sun, at least for parts of each orbit; there will be phases where that heat shield will block antennas from Earth and make communication impossible.
I'll leave it to others to decide what, from this source, is appropriate for the Wikipedia article, and how it should be presented and cited. Uporządnicki (talk) 16:50, 25 October 2018 (UTC)

Planned timeline

Current two dimensional table is hard to read. A simple table like below is better.―― Phoenix7777 (talk) 04:00, 13 August 2018 (UTC)

Planned timeline
Year Date Events Distance
(million km)		 Velocity
(km/s)		 Orbital period
(day)
2018 Aug 12 Launch – – –
Sep 28 Venus flyby #1 – – –
Nov 1 Perihelion #1 25 95 150
2019 Mar 31 Perihelion #2 25 95 150
Aug 28 Perihelion #3 25 95 150
Dec 21 Venus flyby #2 – – –
2020 Jan 24 Perihelion #4 20 109 130
Jun 2 Perihelion #5 20 109 130
Jul 6 Venus flyby #3 – – –
Sep 22 Perihelion #6 14 129 112.5
  • Support the change. Easier to read. Rowan Forest (talk) 04:04, 13 August 2018 (UTC)
  • The intent of this table was to show the gradually reduced periodicity of the orbits, but I agree it doesn't do a great job of that. I spent a lot of time improving it and I'm still not satisfied. On the other hand, a simple 1D table would lose the intuitive timing information. I'm thinking of a graphical timeline view to replace all this. — JFG talk 15:25, 13 August 2018 (UTC)
I added an image for "a graphical timeline view". The table adds only exact dates of events and orbit periods. An editor moved the image to the bottom of the section. I can change the title of the image to "Timeline of Parker Solar Probe" if necessary.―― Phoenix7777 (talk)
Also the simple table can accommodate more information like above.―― Phoenix7777 (talk) 03:08, 14 August 2018 (UTC)
A graph of the velocity and distance from the sun of the probe from launch date until 2026. Legend: ①–㉔: Perihelion; ➊–➐: Venus Flyby
@Phoenix7777 and JFG: The nice graph above (which shows relative scales well) plus the 1-D table for details seems like the best solution to me.
My one complaint about the graph is that the labels are on the speed curve, with flybys at the bottom and perihelions at the top, which is somewhat unintuitive. Admittedly the flyby is visible on the speed curve and not on the distance curve. H'mmm. (Note that technically it's speed (a scalar quantity) and not velocity (a vector quantity) which is plotted.) 209.209.238.189 (talk) 12:02, 16 August 2018 (UTC)
P.S. I went ahead and made the change. Some perihelion speeds are missing from the table; I'm not sure where to find them. 209.209.238.189 (talk) 13:52, 16 August 2018 (UTC)
Looks good. I have updated the dates per source, taking into account the exact launch date. @Phoenix7777: perhaps you have access to the missing velocities, and to distances from the Sun during Venus flybys? — JFG talk 00:03, 17 August 2018 (UTC)
Thanks all of you, I filled out the speed.―― Phoenix7777 (talk) 05:54, 17 August 2018 (UTC)

@Phoenix7777: I see you added JPL Horizons as a source, but it's unclear how it can be queried to generate the necessary data. Can you build a URL that would enable a reader to WP:verify the information? Otherwise, we should find another source, or explain. Also, any chance to get the speeds at Venus, and possibly speed differentials imparted by the gravity assist? — JFG talk 06:56, 17 August 2018 (UTC)

@JFG: I used "HORIZONS Web-Interface" when I downloaded the data. Unfortunately any data download url is not available because HORIZEN employs cgi interface without reflecting all input parameters to its url. Moreover, when I downloaded the data, an available timespan was from 2018-Aug-11 to 2025-Aug-31. But JPL changed it from 2018-Aug-12 to 2018-Oct-10 after the launch. I tried to search SPICE data, but I couldn't find any data. So it is not verifiable now. If the downloaded data which was used to plot the graph is available, any information depicted in the graph including the flyby speed is available.
Anyway I created a url using a batch interface, but a timespan is only from 2018-Aug-12 to 2018-Oct-10.―― Phoenix7777 (talk) 09:46, 17 August 2018 (UTC)

@JFG: @209.209.238.189: HORIZONS Web-Interface now provides a revised data (Aug 24) from 2018-Aug-12 to 2025-Aug-31. Although the minimum time step size is 1 minute, the output length 3,709,503 exceeds 90,024 line max. So I created a url with a time step size of 1 hour.―― Phoenix7777 (talk) 22:42, 25 August 2018 (UTC)

Splendid. Is it possible from this data to fill in the blanks with distance and speed at the Venus flyby events? — JFG talk 08:02, 27 August 2018 (UTC)
Animation of Parker Solar Probe's trajectory around Venus from 12 August 2018 to 31 August 2025
   Parker Solar Probe ·   Venus
It is possible but distance and speed are meaningful only for perihelion. Flyby effect on speed may be of some help but distance of flyby may not add anything and only confuses readers.―― Phoenix7777 (talk) 10:17, 27 August 2018 (UTC)
If you mean the distance from and speed relative to the Sun, I guess you're right. But the approach (asymptotic) speed relative to Venus and the closest approach distance to Venus determine the magnitude of the gravity assist. I think there are also plans to take data during some of the Venus encounters. That's another reason the closest approach distance might be relevant. But if anyone puts that into the table, it ought to be in separate columns. Mixing it in with the solar range and speed would confusing.Fcrary (talk) 20:10, 27 August 2018 (UTC)
This url is Parker Solar Probe's data around Venus. I created an animation of Parker Solar Probe trajectory around Venus with curiosity.―― Phoenix7777 (talk) 21:02, 27 August 2018 (UTC)
I created a graph of Speed and distance of Parker Solar Probe relative to Venus. It seems hard to define "speed of flyby".―― Phoenix7777 (talk) 00:41, 28 August 2018 (UTC)
Speed and distance of Parker Solar Probe relative to Venus
This looks very interesting. Too much OR to place in the article, unfortunately, unless we find a report specifically discussing the probe's trajectory relative to Venus, then we could illustrate it with this animation. — JFG talk 07:29, 28 August 2018 (UTC)

Regarding the Venus gravity assists, I think it would be worthwhile to add extra columns showing speed and distance relative to Venus (+ perhaps Δv imparted), and still fine to list speed and distance relative to Sun in the existing column. — JFG talk 07:29, 28 August 2018 (UTC)

Well, the distance from Parker to the Sun at the Venus passes would be almost exactly the distance from Venus to the Sun; the Venus passes are planned to be anywhere from a couple of hundred to a couple of thousand miles from Venus--an infinitesimal amount in the scale of things. And the orbit Venus, conveniently, is the least eccentric among all the planets--meaning it's the least oval-shaped. In fact it departs only slightly from being a mathematically perfect circle with the Sun at the center. So its distance from the Sun is always pretty much the same.
What I've been searching the Internet for is aphelion figures--the far distances. The Venus encounters generally will NOT take place at aphelion. The aphelia of each group of orbits following each pass of Venus will be the same. As I understand it, the aphelia after the first and second pass will be near the orbit of Earth, almost but a little less than 1 AU. The next several passes will result in aphelia progressively closer to, but outside of, the orbit of Venus. And finally, the last pass will bring about an orbit with aphelion a little inside the orbit of Venus--and there will be no more passes. But I can't find a good, definitive source for this. I've gleaned it from diagrams here and there, and I've seen various sources that hint at parts of it. There's a source cited in the article; it's a large page of numbers that one can apparently use to construct the orbits in detail. Contributors here have been using it, but it's way beyond my tech skill set. Uporządnicki (talk) 13:13, 27 October 2018 (UTC)

I'm afraid I have to disagree with myself. I just realized that SPP is only making Venus encounters and I don't think any major maneuvers are planned. In that case, there is a conservation law which applies and the approach velocity to Venus will be essentially the same on all encounters. That wouldn't be worth giving its own column in the table. Simply stating the number in the text would be sufficient along with the range at which it was calculated (I think the Sphere of Influence is the traditional distance.) For the table, I now think it would be best to simply add a column for the closest approach distance on Venus encounters. Fcrary (talk) 01:08, 29 August 2018 (UTC)

I think it's not correct that the approach velocity to Venus will be essentially the same on all encounters. There are two reasons. First, the encounters in general will NOT happen at Parker's aphelion. Some will happen on its way out to aphelion; some on its way back in. That aphelion will change with each encounter of course--the very purpose of the encounters is to change Parker's perihelion, which will necessarily change the aphelion. The second reason might make only a trivial difference; the passes will happen at various distances from Venus--from several thousand to just a couple of hundred miles. Of course, as Parker approaches Venus, it will be sped up; as it moves away, it will be slowed down. And its trajectory will be altered. I'm supposing that effect will be greater for the close passes.
I've found a couple of good places with information on the individual passes; I'm contemplating adding that information, as soon as I figure out how to cite it properly (my Wikipedia editing to date has involved almost no citation). That information does not include speed of passes, but I'm not sure how interesting that really is. Uporządnicki (talk) 13:42, 27 October 2018 (UTC)

To the extent that the assumptions of the restricted three body problem apply, the approach speed to Venus (and the departure speed after the encounter) are conserved quantities. Those assumptions are that the spacecraft's mass is negligible compared to that of Venus and the Sun (a very good approximation), that the orbit of Venus is circular (it's 0.007) and that only the gravity of the Sun and Venus matter (rocket firings and distant perturbations from other planets cause slight variations.) It doesn't matter where along the spacecraft's orbit the encounter occurs, not does the eccentricity of the spacecraft's orbit. Fcrary (talk) 20:20, 27 October 2018 (UTC)

I'd already worked out that when I went into the business about the eccentricity of Venus, I'd misread the original posting I was responding to. I thought someone proposed adding date on the distance to the Sun at the various Venus passes; I was mistaken.
Now, it does seem to me kind of obvious that when the spacecraft is flying past Venus those seven times, it would necessarily be flying at different speeds. But you clearly have more expertise in this than I have. I have to conclude that "approach speed" has some--no doubt rigorously defined--meaning that I'm not aware of. Uporządnicki (talk) 20:47, 28 October 2018 (UTC)
It's all a question of what the speed is relative to. On the different encounters, the spacecraft is approaching (and departing from) Venus at essentially the same speed. But it's approaching from a different direction. That means the spacecraft's speed relative to the Sun, rather than Venus, is different. Initially, it's moving faster than Venus. Later, it's moving slower. Relative to the Sun. Fcrary (talk) 23:49, 28 October 2018 (UTC)

Animation of orbits--slow? pause?

That animation of the orbits is very interesting. But I wonder if there's a way to slow it down here and there, or pause it. Uporządnicki (talk) 17:26, 24 October 2018 (UTC)

@AzseicsoK: There is a 50 Mpx restriction for gif files in Commons. So the maximum frame count is 212 for this file. (50 Mpx / (560 px x 420 px) = 212 frames) It is possible to make gif delay from 10 ms to 20 ms. But it is hard to see. So I created a webm video with 600 frames. I don't want replace the gif file with this webm file because it requires readers action to enable the file. So I added a link to the webm file for interested readers.―― Phoenix7777 (talk) 23:50, 24 October 2018 (UTC)
I don't understand what you've said here, but no matter; I love what you've done. Thanks!
I'm old enough to have watched a single still image sent via satellite (I think it was Telstar) being built one line at a time on our old Zenith black and white (VHF only); I followed the Mercury program (although at that age, I wasn't paying a lot of attention to detail; John Glenn went around three times, that's about as in depth as I got). After the moon landing, Parker, Voyager, and New Horizons to Pluto (I met Clyde Tombaugh once) are, for me, about the most exciting things NASA has done. Uporządnicki (talk) 16:20, 29 October 2018 (UTC)

Trajectory animation

Does anyone know how to fix the aspect ratio on the trajectory animation? Circular (or near circular) orbits ought to be shown as circular. The animation looks like the x:y scale is about 2:3, not 1:1. Fcrary (talk) 22:04, 12 August 2018 (UTC)

It is intentional. The animation is a view from (100, -100, 100) which means about 45 degree above X and -Y axis not a view from directly above.―― Phoenix7777 (talk) 22:19, 12 August 2018 (UTC)
I have no idea why someone would want to show trajectories from that angle. In any case, if that's what it is, the caption should say so. Fcrary (talk) 23:28, 12 August 2018 (UTC)
I just took a look at that link (first time I've ever seen it), and I think I see an excellent reason--in general--for showing it that way. When I opened it, it happened to be showing an orbit for Halley's Comet, not Parker. And I see that they have a clever way of indicating the body's position above or below the ecliptic throughout the orbit. That clever way will only work with an oblique view; looking straight "down" from the ecliptic pole would lose that advantage. Uporządnicki (talk) 14:22, 28 December 2018 (UTC)
It is a default view of NASA JPL Small-Body Database Browser. I don't think such an explanation is needed.―― Phoenix7777 (talk) 23:52, 12 August 2018 (UTC)
Agree that the "default view" is fine. Certainly a clarification in the caption may help readers unfamiliar with Solar System animated views. — JFG talk 15:28, 13 August 2018 (UTC)

Flight Software

The page discusses the instruments without mention of the flight software itself. The Flight Software Workshop by Christopher Krupiarz (http://flightsoftware.jhuapl.edu/files/2015/Day-1/SolarProbePlusOverviewFINAL.pptx) gives detailed information on the LEON3 flight hardware, software requirements, and functionality. It includes great information on the software architecture noting the it uses RTEMS, OSAL, and the Core Flight Executive along with the "lollipop" diagram of mission functionality attached to the cFE. It would be nice to get a section on the flight software in the page. Any thoughts on where it might go? --JoelSherrill (talk) 15:23, 14 August 2018 (UTC)

I was thinking that the article can be improved if we create a section on the spacecraft's development and construction, especially its radiation and thermal protection, as well as its cooling systems. The flight software can surely be a part of this new section. Cheers, Rowan Forest (talk) 03:06, 15 August 2018 (UTC)
I've got mixed feelings about that. Are we trying to describe what they built or how they built it? A section on development and construction sounds like it would cover things like the design reviews and testing, as much as the hardware (and software) itself. If we want to describe the spacecraft itself, we already have a section on the spacecraft. We could significantly expand that. Either way is fine with me; I'd just like the keep the section title and contents consistent. Fcrary (talk) 21:06, 15 August 2018 (UTC)
Yesterday I gathered that Spacecraft section together. I am not proposing to include design reviews and testing. Most of it is there, just missing software and radiation protection (high energy particles). Cheers, Rowan Forest (talk) 00:51, 16 August 2018 (UTC)
[2] mentions proposed used of LEON3 processor (for spacecraft control including orientation/safety) and also it being triple redundant with a warm and cold backup. Also talks about the software and processors used in the data handling - eg Coldfire implementation in FPGA - based on MAVEN and others. LEON3 was proposed, but did they end up using it ? - Rod57 (talk) 13:12, 3 February 2019 (UTC)

Details of the Venus passes--too much?

I've been very curious, for myself, about two aspects of this mission: the successive aphelia and the Venus flybys. I've found some good information on line about those flybys; from it, I can gather:

  • On which leg of Parker's orbit (outbound, from Solar pass to aphelion, or inbound, from aphelion to Solar pass) will the flyby take place;
  • Will the flyby happen inside or outside Venus's orbit;
  • Which flybys will happen at the same points in the orbit of Venus;
  • And how far from Venus the flyby will happen (in one instance, it's a few hundred miles).

I've been contemplating ways of incorporating that information in the table of perihelia and other events. Whatever I've thought of will certainly add a lot to the table--at least in terms of stuff; whether it will add to it in terms of quality, usefulness and interest, I haven't decided. Thoughts, anybody? Is all/any of that of sufficient interest to warrant inclusion? One thought I had--the one that would clutter the table the least--is to add the distance of the flyby, and whatever I wind up including of the rest of the information--relegate that to notes. Uporządnicki (talk) 18:33, 27 November 2018 (UTC)

OK, MORE ON THIS! I started a draft of what I talk about above, to see how it all looks when it's done. And I've run into some complications.
I took the data on the Venus flybys from a scientific paper (Guo et al, Mission Design Overview ...) that seems very authoritative, but was, nevertheless, published four years before the mission launched. That's where it said that the first flyby (a few weeks ago) was to be at an altitude of 2548 km over Venus. That comes to 1583 miles. After the flyby, NASA's (and Hopkins's) press announcements said "within about 1500 miles." Other news reports also say it was about 1500 miles; presumably, they got it from NASA/Hopkins. Some of them add 2414 kilometers, but since neither NASA or Hopkins gives a figure in kilometers, I assume these other reports undertook to convert the figure. The small, apparent discrepancy--83 miles/134 km--raises two possibilities in my mind:
  • NASA's/Hopkins's press releases provided only a very rounded off figure, and the other news reports converted it to a precision not called for;
  • Sometime after the publication of Guo et al, the details changed--perhaps due to NASA having to skip one launch window and wait for another.
Additionally, I played with that Horizons system from NASA, and got a third altitude figure, 2456 km = 1526 miles--in between the other two. (If I did and understood things right, it gave me a distance from the center of Venus; I subtracted Venus's radius.) Two questions with this:
  • I learned of this Horizons system right here on this Talk page; I'm sort of muddling my way through it, and I can't be absolutely sure I know what I'm doing;
  • It's beginning to feel a little like Original Research (although I gather that some of the charts and videos on this page are based on that).
Would people please take a look at this, User:AzseicsoK/Parker_Table, and tell me what you think. Not valid? Way too much? Both? Or, a brilliant piece of work? Uporządnicki (talk) 14:10, 28 December 2018 (UTC)
Uporządnicki, I'd put in the altitudes from the Guo et al. paper. I don't see using Horizons as original research, but some people do. Also, it isn't stable. If there are future tweaks to the trajectory (and there probably will be) someone, at some later date, would get different numbers from Horizons. So I'd use Guo et al., but also add a note saying those altitudes are for the reference trajectory of 2014, and that Horizons can be used to find the current, exact values. Fcrary (talk) 22:10, 3 January 2019 (UTC)
Fcrary, thanks for this. But as it turns out, I'm not going to be able to get to this until almost February. Right now, I'm just checking in briefly. To put my draft into the article and get everything to connect right is going to take some time and care. I'm going to be traveling, starting in just a few hours, and I have a feeling I won't even get to look at Wikipedia very much. Uporządnicki (talk) 02:31, 8 January 2019 (UTC)
I've returned from my trip, and I finally got around to this. I replaced the table with the version I edited to give details of the Venus flybys. PLEASE NOTE: If you feel that I've done too much, be aware that I've wondered that myself. If it is decided to revert the table to what it was before I tinkered with it, do not feel that you're destroying my work. I have my version saved in my own sandbox, so the considerable work I did will not be lost. Uporządnicki (talk) 20:27, 24 February 2019 (UTC)
It looks fine. If people don't care about the details, they can scroll past them. In my opinion, too much would be creating formatting problems fitting everything in browser window, and you don't seem to have done that. I did find a typo and corrected it. Fcrary (talk) 20:50, 24 February 2019 (UTC)
Thanks. BTW, Vietnam was fantastic.
FcraryFor whatever interest (if any) it might hold: When you found and fixed my typo, you didn't catch my "John's (sic) Hopkins" howler. I just spotted it myself, while tidying up some redundancy in the related footnotes. Uporządnicki (talk) 14:29, 7 March 2019 (UTC)

Editors editing AU/au

A couple of editors (one named and one IP) have lately undertaken to go through and make a number of largely cosmetic edits to this page. One of those has been to change "au" (astronomical units) to "AU". Nobody has caught them all, so as I write this, both are to be found in this page.
Let me point out, please, that according to the Wikipedia Manual of Style, "au" is preferred.
Wikipedia:Manual_of_Style/Dates_and_numbers#Units_of_measurement
Both "au" and "AU" are allowed, insofar as we're advised NOT to go through fixing an article that uses "AU". The Manual encourages a consensus for any one article. Uporządnicki (talk) 15:31, 6 March 2020 (UTC)

The Manual of Style has some internal contradictions. We're also supposed to follow the usage of the sources. The Parker Solar Probe project uses "AU" (e.g. on the APL web site for Parker.) Since "AU" rather than "au" is allowed, and it's what the project itself uses, I think we should as well. But I do agree about consistency. Fcrary (talk) 23:01, 6 March 2020 (UTC)
Personally, I like AU better.Uporządnicki (talk) 02:31, 7 March 2020 (UTC)

Where's information about the alleged distance record?

User:Randey1970 just made an edit changing the date of Parker's most recent record for proximity to the Sun from September 27, 2020 to January 17, 2021 (the day I'm writing this). It is true that the Probe was supposed to reach its latest perihelion today. But since there was no intervening gravity assist from an encounter with Venus, that perihelion should have been exactly the same as the earlier one. As I understand the term, you set a record the first time you reach some milestone, not a subsequent one. And the source cited, dated September 25, doesn't even address the perihelion of January 17. User:Randey1970 added one of those notes that doesn't appear in the article; it says the probe beat its own record by "a mere 531 kilometers." I'd like to know where that came from. Uporządnicki (talk) 02:49, 18 January 2021 (UTC)

A reference is needed, but we're talking about a 531 km difference out of a perihelion distance of 13.5 million km. That's a difference of 37 millionths. The perihelion distances would not be exactly equal from orbit to orbit. Just perturbations from Jupiter could easily produce a few dozen parts per million difference. I think a more important question, in addition to the lack of a reference, is whether or not the difference is noteworthy. In aviation, the FAI requires that a new record must exceed the previous one by a certain percent, before it actually counts as a new record. So I'm inclined to say a 531 km difference in perihelion isn't significantly different to be noteworthy. Another concern is that Randey1970 seems to know the perihelion distance to within a kilometer on the day of the event, which probably isn't possible. As I understand it, Parker doesn't send down telemetry in the days around perihelion. I suspect he's got a source within the project, which is information we can't use on Wikipedia, and basing the statement on the predicted ephemeris. Fcrary (talk) 04:09, 18 January 2021 (UTC)
On second thought, I don't think I disagree with the edit. The text says, "As of its perihelion on 17 January 2021..." It doesn't claim the closest perihelion was set on January 17th. Updating the date of an "as of" statement is fine. But the comment about the Jan. 17th perihelion being 531 km closer should be removed. I'll do that now. Fcrary (talk) 04:15, 18 January 2021 (UTC)
I wonder if the user got it from the Horizon system. Which brings up a point. I'd been updating that table of mission highlights, and filling in details, when the highlights have actually happened. You'll note I have not gotten around to updating last September's perihelion. I try to get something after the fact, and I try to get something other than NASA's/Hopkins's own announcements (even though the announcements I've seen in other sources have often copied the NASA/Hopkins press releases verbatim). I don't know if it's COVID or a waning in interest, but I still haven't found anything about that; I only find something that says it's "about to happen" (tomorrow), and it doesn't say anything about the actual distance or the specific time.
I keep thinking of gleaning it all from the Horizon system--but first, I still feel like that's somewhat less than kosher; and second, I still kind of muddle my way around the Horizon system without entirely knowing what I'm doing.
I could, I suppose, get some of it ahead of time (at least the time of the event) from the Hopkins site where it notes the time to the next highlight, but then I'd be citing a source that will disappear as soon as it's superseded. I've also just noticed that the same page gives a time and distance for the current record approach. So I could update September's perihelion from that. But since January's perihelion did not set a new record, the data for that one will never show there. And again, that presumably WILL disappear with the next perihelion, this April (there will be an outbound Venus flyby in February). Uporządnicki (talk) 20:11, 18 January 2021 (UTC)

Speed of probe--speed of light, somebody's (twice) "correction."

I see that someone has twice made an edit to "correct" a point about the maximum speed of the probe as it relates to the speed of light. The second time, this someone carefully explained him/herself, but s/he is still in error. And unfortunately, this is not a registered User, so there's no way to get back to him or her to point out the error. Maybe "someone" will read it here.
Dear Mr./Ms. Someone, you keep changing 0.064 to 0.00064. You are correct, up to a point. The maximum speed the probe is planned to reach will indeed be 0.00064 of the speed of light. But the statement you keep "fixing" actually says 0.064% of the speed of light. Notice the "percent" sign, which I've bolded; that's the key. 0.99 of the speed of light IS 99% of the speed of light. 0.50 of the speed of light IS 50% of the speed of light. 0.01 of the speed of light IS 1% of the speed of light, and 0.001 of the speed of light IS 0.1% of the speed of light. Similarly, 0.00064 of the speed of light--the figure you've correctly arrived at--IS 0.064% of the speed of light--the figure given in the article.Uporządnicki (talk) 18:05, 1 April 2019 (UTC)

Yes, even since Uporządnicki‘s informative comment in April, the article has been reverted to incorrect value (0.00064%) and then fixed to correct value (0.064%) several times. Whoever keeps changing it to the wrong value seems to not understand percentages or is not noticing the percent sign. The speed is 0.00064c, which is 0.064% of the speed of light (not 0.00064%). Similarly, a speed of 0.12345c is 12.345% of the speed of light (not 0.12345%). Please read this carefully and understand, rather than again changing it to the incorrect value of 0.00064%, which is too small by a factor of 100. In summary: CORRECT = 0.064% of speed of light = 0.00064c —— INCORRECT = 0.00064% of speed of light = 0.0000064c. 82.22.66.201 (talk) 00:32, 5 December 2019 (UTC)

There is no known material in the entire world, not even from 'NASA' that can withstand the speeds & temperatures claimed here - this is ludicrous to attempt to 'pass off' as FACT today. — Preceding unsigned comment added by 160.2.51.245 (talk) 02:57, 22 October 2021 (UTC)

To say that it can't withstand the "speed" is the only thing ludicrous here. What is there about speed to "withstand"?? Uporządnicki (talk) 09:17, 22 October 2021 (UTC)

End of Life

I don't see any information about the end of mission, only "Mission duration 7 years (planned)". what happens in 2026, will it be left in orbit or deliberately crashed into the sun?

It would be extremely difficult to deliberately crash it into the Sun, and I don't know of any reason why it should be done. I suppose it'll do so eventually. Well before that, presumably they'll stop trying to control it--then, inevitably, it will be facing the Sun the wrong way on one of its close passes and be fried to uselessness. Uporządnicki (talk) 17:43, 10 August 2021 (UTC)
I guess they might try a manoeuvre that brings it even nearer to the sun that eventually might damage the probe, or it just will have critical failure and stop working or run out of fuel.--Giftzwerg 88 (talk) 00:20, 23 November 2021 (UTC)
Such a "manoeuvre" would probably need another close pass of Venus. Once those aren't happening anymore, I doubt if such a change could be made. They can tweak the approach to Venus to fine-tune the gravitational assist, but I doubt that the thing has enough fuel to change its close approach to the Sun to any degree that would be significant. Uporządnicki (talk) 13:14, 23 November 2021 (UTC)
I too am curious to know how this mission is to end. Given that the objective is to gather measurements as close to the Sun as possible, this leads me to think that (perhaps) the objective is served by getting progressively closer to the sun until - at some indeterminate point - the probe fails. If that is the case, then one would hope that the ultimate failure mode is determined before communications is totally lost. Such failure data - in addition to any primary mission data collected - would be invaluable to the definition and design of a future successor mission. In any event, the absence of end of mission detail is glaring.
Enquire (talk) 04:51, 15 December 2021 (UTC)
@Enquire: I'll start by repeating what I said earlier. It's the close passes by Venus that bring about the closer approaches to the Sun. After the last scheduled close pass of Venus, if no more such passes are mathematically possible, then there probably isn't a way to bring the close pass of the sun any closer than it will already be. As for what might happen after the end of the planned mission, Wikipedia can't really say anything on it unless something authoritative and reliable has been published. Uporządnicki (talk) 16:36, 16 December 2021 (UTC)
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