Talk:Luna 3

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I agree that it makes sense for Yenisey-2 to be merged into this article. ThreeBlindMice 20:12, 14 September 2006 (UTC)

Upon complete reading of this article I'd say that most of the information contained in Yenisey-2 is already included here under Lunar Photography. Thus, merging the remaining information from Yenisey-2 seems the obvious thing to do. ThreeBlindMice 20:18, 14 September 2006 (UTC)

• Yes, it makes sense to merge Yenisey-2 into this article. Ricnun 22:20, 14 September 2006 (UTC)

There wasn't much information in the Yenisey-2 article that wasn't already here, so I just grabbed what was missing and completed the merge. Hope no one minds. ThreeBlindMice 01:00, 16 September 2006 (UTC)

Merging was the proper thing to do. The Yenisey-2 system was used only on the Luna 3 mission so it was unnecessary to have a separate, common article for other missions to link to. A Stand Up Guy 15:37, 18 September 2006 (UTC)

Apoastron and periastron are incorrect terms, as the sattelite was orbiting Earth, not a star. Apogee and perigee are the correct terms.203.143.164.204 04:49, 28 August 2007 (UTC)

Much of the body of this article has been plagiarised from http://nssdc.gsfc.nasa.gov/nmc/masterCatalog.do?sc=1959-008A. If someone could paraphrase the text so that this isn't an issue?? 130.217.188.28 (talk) 04:12, 6 December 2007 (UTC)

Yes, and both this article and the NASA page have many mistakes. They are ultimate derived from old Western publications rather than research from Russian sources. It needs extensive revision. DonPMitchell (talk) 04:54, 15 April 2008 (UTC)

Launch time

The launch time is wrong (for many space probes!). Here's what happens. The RAE table lists the launch time of Luna-3 as "Oct 4.1". If you convert the one-digit approximage time ".1 days" to four digits of accuracy, you get 02:24 UT. Wrong. The actual launch date for Luna-3 was 00:43:39.7 UT (given by Baikonur telemetry specialist and historian, Vladimir Poroshkov). I'll edit in, but it's likely to get undone someday, because the NASA website is mistaken. DonPMitchell (talk) 07:28, 31 August 2008 (UTC)

Russian POV

I think this page is unfairly biased towards the Russian space exploits! AN objective page would include several mentionings of the achievements of FREEDOM. 63.214.229.68 (talk) 22:05, 18 January 2009 (UTC)

Where are the pictures?

I can't believe there aren't any pics from this mission on this page. If I have time, I'll go find some. fvincent (talk) 17:25, 10 December 2010 (UTC)

Agree... AnonMoos (talk) 13:33, 22 January 2011 (UTC)

I thought there used to be some. Bubba73 ^{You talkin' to me?} 23:36, 15 August 2011 (UTC)

There are none in Commons, but there are in Google Images. Bubba73 ^{You talkin' to me?} 06:40, 21 December 2011 (UTC)

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A Commons file used on this page has been nominated for deletion

The following Wikimedia Commons file used on this page has been nominated for deletion:

• Luna 3 moon.jpg

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"First gravity assist" - a specious claim

This article has a section which states:

"The gravity assist maneuver was first used in 1959 when Luna 3 photographed the far side of Earth's Moon."

The most obvious problem with this statement is that gravity assist is not being "used" when flying out to the Moon to take images. Gravity assist is used by virtue of what happens after a probe encounters the gravity well of another body. So if it is used at all on this mission, it would have to be something that happened after it flew away from the Moon. And this is the larger point. I have not looked deeply into this, but just from basic info about this mission, I don't see anything useful that was done as a necessary result of this probes' trajectory having been altered by its encounter with the Moon's gravity well. The only way it can properly be considered a "gravity assist" is if that gravity effect was used to actually assist in doing anything. I see nothing here. Nothing at all.

Yes, its trajectory was altered by the Moon's gravity. But this claim to being the "first gravity assist" needs to be removed, unless anyone can support this view with a sound argument. And there should also be verifiable sources which present the same kind of claim and supporting argument.

From the totality of everything I know about this, I see absolutely no basis for this statement. Best I can tell, the gravity-induced trajectory change was merely incidental, and obviously unavoidable. But had absolutely nothing to do with the mission's primary objective. And I don't see any secondary or other objective from this mission which required this trajectory change. So the clear conclusion is that "gravity assist" was not used. Nothing useful was derived out of it.

Now the changed direction may have incidentally brought the probe closer to Earth during its leg after leaving the Moon. But if all it was doing was sending signals, and those signals could have been received just as easily as if the probe did not get changed to this course bringing it closer, then no practical benefit was derived from having its path coming back toward Earth being closer rather than further. The results of the mission would have been the same if the return leg had been further away, because the transmission signals don't care about the distance. So long as there is sufficient power in the transmitter, the only impact is an insignificantly shorter transmission time. So here too, the gravity-induced change in trajectory was not used for any mission benefit. Gravity was not used to assist.

I am open to the possibility that I am missing something very basic. And if anyone knows of any reason why this was indeed a legitimate use of gravity assist, I would be very interested to learn about that. But if no one can do that, then this needs to be removed.

At most, from what I see here, the best statement to be made for Luna 3 is that this mission is the first time that the gravity well of another celestial body caused a significant trajectory change for a space probe. But again, if that change is not used for anything productive, then it is not a gravity assist.

As far as I can tell, this is a bogus claim. -- Tdadamemd19 (talk) 07:21, 14 July 2019 (UTC)

You write: "...if all it was doing was sending signals, and those signals could have been received just as easily as if the probe did not get changed to this course bringing it closer, then no practical benefit was derived from having its path coming back toward Earth being closer rather than further. The results of the mission would have been the same if the return leg had been further away, because the transmission signals don't care about the distance. So long as there is sufficient power in the transmitter..."

I have to disagree completely. The amount of data which can be downlinked from a spacecraft is critically dependent on the range, and the amount of time with a line of sight to available ground stations. The transmission signals (and the link budget) do very much care about distance. As a general rule, spacecraft never have "sufficient power" to do everything one might like. Given the limits on available power, it's always beneficial to do other things to increase the amount of data which can be sent back. If the Luna 3 team picked their encounter geometry so that the post-encounter trajectory maximized the returned data, that's using the encounter to assist the mission. Fcrary (talk) 21:47, 14 July 2019 (UTC)

You are disagreeing completely, presenting your counter-argument based upon power constraints after I had already acknowledged that power can be an important mission design constraint.

You and I are not disagreed on that point. The problem is that no one has shown that power was the driving consideration regarding the choice of trajectories. (Eg: Receiving signals from Mars wasn't all that big a deal, but for some reason, back in '59 signal power from well within lunar distance was a major constraint?) We are also agreed that "the amount of time with a line of sight to available ground stations" is also an important consideration. Here too, no one has shown that this particular slingshot was selected for the purpose of increasing line of sight (duration of available comm time prior to LOS).

Those are two major factors that this specious claim is missing. If anyone wants to present a valid argument that the Moon's gravity was used to assist this mission in any way, then it needs to be explained how. As it stands today, this claim is unsubstantiated.

I've explained how mission designers could very well have preferred it if they did not have to deal with the Moon's gravity, and all it did was complicate things for them. Substantial evidence supporting my argument can be found in the facts of the Zond 4 mission from 1968:

"The spacecraft was successfully launched into a 354,000 km apogee orbit 180 degrees away from the Moon, It was launched away from the Moon probably to avoid trajectory complications with lunar gravity."

Lunar gravity in the case of the Luna 3 mission was a nuisance. Not an "assist". This is what all of the evidence that has been produced to date shows. Again, I would readily agree that lunar gravity had the potential to do something beneficial for the mission. But until solid facts can be produced to show exactly how this was done, then this claim as being "the first gravity assist mission" needs to be removed.

Your objection has no teeth. What an objection of substance would look like is that it would contain specific facts of exactly how the encounter with lunar gravity had helped the mission (assisted). Something along the lines of:

"It brought the spacecraft [this many] miles closer to Earth, and without this change of trajectory, the spacecraft would not have had sufficient power to transmit the signals." And/or:

"It moved the spacecraft onto a trajectory which increased line-of-sight communications with the tracking station, and without this change, the spacecraft would not have had sufficient time to transmit the signals."

I have never seen any such argument presented. And your rebuttal only speaks of possibilities, not specifics of the mission. I agree that it was possible to use lunar gravity to help. But we have no evidence that this is what happened. Here is the statement posted in that section which this claim rests upon:

"The maneuver relied on research performed under the direction of Mstislav Keldysh at the Steklov Institute of Mathematics."

And that statement is consistent with the understanding that lunar gravity was a nuisance. Instead of helping the mission, it forced them to do significantly more complicated calculations. They had to do stepwise integration of this three-body problem, instead of a simple conic section (a perturbed ellipse). For the Zond 4 mission, they had the option to fly its trajectory with no lunar gravity causing a major trajectory change. And that is exactly what they opted to do. They had this luxury because no closeup photos of the Moon were involved.-- Tdadamemd19 (talk) 14:12, 28 July 2019 (UTC)

I'm afraid you're asking the impossible. You're asking about the motives for an internal, mission planning decision. Even today and in reasonably open programs like NASA or ESA missions, that information is often not publicly available. For a Soviet mission launched in 1969? I don't think there is any hope of finding references on why they did what they did. But we have two references, admittedly vague ones, saying the selected trajectory had benefits. I think we have to go with that, unless you have a reference saying the benefits were just a coincidence.

However, I disagree about the Moon's gravity being a nuisance for Luna 3. It was an inevitable fact. Depending on the trajectory, it could either be a nuisance or a benefit. The picked a trajectory where it would be a benefit.

As far as power and station coverage, sure. The Soviets did manage to send data back from Mars. In 1971, 12 years after Luna 3 (And even NASA didn't send data back from Mars until five years after Luna 3.) But how much? Luna 3 would certainly have been able to send some data back, regardless of its post-encounter trajectory. But getting it close to the ground stations increased the amount of data it could downlink with the available power. Fcrary (talk) 19:54, 28 July 2019 (UTC)

Quote:

"I'm afraid you're asking the impossible." - Fcrary

I have absolutely no burden here to prove that the Luna 3 was not assisted by gravity.

The burden here is incumbent upon whoever initiated this claim to back that up with a reliable source which spells out that the mission was indeed assisted. You have not presented any such source. You have chosen to rest your argument on:

"...we have two references, admittedly vague ones..."

"I think we have to go with that, unless you have a reference saying the benefits were just a coincidence."

No. We do not have to go with vague references. It is actually our duty to remove info that cannot be solidly supported.

And again, it is not any requirement I have to come up with a source to say it was a coincidence. There is no coincidence here. The probe encountered the lunar sphere of influence. It is not proper to fabricate a case that this trajectory alteration benefited the mission when it did not. Or from your perspective on this: to rest such an argument upon vague claims of benefit. We must do better than vague.

There are those who say "Pictures, or it didn't happen." Well the mantra of Wikipedia is "Reliable sources, or the info must be removed." Two vague sources do not cut it. Especially when this all serves to radically change what the vast majority of astrodynamicists mean when they say the term "gravity assist." (A major aspect of the initial objection here.)

I will continue to patiently wait before removing this unsubstantiated claim, both here and at gravity assist.

I remain open to the possibility that some editor here will be able to produce a solid source which achieves the minimum standard upheld by Wikipedia Policy. And let's be clear that if someone were to cite a book which makes this claim as loosely as it has been made here, that will not cut it. It needs to be a reliable source which presents this claim in a substantial way.

Perhaps you will be the one to provide such a source. Or perhaps, in its absence, you could also be the one to recognize the validity in the argument presented here, and arrive at agreement that this claim needs to be removed from our encyclopedia. But even if you yourself were to never reach this position, policy here is clear that consensus is not a matter of what a majority of editors might feel. Consensus is established by what the reliable sources support. -- Tdadamemd19 (talk) 08:55, 30 July 2019 (UTC)

Actually, the sources are already there. I probably shouldn't have called them vague. They are actually quite specific. In the referenced book, Essential Spaceflight Dynamics and Magnetospherics, it says,

"Gravity-assist maneuvers are widely, and effectively, used for interplanetary missions. The first time such a maneuver was realized was during the flight of the Soviet SC Luna-3 in 1959... The simple transfer trajectory shown in Fig. 12.5 presents an obvious candidate orbit... In 1959 a disadvantage of this trajectory was that, in returning from to the Earth, the SC would approach from the South and count not... be contacted from the territory of the former Soviet Union. To overcome this a trajectory was chosen involving a gravity-assist maneuver." (Emphasis added and ellipsises are mostly skipping references to a figure.)

That book, by the way, is published by Kluwer Academic Publishers, which is a reputable source. Not that the source specifically states that an alternative trajectory was chosen, to avoid a problem another trajectory would have had.

One of the other references looks like a short biography of M. V. Keldysh, off the web site of the Keldysh Institute of Applied Mathematics. That's a less ideal source, since they are probably a little biased. But no worse than many sources cited on Wikipedia. That states (although I had to use Google Translate, since it's in Russian):

"Initially, the main efforts were aimed at solving the problem of reaching the moon and exploring the near-moon space. The relevant work was carried out in a short time under the general guidance of M.V. Keldysh. A brilliant example of work from the "lunar" cycle was the choice of flight paths and photographing the invisible side of the moon for the Luna-3 satellite. Here, for the first time in world practice, a "gravitational maneuver" was proposed and successfully implemented - a purposeful change in the trajectory of a spacecraft as a result of perturbation of its motion by a celestial body (the Moon)." (Again, emphasis added.)

So we've got two references saying the trajectory was a choice, not a fortunate coincidence, one saying the change to the trajectory was "purposeful" and the other saying it allowed telecommunications coverage where other trajectories would not. I haven't seen anything other than your assertions to contradict those references. Fcrary (talk) 22:51, 1 August 2019 (UTC)

--------

To better analyze the merits of this claim, it will help to look at the exact quote from the reference that was provided:

"...a disadvantage of this trajectory was that, on returning to the Earth, the SC [I assume this means 'SpaceCraft'] would approach from the South and

  could not, along the orbit segment CD [referring to the diagram presented] closest to the Earth, be contacted from the territory of the former Soviet Union.

  To overcome this a trajectory was chosen involving a gravity-assist manoeuvre." (Ref#6)

What this is describing is merely accounting for the trajectory alteration, and then planning the trajectory in a way which makes for convenient communications. This is categorically distinct from taking advantage of the free delta-v imparted by the encounter with the celestial body. The argument for removal is that this is an adulteration of the typical meaning of the usage of the term "gravity assist" in regards to spacecraft mission design. What the planners of Luna 3 apparently did was adapt to the unavoidable trajectory alterations which resulted from the lunar encounter so that their communications plan worked more effectively.

Making plans so that your communications still work conveniently after the trajectory change is not a "gravity assist". This would be better described as a "mission plan adaptation to the unavoidable gravity-induced trajectory change". The planners tweaked their trajectory in order to accommodate for the delta-v change. Not for the purpose of taking advantage of a propellant-free maneuver.

A key consideration for what gets done with the article here is whether there are any sources other than this book which makes the same claim regarding Luna 3, and more importantly, whether their basis for such a claim is just as weak as the one presented in this book. -- Tdadamemd19 (talk) 07:57, 14 July 2019 (UTC)

Hypothetical situation where lunar gravity can be turned off

This might be a much easier way to show how bogus this claim is...
The purpose of this mission was to fly out to lunar distance and take photographs of the Moon. Now consider a hypothetical where the Moon is an object of very little mass. It would not alter Luna 3's trajectory in any significant way. A probe can fly out there, take pictures of this object, and fly back on an essentially unaltered elliptical trajectory. Because of this hypothetical, the mission's path now becomes a two-body problem, no longer a three-body problem.

So the question becomes this: In such a hypothetical case, would the mission planners want to have additional thrust made available for their probe so that its mission objectives can be improved? A delta-v that would assist this mission?

It is clear to me that the answer to this is 'no'. Adding thrust upon passing the Moon gives no advantage to the mission objectives whatsoever.

Now flip a switch which turns lunar gravity back on, and all this does for the mission planners is complicate their work. It gives them no advantage. It produces no "assist". Lunar gravity, for the case of Luna 3, can be understood as having been a nuisance which complicated their planning calculations. It was in no way an "assist". This argument might be the clearest way to illustrate that calling Luna 3 a "gravity assist" mission is an utterly bogus claim. If the mission planners for Luna 3 had a switch that had the ability to turn lunar gravity off, and it can be clearly seen that this would have made their job much easier, then it is completely improper to say that they used the lunar gravity to assist in achieving their mission objectives.

This stands in stark contrast to bona fide gravity assist missions where the mission could not have been accomplished were it not for this free delta-v infusion. Or it would have required a significantly bigger rocket at a significantly bigger expense. The essence of gravity assist is that you are using gravity to assist you. Whoever concocted this notion that this qualifies as anything that happened with Luna 3 has lots of 'splaining to do. I myself see absolutely no justification for this claim. -- Tdadamemd19 (talk) 08:35, 14 July 2019 (UTC)