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NASA's Manned Voyage to the Inner Planets - Article by Amy Shira Teitel

Among the contingency plans prepared by NASA in the XNUMXs, there was a proposal to send astronauts to a flight beyond Venus and Mars in the XNUMXs at the latest

Earth as seen from Gemini-11's high orbit in 1966. This is what the crew's view might have looked like just before the engine started to take them on a triple close pass mission. Credit: NASA
Earth as seen from the high orbit of Gemini-11 in 1966.
This is what the crew's view could look like just before starting the engine
Let him take them out on a triple close pass mission. Credit: NASA

[When I did research for the lecture on the future of spaceflight, I discovered that in the 60s, NASA had many ambitious plans for the phase that would follow the manned landing on the moon. Looking at history, we know that none of these plans came to fruition, at least not according to the original plan, but technologically we could have gone very far already 30 years ago.

The article before you deals with an old plan for a two-year manned mission to visit Venus and Mars. The article was written by space historian Amy Shira Teitel, and translated with her permission and courtesy by me.
Amy writes the great blog Vintage Space, which deals with the history of the space programs, especially the American one. A translation of her previous article, about the nuclear propulsion programs, has already appeared in "Critical Mass".]

The article was first published on Yoav Landsman's "Critical Essay" blog
In the 60s, close transit flights to the planets were the height of fashion at NASA. In 1966, graduate student Gary Falandro discovered that the planets were about to line up in a column suitable for planetary hopping, a discovery that was used to plan the Voyager missions. In the same year, Bellcomm, a NASA contractor, began to examine the possibility of missions that could send a crew to Venus and Mars in the same flight, using close passes and using Apollo hardware.

Close planetary transits are ambitious missions that use gravity to send spacecraft great distances while using minimal fuel. When the spacecraft passes near the rear side of the planet [rear in terms of the direction of its movement - YL] it gains speed, and if the geometry of the planets is suitable, then it will accelerate straight to its next destination with little consumption of fuel for guidance or control of its flight. The proposals for planning close-passing missions came from Belcom, a division of AT&T established in 1963 to help the space agency with overall systems integration research, development and documentation. Using upgraded Apollo hardware, these close passes were considered a natural stepping stone between the Apollo program and lofty goals such as space stations around Earth, manned landings on Mars and orbits around Venus.

Earth and the Moon as seen by Mariner 10 on its way to Venus in 1973. Credit: NASA
Earth and the Moon as seen by Mariner 10 on its way to Venus in 1973. Credit: NASA

In 1966, a study showing possible opportunities for a manned mission involving a close pass to Mars between 1978 and 1986 was presented. The study was presented at the Space Flight Mechanics Conference by Ai. Islands. and Andrewin, a mathematician from Belcom. Androuin presented an ideal time frame, he said, since manned missions to Mars would likely be of great interest in those years; The Apollo program would end, and the next logical step in manned research flights, after the moon, was our less hostile neighbor of the two.

According to the research, very little motivation is required for this task. After the launch, the team will make small corrections to adjust the trajectory, but physics will be the one driving the spacecraft. The mission will look like a simulated version of the Apollo 13 flight except for the explosion of the oxygen tank; One big engine burn will send the crew to Mars, where they will accelerate around its far side and be flung back toward Earth. The hard work will fall on the backs of scouts in this type of task. The team will release a variety of automated probes to Mars, and at least one of each type will land and ideally return a soil sample to the team.

Venus, in visible light-adjusted colors, is the first target of the triple close transit team. Credit: NASA
Venus, in visible light-adjusted colors, is the first target of the triple close transit team. Credit: NASA

Androuin identified 5 oppositions (the point at which Mars and Earth are at their closest points on their orbits) to occur between 1978 and 1986. This is the best time for a close pass to Mars, as the geometry between the planets allows for the shortest flight duration. But the duration of the flight is not the main limitation of the mission, but the weight at launch. The first burn that will send the crew to Mars requires a lot of fuel, and some of the planetary alignments are not good enough, so that a much higher amount of fuel will be needed than is possible to launch into orbit around the Earth. Androuin identified two good launch opportunities: in 1979 and 1983. Both would be suitable for the mission given the positions of the planets and available propulsion technology.

In 1967, Vanderwein wrote another report on a close-pass mission to Mars, and added Venus to the mission. Using the gravity of Venus to fly the spacecraft to Mars can solve the weight problem when launching from Earth.

Mars, Earth, and Venus align with the Sun five times every 32 years, but Venus and Mars align more often, creating double close transit frequency opportunities. The report found that a close flyby of Venus on both the outbound and return flights from Mars is possible, making the mission a triple close pass.

The first opportunity for a triple close pass identified in the report will occur in February 1977. The next opportunity for such a pass will be in 1983. At the time the report was published, it was expected that in the early 80s there would be a manned landing on Mars and the coffee mission around Venus, so the chance of launching a close triple pass mission In these years it will probably be very low.

The chances of launching a triple close pass mission improved when VanAndrewyn, along with another Belcom engineer named J. Bankovskis, discovered another opportunity for a triple close pass with a launch window in 1981. They described the mission in a September 1967 report. The ideal launch on May 26, 1981 would have sent the crew on a 790-day mission. They planned to fly by Venus on December 28, by Mars on October 5, 1982, again by Venus on March 1, 1983, and land in the ocean on Earth on July 25. A sub-optimal launch was also a good option. There was a 30-day launch window for the mission, and even the worst chance in that window would have extended the mission to only 850 days.

Mars, the second target of the triple close pass team. Credit: NASA
Mars, the second target of the triple close pass team.
Credit: NASA

Finding a previously unknown launch opportunity inspired Androuin to look for more triple close passes. In a report from October 1967 he reported a double transit in November 1978, an Earth-Venus-Mars-Earth mission. With a slight modification, it can become a triple close transition. Adding a suit near Venus on the way back from Mars was possible. For a launch on November 28, 1978, the crew would pass Venus on May 11, 1979, Mars on November 25, Venus again on January 29, 1980, and return to Earth on January 31, 1981. In total, the mission was 800 days, and a different date in the 35-day launch window would have allowed the mission to be shortened to 760 days.

What is really interesting about the triple close pass missions, is that they are not only a chance for the crew to go on a journey in the inner solar system, but each close pass is a unique scientific opportunity. Because of the geometry of the planets' orbits, each mission, and even just one direction of each mission, would take the crew to a different side of the planet. One pass would take the crew to the bright side of the planet near its equator, while the next would take them around the dark side or near one of the poles. Not a single pass was a bad close pass. Infrared sensors and mapping radar could make observations that the crew was unable to make visually.

The Earth and the Moon as seen by the HiRISE camera on NASA's MRO orbiter. October 3, 2007. Credit: NASA
The Earth and the Moon as seen by the HiRISE camera on
NASA's MRO program. 3 October 2007. Credit: NASA

Whatever the shape of the mission, triple close passes promised great scientific payoff and a very interesting mission. However, like many exciting programs in the 70s and 80s, it never materialized beyond the proof of concept.

Maybe triple close passes will come back into vogue if NASA or some private company pushes forward with a mission to Mars. If you plan to do a planetary tour for a landing mission, why not do some science along the way, and photograph Venus up close at the same time.

for further reading:

VanderVeen and Bankovskis. "The Existence of a Triple-Planet Ballistic Flyby." Bellcomm. September 19, 1967. Washington.

VanderVeen and London. "Existence of a Favorable 1976 Dual-Planet Ballistic Flyby." Bellcomm. February 14, 1967. Washington.

VanderVeen. "The 1975 Mars-Venus Ballistic Dual-Planet Flyby." Bellcomm. December 19, 1967. Washington.

VanderVeen. "Venus Swingbys for Manned Mars Missions During the 1978-1986 Period." Bellcomm. August 9, 1966. Washington.
Link to the original article

28 תגובות

  1. That's probably the explanation. The distant stars are just far away and offset.
    By the way, Prof. Woodward, the author of the article, invented and patented more than twenty years ago an engine to propel spacecraft based on the Mach principle called the Woodward effect.

    At the time, there was a lot of opposition to the idea, which apparently contradicts the law of conservation of momentum. A few months ago an article appeared here on the website about spaceships propelled by the gravitational force of distant stars that reminded me of his idea, and also in its name I think the same problem of the law of conservation of momentum appears.

  2. Israel,

    From what I understand, every contributing star in the universe contributes its part, especially those of the Milky Way. According to the equations written in your article, those of the Milky Way contribute more because they sacrifice more (the contribution to the potential goes like 1 divided by R)

  3. Emanuel,
    Physics is my blade. What is the main point of the phenomenon -
    The claim concerning perfect spherical bodies is very relevant to physical reality because because the Earth is approximately round, the effect on the moon's orbit is a few cm per year and not tens of thousands of km per month as expected in the case of non-spherical bodies.
    The lack of perfect sphericity is a disorder….

  4. I understood your argument. Until now I thought that the constant was simply 1 because that is what came out to a newton, and if all the masses in the universe were doubled, the inertial force in newtons on a test charge (like the one that appears in the article) would also be doubled. It is possible that the trick only works when the integral is certain.

    Dennis Schieme shows quite nicely that both the gravitational constant G and Newton's second law can be derived from Mach's principle.

    However, the essence of my question is different: it is hard for me to see how Mach's principle is wrong, and this is because of the correlation that exists between absolute rotation and the stars. It is of course possible that there is some other explanation for the correlation - but it is hard to accept that there are coincidences here.

    But the stars we see are only those of the Milky Way, while Mach's principle, and all the derivations of gravitation and inertia derived from it according to Schieme, refer to all the mass in the universe. So either all the galaxies, (whose rotational preference must be assumed to be different from ours) offset this one, or their distance is too great (also unlikely, quantity wins here).

    So why then is our rotation complete only relative to the stars of the Milky Way? Why not the stars of Andromeda, or any other galaxy, or some combination of them all?

  5. Lezvi is right, this is the difference between mathematics and physics
    Most of the stars in the universe are not perfect spheroids even if they are solid
    They are all flattened lengthwise at the ends of the axis of rotation because of the rotary motion
    Even if there were no oceans there would be a transfer of energy from the Earth to the Moon although to a lesser extent
    Elasticity exists even in the hardest materials

  6. Emanuel,

    You are right, but the above-mentioned moving away is a disturbance that results from the fact that the Earth is not absolutely round (specifically, this results from the fact that the water can change its height in the ocean).

  7. The article you saw is interesting.
    I did not read the whole thing because its purpose is to show a certain result of Mach's principle and not necessarily to show that it is true, although there is no doubt that the article is biased towards the idea. If so, in my opinion he does not emphasize enough the problematic nature of Mach's principle.
    In my previous response to you I emphasized that:
    "The mass of the universe does not enter here, nor any constant that may in theory depend on it - therefore I don't really see how this statement can be true.", that is, it bothered me that in normal Newtonian mechanics the mass of the universe is not required at all to make the calculation and here you tell me that the centrifugal force is affected by it.
    The article refers to the matter on page 5, in the paragraph before the beginning of part 2.1, where it states that the meaning of the requirement of Mach's principle is that the gravitational potential in the universe (the integral in equation 2.2) will be certain, meaning that you cannot multiply it by a constant and keep everything in order (as Newton would claim ). This statement actually states that the universe must have a well-calibrated density so that the Newtonian explanation and the Machian explanation can coexist side by side without us being able to decide between them easily.

    By the way, it may be implied that I am completely dismissing your argument - so not so,
    Even in conventional cosmology there are many "precise calibrations" of this kind - the universe, for example, reveals a surprisingly flat matrix (inflation probably somewhat explains this), dark energy is more or less equivalent to matter nowadays, etc. Still, I think there is a major weakness of Mach's model here that deserves consideration.

  8. A rotating body affects the motion of any body relative to a non-rotating body
    The moon, for example, is slowly moving away from the earth because its movement is in the direction of the earth's rotation
    If the direction of the moon was reversed it would slowly approach and finally collide with the earth

  9. Look at the link:

    Equation 2.2
    followed by:
    which, neglecting factors of order of unity, integrates to GM/R, M
    and R being the mass and radius [particle horizon] of the universe
    respectively. Since this is true for arbitrary points in the universe,
    V¢ vanishes everywhere and no Newtonian interaction of the test

    Note also that the equation can be written as follows:


    G, R radius and mass of the universe, G the universal gravitation constant (you can check on Wikipedia, quite suitable).

    Note also that a dimensional analysis of both sides of the equation leaves us with only:
    F=ma, Newton's second law, the law of inertia.

    I did not find Shaima's analysis online, but it is very beautiful and appears in his book: The physical foundations of general relativity

  10. I'm not sure that your statement about the decrease in centrifugal force (if you decrease the mass of the rest of the universe) is correct. When calculating the centrifugal force acting on a rotating body the result is:
    a = R omega^2
    (a is the acceleration, R is the radius of rotation and omega is the angular velocity)
    The mass of the universe does not enter here, nor any constant that may in theory depend on it - so I don't really see how this statement can be true.

  11. Why as we know?
    According to my understanding of Mach's principle, if the entire universe remains the same but the mass of every body in the universe (except you) will be only half of the original, then the centrifugal force acting on you will also be reduced by half. If the masses are reduced by 90%, so is the power.

    A single atom will exert a completely negligible force. In a universe where it's just you and a single atom, no matter how fast you spin, your head won't spin. Inertia will disappear completely.

    Scheima, by the way, showed that if you use Mach's principle, you can mathematically derive inertia from gravity and vice versa.

    And secondly: if Mach's principle is not true, and there is no connection between rotational motion and the distant stars, then how is it that in a sealed spaceship I can tell if the sky is stationary or rotating, and this is only by measuring the centrifugal force in the spaceship? If two flying saucers that have a rotational ratio of 2 rotations per second video each other, we will not be able to tell who is really spinning just from the footage. Each can claim that the other is the one rotating, just as spaceships in linear motion relative to each other can claim in inertial systems.

    If we measure the centrifugal force inside the rotating spacecraft, on the other hand, we can know exactly who is resting, who is rotating, and at what angular speed and clockwise or counterclockwise. The same also with 10 plates. And without a doubt, after we opened the windows, the plate that did not measure force is the only one that rests relative to the sky, and for all the others the sky rotates, and exactly according to the rotational speed deduced from the centrifugal force.

    So how come there is no connection to the stars? And if the connection exists - how is there no Mach principle?

    On the other hand, this is what Einstein claimed - that there is no Mach principle - so of course the lack of understanding is on me. I would just be happy if someone would explain.

  12. As I told you, I do not understand the subject well enough.
    To me, compared to you, the Mach principle always sounds absurd
    Assume a completely empty universe (except for you) - in such a universe it is impossible to feel rotation according to the Mach principle.
    Now put a single atom thousands of light years away from you and suddenly there is a rotation and everything will be as we know it?

  13. Thanks Zvi.

    I have never been able to understand how Mach's principle can be dispensed with. After all, it all started with Newton's rotating bucket, in which the surface of the water bowls due to the centrifugal force. Newton asked - rotating relative to what? Berkeley and Mach answered: relative to the distant stars. Fact: Send me a video from a camera attached to a centrifuge that takes pictures of the sky at night, and I'll tell you exactly what the force acting on its orbit is, and how much uranium it separates.

    However, this complete rotation is only relative to our Milky Way - so what about the rest of the universe? It is clear that if another galaxy, whose rotation axis is the same as ours, has a different rotation speed, then what is defined as a state of rest, where there is no centrifugal force, will also be different.

    Therefore, it follows that if the mutual interaction between the masses determines what we define as resting and rotating, then there is no such thing as a universal state of rest or rotation, but only a local one, each galaxy and its preferred system.


  14. Israel Shapira

    As far as I know, I'm pretty sure because it's usually not assumed that there is a universal correlation in the directions of rotation of the planets. In fact, this contradicts one of the fundamental assumptions of cosmology, according to which there is no preferred direction in space (not that I am saying that this assumption is necessarily true without a shadow of a doubt, only that it is very acceptable, gives really good results, so you should think carefully before throwing it in the trash).
    I'm also not so sure that the interaction between galaxies that would cause this kind of rotation is so strong since galaxies are quite spherical in terms of gravity (don't forget that we don't see most of the material that contributes gravitationally - it's dark matter that is distributed quite spherically).

    And as for the Mach principle...
    Don't go too far with him - this is a principle established by Mach and Newton, for example, would not agree with him.
    The principle was established before they knew how to look at the world in the form of general relativity which is what is required to deal with problems of this kind. On the question of whether general relativity is decisive in favor of Newton or in favor of Mach, I do not know how to answer you with certainty because I do not understand enough about general relativity, but my impression was that the decision is actually in favor of Newton.

  15. Maybe….

    I understand your intuitive thought but it is incorrect.
    The mutual effects between planets do not necessarily make them reach the same plane.
    The main problem is that when it comes to a multi-body system (meaning a system of more than two bodies) life becomes very difficult. A three-body system does not have an analytical solution and most solutions rely on certain assumptions or on a computer solution. According to Wikipedia: Specific solutions to the three-body problem result in chaotic motion with no obvious sign of a repetitive path, (from an entry called an entry in Wikipedia called "n-body problem") that is, it is not possible to describe even in a sort of slogans what will happen.

    In this case, it is indeed a multi-body problem with a simplifying assumption (the mass of the Sun is much greater than the mass of all the other planets), but it is still an unusually complex problem that is usually solved numerically. I therefore do not think that you can say on one foot that a more stable situation will exist with the planets aligning.

    simple or which does not have a clear physical solution and which depends very much on the specific conditions that prevail in it. According to Wikipedia
    three-body problem
    Therefore it is very difficult to say on one foot what will happen. There is an entry in Wikipedia called "n-body problem"
    Specific solutions to the three-body problem result in chaotic motion with no obvious sign of a repetitive path

  16. Another question about the rotation:
    Mach's principle holds that every rotation is relative to the distant stars. Example: If you are in a spacecraft whose windows are closed and you measure a centrifugal force that corresponds to a certain rotation speed, then after you open the window you will see the stars rotating according to the same rotation speed.

    However, these stars belong to our galaxy - the Milky Way, which has a certain axis of rotation.

    The question is: Is there a connection between the rotation axes of the different galaxies? Is there a variation of the universal Mach principle, or is each galaxy an independent mass puddle?


  17. They will line up… so clumsy… I mean they'll be in the same plane around the sun.

  18. Thank you very much Zvi, but it seems to me that you did not understand me regarding "Yishro Ko"
    My intention is that all the stars in the solar system should at some point be on the same axis in a straight line (of course they all revolve around the sun but they will all be at the same latitude and longitude).
    Their influences on each other tilt each other a bit each time they pass by each other and end up aligning with each other, don't they?
    For example, if we put a "sun" in a vacuum, and rotate two "stars" around it, one around the X axis and the other around the Y axis, it is enough that there is a slight difference between them (velocity or mass) and the center of mass of the system changes, and each time the two bodies are attracted to the center of mass, essentially changing direction towards each other, so that eventually they will line up.
    So although the effects are negligible, they still exist.
    Can it be said that after some time all the stars will rotate around the same axis, Y or X or between them, but on the same "line"?

  19. Classically, if you are near a round body, or a body symmetric along the axis of rotation, your trajectory will not be affected if it rotates or not. This is also the reason why the planets will not line up - if they are round (and they are quite round) they simply do not know anything about the rotation of their neighbors.
    Relativity is different and a rotating massive body changes the space around it in a different way than a non-rotating body. This effect is of course relevant almost only for black holes and even then it is very difficult to detect (it is a relatively low order effect and fades very quickly with the distance from the black hole).
    In this context, very recently, a rotating black hole was discovered:,7340,L-4350651,00.html
    If I'm not mistaken (it's not written in the article), the discovery relied precisely on the fact that a black hole is rotating, the absorption disk has to reach deeper into the black hole, so the spectrum of light emitted from it is expected to be different than usual.

  20. Zvi, great answer.
    If you could close a corner for me to be sure, I would greatly appreciate it:
    Does the self-rotational motion of a star affect an object near it?
    For example: Does the self-rotation of the sun affect the stars in any way?
    Does it matter if she changes direction right now? Does it last long? in what way?

    One more thing, regarding the axis of motion of the stars:
    Wouldn't we expect to find symmetry in the solar system?
    I mean, after so much time, the stars should start to "align" right?

  21. When talking about a planet orbiting the sun, there are three relevant axes that can be talked about:
    – the rotation axis of the planet around itself.
    – the rotation axis of the sun around itself.
    - the axis perpendicular to the plane of rotation of the planet around itself.

    In general, one can expect that all three of these rotation axes will be well correlated, and this is based on the assumption that the planets and the star were formed from the same original gas disk (the gas disk has a mass and as soon as you assume that the sun is much heavier than the planets, you accept this as a natural result).
    So, if we are looking at an ancient solar system, we should expect all the planets to circle the sun with their axes in the same direction, they all revolve around themselves in the same direction and the sun itself also revolves around itself in the same direction.
    Over time there is development - planets change their orbits (due to the influence of other planets), planets collide and the star itself evolves, which causes changes in this symmetry.

    In our solar system the anomalies are relatively small:
    The orbits of all the planets around the sun are all in the same plane (less than 10 degrees) and this is more or less the plane of the sun's rotation as well. In addition, most of the planets revolve around themselves more or less in this plane and the disturbances are not serious.

    Exceptions in this regard are Venus and Uranus whose rotation axis directions differ significantly from the direction of the rotation axis around the Sun - apparently due to collisions (read on Wikipedia). Regarding Nega, by the way, note that the speed of its rotation around itself is extremely slow (a day lasts more than a year), to teach you that there is something unusual there and teaches about a violent history.

    In recent years, it has become possible to locate the direction of rotation of other stars in relation to the direction of rotation of their planets (the Rossiter-McLaughlin effect) and it turns out that in most cases there is indeed the expected correlation - if it is larger than expected anomalies that sometimes appear show that stars also change their directions of rotation.

  22. Correction: "(or the direction of its rotation around the bone)" -> "(or the direction of its movement around the bone)"

  23. Hi, thank you very much for the interesting answer!
    However, I did not properly formulate the original question, and I will try to refine it after browsing the net:
    Is there a relationship between the angle of the "tilt of the axis of rotation" of a planet and the direction of the object around which it revolves (or the direction of its rotation around the object)? It seems that most of the planets in our system have an axis of rotation that is close to being perpendicular to the direction of the sun and also perpendicular to the direction of their movement. (Except for Uranus: axis inclination 97.77°. and Pluto: 119.61°).
    In addition, is there a connection between the angle of the rotation axis of the planet and that of the sun (7.25°)?

  24. Probably not, proof of this is the star Venus whose direction of rotation is opposite to the direction of the Earth's rotation around itself.

  25. Is there a relationship between the direction of the self-rotation axis of planets and the direction of the object around which they move? Is there a relationship between the direction of the self-rotation axis of the planets and the direction of the self-rotation axis of the object around which they move?
    Is there a forum on the site?

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