Opinion/gravity and maximum speed - the ultimate ambition in long manned space flights

In long manned flights, the conditions of weightlessness that exist in space are not the ideal conditions necessary for space travelers of all kinds.

introduction

Future space flights will be divided into two main categories: manned flights and unmanned flights. Regarding the unmanned flights, the existing weightlessness for most of the flight will not be important. Most likely this will not interfere and most of the time it will. On the other hand, in long manned flights, the conditions of weightlessness that exist in space are not the ideal conditions necessary for space travelers of all kinds. The phenomenon of loss of bone material for passengers in zero gravity is known and there will be other psychological phenomena resulting from the weightlessness. Passengers' ambition will usually be to fly most of the flight time, with the feeling of gravity they are used to on Earth, and future flight planners must provide this important "commodity". Another requirement of the space travelers is to do it at the maximum possible speed.

How will gravity be achieved?

We know from relativity that acceleration is equivalent to gravity. A person in a closed cell will not be able to distinguish whether the sensation of gravity he feels is due to the fact that he is near a large mass acting on him, or if he is in acceleration.

Therefore, in order to meet the demand for gravity for future space travelers, it will be convenient to provide them with a flight at an acceleration of one G (9.8 meters per second squared) to reach a feeling of gravity identical to that on Earth.

The possibility of obtaining acceleration G can be done in two ways:

A. With the help of radial acceleration created by rotation.
B. Linear acceleration in the direction of the spacecraft's motion.

The radial method will be done by rotating the spacecraft around an imaginary axis located at its center of gravity, when gravity itself will be achieved by the centrifugal force, which pushes the bodies from the center, outward. The magnitude of gravity will be calculated according to the formula: G is equal to V squared divided by R. Where V is the peripheral speed of the traveling area in meters per second and R is its distance in meters from the axis of rotation and G is the acceleration of gravity (9.8 m per second squared).
We can also say that since V can be calculated as the circumference of the rotation divided by one rotation time T, then if we put it in the formula we will get that T is equal to two roots of R. (For anyone who wants, the development of the formula is really simple and you can do it yourself).

We will give numerical examples:
Let's say R is 100 m, then the cycle time of the passenger area around the axis to achieve an acceleration of one G will be 20 seconds. And if we assume R will be only 10 meters, then the cycle time for obtaining one G will be 6.3 seconds.

From the moment the aforementioned rotation is achieved, there is no need for additional energy and the rotation will fulfill its role of gravity successfully. This is why this is the chosen method for performing gravity in most scientific articles. But we must not ignore a number of disadvantages inherent in this method:

A. It would be impossible to follow this method in small spaceships because of a disturbing phenomenon of vertigo resulting from the constant rotation.
B. A small turning radius will also cause discomfort because of the differences between the gravity that will act on the passenger's head, and the greater gravity that will act on his legs.
third. The need for a large spaceship in order to obtain a favorable gravitation effect.
d. A larger spacecraft would create a greater possibility of encountering interstellar material.

We will now examine the possibility of achieving gravity according to method B - linear acceleration in the direction of the spacecraft's movement.

Before we begin to discuss this method, the author of the article states in advance that the method requires means of propulsion that do not yet exist today and are, at best, in preliminary experimental stages., but the situation is promising. We will discuss the method, open it and later we will also mention the means of propulsion.

Well, with this method we will achieve gravity, by giving acceleration G to the spaceship in its trajectory. (it is not important at the moment how).
When the spaceship reaches half way to its goal, it will turn half a turn around an axis, and go into a hover mode. The effect of the deceleration in this respect will be the same as the acceleration for the purpose of receiving gravity.
What is this similar to, let's say we are in an elevator, at the beginning of the climb we are pushed to the bottom of the elevator and towards the end, when the elevator slows down, we strive to "stick" to the ceiling.

Using the linear acceleration method we will obtain the following solutions:

A. gravitation
B. The method is also possible in small spaceships.
third. No side effects.
d. The space vehicle will be reusable.
God. Minimum flight time.

Regarding sections A, B, C, things are clear. The acceleration creates gravity, it can be used even on small bodies and there are no side effects of dizziness and the like.

Regarding Section D, going into space and especially returning to Earth will be done at a slow speed so as not to cause the sides of the spacecraft to heat up with all that follows, so that the spacecraft, just like an airplane, can be reused.

A result of using this method is the high speed of the spacecraft. Since the most favorable conditions are of G acceleration, this is the most convenient and greatest speed to reach the goal.
We will now discuss the flight time obtained by this method (section XNUMX).
We will use the formula that links the path with the acceleration as it appears in every mechanics book (S equals G times T squared divided by two). If we don't forget that we start to slow down halfway, we will get the formula for T the flight time in seconds and S the overall flight distance to landing in meters:

T is equal to 0.64 times the square root of S. (Everyone is welcome to do it themselves)

We will check several flight times:

A. The flight to the moon is about four hundred thousand km - less than 4 hours!
B. The flight to Mars is about seventy million km - less than two days!
third. The flight to Saturn is about a billion km - only about a week!
d. The flight to Neptune, five billion km - about two and a half weeks!
and. The flight to the center of the Kuiper Belt, incl
Landing on one of the comets there, about 500
Astronomy units from Earth,
which are about 75 billion km - about two months!
(1 astronomical unit is equal to 150 million km.)

We see that the duration of the flight will be short and comfortable!

Note: The flight examples given in this article are to the center of the Kuiper Belt which extends from a distance of thirty astronomical units, up to a distance of one thousand astronomical units. In the flight to it, the speed of the spacecraft will approach 10% of the speed of light (in the middle of its path) and we are approaching relativistic calculations, which are not the interest of this article.

The planned means of propulsion.

There are several means of propulsion designed today, which are able to give us the high and prolonged accelerations.

A. An engine that runs on atomic energy.
B. ion engine.
third. Movement by the solar wind.
d. Movement by a laser beam.
God. Utilization of the isotope helium three for the production of energy for flight.

All of these methods have already been researched and written about and anyone will be able to obtain material about it on the Internet.

We will only add the following details:
The solar wind reaches up to a million kilometers per hour.
Utilization of the helium-3 isotope would require mining and collecting means on the moon, where it is found in large quantities.
Movement on a laser beam will require its creation from solar energy by a satellite located in space, or by other means on Earth. The beam, despite being a concentrated laser beam, will again and again require its concentration in its path.

In conclusion

The problem of the lack of gravity in long space flights endangers the health of the pilots. Attempts to stop the deterioration of the bone material by massive exercise throughout the flight are only partially beneficial. Only full gravitation according to one of the two methods we mentioned (radial acceleration or linear acceleration) will provide a solution to the problem.
The linear acceleration, despite being wasteful in energy can be the solution when the energy is given almost free, such as the solar wind, laser beam, atomic engine and other future methods.
This method, once achieved, can make space flight comfortable, fast, as the space vehicle
Can be reused.
The linear acceleration method will be the optimal method of movement in the solar system (at least) and any other form of movement should strive to reach this movement if possible.

bibliography

The Guide to the Cosmos by John Gribbin, Dvir Publishing, 2002.

High School Physics - Mechanics, Sears-Zymansky, Yavne Publishing.

Astronomy - a guide to knowing the sky / Yigal Fat-El.

The universe - fundamentals of astrophysics, Meir Midev, Noah Barosh, Hagai Netzer,
Open University Press, 2000 edition.
.
For the compilation of Yehuda Sabdarmish's articles on the Hidan site

https://www.hayadan.org.il/BuildaGate4/general2/data_card.php?Cat=~~~961508397~~~129&SiteName=hayadan