Why fly somewhere when there are telescopes?

“If we can get somewhere, what other reasons do we need to do it?»

Veprintsev V. I.

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When you start doing something, you should at least answer the question for yourself: why do you need to do this? Indeed, why create an interstellar automatic station for the sole purpose of taking a few photographs and sending them to earth? Why fly somewhere if it is easier and faster to create a system of space telescopes-interferometers, the resolution of which will be many times greater than any of the existing ones, including the James Webb Space Telescope. And the result will be obtained during the lifetime of the current generation of people, and not after hundreds of years or more – after all, it will not be possible to overcome several light years instantly; you will have to accelerate for a long time, and then slow down for the same amount of time. And the volume of data obtained from one telescope/telescope system will be orders of magnitude greater. In addition, we must not forget about the likelihood of an accident as a result of an error or failure of one of the interstellar probe systems.

Here I will try to convey to the reader why it is necessary to fly, and not to improve the means of remote study of other planetary systems.

How to study exoplanets without leaving the solar system?

Remote study of exoplanets is possible using telescopes. Their capabilities already make it possible to take photographs in which exoplanets in other stars can be distinguished in the form of small spots. As an example, below are images of the exoplanet HIP 65426 b taken by the VLT (Very Large Telescope) and JWST (better known as James Webb). The image from the first telescope has higher angular resolution because it is located on Earth, is larger, and operates at shorter wavelengths. JWST is located in space, the largest telescope ever launched, and operates in the infrared range, which is inaccessible to observations from Earth (the atmosphere absorbs this range). These telescopes are the most advanced ever created, but despite this, their angular resolution does not allow them to see the surface of exoplanets.

HIP 65426 b is a giant planet, larger and heavier than Jupiter, with an angular size of 10-7 arcseconds when observed from the Solar System. To make the angular resolution of a telescope commensurate with the angular size of exoplanets, it is necessary to increase its size (or base in the case of a telescope system) to hundreds of kilometers, or move to a shorter wavelength range of light waves. Similar projects exist, but so far only in the form of projects. For example, project LIFE – a system of four or more telescopes operating on the principle nulling interferometry.

You can write and talk a lot about telescopes for a long time. I hope the material presented here is enough to show that the capabilities of telescopes in the study of exoplanets are wide, but at the same time very limited due to the enormous distances.

Why do we need to learn how to fly to other exoplanets?

I will give some numbers, but with one caveat – the values ​​​​given below are very approximate, they have some differences in different sources, but this is quite enough to present the general picture:

• The earth formed about 4.5 billion years ago;

• The first traces of life were found in rocks 4.1–3.5 billion years old—it took about 0.5 billion years for the first forms of life to appear;

• Another 1 billion was required for the emergence of photosynthesis – 2.5 billion years ago the atmosphere began to fill with oxygen;

• The next 2 billion years were spent on the formation of multicellular life: plants, fungi, animals;

• Over the past 4.5 billion years, the Earth has experienced several glaciations. During one of them, almost the entire surface of the Earth was covered with snow (see. “Snowball Earth”) – this glaciation could end in complete glaciation (since ice and snow increase the reflectivity of the earth's crust, the Earth begins to receive less heat, the temperature drops even lower, etc. until complete freezing). In this case, earthly life would be completely frozen and dead;

• Homo sapiens appeared about 400 thousand years ago;

• According to some estimates, conditions suitable for life on Earth will continue for about 1 billion years. After this, due to the gradual increase in energy emitted by the Sun, the temperature on Earth will increase significantly, which will lead to the gradual death of life.

It took about 4.5 billion years of evolution for the emergence of man, and after one billion years there will most likely be no people left on Earth, as well as nothing alive. Over the past 4.5 billion years, the Earth has experienced several ice ages, each of which could have been the last for life. We are left with less than 20% of the total time of habitable conditions on Earth. Or less. But probably no more. All this suggests that the emergence and preservation of life on our planet is a great success. We are very lucky to be alive now. And although we cannot now reliably estimate the probability of life appearing on a planet suitable for this, most likely it is very low (it seems so to me). In any case, of the three planets currently located in the Sun’s habitable zone, only Earth arose and developed complex life.

Having telescopes, we will be able to to some extent study the exoplanets closest to us and find those suitable for life. We may discover a couple of planets with signs of life. Or we won't find out. But it will not be possible to preserve the earthly form of life with the help of telescopes. We will have to first explore the nearest planets, creating technologies necessary for human life outside the Earth. And then think about settling in other star systems, if we want to preserve the earthly form of life in general and people, as representatives of an intelligent species, in particular.

It is impossible to predict what will happen next, but if the problem of the spread of earthly life forms is not solved, the end is known.

The goal of mastering interstellar flights is to spread the terrestrial form of life to discovered lifeless but habitable exoplanets.

Prerequisites

Traveling to the nearest star is a complex and expensive technology that will take decades to develop. Now there are many projects of interstellar ships, including well-developed ones and, in theory, being implemented (though not now). But none of them even began to be built. The main problems of most such projects:

• huge payload mass – requires a huge amount of fuel, resulting in a structure that cannot be torn off the Earth;

• the use of “promising” but currently not implemented technologies for the engine (for example, thermonuclear fusion);

• short flight times – great to survive until the end of an interstellar mission, but very expensive.

All this leads to the fact that not a single country in the world or cooperation of countries undertakes the implementation of such projects.

Therefore, I am interested in calculating, at least on paper, whether it is possible to create a small device that, even if not during my lifetime and not even during the lifetime of my children, grandchildren and great-grandchildren, will be able to reach the nearest star. Based on these considerations, we obtain the following conditions:

• autonomous automatic spacecraft – a person does not fly anywhere, but while remaining on Earth monitors the progress of the mission;

• payload (excluding communications system) the size of a 3U cubesat (on-board computer, camera, scientific sensors). It turns out less than 3U means even better;

• parabolic antenna or flat phased array antenna for communication with the Earth. Besides the engine, communication is one of the problems: a small antenna will not be able to maintain communication over such distances, and a large one will weigh too much;

• flight time is hundreds of years. Several hundred years is the “memory of generations.” There are no guarantees that such a device will not be forgotten in a hundred years, but there is hope. In any case, we remember quite well what happened 1-2 centuries ago and even earlier;

• It is permissible to use only those types that are actually used as a motor. There are no promising thermonuclear technologies, if suddenly such an engine is created tomorrow and it flies, then we will consider it, but for now it is fantastic. Most likely ionic or something similar.

Minimum dimensions and long flight time are a necessary measure to save on fuel. You will have to pay for this with the high reliability of all components – no one has ever created and launched devices that can operate for hundreds of years, but this is at least an engineering problem that can be solved. Most likely the solution will be simple: lowering the temperature and increasing the mass of the components, plus the absence of moving parts.

Conclusion

Perhaps the origin of life is an event with an extremely low probability, but if life once appeared somewhere, its task is to spread to the maximum extent. Having once appeared on Earth, life penetrated into all possible places and occupied the entire surface of the Earth. Then life developed to man. Now man must spread life further into other star systems.

What if life always appears where the conditions are right? Then all the planets suitable for life are already occupied and there is no need for us to fly. And settling another exoplanet on which other life exists is not humane. But if our galaxy is full of habitable but lifeless planets, we must fly there and populate them. In any case, the only way to reliably find out whether there is life on another exoplanet is by flying to it, and for this we need to master the technology of interstellar flights. And if we see that there are lifeless planets, then we will develop technology for the settlement of life.

And one last thing. We should not hope that someone will create some new engine with the help of which we can easily and quickly travel many light years for an acceptable amount of resources (for example, they will develop teleportation technology). You can often hear: “Let's wait until they create X engine – then we’ll fly” (instead of X substitute any “promising” type of engine that you personally like). What if they don’t create it? Or will the cost of moving be prohibitive and you won’t be able to use it? Why do we need to wait for the invention of any new technologies? Boris Evgenievich Stern said this about it:

“Hoping for some miracles in the future is equivalent to giving up mental activity in the present.”

B. E. Stern

I agree with him. I no longer want to rely on someone to make an interstellar probe. I’ll just do everything in my power to bring this moment closer.

This was the second and last non-technical article. In the next article I want to give calculations of the communication system and understand whether it is possible to communicate at a distance of four light years or not? And what size and power will be required for this.

If you have something to say or questions, please comment!