NASA will answer the fundamental question: are we alone in the universe?

(ORDO NEWS) — Humanity has always been concerned about the question of whether we are alone in the universe, writes Big Think.

It seems that this mystery will soon be solved: by 2040, NASA plans to explore the most distant corners of space in order to detect signs of alien life. If the mission succeeds, it will be a real scientific breakthrough.

Around 2040, NASA plans to launch a flagship space exploration mission (like the Hubble and JWST projects). Now the discovery of alien life is becoming an achievable goal.

There are several fundamental questions that human minds have always wrestled with. However, it is possible to get any definite answers to them only with the accumulation of scientific baggage. Here are just a few of them:

– What is the Universe?

– How did it come about?

– Why did she become like this?

– What will she end up with?

All these questions have troubled mankind since time immemorial.

And yet, in the 20th, and now in the 21st century, we are finally starting to get more detailed answers to them thanks to incredible achievements in the field of physics and astronomy.

However, perhaps the most important of all questions – are we alone in the universe – remains unsolved.

The answer to this question has not yet been found, despite the fact that with the help of the current generation of ground and space telescopes, man is able to explore the distant expanses of the universe.

But to get to them, we need to directly image Earth-like exoplanets that is, planets that are similar in size and temperature to Earth.

In addition, these planets should orbit stars like the Sun, and not around the more common red dwarfs in the universe, such as Proxima Centauri or TRAPPIST-1.

It is the search for objects with such parameters that will be carried out as part of the flagship space research mission, which NASA recently announced.

Too ambitious intention, but it’s worth it. And yet, if it suddenly turns out that we are not alone in the Universe,

In our time, humanity is looking for alien life mainly in the following three ways.

– We explore the planets of the solar system and their satellites (including Mars, Venus, Pluto, Titan and Europa) remotely, by flying around these celestial bodies with orbiters, as well as with the help of landing modules and even planet rovers.

The goal is to find some evidence of primitive life forms that may have appeared on these planets in the past, and may still exist today.

– We study exoplanets in order to find evidence of the existence of life on them: everything is studied here – from the surface to the atmosphere (including areas adjacent to it from the outside). At the same time, its color, seasonal changes and composition are analyzed.

– As part of projects such as SETI and Breakthrough Listen, humanity is trying to catch at least some signals that would confirm the existence of intelligent alien beings.

Each of these approaches has its own advantages and disadvantages. However, most scientists believe that it is the second method that will bring us the first success.

If it turns out that conditions similar to those on Earth are required for the emergence of life, then our planet may well turn out to be the one and only in the entire solar system, and nowhere else in other regions of the Universe can life arise, survive and flourish.

If there are no intelligent civilizations near the Earth that can actively transmit radio signals, then the SETI project, of course, will not give any positive results.

However, if there are even a small number of some exoplanets on which the natural conditions will resemble those of the earth and on which life exists, then the study of such cosmic bodies may well be crowned with success, which we could not achieve using the first and third options.

We have been doing exoplanet research for quite some time now: More than five thousand such exoplanets are known to specialists in the Milky Way. Moreover, the mass, radius and period of revolution of most of these objects are known.

Unfortunately, the available information is by no means sufficient to definitively state that some of these planets are habitable. In order to accurately establish the fact of the existence of life, we need something more. You need to get answers to the following questions:

Does an exoplanet have an atmosphere?

– Are there clouds on it, is there precipitation, is there climate change?

– Does the color of the continents on this exoplanet change depending on the season, as it happens on Earth, from green to brown?

– Are there certain gases or their mixtures in the atmosphere of an exoplanet, the presence of which can be used to judge any biological activity? Do percentages of these gases fluctuate seasonally, just as carbon dioxide does on Earth?

Today, such studies are carried out using advanced scientific equipment: the James Webb Space Telescope (JWST) and ground-based ten-meter telescopes. With their help, images of exoplanets are obtained and transit spectroscopy is carried out.

Unfortunately, these telescopes are not enough to study the characteristics of Earth-sized planets orbiting in the same orbits as our planet around stars like the Sun.

Experts have learned to get direct images of planets the size of Jupiter, which are at a distance exceeding the distance from the Sun to Saturn – all this, of course, is good for gas giants, but not suitable for searching for life on those planets that are composed of solid matter.

Transit spectroscopy involves observing the light that passes through the atmosphere of a terrestrial planet at the moment when this planet passes against the background of a red dwarf disk. However, terrestrial planets orbiting stars like the Sun are very far away – beyond the reach of modern equipment.

In some ways, experts have already succeeded, but if we want to find and describe any habitable planet, we need to go further.

Currently, experts are building ground-based telescopes of a new generation – the era of thirty-meter telescopes, for example, the Giant Magellan Telescope (GMTO) and the Extremely Large Telescope (ELT), is beginning.

Experts look forward to NASA’s next flagship project in astrophysics, the Nancy Grace Roman Space Telescope (NGRST), which has the same capabilities as Hubble, but there are differences – it has excellent equipment.

Its field of view is 50-100 times greater than that of Hubble. In addition, a coronograph is installed on it, which allows you to observe the planets in the light of their parent star. Wherein,

However, even armed with such powerful instruments, we can only observe terrestrial planets orbiting the red dwarfs closest to us, as well as planets whose mass exceeds that of the Earth, but does not exceed the mass of Neptune, which orbit stars like the Sun.

In order to get an image of a truly Earth-like planet, we would need to use a more advanced observatory with even more capabilities.

Fortunately, technology does not stand still, and we are by no means satisfied with the current achievements.

Every decade, the National Academy of Sciences of the United States, at a general meeting, determines the main priorities in the field of astronomy and astrophysics, and also makes recommendations as part of a ten-year review. As a result, four strategic programs were proposed:

1- Lynx is a new generation X-ray observatory. Its significance is especially great, given the reduction in the scale of the forthcoming mission of the European Space Agency Athena

2- Origins is a next-generation far-infrared observatory. It fills a huge gap on the scale of the electromagnetic spectrum, within which specialists study the Universe;

3- HabEx is a single-mirror telescope designed for direct observation of exoplanets closest to the Earth;

4- LUVOIR is an ambitious project to build a giant telescope with a segmented mirror. This telescope should become a universal astronomical observatory that one can only dream of.

On the one hand, it was recommended to build all four telescopes. At the same time, the highest priority should be given to an advanced version of the HabEx telescope, which should take into account the features of not only the HabEx telescope, but also LUVOIR in order to create the Habitable Worlds Observatory (HWO).

By and large, the proposed project is a compromise between, on the one hand, the level of development of modern technologies, the ability to detect exoplanets based on the available information, and, on the other hand, economic efficiency, including the experience gained as a result of solving those problems that arose during creation and launch of the JWST telescope.

The requirements for the project proposed so far are very encouraging, we list them:

– The design of the segmented optical mirror is similar to that already used in the JWST telescope;

– The same type of coronagraph that is currently being developed and tested for the NGRST telescope;

– Modern sensors that can control different segments of the mirror to achieve stability with an accuracy of approximately up to a picometer;

– Compatibility with next-generation missiles that will be used in the late 2030s – early 2040s;

– Scheduled robotic maintenance of components at the Lagrange point L2, located approximately 1.5 million kilometers from the Earth;

– All available new technologies were fully tested up to the stage of development/implementation of the project.

All of the above is extremely encouraging, since the presented plan is quite feasible, it can be implemented without much delay and cost overrun, which arose primarily due to the fact that specialists had to, among other things, create completely new technical equipment (these problems pursued JWST project for many years until its implementation).

Thanks to its technical equipment, the Habitable Worlds Observatory (HWO) will have a great chance to realize the most cherished dream of astronomers – to discover a habitable planet for the first time in history.

With HWOs measuring between 6.0 and 6.5 meters (comparable to JWST), researchers can directly image terrestrial planets orbiting stars within about 14 light-years of Earth.

And here every additional centimeter of diameter is important: if you double the observation radius, then the search volume and the expected number of objects increase eight times. At a relatively close distance from the Sun are:

– Within 10 light years from Earth – nine star systems;

– Within 12 light years from Earth – 22 star systems;

– Within 15 light years from Earth – 40 star systems;

– Within 20 light years from Earth – 95 star systems.

Due to its design, the HWO observatory is quite capable of observing approximately 20 to 30 Earth-like planets.

If there is even a small chance that there is life on some terrestrial planet, then this means that the HWO observatory will be able to detect the first inhabited planet in history outside the solar system, and perhaps several such planets, if the Universe is favorable to us. .

No nasty surprises are to be expected in the construction of the HWO, as experts have already had to deal with many advanced technologies such as the JWST five-layer sunshield, the JWST folding/segmented mirror design, and the variable surface mirror used in the coronagraph on the NGRST telescope (it is currently being tested during the PICTURE-C experiment on a probe balloon).

Since the difficulties have already been overcome, it is unlikely that HWO will face surprises, as it did with JWST.

Yet technical innovation always comes with risks. So, for example, the idea of ​​robotic service is encouraging, because it is not something new, but we have only used it in low earth orbits.

However, at a distance to the Lagrange point L2 (1.5 million kilometers), even signals sent to the device from the Earth at the speed of light will still arrive with a delay of ten seconds. Thus, the operation of the equipment will require not only appropriate rocket technology, but also automated robotics, which currently do not exist.

Aligning mirrors with a tolerance of up to a few picometers is a big technical problem, and to solve it, you need to cope with other tasks that go far beyond the problem of mirror alignment in the nanometer range, solved to date.

To this end, it will only be necessary to gradually bring to mind the current technology, which will require significant resources. True, they are currently already allocated as part of the development of technologies at the design stage and at the pre-design stage.

A big problem is the suitability of the currently developed NGRST coronograph for HWO. The performance of the JWST coronagraph lives up to our expectations, this coronagraph allows specialists to find and image planets that are only one hundred thousandth as bright as their parent stars.

The NGRST telescope is expected to be a thousand times more powerful than the JWST telescope. The variable surface coronagraph mirror is optimized to deal with the interference patterns and scattered light coming from the perfectly round coronagraph.

One thing to note here is that one of the reasons why the NGRST coronagraph will perform much better than the JWST coronagraph is that the JWST has a segmented mosaic mirror, while the NGRST will have a single round monolithic mirror.

It is because of the shape of the JWST telescope mirror around each star and the bright point source of light captured in the images that a characteristic “snowflake” halo appears – and this defect occurs due to the design features of the optics.

However, coronagraphs are round in shape and are not able to effectively “deal” with scattered light that comes from sharp edges (including hexagonal segments, from “corners” on the outer edges of the mirror, as well as from “gaps” of almost a millimeter size located between different segments).

All this is a very big problem for the HWO as well, since the design of this observatory resembles that of the JWST, and especially because it must be equipped with a coronographic equipment with a resolution of one ten-billionth, which will make it possible to obtain images of planets similar to The Earth, which revolve around stars similar to the Sun – and this is about a hundred times more than that of the coronagraph mounted on the NGRST telescope.

One possible solution is to launch, with or even after the HWO, a so-called “star shield” (“star shield” or “starshade” is a structure designed to keep starlight out of the HWO’s primary mirror). ).

This technology is quite possible to implement, although it is expensive and its effectiveness is limited: whenever the HWO observatory needs to move from one target to another, it will have to move almost 80 thousand kilometers in outer space.

Thus, it will be able to receive images of about one or two space systems annually – and this is the limit.

It is possible to offer a completely non-standard solution, namely: instead of a traditional segmented mirror, create a combination of circular mirrors, like the Giant Magellan Telescope, which is currently under construction.

In this case, instead of eighteen hexagons joined to each other, seven circles will be installed, while the aperture value of the telescope will be equal to the area of ​​all seven circles taken together, but the resolution will be determined by the diameter of the circle covering all the main mirrors. In this design:

– Fixed all stray light problems that occur with telescopes resembling JWST;

– It would be possible to use the existing technology of folding the main mirror;

– A technology operating in the range of several picometers, which is being developed for mirror segments, will be used;

– Instead of one secondary mirror and/or one coronagraph, each of the seven segments can have its own mirrors and coronagraphs, and, at the same time, no wires will interfere with the operation of the optical system of the primary mirror, since the secondary mirror (mirrors) can be held with wires, which in this case will pass in the gaps between the round segments.

It is for this reason that the Giant Magellan Telescope will be the first world-class observatory to provide us with images of stars without diffraction rays.

If the HWO space telescope can be successfully designed and implemented, then:

– It will be launched already in the late 2030s – early 2040s;

– The cost estimate will not be exceeded and the project will be implemented on time;

– Due to its design, the HWO will be able to carry out observations without a “star shield”;

– He will have enough of his energy, and his equipment can be serviced and replaced;

– You can add a “star shield” to it at any time;

“It is quite possible that with the help of HWO, specialists will receive a sufficient number of images of terrestrial planets, which will allow us to detect at least one exoplanet (and maybe even several) that has life.

In designing this telescope, the following important question remains to be answered: what is the ratio between the number of Earth-like exoplanets that this telescope can image and the cost of building it.

The diameter of the lens (it is in the range of six to seven meters) seems to be quite optimal, but this is probably not enough, since this observatory is too small and it would be necessary to spare no expense for funding. After all, in the end, we are faced with the task of finding a habitable planet.

We must never forget that when we try to find life beyond Earth, we are playing the lottery. Each terrestrial planet that we want to capture and whose parameters we want to determine is a kind of lottery ticket, and the probability of winning on it is unknown.

This probability depends entirely on which tickets are winning and whether we bought enough of them. But until we get the data from the HWO, we can’t determine the conditions under which the probability of winning will be high – that’s the whole point.

It is for this reason that we need to design a telescope in such a way as to increase the chances of discovering an exoplanet that has life. If, nevertheless, it is possible to do this, then humanity will quite possibly be able to answer the question of whether we are alone in the Universe. And maybe

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