The 'James Webb' prepares for its great milestone: the first images

telescope for the afternoon of July 13

The celestial objects that will appear in them are kept secret, but it has been announced that the event will be broadcast not only on the NASA website, but also on all digital channels and social networks (also in the Spanish version). : Facebook, Twitter and YouTube.

There is much speculation about the content of these images, which will show the sky in infrared with extraordinary clarity.

For thirty years,

has provided magnificent views of galaxies and nebulae in which huge clouds of opaque dust stand out;

This is the case of the famous image of the "Pillars of Creation" or the spectacular "Head of a Horse", The

will be able to cross that obstacle and reveal the thousands of stars that are hidden inside.

In any case, NASA has advanced some general aspects of the first collection of

photos : they will show themes related to the early universe, the evolution of galaxies and the life cycle of stars.

But it will be a minuscule fraction of what remains to come: the program for the first year of observations is already full, except for a few hours reserved for unforeseen events, such as the appearance of interstellar comets or supernovae, for example.

The key to the new telescope is that it will observe in the infrared, a band of frequencies that

only sees from the side.

Infrared is essentially heat;

That is why it has been necessary to keep the

in the refrigerator of space for almost six months, until the mirror and instruments have reached a temperature of a few tens of degrees above absolute zero.

And one of its sensors, equipped with an additional cooler, is only seven Kelvin away.

The definition that can be achieved by working at such long wavelengths is worse than if the visible spectrum is used.

Therefore, to achieve the same quality that

offers ,

needs a much larger mirror.

In principle, the sharpness of one and the other should be comparable.

The mirror's six-meter diameter posed problems from the start: it had to be broken into separate segments and folded to fit into the launcher's hood.

Its mechanical structure is both very rigid and very light, so that it maintains its shape unchanged even at very low temperatures.

telescope

cannot point anywhere at any time.

Mirror, instruments and parasol form a whole that must be oriented with your back to the Sun at all times. It is a matter of keeping them in the shade at all times to avoid overheating that would spoil any observation.

Thus, tilting up to 45º up and down, and turning on its longitudinal axis (but always with the Sun behind it) the

can sweep a ring that represents 45% of the sky.

No more.

If it is a question of observing a body outside that zone, it will be necessary to wait until it reaches a more favorable position, where the Sun does not threaten to dazzle it.

Sometimes it's months of waiting, when the Earth pulls it to the other end of its orbit.

Waiting for the

to officially enter service, both NASA and other agencies are already studying who its successors will be.

And their goals, certainly ambitious.

successors

The first candidate is the

intended to identify exoplanets with the potential to host life as we know it.

It will be equipped with a telescope with a diameter of four meters, an intermediate size between

and

.

But what is truly novel is that it will display a shield in front of it to block the light of the stars, letting through only that of the planets that revolve around it.

The shield looks like a huge sunflower that will unfold in space like an origami model.

It will be about 50 meters in diameter and will only let through its petals those few photons that come from planets located in the habitable zone.

Sensitive spectrometers will analyze the light for biomarkers: oxygen, ozone, water or methane, for example.

Another telescope under study is the

, an acronym that refers to its ability to work in the ultraviolet and infrared bands.

Also with the aim of locating -and, in addition, photographing- habitable exoplanets.

's mirror

: 15 meters in diameter.

Today its cost is estimated at 24,000 million, but, based on previous experiences, there is no doubt that it will increase.

A third project that is still in the study phase is the

telescope .

Basically, an improved

: a thousand times more sensitive and able to see in even farther infrared bands.

But, in any case, all these telescopes are still very far away in time.

None will fly before 2035. In fact, today there is not even a rocket launcher capable of taking them into space.

Closer to home are other projects such as the

telescope (named after the first female astronomer to hold a managerial position at NASA).

This came out somewhat cheaper because NASA was able to use a mirror gift from the National Security Agency: an 2.4-meter reflector originally designed for a spy satellite, but no longer useful to them.

telescope

will be used to increase the census of exoplanets, including some the size of Earth or even smaller.

Spectral analysis of their atmospheres will also be attempted and, in other fields of cosmology, studies on dark energy.

In this work you will have company: the European satellite

which should be launched next year from Guiana.

Roman

be delayed until at least 2027. By then, European PLATO, another extrasolar planet seeker, is also likely to be in space.

Along with these initiatives, other national agencies announce the launch of more satellites for astronomical use.

Australia hopes to do so next year, with a relatively modest observatory focused on studying our closest neighbor: Alpha Centauri and its possible planets;

in 2024 China plans to send the

telescope , a kind of

with a field of view 300 times wider.

India and Japan are also developing similar programs, although the launch dates are past the second half of this decade.

now rotates

.

In the next few years that is going to be a very crowded place.

Rafael Clemente

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