“There are still planets like ours”

In the control room of the Complutense University of Madrid there are six screens dedicated to viewing the World Space Telescope in Ultraviolet (WSO-UV), a collaboration between Spain and Russia to study exoplanets (worlds beyond the solar system) that have remained truncated. after the invasion of Ukraine. Spain’s participation in the mission was paralyzed by a European decision after ten years of work and only three years after launch, when almost everything was completed. The main researcher in our country was the astrophysicist Ana Ines Gómez de Castro (Vitoria, 1961), director of the Research Group for Space Astronomy (Aegora). His gaze dims when he remembers this. “It’s a shame. “Space exploration has always united humanity,” he laments. A projection of the WSO’s orbit is still displayed on one of the monitors, waiting for perhaps one day renewed cooperation.

But the opportunities, hard work and acquired skills were not lost. Some screens are dedicated to tracking scientific nanosatellites. And the most important thing is what is not visible. The knowledge that Gomez de Castro and his team have acquired over the years will be used for an even more ambitious mission – NASA’s Habitable Worlds Observatory (HWO). The space telescope will be the first specifically designed to look for signs of life on planets orbiting other stars. This is a titanic work, the results of which can change the history of mankind. The researcher has been selected by the European Space Agency (ESA) as one of three continental representatives on a team that will shape the mission, consisting of thousands of scientists from around the world. “We already have a lot of exoplanets. Now it’s time to look for clones of Earth,” he says. And get your enthusiasm back.

Since the first exoplanet was discovered in 1995, the list has continued to grow thanks to new missions and detection methods, so that there are already more than 5,000 confirmed. But we have no idea whether any of them are capable of containing life, because Currently, there are no instruments either on earth or in space that could detect it. Hopefully this will change with the advent of HWO, which can observe from the ultraviolet to the near-infrared.

25 candidates

The new telescope, which will see billions of euros invested in its development, will be around six or eight meters long, comparable to the James Webb Telescope, the current jewel in the crown of observing the universe. It will be located at Lagrange point 2 (L2), located one and a half million kilometers behind the Earth in the direction opposite to the Sun. “Its main task will be to identify and image at least 25 systems where they exist. a planet that “due to its mass and environment (the characteristics of the star and the distance between them) can support life,” explains the astrophysicist. This represents an unprecedented effort. “We want to observe a planet very close to a star, billions of times brighter. The first idea that comes to mind is to block the light of this star, right? But it turns out that this generates reverberations, rings of light even more intense than the signal from the planet. We have to develop very sophisticated optical technology so that this effect does not harm the image quality,” he explains.

The 25 candidates have not yet been selected and may represent worlds that have not yet been discovered. They must orbit relatively nearby stars, between three and 50 light-years away, so that they appear far enough from their star in the image to be identified. Once achieved, HWO will look for chemical “biosignatures” in the planet’s atmosphere, “gases such as oxygen or methane that may indicate the existence of life, and evidence of clouds, chlorophyll, global weather patterns…”. The observatory “will be able to detect signs of life, but probably not organized life itself.” The biggest challenge, he says, will be detecting the plant matter. “Imagine that we find a planet with vegetation similar to Earth. The global community will focus on monitoring it to see if there is life in it. And if it has a technological life, we could send a message that will arrive decades later. From a philosophical point of view, this will have a huge impact,” he says.

Gómez de Castro is convinced that at least one habitable world will be found. “I firmly believe that there should be more Earths. And this is not an unfounded statement,” he says.

Space bombardment

“A year ago, a mission from the Japan Aerospace Exploration Agency (JAXA) reported the first detection of uracil (a nucleotide found in RNA) on an asteroid called Ryugu. We know that life on Earth began about 3.7 billion years ago, coinciding with heavy bombardment from comets. Perhaps the foundations of life reached our planet from space. This means that these bases are produced naturally through chemical reactions in space. The only thing you need is a star like the Sun, ice, ammonia and CO2, very rich ingredients. Life could arise anywhere in the universe, and it would also be very similar to what we know,” he notes.

This similarity is an advantage not only when searching for a habitable planet, but also in case we one day have to leave Earth. “You have to go there. We must preserve our planet, but our survival as a species may depend on it,” he notes. A defender of the Spanish scientific tradition – “very influential” – Gomez de Castro knows that when the HWO flies she will be “more than retired”, but she doesn’t care. These great spatial projects “represent modern cathedrals. They are started by one generation and finished by another. This is the idea.”

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