The James Webb telescope is far from having finished its mission, but scientists are already seeing further. In Europe or the United States, space agencies are planning space telescopes dedicated to the search for habitable worlds.
” We want a launch by 2041, but we will try to go faster. ” It is A declaration by Jason Tumlinson, astronomer at the Space Telescope Science Institute in Baltimore, who mentioned on January 11, 2023 a project called for the moment “Habitable Worlds Observatory”. This telescope could find Earth-like worlds. It is already beginning to be thought out and financed, even though it will take almost thirty years, in the best case scenario, to see it take off.
Periods that seem excessively long from an outside perspective. How can we project ourselves so far, especially in a world where technology is changing so rapidly and where no one can say what spacecraft will be made of in ten or fifteen years?
Yet this is the lot of every somewhat ambitious space mission. The James Webb Space Telescope was initiated as a project in 1989, when the USSR still existed and France had just discovered Roch Voisine!
Anticipate the evolution of technology
” We know that these developments are very longtells Numerama Alexandre Santerne, astronomer at the Marseille astrophysics laboratory. There are often technological barriers to overcome, you have to know how to predict how the technology will evolve. »
The French researcher is working on a telescope called PLATO, which should take off at the end of 2026, to discover exoplanets similar to Earth. The philosophical successor to Kepler, a NASA telescope launched in 2009 to find exoplanets, PLATO has the same goal, although that has changed a lot as development has gone on. ” The first time the idea was raised was in the 1990s, but we weren’t even talking about exoplanets! The mission has evolved in its objectives since then, but the technology has remained more or less the same: it involved observing a large number of bright stars, and providing data very regularly. »
For PLATO, the challenge was above all to transmit a very large amount of data, because the mission aims to detect exoplanets by the transit method. This technique has proven itself, the idea being to see the planet pass in front of its star. But, that remains complicated, because it is necessary to find a star with a planet whose plan is close to that of the Earth, and which passes in front of it at the time when the observer is there to attend the event. In other words, to have a chance of success, you have to observe a large number of stars, and constantly to be sure not to miss anything.
” At the end of the mission we will reach approximately 1 petabyte (1 million gigabytes, editor’s note) of datasays Alexandre Santerne. But, when this constraint came on the table in 2006, we were confident that computing would continue to evolve rapidly, and that this amount could be handled. »
History has proven the researchers of the past right since Big Data today allows the transmission of so much information.
Inventing the telescopes of tomorrow, today
This can be more difficult when the machines in question require technologies that do not yet exist. For example, the Planck telescope launched in 2009 required the launch of numerous studies to find a way to cool its sensors to 0.1 degrees Kelvin, the coldest point ever reached in the known Universe!
This is also the case for NASA’s famous Habitable Worlds Observatory. The future telescope is inspired in particular by what is being done at the moment with James Webb and his segmented mirrors which are perfectly deployed. The researchers also intend to make it compatible with satellite services in order to be able to make software updates once the machine has left. The engineers, for their part, provide margins for the design, pending possible technical progress that will lead to the use of different shapes or materials.
The idea is that before embarking on such a mission, researchers must prove that what they claim will be possible by launch. For the Habitable Worlds Observatory, the benefits of James Webb mirrors showed that this technology could be viable for even more ambitious observations. For Kepler, it was necessary to show that it was possible to accurately measure the luminosity of stars, and then that a planet the size of Earth was detectable. It was only afterwards that the mission could be truly validated.
” On our side, we look a lot at what Kepler doessays Alexandre Santerne. The two machines have a lot in common, Kepler cleared the area. Our ambition is to do a better mission on all fronts, to go further. »
Thus, PLATO took a slightly different direction from its elder: Kepler was specialized in distant and faint stars, PLATO will seek the brightest stars in the sector. Kepler saw far, but with a field of view of 10 degrees, PLATO aims for a field five times larger to maximize the chances of observing a transit.
On the NASA side, after the Habitable Worlds Observatory, the agency is also looking for telescopes specializing in infrared and X-rays… With a delivery date for 2050!
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