The European Space Agency Wants to Send an Inflatable Telescope to the Moon
The ESA is working on creating an inflatable radio telescope.
The telescope would be destined for the dark side of the Moon, where it could observe radio signals from the universe’s Dark Age.
The idea is still in the prototyping phase, but researchers are looking into how to make the concept compatible with the agency’s Argonaut lander, expected to launch around 2030.
Not content with creating space telescopes that unfold, scientists are now working on building one that inflates. Even better—it’s destined for the Moon.
Engineers at the European Space Agency (ESA) are looking to construct an inflatable radio telescope to be set up on the dark side of the Moon. The whole device would be printed on what is functionally space-blanket material, and would ideally be sent up by the agency’s Ariane 6 rocket.
“You fold up the system, then you push gas into it and you inflate it. It’s like an inflatable mattress on the moon,” Marc Klein Wolt, one of the leads on the ESA Astrophysical Lunar Observatory science team, said at the Astronomy from the Moon conference earlier this year, according to Space.com.
The overall goal of the project is to finally be able to look back into a period of the universe known as the cosmic Dark Age—the first hundreds of millions of years right after the Big Bang. It’s a period we don’t know much about, as a result of it simply being so long ago that any evidence is extremely far away. Not even the James Webb Space Telescope can see that far.
But, theoretically, a very high-resolution and well-placed radio telescope could. During the cosmic Dark Age, the universe was dominated by hydrogen. So, when looking for evidence of that period, researchers look for the atomic-hydrogen-signaling 21 centimeter emission line. Studying those signals is the window into the Dark Age for researchers.
Now, technically, the 21 centimeter emission line falls in the microwave part of the spectrum—its wavelength is a little short to fall in the radio category. But because of the expansion of the universe, signals from very far away get stretched out, or redshifted. What started as a microwave, therefore, will reach us as a radio wave.
The thing is, it’s really hard to detect radio waves from on or near Earth. We as a planet produce a lot of radio interference for telescopes to work around, not to mention the atmosphere getting in the way. Even the Sun can drown out radio waves.
Hence the plan to put this inflatable telescope on the dark side of the Moon. The face of the Moon constantly turned away from our planet is protected from all of our radio emissions by virtue of the rest of the Moon being in the way. The Moon also doesn’t have an atmosphere for a telescope to contend with. And on top of all of that, a night on the Moon is two weeks long, meaning there will be repeated stretches of two weeks where the detection power of the radio telescope is not interrupted by the Sun.
So, considering the perfection of the dark side of the Moon as a potential radio telescope home, the ESA has been working to figure out the best way to get such a telescope to its waiting home. Current technology limits how much weight we could take to the Moon, so a standard radio array is out of the question.
The inflatable solution fixes that weight constraint issue—if it can be developed. The ESA is looking to build it in such a way that it could be delivered to its desired location by the agency’s Argonaut lander, set to head to the lunar surface in approximately 2030. But right now, researchers are still very much in the prototyping phase, and are working on several different potential antenna designs.
“We have several options of building prototypes and testing them,” Klein Wolt said. “That’s what we are working on today. It doesn’t have to be [tested] on the far side; it could be a nearside mission, like the Apollo missions. There are plenty of options that we can explore.”
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