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China wants to put a small constellation of satellites into orbit around the moon to create a radio telescope that will open a “new window” on the universe.
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- The set consists of a “mother” satellite and eight baby “daughters” crafts;
- the mother processes the data and communicates with the Earth;
- The girls will discover radio signals from the far corners of the universe.
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The information was shared by Xulei Chen, an astronomer with the China National Space Administration (CNSA), at the Astronomy from the Moon conference held earlier this year in London, UK.
Placing such an array in lunar orbit would be more technically feasible than building a telescope directly on the lunar surface, an undertaking that NASA and other space agencies are currently considering as one of the next big steps in astronomy.
There are a number of advantages to doing this in orbit rather than on the surface, as it is much simpler in terms of engineering. There is no need to land and deploy, also because the lunar orbital period is 2 hours, we can use solar power, which is much simpler than doing it on the moon, which, if you want to observe during the lunar night, so you have to save power for about 14 days.
Xuei Chen, astronomer with the China National Space Administration (CNSA), at the Astronomy from the Moon conference
He added that the proposal for “discovering the sky with the longest wavelength”, or the Hongmeng project, could orbit the moon as early as 2026.
Reasons for building a lunar telescope
Astronomers say that having a telescope on the Moon will finally allow them to see cosmic radiation in a part of the electromagnetic spectrum that is impossible to study from the Earth’s surface: radio waves longer than ten meters, or in other words, waves with frequencies less than 30 megahertz.
If you look at the lower frequency part of the electromagnetic spectrum you will find this is due to strong absorption [pela atmosfera da Terra]We know very little about it [a região] less than 30MHz. It is an almost empty part of the electromagnetic spectrum. So we want to open this final electromagnetic window to the universe.
Xuei Chen, astronomer with the China National Space Administration (CNSA), at the Astronomy from the Moon conference
Astronomers are interested in this part of the electromagnetic spectrum for good reason. They believe that this type of radiation could allow them to learn about the so-called dark ages, which is the period of the first hundreds of millions of years after the birth of the universe in the Big Bang.
At that time, the emerging universe was filled with an impenetrable haze of hydrogen atoms. Even when the first stars started to form, their light could not pass through this haze at first.
Astronomers do know, however, that this same atomic hydrogen emits a type of signal known as an 8-inch line. Part of the microwave band of the electromagnetic spectrum, the 21cm line has been helping astronomers track clouds of hydrogen in our galaxy, the Milky Way, since the 1950s, according to astronomer Ian Crawford of University College London.
But when searching for a 21-cm line from the oldest era in the universe, astronomers have to look for radiation with much longer wavelengths.
Like effect redshift What was microwave radiation emitted by hydrogen atoms during the early universe today appears to observers on Earth as long radio waves. And this is exactly the kind of electromagnetic radiation that cannot be seen from the surface of the planet.
However, the far side of the Moon is probably the best place in the solar system to look for this mysterious signal.
Away from Earth’s obstructive atmosphere, the far side of the Moon is also shielded from human-caused radio noise. During the lunar night, it also moves away from the Sun, which is also a powerful source of radio waves.
Astronomers say that the far side of the moon is actually the quietest place in the entire solar system.
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Because radio waves are a type of electromagnetic radiation with longer wavelengths, telescopes that can map their sources on the sky with high enough accuracy need to use multiple antennas spread over a large area.
China Constellation will achieve this in space, with satellites orbiting the Moon in the same orbit. The satellites will collect data while on the far side of the moon. The mother spacecraft will transmit measurements back to Earth as it crosses the planet-facing side of the Moon.
Chinese scientists had already tried to test this approach with two small satellites, called Longijang 1 and Longijang 2 on the lunar surface in 2019. However, Longijang 1 failed to enter lunar orbit, so astronomers only received data from Longijang 2. Probe measurements It showed that the far side of the moon is indeed incredibly quiet, Qin said.
We had Longijang 2, which circled the moon for a while, and [seu] The spectrum shows that when a satellite enters the moon’s shadow or leaves the shadow, you can see where radio interference appears and disappears. This shows that the far side of the Moon provides an ideal environment for this type of measurement.
Xuei Chen, astronomer with the China National Space Administration (CNSA), at the Astronomy from the Moon conference
Astronomers hope to discover much more than just a signal of atomic hydrogen from the Dark Ages. A new, never-before-seen facet of the universe is likely to emerge once astronomers know how to look for it.
The magnetospheres of exoplanets outside our solar system can reveal themselves at long radio waves, and some researchers are hopeful that such an arrangement might even allow intelligent extraterrestrial life to communicate. “If we open a new window, we might see some interesting new things,” Chen concluded.
with information from space.com
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