Building telescopes on the moon could transform astronomy, and it’s becoming an achievable goal
Lunar exploration is undergoing a renaissance. Dozens of missions, organized by multiple space agencies—and increasingly by commercial companies—are set to visit the moon by the end of this decade. Most of these will involve small robotic spacecraft, but NASA’s ambitious Artemis program, aims to return humans to the lunar surface by the middle of the decade.
There are various reasons for all this activity, including geopolitical posturing and the search for lunar resources, such as water-ice at the lunar poles, which can be extracted and turned into hydrogen and oxygen propellant for rockets. However, science is also sure to be a major beneficiary.
The moon still has much to tell us about the origin and evolution of the solar system. It also has scientific value as a platform for observational astronomy.
The potential role for astronomy of Earth’s natural satellite was discussed at a Royal Society meeting earlier this year. The meeting itself had, in part, been sparked by the enhanced access to the lunar surface now in prospect.
Far side benefits
Several types of astronomy would benefit. The most obvious is radio astronomy, which can be conducted from the side of the moon that always faces away from Earth—the far side.
The lunar far side is permanently shielded from the radio signals generated by humans on Earth. During the lunar night, it is also protected from the Sun. These characteristics make it probably the most “radio-quiet” location in the whole solar system as no other planet or moon has a side that permanently faces away from the Earth. It is therefore ideally suited for radio astronomy.
Radio waves are a form of electromagnetic energy—as are, for example, infrared, ultraviolet and visible-light waves. They are defined by having different wavelengths in the electromagnetic spectrum.
Radio waves with wavelengths longer than about 15m are blocked by Earth’s ionoshere. But radio waves at these wavelengths reach the moon’s surface unimpeded. For astronomy, this is the last unexplored region of the electromagnetic spectrum, and it is best studied from the lunar far side.
Observations of the cosmos at these wavelengths come under the umbrella of “low frequency radio astronomy.” These wavelengths are uniquely able to probe the structure of the early universe, especially the cosmic “dark ages“—an era before the first galaxies formed.
At that time, most of the matter in the universe, excluding the mysterious dark matter, was in the form of neutral hydrogen atoms. These emit and absorb radiation with a characteristic wavelength of 21cm. Radio astronomers have been using this property to study hydrogen clouds in our own galaxy—the Milky Way—since the 1950s.
Because the universe is constantly expanding, the 21cm signal generated by hydrogen in the early universe has been shifted to much longer wavelengths. As a result, hydrogen from the cosmic “dark ages” will appear to us with wavelengths greater than 10m. The lunar far side may be the only place where we can study this.
The astronomer Jack Burns provided a good summary of the relevant science background at the recent Royal Society meeting, calling the far side of the moon a “pristine, quiet platform to conduct low radio frequency observations of the early Universe’s Dark Ages, as well as space weather and magnetospheres associated with habitable exoplanets.”
Signals from other stars
As Burns says, another potential application of far side radio astronomy is trying to detect radio waves from charged particles trapped by magnetic fields—magnetospheres—of planets orbiting other stars.
This would help to assess how capable these exoplanets are of hosting life. Radio waves from exoplanet magnetospheres would probably have wavelengths greater than 100m, so they would require a radio-quiet environment in space. Again, the far side of the moon will be the best location.
A similar argument can be made for attempts to detect signals from intelligent aliens. And, by opening up an unexplored part of the radio spectrum, there is also the possibility of making serendipitous discoveries of new phenomena.
We should get an indication of the potential of these observations when NASA’s LuSEE-Night mission lands on the lunar far side in 2025 or 2026.
The moon also offers opportunities for other types of astronomy as well. Astronomers have lots of experience with optical and infrared telescopes operating in free space, such as the Hubble telescope and JWST. However, the stability of the lunar surface may confer advantages for these types of instrument.
Moreover, there are craters at the lunar poles that receive no sunlight. Telescopes that observe the universe at infrared wavelengths are very sensitive to heat and therefore have to operate at low temperatures. JWST, for example, needs a huge sunshield to protect it from the sun’s rays. On the moon, a natural crater rim could provide this shielding for free.
The moon’s low gravity may also enable the construction of much larger telescopes than is feasible for free-flying satellites. These considerations have led the astronomer Jean-Pierre Maillard to suggest that the moon may be the future of infrared astronomy.
The cold, stable environment of permanently shadowed craters may also have advantages for the next generation of instruments to detect gravitational waves—”ripples” in space-time caused by processes such as exploding stars and colliding black holes.
Moreover, for billions of years the moon has been bombarded by charged particles from the sun—solar wind—and galactic cosmic rays. The lunar surface may contain a rich record of these processes. Studying them could yield insights into the evolution of both the Sun and the Milky Way.
For all these reasons, astronomy stands to benefit from the current renaissance in lunar exploration. In particular, astronomy is likely to benefit from the infrastructure built up on the moon as lunar exploration proceeds. This will include both transportation infrastructure—rockets, landers and other vehicles—to access the surface, as well as humans and robots on-site to construct and maintain astronomical instruments.
But there is also a tension here: human activities on the lunar far side may create unwanted radio interference, and plans to extract water-ice from shadowed craters might make it difficult for those same craters to be used for astronomy. As my colleagues and I recently argued, we will need to ensure that lunar locations that are uniquely valuable for astronomy are protected in this new age of lunar exploration.
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Building telescopes on the moon could transform astronomy, and it’s becoming an achievable goal (2023, April 19)
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James Webb Space Telescope finds water in super-hot exoplanet's atmosphere – Space.com
The James Webb Space Telescope has found traces of water vapor in the atmosphere of a super-hot gas giant exoplanet that orbits its star in less than one Earth day.
The exoplanet in question, WASP-18 b, is a gas giant 10 times more massive than the solar system‘s largest planet, Jupiter. The planet is quite extreme, as it orbits the sun-like star WASP-18, which is located some 400 light-years away from Earth, at an average distance of just 1.9 million miles (3.1 million kilometers). For comparison, the solar system’s innermost planet, Mercury, circles the sun at a distance of 39.4 million miles (63.4 million km).
Due to such close proximity to the parent star, the temperatures in WASP-18 b’s atmosphere are so high that most water molecules break apart, NASA said in a statement. The fact that Webb managed to resolve signatures of the residual water is a testament to the telescope’s observing powers.
Related: Exoplanets, dark matter and more: Big discoveries coming from James Webb Space Telescope, astronomers say
“The spectrum of the planet’s atmosphere clearly shows multiple small but precisely measured water features, present despite the extreme temperatures of almost 5,000 degrees Fahrenheit (2,700 degrees Celsius),” NASA wrote in the statement. “It’s so hot that it would tear most water molecules apart, so still seeing its presence speaks to Webb’s extraordinary sensitivity to detect remaining water.”
WASP-18 b, discovered in 2008, has been studied by other telescopes, including the Hubble Space Telescope, NASA’s X-ray space telescope Chandra, the exoplanet hunter TESS and the now-retired infrared Spitzer Space Telescope. None of these space telescopes, however, was sensitive enough to see the signatures of water in the planet’s atmosphere.
“Because the water features in this spectrum are so subtle, they were difficult to identify in previous observations,” Anjali Piette, a postdoctoral fellow at the Carnegie Institution for Science and one of the authors of the new research, said in the statement. “That made it really exciting to finally see water features with these JWST observations.”
In addition to being so massive, hot and close to its parent star, WASP-18 b is also tidally locked. That means one side of the planet constantly faces the star, just like the moon‘s near side always faces Earth. As a result of this tidal locking, considerable differences in temperature exist across the planet’s surface. The Webb measurements, for the first time, enabled scientists to map these differences in detail.
The measurements found that the most intensely illuminated parts of the planet can be up to 2,000 degrees F (1,100 degrees C) hotter than those in the twilight zone. The scientists didn’t expect such significant temperature differences and now think that there must be some not yet understood mechanism in action that prevents the distribution of heat around the planet’s globe.
“The brightness map of WASP-18 b shows a lack of east-west winds that is best matched by models with atmospheric drag,” co-author Ryan Challener, of the University of Michigan, said in the statement. “One possible explanation is that this planet has a strong magnetic field, which would be an exciting discovery!”
To create the temperature map, the researchers calculated the planet’s infrared glow by measuring the difference in the glow of the parent star during the time the planet transited in front of the star’s disk and then when it disappeared behind it.
“JWST is giving us the sensitivity to make much more detailed maps of hot giant planets like WASP-18 b than ever before,” Megan Mansfield, a Sagan Fellow at the University of Arizona and one of the authors of the paper describing the results. said in the statement. “This is the first time a planet has been mapped with JWST, and it’s really exciting to see that some of what our models predicted, such as a sharp drop in temperature away from the point on the planet directly facing the star, is actually seen in the data.”
The new study was published online Wednesday (May 31) in the journal Nature.
JWST Scans an Ultra-Hot Jupiter's Atmosphere – Universe Today
When astronomers discovered WASP-18b in 2009, they uncovered one of the most unusual planets ever found. It’s ten times as massive as Jupiter is, it’s tidally locked to its Sun-like star, and it completes an orbit in less than one Earth day, about 23 hours.
Now astronomers have pointed the JWST and its powerful NIRSS instrument at the ultra-Hot Jupiter and mapped its extraordinary atmosphere.
Ever since its discovery, astronomers have been keenly interested in WASP-18b. For one thing, it’s massive. At ten times more massive than Jupiter, the planet is nearing brown dwarf territory. It’s also extremely hot, with its dayside temperature exceeding 2750 C (4900 F.) Not only that, but it’s likely to spiral to its doom and collide with its star sometime in the next one million years.
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For these reasons and more, astronomers are practically obsessed with it. They’ve made extensive efforts to map the exoplanet’s atmosphere and uncover its details with the Hubble and the Spitzer. But those space telescopes, as powerful as they are, were unable to collect data detailed enough to reveal the atmosphere’s properties conclusively.
Now that the JWST is in full swing, it was inevitable that someone’s request to point it at WASP-18b would be granted. Who in the Astronomocracy would say no?
In new research, a team led by a Ph.D. student at the University of Montreal mapped WASP-19b’s atmosphere with the JWST. They used the NIRISS instrument, one of Canada’s contributions to the JWST. The paper is “A broadband thermal emission spectrum of the ultra-hot Jupiter WASP-18b.” It’s published in Nature, and the lead author is Louis-Philippe Coulombe.
The researchers trained Webb’s NIRISS (Near-Infrared Imager and Slitless Spectrograph) on the planet during a secondary eclipse. This is when the planet passes behind its star and emerges on the other side. The instrument measures the light from the star and the planet, then during the eclipse, they deduct the star’s light, giving a measurement of the planet’s spectrum. The NIRISS’ power gave the researchers a detailed map of the planet’s atmosphere.
With the help of NIRISS, the researchers mapped the temperature gradients on the planet’s dayside. They found that the planet is much cooler near the terminator line: about 1,000 degrees cooler than the hottest point of the planet directly facing the star. That shows that winds are unable to spread heat efficiently to the planet’s nightside. What’s stopping that from happening?
“JWST is giving us the sensitivity to make much more detailed maps of hot giant planets like WASP-18 b than ever before. This is the first time a planet has been mapped with JWST, and it’s really exciting to see that some of what our models predicted, such as a sharp drop in temperature away from the point on the planet directly facing the star, is actually seen in the data!” said paper co-author Megan Mansfield, a Sagan Fellow at the University of Arizona.
The lack of winds moving the atmosphere around and regulating the temperature is surprising, and atmospheric drag has something to do with it.
“The brightness map of WASP-18 b shows a lack of east-west winds that is best matched by models with atmospheric drag,” said co-author Ryan Challener, a post-doctoral researcher at the University of Michigan. “One possible explanation is that this planet has a strong magnetic field, which would be an exciting discovery!”
In our Solar System, Jupiter has the strongest magnetic field. Scientists think that swirling conducting materials deep inside the planet, near its bizarre liquid, metallic hydrogen core generates the magnetic fields. The fields are so powerful that they protect the three Galilean moons from the solar wind. They also generate permanent aurorae and create powerful radiation belts around the giant planet.
But WASP-18 b is ten times more massive than Jupiter, and it’s reasonable to think its magnetic fields are even more dominant. If the planet’s magnetic field is responsible for the lack of east-west winds, it could be forcing the winds to move over the North Pole and down the South Pole.
The researchers were also able to measure the atmosphere’s temperature at different depths. Temperatures increased with altitude, sometimes by hundreds of degrees. They also found water vapour at different depths.
At 2,700 Celsius, the heat should tear most water molecules apart. The fact that the JWST was able to spot the remaining water speaks to its sensitivity.
“Because the water features in this spectrum are so subtle, they were difficult to identify in previous observations. That made it really exciting to finally see water features with these JWST observations,” said Anjali Piette, a postdoctoral fellow at the Carnegie Institution for Science and one of the authors of the new research.
But the JWST was able to reveal more about the star than just its temperature gradients and its water content. The researchers found that the atmosphere contains Vanadium Oxide, Titanium Oxide, and Hydride, a negative ion of hydrogen. Together, those chemicals could combine to give the atmosphere its opacity.
All these findings came from only six hours of observations with NIRISS. Six hours of JWST time is precious to astronomers, and that’s all the researchers needed. That’s not only because the JWST is so powerful and capable, but also because of WASP-18 b itself.
At only 400 light-years away, it’s relatively close in astronomical terms. Its proximity to its star also helped, and the planet is huddled right next to its star. Plus, WASP-18 b is huge. In fact, it’s one of the most massive planets accessible to atmospheric investigation.
The planet’s atmospheric properties also provide clues to its origins. Comparisons of metallicity and composition between planets and stars can help explain a planet’s history. WASP-18 b couldn’t have formed in its current location. It must have migrated there somehow. And while this work can’t answer that conclusively, it does tell us other things about the giant planet’s formation.
“By analyzing WASP-18 b’s spectrum, we not only learn about the various molecules that can be found in its atmosphere but also about the way it formed. We find from our observations that WASP-18 b’s composition is very similar to that of its star, meaning it most likely formed from the leftover gas that was present just after the star was born,” Coulombe said. “Those results are very valuable to get a clear picture of how strange planets like WASP-18 b, which have no counterpart in our Solar System, come to exist.”
Private astronaut crew, including first Arab woman in orbit, returns from space station – Indiatimes.com
An all-private astronaut team of two Americans and two Saudis, including the first Arab woman sent into orbit, splashed down safely off Florida on Tuesday night, capping an eight-day research mission aboard the International Space Station (ISS).
After spending 8 days on a space exploration mission, four astronauts, including two from the United States and the other two from Saudi Arabia, returned to Earth safely off the coast near Florida. Although the mission was funded by private entities, the mission included deep space exploration and was a landmark achievement in terms of the inclusion of women in this field.
— Axiom_Space (@Axiom_Space)
The space crew came back in a SpaceX Dragon capsule, after completing 12 hours in the return journey. The space capsule is said to have descended in a very hot environment at blazing speeds through Earth’s atmosphere. The splashdown was carried live by a SpaceX and Axiom Space joint webcast.
Axiom Space spent millions of dollars off its own pocket to send a private expedition to the space station. The company organized, prepared and funded the mission that involved their second attempt to get into space, without any government intervention. Axiom Space is based in Houston and is run by a former NASA researcher, who had worked on the initiation of NASA’s International Space Station program.
Peggy Whitson, who is 63, led the Axiom 2 crew. She holds the record for most time spent in orbit with 665 days divided into 3 long space missions. This includes her 10 spacewalks. Along with her were John Shoffner, who is a professional race car driver and investor, and two astronauts from Saudi Arabia, who helmed cancer stem cell research, and were fighter pilots by profession.
Barnawi and Alqarni are two Saudi women who went to space just five years after Saudi Arabia removed restrictions on women driving. Sara Sabry was another woman from Egypt who went into space in 2022 for a short duration. At that time, Alqarni and Barnawi were on board the international space station with Sultan Alneydi from UAE. They made history as the triplets were the first three astronauts into space from Saudi Arabia.
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