Astronomers refute the claim that the Canary Islands are comparable to Mauna Kea for TMT

(BIVN) – The Mauna Kea offers significant advantages over an emergency location in La Palma, Spain, say astronomers who favor the construction of the thirty-meter telescope on the top of the island of Hawaii , contrary to recent press articles.

An Associated Press article from August 25 – Hawaii or Spain? Telescope experts say it does not matter: TMT's first choice, Mauna Kea's northern plateau, is "barely" better than the observatory's second choice atop a peak in the Canaries.

A recent article published in Astronomy Hawaii challenges the history of the PA, claiming that "Mauna Kea offers significant advantages over an emergency location in La Palma," according to "experts working in key areas for the scientific objectives of TMT and familiar with different sites of telescopes across the Earth. "

"Mauna Kea will make TMT a better observatory than La Palma and even allow her to reveal invisible objects for NASA's next missions," said Thayne Currie in the article. Currie is an astrophysicist at the NASA-Ames Research Center in Mountain View, California, and an expert in high-contrast imaging of extrasolar planets.

The opposition to TMT on Mauna Kea ended the project in Hawaii. 53 days have passed since the planned start of construction of the observatory, and crews were unable to climb the Mauna Kea access road due to the current stalemate. The state of Hawaii recently granted the project a two-year extension to begin construction to meet the conditions of its permit.

Gordon Squires, TMT's Vice President of External Affairs, said the observatory project was "definitely" to start "in less than two years" before the decision was made to retreat to the Canary Islands.

But astronomers who have contributed to the article of Astronomy Hawaii are not very enthusiastic about La Palma when comparing the location at Mauna Kea. The article says:

A detailed report by a team of expert astrophysicists confirms that Mauna Kea is "highly preferred" in La Palma for the TMT site. They found that Mauna Kea would even give TMT a distinct advantage[s] observatories to come, such as the very large European telescope (E-ELT). The report was led by Canadian astrophysicists and used site test data for Mauna Kea and La Palma, international experts in areas such as adaptive optics, as well as TMT reactions.

The rescue plan to move TMT to La Palma is a way for the project to stay alive, if the international group of partners agrees. But it is also a potential pressure point for Hawaiian officials wishing to host the observatory on Mauna Kea and faced with the dilemma of how to effectively clear the access road for construction crews. This is also a glimmer of hope for TMT opponents who want the observatory to abandon its plan to build the telescope on Mauna Kea.

The validity of the story that La Palma is a comparable alternative to Mauna Kea is questioned in the article by Astronomy Hawaii, which explains:

The biggest advantage of Mauna Kea on La Palma is that Maunakea is a cooler and much drier site, which makes it much more suitable for longer wavelengths than the human eye can see. These "thermal infrared" (thermal IR) wavelengths are essential for many scientific cases related to TMT technologies. For example, light from Earth-like planets around Sun-like stars is directly detectable in the thermal infrared spectrum. The report concludes that TMT on Mauna Kea would be 4 or 5 times more efficient than Palma in thermal infrared IR and also more efficient than the E-ELT, located in Cerro Armazones in Chile.

The report also challenges La Palma's adaptive optics (AO) capabilities, a technology that corrects atmospheric blur caused by turbulence and allows rocky planets to be seen around the nearest stars and the center of our planet. galaxy. La Palma has been touted as the second position behind Mauna Kea for adaptive optics. However, the report notes factors – such as "soil layer turbulence" – that can make La Palma's exit insurance performance worse than the one announced: far worse than Mauna Kea and maybe not even better that a lot of sites in Chile.

"La Palma is too low, too hot and too wet to compete with Mauna Kea in the thermal IR and is not good enough with AO to really make a difference. Some sciences, including that on exoplanets, could hardly be realized by La Palma, but that would be achievable with Mauna Kea, "said Currie, who is familiar with the basic data of the report.

In addition to Mauna Kea, Currie suggested that many sites in Chile are globally superior sites in La Palma, including the very large European telescope and its future telescope, the 39-meter E-ELT.

The benefits of Mauna Kea on La Palma persist even when considering space telescopes. The Associated Press article states that even though TMT hopes to use its advanced optics to do key scientific research, such as giving direct images of "distant planets around bright stars", including those with life, a NASA's upcoming mission, particularly the James Webb Space Telescope (JWST)), could provide this same data instead. As the article claims, "the data from [JWST] could be combined with La Palma to offset the benefits of Mauna Kea.

Professor Ben Mazin, a physicist at the University of California at Santa Barbara and a leading specialist in exoplanet direct imaging technology, draws a different conclusion: "This is true for some scientific goals, like the one I have. observation of galaxies at high redshift, but not for all the science we want to do with TMT. JWST will have excellent sensitivity, but the small size (6 m) of the telescope means that it does not have a very good angular resolution. We can not look at planets very close to a star [like rocky, Earth-like planets]. For near-infrared exoplanets, JWST will be worse than 10-meter Keck telescopes, not to mention the 30-meter TMT. "

The new technological innovations do not necessarily cancel the benefits of Mauna Kea. The Associated Press article mentioned a concept of associating large ground-based telescopes with a very large "hamburger" (several tens of meters), a circular structure with petal-shaped edges that blocks the light stars in orbit around the Earth. The article implied that the starshade could cancel Mauna Kea's advantage with adaptive optics.

Mazin believes, however, that this idea is too speculative to be considered in TMT's planning, saying that it "is at a very early stage of development and faces technical and financial hurdles".

This is what Currie said, adding that "even if it worked, the light of the stars should always cross an atmosphere. Mauna Kea advantage. "

For other key scientific areas, even speculative technological advances could not compensate for La Palma's weaknesses. Mazin notes that La Palma is at a higher latitude than Mauna Kea, perhaps too high to effectively see the center of our Milky Way. In fact, TMT was specifically designed to study the galactic center immediately after completion, "thus meeting the requirements of one of TMT's key instruments," said Mazin.

The Associated Press article also quotes Avi Loeb, who said Mauna Kea was a better infrared site, but that these weaknesses could be offset by technology. Loeb is a trained theorist and best known for claiming that "Oumuamua is an extraterrestrial spaceship, which was recently refuted by a team of scientists at the University of Hawaii.

The experts were clearly in disagreement. "Of course, technology generally improves things, but you can not magically eliminate all the humidity in the air above La Palma. We do not have a giant dehumidifier in the stratosphere, "said Currie.

The scientific performance of current telescopes also imply that Mauna Kea would be a better site for TMT, concluded astronomer Roy Gal of the Institute of Astronomy at the University of Hawai'i. He cites statistics comparing the scientific impact of ground-based telescopes around the world, compiled annually by Dennis Crabtree of the National Research Council of Canada.

"The Maunakea observatories are by far the most scientifically productive on the planet. They count for 3 of the 5 biggest impactors, Keck being the number one. UKIRT is one of those top five competitors, which we have agreed to take out of service by the time TMT becomes operational, "said Gal. "This is not a coincidence, it is a proof of the superiority of Maunakea as an astronomical site. On the other hand, the telescope with the highest impact on La Palma is ranked eighth and the telescope with large aperture (Gran Telescopio Canarias or GTC) is number 25. "

Finally, La Palma faces an opposition of its own, in contradiction with the Associated Press article claiming that there is no significant opposition. There is indeed an environmental group in the Canary Islands, Ben Magec, which has already expressed strong opposition to the project and has already won a court challenge delaying any license TMT despite the support of the Spanish government telescope.

"It could slow things down a lot [for La Palma]"Said Mazin.

The El Roque de los Muchachos observatory in La Palma, where the TMT would be located, "has all the capacity to meet the scientific objectives of the TMT and provides atmospheric characteristics very similar to those of Maunakea at visible wavelengths. and in the near infrared, "says the TMT La Palma website.