Daily Archives: October 11, 2022

There were 4,852 active satellites in orbit around Earth at the beginning of 2022, and the number is growing rapidly.

The night sky is a resource open to all of us, but it's rapidly becoming a 'tragedy of the commons' scenario. Thousands of satellites in the night sky are not only ruining the beauty of the stars, but are seriously hampering astronomers and pose a very serious space debris threat.

As World Space Week this year looks at the message of sustainability in space, it is important to ask: Are we reaching a point where the number of satellites in the night sky is becoming unsustainable?

Related: Wow! Shiny SpaceX Starlink satellites soar with glowing aurora in stunning video

SpaceX's Starlink internet satellite constellations now number more than 2,300 satellites with many thousands more on the way. Other internet providers also have plans to launch hundreds or thousands of satellites. In the latest turn of events, AST SpaceMobile's BlueWalker 3 communications satellite launched on Sept. 10, 2022 with a highly reflective 693-square-foot (64.4-square-meter) antenna that could shine brighter than anything in the sky other than Venus, the moon and the sun.

There are plans for more BlueWalker launches in the future, with even larger antenna arrays. SpaceX, meanwhile, wants to launch Starlink Generation 2, totaling 30,000 satellites. In total, various companies around the world are proposing to launch 400,000 satellites in the near future.

"We're sitting at a crucial branching point," said Andy Lawrence, Regius Professor of Astronomy at the University of Edinburgh, in an interview with Space.com. Lawrence has campaigned against the unregulated expansion of satellite constellations, writing a book on the topic called Losing the Sky (opens in new tab).

In addition, he has appeared as an expert witness in a legal case brought by a U.S. company, ViaSat, against the Federal Communications Commission (FCC) for excluding Starlink and other satellite constellations from being subject to environmental assessments. Although ViaSat lost their case, it was on a technical basis, and so a court has yet to crucially rule whether or not satellite constellations are exempt from environmental scrutiny. This is important because the FCC is currently considering SpaceX's proposal for their Gen 2 constellation.

"Starlink Gen 2 has made a request for 30,000 satellites, and they're ten times bigger [than the generation 1 satellites]," said Lawrence. "So this really is a crucial point. The FCC is really the gatekeeper on the decision of whether to go ahead with this."

Satellite megaconstellations are bad news for astronomers of all kinds. Long, deep exposures of the night sky become disfigured by the streaks of satellites passing through the field of view. The work of the Vera C. Rubin Observatory in Chile, with its 26.2-foot (eight-meter) survey telescope that is set to begin science operations later this decade, is under threat from the growth of satellite constellations. Asteroid hunters increasingly find the trails of satellites rather than the fainter streaks of potentially hazardous near-Earth asteroids. Astrophotographers discover their hard work spoiled by intruding satellites, and radio astronomers are in danger of being drowned out by the incessant chatter of satellites.

While there are ways around these problems writing software to try and remove the satellite trails from images, or pausing exposures if there is a satellite passing over head, for example it ultimately results in more work that costs more money, says Lawrence.

"It's a percentages game, because it won't make any particular type of astronomy suddenly impossible, but it does mean that we will miss some things, it will all get harder," said Lawrence. "We're developing software to try and take satellite streaks out, and that will work to some extent but not completely, depending upon how bright they are. We may just have to accept our losses, that a certain fraction of images will be ruined."

Lawrence and fellow astronomers aren't ready to throw in the towel just yet. He's also keen to point out that they're not being luddites. Satellite internet clearly has very important uses, as we have seen recently with Starlink bringing emergency internet connection to areas of Florida hardest hit by Hurricane Ian, or providing internet access to Ukraine during the ongoing Russian invasion.

"Those of us who are concerned just want to say, 'whoa, slow down'," said Lawrence. "Let's do some independent environmental assessments, they may take a couple of years and that might be uncomfortable for SpaceX, but they're so far ahead of the competition that they should be able to live with that."

It would be unfair not to mention that engineers from SpaceX and one of its rival satellite companies, OneWeb, are working with astronomers to try and find solutions to these problems.

"They do speak to astronomers, and there are parts of their organizations that are quite serious about that," said Lawrence. "They want to help because astronomy is cool. For example, the engineers at SpaceX are working really hard on experiments such as VisorSat and new dark coatings [to make the satellites less reflective], but its all about mitigating the problems, and the only way to really mitigate them is to launch just 3,000 instead of 30,000."

Then there's the problem of space debris. The more satellites there are in orbit, the greater the chance of collisions between them, scattering debris across Earth orbit. These collisions can increase the chance of further impacts that produce even more debris in a runaway effect that, in the worst and most extreme scenario, could make launching new spacecraft too dangerous because there would be too much debris circling the Earth. It's called the Kessler syndrome, and it's beginning to become a real concern for some in the satellite industry.

"The debris problem is really quite worrying," said Lawrence. "It could end up being disastrous, and the whole industry could shoot itself in the foot. Some people in the industry are very concerned about it, but it's almost like, if it's going to be bad then we better get in there quick before it becomes impossible to launch a new satellite without it getting taken out by shrapnel."

Read more: Kessler Syndrome and the space debris problem

That would be the very definition on unsustainability, but Lawrence is keen to emphasize that we haven't reached that point yet. Much will depend upon the FCC's decision regarding Starlink Gen 2 and environmental assessments for satellite constellations in general. In the United Kingdom there have been discussions about having the equivalent of a 'Kitemark' (in the U.K. this is a certification that a product has been safety tested), where investors and insurers could buy into satellite internet, for example, knowing that it has been environmentally assessed and is mitigating its impact.

In the United States, Moriba Jah, a professor of aerospace engineering at the University of Texas at Austin, is leading an initiative called the Space Sustainability Rating that is connected to the World Economic Forum and encourages responsible behavior from satellite providers.

You, too, can get involved, by participating in a letter writing campaign to the FCC ahead of their decision regarding Starlink Gen 2.

"Anyone can write a letter to the FCC and say what they think," said Lawrence. "With my friends at ViaSat, I've put together instructions on how to write a letter to the FCC, and that seems to be slowly working with a number of people having written letters."

Lawrence recommends keeping letters short, describing how satellite constellations could adversely affect your own experience of the night sky, and how they are bad for both science and the sustainability of commercial activities in Earth orbit. You can find Lawrence's advice here (opens in new tab).

So what would be a sustainable number of satellites? Lawrence admits he's not sure. "My gut instinct is that we've not passed that point yet, but we will if we end up with 400,000 satellites. But I think this is a battle that, while I hesitate to say 'win' because we're not really trying to beat someone, we can hopefully arrive at a sensible solution."

For more details, you can also visit the website of the International Astronomical Union's Center for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference, or CPS (opens in new tab).

Follow Keith Cooper on Twitter @21stCenturySETI. Follow us on Twitter @Spacedotcom and on Facebook.

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World Space Week: Sustaining astronomy in an age of satellite megaconstellations - Space.com

According to the predominant cosmological model, the first stars in the Universe formed roughly 100,000 years after the Big Bang. Known as Population III stars, these early stellar masses were very large, short-lived, and contained virtually no metals or heavier elements. Over time, elements like carbon, nitrogen, oxygen, and iron formed in their interiors through nucleosynthesis. When these stars reached the end of their lifespans, they exploded in a supernova many times greater than anything we see today (a super-supernova), causing these elements to be dispersed throughout the cosmos.

For decades, astronomers have been attempting to find evidence of these earliest stars, yet all attempts to date have failed. But thanks to a recent study, a team led by the University of Tokyo thinks they may have finally spotted the first traces of one of the earliest stars in the Universe. While analyzing data previously obtained by the Gemini North telescope of the most distant quasar ever observed, the team noticed a massive cloud of material around it. Based on their analysis, they believe the material came from a first-generation star after it went super-supernova.

The study, which recently appeared in The Astrophysical Journal, was led by Yuzuru Yoshii, a laureate professor of astronomy at the University of Tokyo and the Steward Observatory at the University of Arizona. He was joined by researchers from the National Astronomical Observatory of Japan (NAOJ), Tokyo Universitys Research Center for the Early Universe (RESCEU), the JINA Center for the Evolution of the Elements (JINA-CEE) at the University of Notre Dame, and the Australian National Universitys Mount Stromlo Observatory.

As they indicate in their study, the team believes the most likely explanation for what they observed is that the material is the remains of a first-generation star that exploded as a pair-instability supernova (aka. a super-supernova). These happen when photons in the center of a star spontaneously turn into electrons and positrons the antimatter counterpart to the electron which reduces the radiation pressure inside the star, causing it to collapse. Much like how Population I and II stars collapse after exhausting their hydrogen and helium, this process caused Population III stars to go supernova.

While such an event has never been witnessed, they are theorized to occur when gigantic stars (between 150 and 250 Solar masses) reach the end of their lives. Unlike other supernovae, a pair-instability supernova leaves no stellar remnants and ejects all of the stars matter into its surroundings. In addition, astronomers theorize that this material would contain over ten times more iron than magnesium compared to the ratio of these elements in our Sun. Because of their peculiar characteristics, there are only two ways to find evidence of Population III stars.

First, astronomers can attempt to observe a pair-instability supernova as it happens, the odds of which are very slim. Second, they can attempt to detect the material these stars eject into interstellar space by identifying its chemical signature. In this case, Yuzuru and his colleagues relied on the latter method, which consisted of consulting previous observations made with the Gemini Near-Infrared Spectrograph (GNIRS) on the 8.1-meter Gemini North Telescope.

This telescope is one of two (located in the northern and southern hemispheres) that make up the International Gemini Observatory, which is operated by the National Optical-Infrared Astronomy Research Laboratory (NOIRLab). To identify the quantities of each element present, the team employed an analytical method developed by Yuzuru and co-author Hiroaki Sameshima, a project research associate at the University of Tokyos Graduate School of Science. This method involves measuring the intensity of wavelengths in the quasars spectrum, from which the chemical spectra of the material is extracted.

From their analysis, Yuzuru and his colleagues noted that ejected material contained over ten times more iron than magnesium compared to the ratio of these elements found in our Sun. As Yuzuru explained in a NOIRLab press release:

It was obvious to me that the supernova candidate for this would be a pair-instability supernova of a Population III star, in which the entire star explodes without leaving any remnant behind. I was delighted and somewhat surprised to find that a pair-instability supernova of a star with a mass about 300 times that of the Sun provides a ratio of magnesium to iron that agrees with the low value we derived for the quasar.

Similar searches have been conducted in the past, where astronomers looked for chemical evidence of Population III stars in the Milky Way. And while one tentative identification was made in 2014, Yuzuru and his colleague believe these new results are the clearest indication of a pair-instability supernova to date. If their findings are confirmed, it will provide new insight into how our Universe has evolved since the first stars and galaxies formed. In the meantime, more observations are necessary to see if there are other objects out there that have similar characteristics.

Evidence of these stars could also be found within the Milky Way, where ejecta from primordial stars could be found among objects in our local Universe. With this latest study, astronomers now have a potential pathway for identifying the chemical signatures of the stars that played a vital role in the evolution of the cosmos, gave rise to the first planets, and even life itself.

Further Reading: NOIR Lab, The Astrophysical Journal

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Astronomers see Tantalizing Evidence for one of the First Stars to Form in the Universe - Universe Today

Clean skies, high altitude and complete darkness are vital for Indias cutting-edge astronomical observatory in Ladakhs Hanle village. Jacob Koshy reports on the challenges in having it declared an International Dark Sky Reserve, and the efforts to make residents stakeholders in the process

Clean skies, high altitude and complete darkness are vital for Indias cutting-edge astronomical observatory in Ladakhs Hanle village. Jacob Koshy reports on the challenges in having it declared an International Dark Sky Reserve, and the efforts to make residents stakeholders in the process

Srinivasa Ramanujan was discovered twice in the 20th century. The first was when English mathematician G.H. Hardy discovered the genius mathematician in 1914; and the second was when Indian astronomers in India, led by R. Rajamohan, discovered an asteroid that was later named 4130 Ramanujan. It was the first time in 104 years that asteroids were discovered from India. Their instrument, the 45-cm Schmidt telescope, was housed on the Javadi hills in Kavalur, Tamil Nadu.

This spot is today the Vainu Bappu Observatory and is run by the Indian Institute of Astrophysics (IIA), Bengaluru, and is among India's foremost observatories. It was chosen in the 1960s because it was an impressive 750 metres above sea level, located amid a forest and offered fairly unobstructed vistas of the night sky.

Read | Can the Dark Sky Reserve at Hanle be a gamechanger for stargazing in India?

But this wasnt ideal. Kavalurs geography put it in the path of both monsoonal clouds, during June-September and the returning, or northeast, monsoon in November, forcing the observatory to often shut down for months. Rainclouds absorb starlight and radiation from cosmic objects, preventing them from being caught on the telescopes of cameras. So IIA scientists began their search in the early 1980s for a place least affected by the monsoon.

To be able to detect stars or traces of cosmic phenomena, such as supernovae or nebulae from light years away, astronomers must be able to catch the faintest slivers of their radiation that often lie outside the range of visible light. Such radiation is, however, easily absorbed by water vapour and so it helps to have a telescope high above ground where the atmosphere is drier. A dry, high-altitude desert is in many ways the ideal location, says Annapurni Subramaniam, Director of the IIA. Such terrain is difficult and quite inaccessible. We commissioned several expeditions and teams to different parts of the Himalayas and finally Hanle, Ladakh was chosen.

A largely smooth double-lane highway from Leh, the capital of Ladakh, to Hanle cuts through a valley scooped out of the mountains of the Ladakh range and the teal-coloured Indus. Army units and border check-posts punctuate the landscape that opens out into the Changthang Wildlife Sanctuary, where you can spot the occasional herd of the Tibetan wild ass and swarms of leaf warblers. As the road ascends, a smattering of hamlets, surrounded by pasture land, comes into view with herds of Changthangi sheep, the source of pashmina wool.

Situated at 14,000 ft above sea level and a little over 250 km southeast of Leh, Hanle is a village of about 320 houses and a population of about 1,500, according to Paljor Therchin, the sarpanch of Hanle.

Against the backdrop of a blue sky flecked with cottony clouds, two huge metallic capsules one higher than the other incongruously rise out of the hills. Next to them, satellite dishes, like ushers, point to the sky. From here, a tarred road spirals down about 900 ft to flat land where makeshift cabins and a small building serve as ancillaries to a giant, parabolic dish that is a complex of a thousand mirrors bathed white in sunlight, resting on criss-crossing steel frames of red and blue. Men, some perched, some dangling on the beams, weave out of the meshes of this honeycomb structure.

Facing this are what look like seven concrete cannons, one in the centre and six surrounding it. Each has seven mirrors that together resemble a robot-contingent of photographers training their apertures at some uncertain blink-and-you-will-miss cosmic event.

This entire set-up, laid out on the mountain called Digpa-Ratsa Ri, aka Mt Saraswati, comprises the Indian Astronomical Observatory (IAO). The multicoloured dish is the Major Atmospheric Cherenkov Experiment Telescope (MACE) built by a consortium of the Bhabha Atomic Research Centre, the Tata Institute of Fundamental Research, the Electronics Corporation of India Ltd. and the IIA. The dish, with a diameter of 21 m, is the second largest of its kind in the world and the only one at such an elevation. Its goal is to detect Cherenkov radiation from space.

This is a special kind of light from gamma rays, or the most energetic sources of radiation, that can result from dying stars or several galactic events. The seven-telescope contingent, called HAGAR (High Altitude Gamma Ray), also looks at Cherenkov radiation, although at a lower range of energies. The metallic capsule, the highest of the observatories, is the Himalayan Chandra Telescope (HCT), the oldest and active since 2000. An optical-infrared telescope with a 2-metre lens is designed to detect light from the visible range of the electromagnetic spectrum as well as that just below it, or the infra-red spectrum. The second capsule, situated slightly lower than the HCT, is the GROWTH-India telescope, a 70-cm telescope made by IIA and the Indian Institute of Technology, Mumbai that is equipped to track cosmic events that unfurl over time, such as afterglows of a gamma ray burst or tracking the path of asteroids. Because of the wide span of frequencies covered collectively, the IAO provides multiple vantage points to observe a range of cosmic phenomena and investigate the mysteries of the universe. Telescopes with small diameters generally can track a greater swath of sky but those with larger diameters can peer deeper when trained towards desired locations.

The Indian Astronomical Observatory at Hanle village in Ladakh.| Photo Credit: R.V. Moorthy

The flip-side of Hanles seclusion, making it ideal for astronomy, is the weather and climate. The altitude means that atmospheric oxygen is low, making one prone to mountain sickness.

Among the recommended paraphernalia on a trip to Hanle are cans of oxygen cylinders. The desiccated air that helps the telescope catch ephemeral interstellar light translates to sub-zero winters for at least six months of the year. The summer months from April to September have cold, windy nights, and with no access to the electric grid, the eager stargazer must brave runny noses and chills.

The IAO telescopes, however, can be controlled remotely via a satellite link. Whatever the weather, astronomers at the IIAs Centre for Research and Education in Science and Technology (CREST), about 35 km from Bengaluru, can manoeuvre the HCT to face their desired spot of sky. The other instruments too are equipped to be remotely controlled. While the HCT is manned 24/7, those on site are required only for maintenance and not for using the telescopes. Researchers who want a shot at using the instruments must apply, in fact compete, for observation time made available in quarterly slots; the applications are scrutinised by scientific committees.

The available time is over-subscribed three times. Every astronomer, even when they have their own telescopes, applies to use these because of the quality of sky and the large number of viewable nights that the telescopes offer. It is their bread and butter, says Subramaniam.

In recent years, these telescopes have helped gain a better understanding of a system of Earth-sized planets orbiting the TRAPPIST-1 star, about 40 light years away from Earth, as well as gravitational waves that resulted from the collision of neutron stars from a billion years ago, she adds.

While these sophisticated instruments and their images are manipulated by scientists, all that novice visitors have to do to realise they are in a special place is look up at the night sky. At least 300 nights a year, the clouds would have been swept away, and the vista looks as if some invisible, giant being had kicked up a sandstorm of stars. Contrary to the thumb rule that the lights that twinkle are stars, those that dont are planets, the sky is studded with unblinking lights.

Twinkling stars imply starlight is being bounced around by atmospheric gases, dust and water vapour, and therefore obscuring to us on land its origins. At Hanle, the thinner air and the elevation means starlight is relatively unimpeded until it descends into the lower, more polluted stretches below.

Heres Jupiter, that bright point straight ahead. From here trace a straight line to the right till you see that dim star-like point. Thats Saturn, Dorje Angchuk gesticulates to craned necks. You dont need your phones flashlight to navigate here. Close your eyes, clear out the artificial light, absorb the darkness, and open them. Youll see everything. As chief engineer at IIA, Angchuk, a native of Leh and the person in-charge of the HCT systems, has made countless trips to Hanle in the last quarter century and been closely involved in the installation of IAO telescopes.

In the last couple of years, he has curated an avidly-followed Twitter stream of night-sky photographs of Hanle. Over the last several months, particularly since Ladakh was marked out as a distinct Union Territory from Jammu and Kashmir, he has been in the thick of a project that will shape the future of Hanle.

Light is the enemy, says Pawan Kotwal, Principal Secretary in the Ladakh Administration, referring to the phenomenon of light pollution in which artificial light from cities and home electrification have obscured the natural night sky. Recent studies show that clouds, the biggest reflectors of sunlight, scatter artificial light from ground-based sources, amplifying light pollution.

For astronomy, a discipline that hinges on the wisps of light, artificial sources of light are contaminants. Thubstan Rinchen, the officer in charge of MACE, said in an IIA-commissioned documentary that light from, say, the high beam of a vehicle at night would flood the sensors of the telescope. Separating this light from that collected as part of experiments is a cumbersome process and results in loss of scientific data.

Hanle, as it currently stands, is largely shrouded in darkness. Disconnected from the electric grid, solar panels and a diesel generator are the only sources of electricity. Hanle only gets electricity from 7 p.m. to 11 p.m. The freezing months, says Padma Lazo, who runs a homestay here, can see temperatures dip to minus 40C, though cookstoves and dung provide heat. We dont need electricity all the time but better jobs and schools for our children would be welcome.

Ladakhs recent Union Territory status, a government eager to expand economic opportunities via tourism and the Indian Army expanding its infrastructure development, lighting to bolster its defence at the India-China border which is not far away all these are challenges in keeping light from seeping into Hanle.

To strike a balance, the Ladakh government along with the IIA and Indias Scientific Ministries is laying the groundwork to have Hanle declared as an International Dark Sky Reserve by the International Dark-Sky Association. Since 1988, the U.S.-based non-profit has been advocating the cause of minimising light pollution and certifies places where night skies are least polluted as International Dark Sky Reserves or sanctuaries.

The average tourist visits for high roads, exotic landscape, and the Pangong Lake. Hanle is already in a wildlife sanctuary and developing it as such a reserve would encourage a newer kind of tourism, or astro-tourism, says Kotwal. The most important condition, however, is that it must have the support of the local community.

In the weeks ahead, amateur and professional astronomers have been roped in by the IIA and the local government to give talks on constellations to villagers. As many as 18 telescopes will be set up in village clusters, and homestay owners trained in elementary astronomy to guide astro-tourists. Villagers will also be given dark curtains to minimise outgoing light from residences. Already, at night time, vehicles are restricted from pointing their beams upwards, and roads will be installed with light delineators.

Having been promised electrification in two years and funds from the government to improve their homes to homestays, residents of the village say they would be happy to comply with light restrictions. Thats not a problem for us. However, more than residential lights, its the light from Army bases that are actually stronger. That should be managed too, says Therchin, who is also a religious head at a nearby monastery.

Kotwal and Angchuk say Commanding Officers of the units have readily agreed to comply.

We have a long-standing relationship with the community and they were involved in construction of the existing facilities, says Subramaniam. So far, the relative height of the HCT had protected its observations from light pollution, and while the regions development is inevitable, setting out guidelines and restrictions on light would ensure that both astro-tourism and the immaculate skies can coexist, she adds.

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Indian Astronomical Observatory in Hanle, Ladakh | Where the stars must not twinkle - The Hindu

Have you checked NASA's Astronomy Picture of the Day yet?

Oct 10, 2022, 07:49 pm 2 min read

If Space and the cosmos pique your interest, NASA's daily astronomy pictures will definitely find a spot in your heart. NASA features a different and unique photograph of our Universe every day with a brief explanation by a professional astronomer. Today's Picture of the Day is this surreal photo of a Double Lunar Analemma over Turkey, captured by architect and astrophotographer Betul Turksoy.

Imaging an analemma of the Moon

"An analemma is that figure-8 curve you get when you mark the position of the Sun at the same time each day for one year," read the explanation. To capture an analemma of the Moon one must wait a little longer. "On average, the Moon returns to the same position in the sky about 50 minutes and 29 seconds later each day."

Analemma-like curve forms over one lunar month

If you are intrigued about how this incredible image was captured, read on. To trace the full cycle, the moon must be photographed 50 minutes and 29 seconds later every following day from the first day. Over one lunar month, it will trace out an analemma-like curve since the actual position of the moon wanders owing to its tilted and elliptical orbit.

If you are wondering why there are two sets of moons in similar positions, here's why: "Since the featured image was taken over two months, it actually shows a double lunar analemma," read the explanation. The point where the moon seems to have vanished is where the crescent phases are too thin and become a new moon. The photo was shot during July and August.

Check out the astrophotographer's Instagram post

Instagram post

A post shared by betul_turksoy on October 10, 2022 at 7:16 pm IST

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Have you checked NASA's Astronomy Picture of the Day yet? - NewsBytes