Category Physics

Why can t we bounce radar signal off the sun and determine 1 au directly

 

On April 7, 1959, a three-member team led by Stanford electrical engineer Von R. Eshleman recorded the first distinguishable echo of a radar signal bounced off the sun. A.S.Ganesh tells you more about Eshleman and how his team achieved this success…

When we generally say “reach for the stars,” we use it as a phrase to convey having high or ambitious aims. Some people, however, reach for the stars in the real sense. Stanford electrical engineer Von R. Eshleman was one of them and the star he reached out for was our sun.

Born into a farming community in Ohio, U.S. on September 17, 1924, Eshleman attended the General Motors Institute of Technology in Flint, Michigan, while still being a high school student. Similarly, even before earning his bachelor’s degree in electrical engineering from George Washington University in 1949, he started attending Ohio State University.

Intrigued by wave science

Before this, he had a stint with the navy during World War II, working as an electrical technician from 1943-46. It was during this period that he was drawn towards wave science. Intrigued by both sonar and radar, Eshleman had the idea that he could bounce radio signals off the surfaces of the sun and the moon, in order to study their hidden structures. While his own ship-based experiments of the time weren’t successful, they paved the way for his future research.

Having received his master’s degree from Stanford in 1950, he went on to earn his Ph.D. in 1952. He was recruited by Stanford to be a research professor, a position he held until 1957, when he was promoted to the teaching faculty as an Assistant Professor (Associate Professor back then). By 1962, he had not only managed to bounce radar off the sun, but also became a full professor at Stanford.

The same war that had planted the idea in Eshleman’s mind for bouncing radar off surfaces also saw the rapid development of radar. Bouncing radar off distant surfaces wasn’t an idea exclusive to Eshleman. Radar was successfully bounced off the moon in the 1940s itself and the first attempts to bounce radar off Venus were made in the late 1950s, albeit with mixed results.

16-minute round-trip

Eshleman’s three-member team, including Lt. Col. Robert C. Barthle and Dr. Philip Gallagher, achieved success in bouncing radar off the sun on April 7, 1959. The tests, in fact, were run on April 7, 10 and 12, with an average time of 16 minutes and 32 seconds spent for the signals to travel the 149 million km distance between the Earth and the sun and back again.

The researchers needed many months to confirm that they had indeed succeeded and when they finally made their announcement public with a press conference in February 1960, it was with 99.999% certainty.

Coded pulse

Eshleman had explained to the gathered media persons that the radar antenna consisted of 5 miles of wire that was spread out across over 10 acres of land, and a 40,000 watt transformer.

Every time the test was conducted, a coded pulse was beamed at the sun in 30-second bursts. This was done to enable identification once it returned after bouncing off the sun.

While 40,000 watts were sent out, atmospheric and spatial dissipation meant that only about 100 watts reached the sun. Similar losses during the return journey meant that only a miniscule amount of energy returned, making detection difficult. The task was further complicated by the fact that this small amount of energy was now part of the vast amounts of similar energy that the sun itself radiates. The other wavelengths. By spending over six months with some of the best computers of the time, they were able to conclude that the coded pulse that they sent out was among the radio emissions of the sun.

In 1962, Eshleman, along with Stanford colleagues, founded the Stanford Center for Radar Astronomy to oversee radio experiments. Even though he began his career in radar astronomy, Eshleman is now best remembered for his pioneering work using spacecraft radio signals for precise measurements in planetary exploration. While he briefly served as Deputy Director of the Office of Technology Policy and Space Affairs in the U.S. Department of State, he was most comfortable among academic circles and hence returned to Stanford, where he flourished. Eshleman died in Palo Alto on September 22, 2017, five days after turning 93.

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What will replace the ISS in 2031?

The International Space Station or ISS is to be deorbited by 2031. Where will it go? Satellites and spacecraft are machines, similar to washing machines and vacuum cleaners. They will not last forever. It doesn’t matter what job they do, whether it’s to observe weather, measure greenhouse gases in the atmosphere, or study the stars. All space machines grow old, wear out and die.

For satellites in Low Earth Orbit (LEO), engineers use the last bit of fuel to slow it down. When the fuel runs out, it falls out of orbit and burns up in the atmosphere. The satellites in very high orbits are sent even further away from Earth, since more fuel is required to bring them down! These satellites are sent into a so-called ‘graveyard orbit, almost 36,000 km above Earth. Space stations and large spacecraft that are in LEO are too large to incinerate entirely on re-entry. So the deorbiting is monitored closely to ensure the debris falls on a remote, uninhabited area. There is an area like this. It’s nicknamed ‘spacecraft cemetery’ and it lies in the middle of the South Pacific Ocean at a spot called Point Nemo. (‘Nemo’ is Latin for ‘nobody’.) Point Nemo is so remote that the ISS will meet its watery grave there. It is considered ideal for dumping space debris as the waters are said to be poor in nutrients and biodiversity. No one has really studied the marine life or lack of it in Point Nemo. Environmentalists fear that in addition to the space junk already present in Point Nemo, the ISS debris will add tons of experimental equipment, materials and even traces of altered human DNA.  

What important events happened in space in 2022?

Space and Science: From the spectacular images dispatched by the James Webb Space Telescope and NASA’S ambitious missions to explore the moon to the breakthrough in malaria vaccine and the invention of the half-a-millimetre-wide remote controlled, walking robot, the year 2022 witnessed plenty of wow moments in Space and Science.

1. HD 1

In April 2022, we discovered the most distant galaxy to date. Christened HD 1, this galaxy is some 13.5 billion light-years away. To explain why the galaxy was unusually bright in ultraviolet light, the astronomers propose that either HD1 might be forming stars at a very high rate or may be home to a supermassive black hole. HD 1 could also be home to the Population III stars, the very first stars of the Universe. The discovery of HD 1 also breaks the record of the GN-Z11 galaxy that was discovered in 2017, lying some 13.4 billion light-years away.

The distant early galaxy HD1, object in red, is shown at the centre of this undated zoom-in handout image.

2. China’s space milestones

In 2022, China took a firm foothold in space with significant additions to its own space station called “Tiangong”. The space station will assist future Chinese missions and also help carry out scientific research and enable the stay of astronauts for longer periods in space. In July 2022, it launched its laboratory module called “Wentian”. The final piece “Mengtian”, also a laboratory module, was launched and docked, thereby completing the basic construction of its space station. It may be recalled that China began construction of its space station with the “Tianhe” module, the main living quarters for astronauts in 2021. Seen here is the Long March 5B rocket, carrying China’s Mengtian science module, the final module of Tiangong space station, lifting off.

3. James Webb Space Telescope

The James Webb Space Telescope, the largest and most powerful space telescope (launched in December 2021), has been dispatching stellar images of the universe since July 2022, propelling astronomical research in new directions. It has captured the farthest and oldest galaxies seen to date; offered a detailed image of the famous Pillars of Creation; presented the clearest view of Neptune’s rings, and captured the geographical phenomenon on Jupiter’s surface. It also gave us the first evidence of carbon dioxide in the atmosphere of an exoplanet – all this from its orbit around the second Lagrange point, a million miles away from Earth. Seen here is the detailed image of the Pillars of Creation shared by NASA’s James Webb Space Telescope.

4. DART mission

In a first-of-its-kind mission, NASA launched its Double Asteroid Redirection Test (DART) spacecraft successfully in September 2022. The mission aimed at deflecting asteroids was a step towards preparing the world for a potential future asteroid strike like the one which killed the dinosaurs millions of years ago. The first test DART mission targeted the asteroid moonlet Dimorphos, a small body about 160 metres in diameter. NASA confirmed the mission altered the asteroid’s motion in space. The one-way trip proved how a spacecraft could intentionally collide with an asteroid in order to deflect it – a planetary defence against near-Earth objects. The last image to contain a complete view of asteroid Didymos (top left) and its moonlet, Dimorphos, about 2.5 minutes before the impact of NASA’S DART spacecraft.

5. Women in space

The year 2022 was a milestone year for women astronauts. Nicole Mann became the first native American woman to go to space. She was the commander of NASA’s SpaceX Crew-5 mission that blasted off in the Dragon Endurance spacecraft built by SpaceX in October 2022. Jessica Watkins became the first Black woman on a long-duration ISS mission. Nora Al Matrooshi became the first woman astronaut from the UAE. She trained at the Johnson Space Centre in Houston. She is the Arab world’s first woman astronaut and has joined the second batch of the UAE Astronaut Program, training with NASA for future space missions.

6. Artemis

Half a century after astronauts walked on the moon, NASA is a few steps away from putting humankind back on the Moon. The Artemis 1 mission, launched on November 16, was an uncrewed mission designed to test the viability of the Space Launch System, NASA’s next-generation rocket ship, and the Orion Space Capsule scheduled to enter lunar orbit and return to Earth after about 25 days. Artemis 1 demonstrated the capabilities of both SLS and Orion. Its success has cleared the path for Artemis II and III in 2024 and 2025, when astronauts will embark on lunar-flyby-return-to-earth test missions. Seen here is the Orion Capsule, launched on the Artemis rocket, getting drawn into the well deck of the USS Portland during recovery operations.

7. ISRO’s major milestones

Indian Space Research Organisation (ISRO), the country’s space agency, hit many milestones in 2022. The agency launched India’s first privately developed rocket “Vikram-suborbital (VKS)” in November 2022. It also test-fired the Astronaut Safety System for India’s ambitious Gaganyaan mission- the country’s manned mission to space. The year 2022’s last PSLV mission blasted off with one ocean research satellite and eight nanosatellites by Indian start-ups and Bhutan. The 200th consecutive launch of the multipurpose sounding rocket RH200 was also held. The agency successfully launched 36 Gen-1 satellites via the LVM3 launch vehicle as part of its commercial mission for the U.K.-based communications company OneWeb. Seen here is ISRO’s first privately developed Indian rocket Vikram-S being launched from the Satish Dhawan Space Centre in Sriharikota.

8. Human Cell Atlas

In May 2022, about 2.300 researchers from 83 countries came up with a compilation called the Human Cell Atlas. The task involved mapping the positions of over a million cells across 33 different organs in the healthy human body. The aim of this international collaborative consortium is to help understand biology and diseases better. Cutting-edge single cell and spatial genomics and computational techniques were used. The compilation is seen as a major step towards analysing how illnesses can be diagnosed and treated. It is expected to eventually transform our understanding of the 37.2 trillion cells in the human body.

9. Monkeypox

In May 2022, another global health concern arose, when the viral disease Monkeypox was detected in the U.K Monkeypox is a viral zoonotic disease that has symptoms similar to those in smallpox patients. Come July and 90 percent of the cases were centered mainly around Europe. The World Health Organisation declared the monkeypox outbreak a Public Health Emergency of International Concern. Over the months, with testing, surveillance, and vaccination, cases declined. JYNNEOS, a two-dose vaccine that was developed to protect against both mpox and smallpox was used during the outbreak. Monkeypox was renamed Mpox by the WHO. Seen here is a magnifying glass focusing on a vesicle rash created by monkeypox disease.

10. World’s smallest remote-controlled, walking robot

In May 2022, a team of engineers at the Northwestern University in the U.S. demonstrated the world’s smallest walking robots. They measured just half-a-millimeter wide. The crab-shaped remote-controlled invention is a milestone in the field of robotics because they are capable of performing practical tasks in tight spaces. The micro robot, scientists say, could repair small machines and even offer help in performing surgical tasks such as clearing clogged arteries or eliminating cancerous tumours. They are still in developmental stage and were primarily created for academic purpose. Nevertheless, the technology used to create them has potential for scaling.

11. Earth’s shortest day on record

On June 29 2022, we had the shortest day ever to be recorded since the 1960s. The Earth completed its rotation in 1.59 milliseconds less than its routine 24  hours. Scientists recorded this using atomic clocks. In recent years, Earth has been spinning faster and taking less time to complete its rotation. A study in 2016 found that in the previous 2,740 years, Earth’s rotation slowed by about six hours. This truncation of day length is attributed to climate effects. The speed depends on factors such as gravity, changes in winds, ancient ice sheets, dynamics of the planet’s core, and so on.

12.  Paper coating that behaves like plastic

Plastic is problematic. So, a team of researchers from the University of Japan developed a coating for the paper that makes it behave like plastic in July 2022. The coating, “Choetsu”, is claimed to be a cheap and safe mixture of chemicals. It makes the paper rigid, waterproof, bacteria-repelling, and durable. The initial target is to test its efficacy in food packaging. With the technology, paper is given some of the properties of plastic and is touted to degrade safely. The process involves dipping the paper structure into the coating mixture and drying it. The coating is low-cost and biodegradable.

13. Malaria vaccine breakthrough

In a major boost to the global fight against Malaria, one of the leading causes of child mortality, a new vaccine against the disease has been found to be highly effective. The scientists at the University of Oxford’s Jenner Institute who created the vaccine R21/ Matrix M published their trial results in September 2022. It is also the first malaria vaccine to meet and exceed the World Health Organisation’s (WHO) vaccine target of 75% efficacy against the deadly disease. The vaccine has been found to be 77% effective in early-stage trials. Malaria kills more than 4,00,000 people each year. Seen here is a feeding female Anopheles funestus mosquito, a known vector for malaria.

14. Zombie virus

A 48,500-year-old zombie virus that was trapped under a frozen lake in Russia emerged in November 2022. The zombie virus, which was revived by scientists, emerged as a result of global warming. According to the French scientists who published the study, the thawing of the permafrost a permanently frozen layer on or under – Earth’s surface-led to the release of the virus which was trapped and frozen for up to a million years. Scientists maintained that the zombie viruses are a health threat and that further studies need to be undertaken on the risk posed by ancient viral particles.

15. Nobel Prize for Science and Medicine 2022

Alain Aspect, John Clauser, and Anton Zeilinger were awarded the 2022 Nobel Prize for Physics in December 2022. Their work established the quantum property of entanglement. The trio worked independently and were awarded for their experiments with entangled photons, establishing the violation of Bell’s inequalities and pioneering quantum information science”. Meanwhile, geneticist Svante Paabo was awarded the 2022 Nobel Prize in Physiology or Medicine. The award was “for his research in the field of genomes of extinct hominins and human evolution”. Instituted by Swedish chemist Alfred Nobel, the Nobel Prize is presented to honour those from around the world for their remarkable achievements.

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What is Sci-fi?

A member of the Reading Club casually remarked about sci-fi and elaborated, “Science fiction is abbreviated as sci-fi or at times, SF, and this genre yokes the two contradictory disciplines together. As we know, fiction is fictitious and science stands for rationality. But some novelists have succeeded in bringing them together. This popular genre transports readers to a future hinging on the concepts such as time travel, space exploration, aliens, parallel universes, and so on, and, to our amazement, some of them are turning out to be real now.” His explanation aroused our interest in reading and discussing H.G. Wells’ ‘The Time Machine’ in the following meeting.

Four of us participated in a group sharing. Each one focussed on an aspect, and the following are some of our key ideas.

Popularity of sci-fi

Although the origin of science fiction can be traced back to the previous centuries, its golden age is the 1940s and 1950s. These were the decades of significant scientific discoveries, namely space exploration and nuclear energy, which the novelists subsumed in their imagination. As is the case with all genres of fiction, sci-fi too has all the elements such as setting, characters. plot development, theme, climax, and point of view. What makes it unique is all these elements are heavily dependent on scientific facts, theories, and principles hinged on an imaginative story.

Sci-fi movies

Sci-fi movies also have become very popular in the last few decades. It is rare to come across anyone who has not watched or heard of films such as ‘Avatar’, ‘Jurassic Park’, ‘Star Wars’, ‘Alien’, ‘The Matrix’, and so on. They also share the same features as the novels, and, in fact, most of them are based on them.

As many as 23 novels and stories of H.G. Wells alone have been made into films, including The Time Machine. These are immensely popular with moviegoers as they are full of action, adventure, and twists and turns, gripping them.

H.G. Wells

H.G. Wells, the “Father of Science Fiction”, was born in Kent, England, in 1866 and died in 1946. He was the son of domestic helpers, and because of his inexhaustible love for reading, he rose to become one of the most influential British authors. He was a prolific writer, equally known for fiction and non-fiction works, which not many have managed to achieve. He wrote more than 50 novels, dozens of short stories, and many non-fiction, including in the areas of politics, history, and social commentary. But he is more known for his sci-fi novels.

The Time Machine

The novel is about a time traveller who builds a machine and travels to a distant future – the year 8,02,700 A.D., and narrates his experiences at ‘the world of the remote future’ to a group of his friends. It is worth sharing the traveller’s initial encounter with the people/creatures living there:

“He (Eloi) was a slight creature-perhaps four feet high… they looked so frail that I could fancy myself flinging the whole dozens of them about like nine-pins… one of them asked me a question that showed him to be on the intellectual level of one of our five-year-old children…”

“A flow of disappointment rushed across my mind. For a moment I felt that I had built the Time Machine in vain.”

The time traveller elaborately describes the two races of humanity occupying the landscape-child-like Eloi and monstrous Morlocks. Eloi are small, unintelligent, weak but kind and happy people but Morlocks are the labourers forced to live underground working for the overlanders. The traveller has varied experiences with them and finally manages to locate his stolen machine and escapes from the dark world. What initially appears like a utopia turns out to be a dystopia to him.

 The story ends with an unnamed narrator informing us about another trip of the time traveller to reach the end of Earth’s existence and bring back proof of his adventure. But three years have elapsed, and the narrator If wonders whether the traveller is still wandering in time or has perished.

‘The Time Machine’, Wells’ first novel, brought him immediate fame, and till today, has been regarded as a masterpiece of science fiction.

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What are UFOs?

Hundreds of new UFO reports, but…there is still no evidence of aliens. The Pentagon, the headquarters of the United States Department of Defense, has set up a new office to track reports of UFO sightings and collect data.

What are UFOs?

A new Pentagon office set up to track reports of unidentified flying objects (UFOS) has received “several hundreds” of new reports. What are UFOS? Over the centuries, people have reported seeing strange airborne objects or unusual optical phenomena in the sky. These are called UFOS. Over the years, the belief that UFOs are the spaceships of aliens from other planets has gained ground – though without any concrete evidence. Are there possibilities of extraterrestrial life? Shouldn’t the sightings be tracked systematically? Well, that’s why the All-domain Anomaly Resolution Office (AARO) was formed.

2. What is AARO?

The AARO was set up in July 2022 to track unidentified objects in the sky, underwater and in space. It was established following more than a year of attention on unidentified flying objects that military pilots have observed.

It focusses on unexplained activity around military installations, restricted airspace and “other areas of interest” and is aimed at helping identify possible threats to the safety of U.S. military operations and to national security.

3. Scientific approach

Sean Kirkpatrick, director, AARO, did not rule out the possibility of extraterrestrial life and said he was taking a scientific approach to the research. Since the launch of the AARO, there have been several hundred new reports.

“We are structuring our analysis to be very thorough and rigorous. We will go through it all. And as a physicist, I have to adhere to the scientific method.”

4. No alien life

The U.S. military officially calls the 144 sightings observed between 2004 and 2021 as “unidentified aerial phenomena.”

But they have seen nothing that indicates alien life. “I have not seen anything that would suggest that there has been an alien visitation, an alien crash or anything like that,” said Ronald Moultrie, Under Secretary of Defense for Intelligence and Security.

5. Quick facts

* The Air Force conducted an investigation into UFO activity called ‘Project Blue Book’. It ended in 1969 with a list of 12,618 sightings, 701 of which involved objects that officially remained “unidentified.”

* In 1994, it concluded that the 1947 famous “Roswell incident” in New Mexico, was not an UFO but a crashed balloon, the military’s long-standing explanation.

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What does a dust devil sound like on Mars?

Mars rover’s microphone captures ten seconds of rumbling noise created by dust devil on the Red Planet. It’s the same microphone that provided the first sounds of Martian wind in 2021.

What does a dust devil sound like on Mars? A NASA rover by chance had its microphone on when a whirling tower of red dust passed directly overhead, recording the racket.

It’s about 10 seconds of not only rumbling gusts of up to 40 kph, but the pinging of hundreds of dust particles against the rover Perseverance. Scientists released the first-of-its-kind audio. It sounds strikingly similar to dust devils on Earth, although quieter since Mars’ thin atmosphere makes for more muted sounds and less forceful wind, according to the researchers.

The dust devil came and went over Perseverance quickly last year, thus the short length of the audio, said the University of Toulouse’s Naomi Murdoch, lead author of the study appearing in Nature Communications.

At the same time, the navigation camera on the parked rover captured images, while its weather-monitoring instrument collected data.

“It was fully caught red-handed by Persy,” said co-author German Martinez of the Lunar and Planetary Institute in Houston.

Photographed for decades at Mars but never heard until now, dust devils are common at the red planet.

This one was in the average range: at least 400 feet (118 metres) tall and 80 feet (25 metres) across, travelling at 16 feet (5 metres) per second.

The microphone picked up 308 dust pings as the dust devil whipped by, said Murdoch, who helped build it.

Given that the rover’s SuperCam microphone is turned on for less than three minutes every few days, Murdoch said it was “definitely luck” that the dust devil appeared when it did on Sept. 27, 2021. She estimates there was just a 1-in-200 chance of capturing dust-devil audio. Of the 84 minutes collected in its first year, there’s “only one dust devil recording,” she wrote in an email from France.

WHAT IS A DUST DEVIL?

  • Common across Mars, dust devils are short-lived whirlwinds loaded with dust that form when there is a major difference between ground and air temperatures.
  • They are a common feature in the Jezero crater, where the Perseverance rover has been operational since February 2021 – but it had never before managed to record audio of one of them.
  • By chance on September 27, 2021, a dust devil 118 metres high and 25 metres wide passed directly over the rover.
  • This time, the microphone on the rover’s SuperCam managed to catch the muffled, whirring sounds.

Sounds…so far

  • The same microphone on Perseverance’s mast provided the first sounds from Mars namely the Martian wind soon after the rover landed in February 2021.
  • It followed up with audio of the rover driving around and its companion helicopter, little Ingenuity, flying nearby, as well as the crackle of the rover’s rock-zapping lasers, the main reason for the microphone.

ROCK SAMPLES

On the prowl for rocks that might contain signs of ancient microbial life, Perseverance has collected 18 samples so far at Jezero Crater, once the scene of a river delta. NASA plans to return these samples to Earth a decade from now. Its helicopter Ingenuity has logged 36 flights, the longest lasting almost three minutes.

CAN ACOUSTIC DATA SOLVE THE MARTIAN MYSTERY?

  • These recordings allow scientists to study the Martian wind, atmospheric turbulence and now dust movement as never before.
  • The impact of the dust-made “tac tac tac sounds will let researchers count the number of particles to study the whirlwind’s structure and behaviour.
  • It could also help solve a mystery that has puzzled scientists. On some parts of Mars, whirlwinds pass by sucking up dust, cleaning the solar panels of rovers along the way.
  • Understanding why this happens could help scientists build a model to predict where the whirlwinds might strike next.
  • It could even shed light on the great dust storms that sweep across the planet, famously depicted in the 2015 science-fiction film “The Martian”.

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