Category Science

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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Is there anything that people can do to save the planet?

We depend on nature for everything from air, water, food and shelter to sources of energy to run our factories and businesses. So, conserving nature and preserving its biodiversity must be our priority. Here are ten simple tips to do your bit for the planet.

1. Plant trees

Trees are carbon sequesters and increasing the tree cover is perhaps one of the easiest ways to conserve nature. A tree can absorb approximately 25kg of CO2 per year. So, plant a tree to mark this day. Make it a tradition to plant a tree during prominent or celebratory occasions of your life. It can be your birthday or when you finish your academic year or any moment you feel is worth celebrating. If you do not have enough space in your home, see if you can adopt your friend’s yard or make use of the space managed by your area’s residents’ association. Where you do it, make sure that the plant is taken care of Encourage friends and family to take up the practice as well.

2. Conserve energy

 We derive our energy from nature. Everything that is manmade runs on energy obtained from nature. Quite often, a lot of energy also goes to waste. By changing a few habits you can help save energy at home. These include small actions such as turning off the lights (when not in use or when you can depend on daylight), unplugging appliances when not in use, not charging your phone overnight, turning off your faucet when you aren’t using water, taking less time in the shower, reusing waste water in the kitchen gardens and so on. This will help reduce carbon footprint and in turn help in conserving nature. PHOTO: UNSPLASH IMAGES

3.3Rs

The 3Rs of “Reduce”, “Reuse”, “Recycle” is perhaps one of the ultimate mantras for nature conservation. These three small words will help manage waste, save the ecosystem, prevent marine animal casualties and address climate change. The first step is to reduce the waste you generate. This will ensure that less waste ends up in landfills or oceans. Effective waste segregation is the key to this. This helps recover materials for recycling and composting. Reuse articles that you can. And lastly, recycle. This helps prevent soil and water pollution. PHOTO: UNSPLASH IMAGES

4. Use public transport

 One of the major polluters is the global transport sector. It is responsible for approximately one-quarter of greenhouse gas emissions, according to experts. And 95% of the world’s transport energy is still obtained from fossil fuels. Personal transportation adds to the probelm, adding to the greenhouse emissions. The easiest way to avoid this is by switching to public transport. If this is not a practical solution every time, you can still choose public transport twice or thrice a week or during specific hours. This, when done on a regular basis, can significantly help reduce carbon emissions. Alternately, switching to green modes of travel such as a bicycle can help prevent your carbon footprint.

5. Stop using single-use plastics and disposables

 Single-use plastics and disposable cups and utensils have infiltrated our day-to-day life and upended it. Those disposable grocery bags and disposable utensils you use eventually ends up on the earth, polluting our soil. oceans, and marine life. These disposables can easily be replaced with environmentally responsible counterparts. Make a commitment to take out at least one disposable article from your lifestyle. Perhaps. carry a cloth bag to the supermarket instead of asking them for a plastic one. Maybe switch out your lunch box for one made of metal. This can be a good start. And slowly you can make a lifestyle switch by eschewing other disposables. PHOTO: UNSPLASH IMAGES

6. Eat less meat

It is estimated that 80% of forest loss is caused by the conversion of forest land to agricultural land. It leads to habitat destruction and loss of our green cover. Eating less meat can help prevent this and preserve biodiversity and the ecosystem. Since we all have our food preferences, it may not be easy to switch to vegetarianism or veganism. But you can be more aware and mindful of the food on your plate and choose to eat less meat. For instance. you can limit meat consumption to one or two days a week or reduce the number of meals with meat. PHOTO: UNSPLASH IMAGES

7. Use windows and not AC

 Our world is heating up and the surging heat has made us all dependent on air conditioning, the demand for which is increasing by the day. Did you know that air conditioners are also a contributor to the climate crisis? They consume more electricity than any other appliance in your home and consume about 10% of global electricity (along with electric fans). So next time, when possible, open the windows and let the cool breeze in.

8. Explore thrifting

 Fast fashion is one of the greatest threats to the environment. Did you know that it takes about 2,700 litres of water to make just one t-shirt. Or that a pair of jeans requires 7,600 litres of water? With a consumer base that updates its wardrobe according to trends in the fashion industry, the damage to the planet has been exponential. This trend depletes natural resources and harms the planet. This is where thrift shopping comes in. Anyone who has had an older sibling would be no stranger to using their toys, books, or school paraphernalia, thus giving the article a fresh lease of life. This is the concept of thrift shopping. It means using hand-me-downs or second-hand articles. It applies to all forms of merchandise such as clothes, games, toys, shoes, books, appliances, furniture, and so on. It’s time to break the cycle of single-use apparel or appliances and shop at thrift stores. Also, remember to let your friends and family know you are using a thrifted article and the positive impact your move has on nature’s conservation.

9. Embrace minimalism

 Minimalism is a lifestyle choice where you make mindful, deliberate choices of buying only what you truly need. As such you make do with less and avoid overconsumption, which is one of the major contributors to the exploitation and depletion of natural resources. By consuming only what’s essential for your living, your ecological footprint gets reduced. Thereby, the individual environmental impact is limited. Replace consumerism with eco-minimalism. PHOTO: UNSPLASH IMAGES

10. Spend time volunteering

 One way to help conserve nature is to help organisations that are working in the field directly. You can do this by volunteering your time and services at non-profit environmental organisations. These organisations run on donations and they are always on the lookout for people who can help them. Here you may get to actively participate in the community and work on projects aimed at conserving nature and get on-field experience.

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What is the mimicry of nature?

Nature has many sustainable solutions to numerous pressing problems that man is struggling to cope with today. Scientists and engineers study these unique models and systems of nature while designing new technologies. This biologically-inspired engineering, called biomimicry, biomimetics or bionics, is fast gaining popularity in many parts of the world.

American biologist Janine M. Benyus, who wrote the book. Biomimicry Innovation Inspired by Nature was the first to propose that learning from nature would be the perfect tool for eco-design

The leaf of the lotus plant has a way surface that is covered with tiny bumps or ridges. These ridges cause water droplets to roll off carrying away dust and dirt. This unique ability of the plant to clean itself called the Lotus Effect, was the inspiration behind self-cleaning paint coatings

Besides paints, roof tiles and optical sensors in public places like toll bridges also use innovations based on the Lotus Effect Research is also underway to create self-cleaning textiles. plastic and metals.

 

Inspired by insects

The Eastgate Centre, an office complex in Harare. Zimbabwe, has been designed to mimic the mounds of the African tower building termites (Macrotermes Michaelseni) which use a unique system to keep their homes cool. The insects have developed a method which involves opening and closing air vents in the mound in such a way that cool air is drawn inside while hot air escapes through the chimney. The Eastgate Centre uses 10 per cent less energy than conventional structures of the same size. by adopting the design and ventilation system of the termites.

Sportswear manufacturer Speedo’s swimsuit. the Fastskin LZR Racer, has been fashioned from fabric that mimics the shape and rough texture of sharkskin. This ‘sharkskin’ swimsuit reduces drag, enabling competitive swimmers to shave a few crucial seconds off their race timings. This technology is also being used to develop coatings for ship hulls, submarines and aircraft fuselage.

The tropical boxfish, a reef-dwelling amphibian, inspired Daimler Chryslers concept car. The Bionic Car, as the automobile is called, mimics the fish’s aerodynamic shape and the structure of its rigid protective skin. This innovation consumes 20 per cent less fuel and emits 80 per cent less nitrogen oxide than conventional automobiles. Researchers at the University of California have created two prototype glues after studying the way geckos move across ceilings and cling to polished glass. The soles of Tokay geckos have sticky ridges which contain half a million microscopic hairs. These tiny hairs which exert an attractive force on the wall or floor are responsible for the lizard’s superb grip. The stickiness of gecko adhesive never wears off. The scientists cast two sets of imitation gecko toe hairs and then tipped the hairs with silicon rubber or polyester. In the lab, both materials adhered as well to most surfaces as gecko’s feet.

Fire-extinguisher

Scientists at the Leeds University in England have built an experimental contraption that can shoot a spray of chemicals up to a distance of four metres. The device mimics the behaviour of the bombardier beetle, which squirts a hot explosive stream of venom to ward off predators. The chemical concoction is mixed in a sort of ‘combustion chamber in the insect’s abdomen, with inlet and exit valves determining the precise blend.

Researchers are utilising this technology to build pharmaceutical inhalers and long-range fire extinguishers.

Bullet train

The world’s fastest train, the Japanese shinkansen bullet train includes a number of biomimetic innovations. The trains, which zip between cities at a speed of close to 321 km per hour, have serrations similar to those that allow owls to fly stealthily through the night. This feature is incorporated in the overhead wire collectors to reduce noise. The train’s nose, which mimics the aerodynamic beak of the kingfisher, enables the train to exit tunnels without emitting sonic booms.

Velcro plants

It was only recently that man discovered the touch and close tape. Velcro. This discovery was inspired by nature, since seeds, fruits and even whole plants stowaway on the coats of animals by gripping on in the same manner as Velcro: and have been doing so since time immemorial.

It was in the 1950s that George de Mestral of Switzerland observed the burdock fruit which led him to develop Velcro. This fruit has barbed hooks that enable it to fasten itself to an animal’s fur. And when the burr is brushed off the coat of the animal the casing splits open. The seeds of the burdock are thus spread over a wide area and do not have to germinate in one place

Stowaways like the burdock can be counted in the hundreds in the plant world

Froggy tape

Researchers at the Indian Institute of Technology (IT) Kanpur, who were working on creating a reusable sticky tape, received inspiration from an unusual source- the humble tree frog.

It was observed that the sticky toe pads of tree frogs have a patter of tiny channels that increase their adhesion to a surface and prevent the spread of cracks when the frog moves away.

Based on this study, scientists designed a novel sticky tape by placing elastic layers embedded with air or fluid-filled micro channels beneath the authesive layer. This new reusable tape is 30 times stickier than other adhesive tapes.

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Does Saturn have a storm spot?

The Great Red Spot is the largest storm in our solar system. An anticyclone that is over 16,000 km wide-large enough to engulf the entire Earth-the Great Red Spot has been on Jupiter’s surface for hundreds of years.

A new study has shown that Satum Jupiters neighbour, also has long-lasting megastorms. While these are less colourful and blander than those on Jupiter, they do have impacts deep in Saturn’s atmosphere that remain for centuries. The study was published on August 11 in the journal Science Advances

Similar to hurricanes

Similar to hurricanes on Earth but much much larger, megastorms on Satum occur every 20 to 30 years. The causes for these megastorms in Saturn’s atmosphere. which is made up mainly of hydrogen and helium along with traces of methane ammonia and water, remains unknown. Based on radio emissions from Satum. astronomers from the University of California, Berkeley, and the University of Michigan, Ann Arbor, noticed anomalies in the concentration of ammonia gas in the atmosphere. While the concentration of ammonia at mid-altitudes is lower, it was enriched at lower altitudes. 100 to 200 km deeper in the atmosphere.

Precipitation and re-evaporation

The researchers were able to connect this to the past occurrences of megastorms in Satum’s northern hemisphere. According to them, ammonia is being transported from the upper to the lower atmosphere. This effect, which they believe can last for hundreds of years, occurs through the processes of precipitation and re-evaporation.

Additionally, this study reveals that Saturn and Jupiter are very dissimilar despite the fact that both gas giants are made of hydrogen gas. The tropospheric anomalies in Jupiter have been connected to its zones (whitish bands) and belts (darkish bands), while those on Saturn are caused by cyclones.

These differences between Saturn and Jupiter challenge scientists on what they know about the formation of megastorms on gas giants and other planets. Understanding this would not only further our knowledge of terrestrial meteorology, but may also inform us as to how they are formed and studied on exoplanets in the future.

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What are the endangered animals in Eravikulam National Park?

 

There is a rise in the Nilgiri tahr numbers in Eravikulam National Park. The annual census held in April sighted 803 tahrs inside the park compared to 785 last year

The Nilgiri tahr is an endangered mountain goat found only in the hill ranges of the Western Ghats in Kerala and Tamil Nadu.

People visiting the Eravikulam National Park (ENP) near Munnar are often amazed to see Nilgiri tahrs grazing nonchalantly in the tourism zone. Most of the park is out of bounds for visitors except for this demarcated area. Here the tahrs are almost tame, even allowing tourists to come close and click pictures!

In stark contrast, the tahrs in the core area of the park, where only park staff and researchers are allowed to go, are extremely shy, fleeing at the sight and sound of humans.

It is said that the tahr in the tourism zone became accustomed to people because of Walter Mackay, the manager of the Rajamalai tea estate in the 1950s. The estate was situated inside the present sanctuary (it was declared a wildlife sanctuary in 1975 and a national park in 1978). Mackay would toot his cars horn while driving through the sanctuary, attracting herds of tahrs. They would mob his car to be rewarded with handfuls of biscuits!

Of course, visitors today are forbidden to feed and pet the tahrs.

The tahr feeds on a variety of herbs, shrubs and grass. Sure-footed and agile like others of its kind, it can negotiate sheer cliffs with amazing ease.

The Nilgiri tahr is endemic to the open grasslands in the upper reaches of the Western Ghats. It is found mainly in the Nilgiri the Anaimalai and Nelliyampathy hill ranges. A mature male tahr has a coat of deep brown and is called a saddleback for the broad swathe of lighter-coloured fur down its back. The females are smaller and lighter in colour. Both have horns that curve straight back.

In the Eravikulam National Park (ENP), the leopard is its only known predator.

The females and juveniles stay close together in a herd. sometimes numbering over a hundred. The males are usually loners and join the herd during breeding time. The females calve from January to February. The park is closed to tourists at this time

There are around 800 tahrs in the ENP and small numbers in the Parambikulam Tiger Reserve and Silent Valley National Park in Kerala. The tahr is also found in Tamil Nadu’s Anaimalai hills. Around 60% of tahr habitat in the Western Ghats could be lost to climate change from the 2030s onwards. There are only around 3,120 tahrs left in the wild.

Back from the brink                                                                                            

In the early 1950s, poachers hunted the tahrs (their meat was a much sought-after delicacy) to the point of extinction. The tea company that then owned the area stepped in and declared it a sanctuary. A check post was set up at the site of the present Forest Department outpost, and all vehicles passing through the area were searched for firearms, snares and tahr carcasses. This went a long way in stamping out poaching.

Munnars High Range Wildlife and Environment Preservation Association is an NGO set up in 1928 by conservation-minded British tea planters.

Even today, tea and coffee planters in south India are actively involved in conservation and the Nilgiri tahr is a symbol of their success.

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How stars like the Sun generate energy through nuclear fusion?

Stars like our Sun radiate huge quantities of energy because of the nuclear fusion reaction taking place inside their core. Can we use the same idea to generate power that is clean and cheap? Where are scientists around the world working on such projects.

The energy scenario in the world is changing as natural sources conventionally used for generating energy like fossil fuels, oil and coal are fast depleting.

But there are abundant energy sources that cause minimal climate change. Nuclear energy is one such option being used worldwide. In this process, energy is released from the nucleus of an atom either by splitting the heavy atom into two (nuclear fission) or by combining two light atoms into a heavier one (nuclear fusion).

For more than 50 years, energy has been generated in nuclear power plants through fission, a process in which heavy elements such as uranium are bombarded by neutrons, resulting in the splitting of the nuclei and the release of huge amounts of energy in the form of heat.

Nuclear fusion is the opposite process. In fusion reactors, light atomic nuclei are compressed under intense pressure and heat, forcing them to combine together to form heavier nuclei. Fusion also results in the release of huge quantities of energy.

Special conditions Normally, atomic nuclei repel each other if we try to bring them closer; to force them to come close and ultimately fuse together, special conditions have to be generated in the form of very high pressure and extremely high temperatures.

Stars like our Sun radiate huge quantities of energy because of the nuclear fusion reaction taking place inside their core- hydrogen is continuously changing to helium.

The core experiences extremely high pressure because of the gravitational force exerted by the mass of the gigantic star itself, this pressure also leads to the generation of very high temperature inside the star. So, the basic requirement for a fusion reaction is to create a star-like situation inside the reactor in terms of temperature and pressure. To generate such conditions, a lot of energy is needed.

The process must be optimised to generate more energy than it consumes. Fusion could be utilised to generate electricity commercially. The main fuels used in nuclear fusion are deuterium and tritium, both heavy isotopes of hydrogen. Deuterium constitutes a tiny fraction of natural hydrogen, only 0.0153 per cent, and can be extracted inexpensively from seawater. The amount of deuterium present in one litre of water can in theory produce as much energy as the combustion of 300 litres of oil! This means that there is enough deuterium in the oceans to meet human energy needs for millions of years.

Building a fusion power plant that can withstand the immense temperature and pressures produced by this process is one of the century’s greatest engineering challenges. The fuel must be heated to about 100 million degrees Celsius. At that hotter-than-the-sun temperature, a fully ionised gas-plasma is formed. The plasma will then be ignited to create fusion.

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