Category Physics

Which is the first comet to encounter a spacecraft?

Discovered first on December 20, 1900, comet 21P/Giacobini-Zinner gets its name from two astronomers. From being one of the last comets to be discovered in the 19th Century, this comet is now best known for having the first encounter with a spacecraft.

Comets are popular for different reasons. There’s Halley’s comet, which is the most famous of them all. Regularly visible to the naked eye from the Earth, Halley’s comet has been observed and recorded by astronomers for over 2,000 years. Then, there is comet Hyakutake. Discovered only in 1996, this comet’s passage near the Earth in the same year was one of the closest cometary approaches in nearly 200 years. We will be turning our attention to comet 21P/Giacobini-Zinner, whose claim to fame now includes being the first comet to encounter a spacecraft. This comet was first discovered on December 20, 1900, making it one of the last comets to be discovered in the 19th Century. A discoverer of a number of comets, French astronomer Michel Giacobini found this comet while skygazing from Nice Observatory. It was followed for two months and orbital calculations revealed that the comet was a periodic object with an orbital period less than seven years.

Recovered in 1913

It wasn’t recovered in 1907, when it was not placed favourably for viewing. Even though the comet was expected to be unfavourably placed in 1914 as well, German astronomer and renowned science historian Ernst Zinner accidentally rediscovered it on October 23, 1913.

Since both Giacobini and Zinner discovered and recovered this comet, it is named after them and is called comet 21P/Giacobini-Zinner. The letter “p” indicates that it is a periodic comet, which are comets with orbital periods less than 200 years. When orbital calculations were revised when the comet was recovered in 1913, its orbital period was found to be close to 6.6 years, and the comet has been observed on almost every return since then.

Draconid meteor shower

This comet had favourable returns in 1959, 1985, and 2018, when it was well observed as its perihelion (closest approach to sun) allowed it to pass close to the Earth. The nucleus of the Giacobini-Zinner sprays ice and rock into space every time it returns to the inner solar system. This makes the comet the parent comet of the Draconid meteor shower, which takes place in early October each year.

While this meteor shower is quite weak in most years, there have been Draconic meteor storms on record, meaning that over 1,000 meteors were seen per hour at the location of the observer. The 1933 and 1946 Draconid storms were particularly intense, with over 500 meteors observed per minute in Europe during the former and 50-100 per minute seen in the U.S. during the latter.

Farquhar’s idea

Comet Giacobini-Zinner’s current claim to fame was a result of its favourable return in 1985. When funding for a spacecraft mission to comet 1P/Halley, which was enroute to its 1986 perihelion passage, didn’t materialise, planetary scientist Robert Farquhar came up with an idea. He suggested that the already existing International Sun-Earth Explorer 3 (ISEE-3) be placed on an alternate path that would take it towards Giacobini-Zinner.

Once the idea was approved, ISEE-3 was sent on a series of lunar flybys that would take it towards Giacobini-Zinner. Following the final lunar flyby in December 1983, ISEE-3 was renamed the International Cometary Explorer (ICE).

On September 11, 1985, ICE passed through the ion tail of Giacobini-Zinner, thereby completing the first encounter between a comet and a spacecraft. While ICE lacked cameras, it did carry scientific instruments that enabled it to record measurements of the electric environment around the comet and also as to how the comet interacted with the solar wind.

Even though an international fleet of spacecraft, including ICE, met Halley in 1986 from a number of vantage points for a study like never before, Giacobini-Zinner will forever hold the title of being the first comet to encounter a spacecraft. While its most recent return in 2018 might be comet 21P’s most favourable return in the 21st Century, you can still look forward to its approach once in less than seven years, and maybe even try and track it.

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Is a missing moon responsible for Saturn’s rings and tilt?

Now known to host at least 83 moons, researchers propose that Saturn at one point must have had at least one more satellite, which they call Chrysalis

While all four gas giants – Jupiter, Saturn, Uranus, and Neptune – have rings, Saturn is the most popular ringed-planet. Swirling around Saturn’s equator, these rings indicate clearly that the planet is spinning at a tilt relative to the plane in which it orbits the sun.

For a long time, astronomers have suspected that this tilt is the result of Saturn’s interactions with neighbouring Neptune. A new modelling study by astronomers at Massachusetts Institute of Technology (MIT). however, suggests that while the two planets may have been in sync before, Saturn has since escaped Neptune’s pull.

Call it Chrysalis

In a study appearing in Science in September, the MIT team

posits that a missing moon might be responsible for this planetary realignment. Now known to host at least 83 moons, Saturn at one point must have had at least one more satellite that the researchers call Chrysalis.

The team estimates that after orbiting Saturn for several billion years, Chrysalis became unstable about 160 million years ago, coming too close to Saturn in the process. As the proposed satellite was long dormant before suddenly becoming active – just like a butterfly’s chrysalis – the researchers gave it the name Chrysalis.

The resulting encounter pulled the satellite apart and the loss of the moon was enough for Saturn to escape

Neptune’s grasp and leave it with its current tilt. Additionally, the researchers suggest that while most of Chrysalis’ shattered body may have impacted Saturn, a fraction of its fragments could have remained suspended in orbit. These could then have broken into small icy chunks to form the planet’s standout rings.

Explains two mysteries

The missing moon hypothesis, the researchers believe, could thus explain two mysteries pertaining to Saturn’s system. While one of these is Saturn’s present-day tilt, the other one is the age of its rings.

The rings are estimated to be about 100 million years old. very much younger than the planet itself. If the rings were indeed formed from fragments of Chrysalis, then the story fits perfectly.

Cassini’s inputs

The team of researchers arrived at this hypothesis by modelling the interior of Saturn. They identified a distribution of mass that matched the gravitational field that was observed by the Cassini spacecraft in its final phases. What they found indicated that Saturn is no longer in sync with Neptune, paving the way for researching various hypotheses, before arriving at their final result. The lead author of the study says that it is “a pretty good story, but like any other result, it will have to be examined by others”.

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U.K. LAUNCHES NEW COURSE TO TEACH STUDENTS HOW TO SAVE THE PLANET.

The U.K. will offer a new GCSE (General Certificate for Secondary Education) from September 2025 that will “offer young people a chance to develop a deeper knowledge and understanding of this amazing planet, its environment and how to conserve it,” said education secretary Nadhim Zahawi.

The qualification will allow students to learn about organisms and their environments, as well as environmental and sustainability issues. Students will also develop skills for future careers in conservation, “from understanding how to conserve local wildlife to conducting the fieldwork needed to identify species”

Students learn about environmental issues already; this course will teach them about the history and evolution of species and the impact of life on natural environments.

Teen conservationist and wildlife writer Kabir Kaul, 15, said the course “will give my generation the knowledge and practical skills they need to value and protect the environment around them”.

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WHICH IS THE FIRST CARBON NEUTRAL VILLAGE IN INDIA?

Palli, a village in Jammu and Kashmir’s border district of Samba, became India’s first “carbon-neutral panchayat on April 24, 2022, with Prime Minister Narendra Modi dedicating to the nation a 500-kilowatt solar plant. Palli, according to the Prime Minister, has shown the way to the country by becoming carbon neutral. But what is carbon neutrality and how can it be achieved? Let’s find out.

What is carbon neutrality?

We all know that carbon dioxide emissions are one of the primary causes of climate change and an increasingly warming planet. Carbon-neutrality is the state of achieving a balance between the greenhouse gases put out into the atmosphere and those removed. The term ‘Net-zero’ is sometimes used instead of carbon neutrality and they broadly mean the same. Increasingly, countries, companies, and organisations have been committing to achieve carbon-neutrality or net-zero carbon emission through measures such as reforestation and artificial carbon sequestering. But some environmental activists have criticised such offsetting measures as an excuse to continue polluting. If you’ve been wondering about the benefits of achieving carbon neutrality, there are many such as less pollution, improved air quality, better health and environment, green jobs, reducing the impact of climate change, and a greener planet.

How can it be achieved?

Carbon neutrality can be achieved by reducing the use of fossil fuels and by adopting renewable energy sources, by developing energy-efficient technologies, by adopting massive reforestation or tree-planting measures and by investing in technologies such as carbon sequestration that can remove carbon from the atmosphere. By the way, carbon sequestration is the process of capturing and storing atmospheric carbon dioxide underground permanently and safely. However, no technology or quantity of trees planted could offset the emissions currently generated globally, unless every country and every household is part of this solution.

Palli’s feat

The unassuming village of Palli has made history by becoming India’s first carbon-neutral solar village. It has achieved this feat with the installation of a 500-kilowatt solar plant. According to reports, the project was finished in record time (of nearly three weeks) at a cost of Rs. 2.75 crore. Under the central government’s ‘Gram Urja Swaraj’ programme, as many as 1,500 solar panels put up on an area of 6,408 square metres will provide clean electricity to 340 homes in the model panchayat.

The green energy generated will be distributed to the village through the local power grid station, which has a daily requirement of 2,000 units.

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WHAT IS JUPITER’S IO MOON?

Io or Jupiter I, is the innermost and third-largest of the four Galilean moons of the planet Jupiter. Slightly larger than Earth’s moon, Io is the fourth-largest moon in the Solar System, has the highest density of any moon, the strongest surface gravity of any moon, and the lowest amount of water (by atomic ratio) of any known astronomical object in the Solar System. It was discovered in 1610 by Galileo Galilei and was named after the mythological character Io, a priestess of Hera who became one of Zeus’s lovers.

With over 400 active volcanoes, Io is the most geologically active object in the Solar System.

This extreme geologic activity is the result of tidal heating from friction generated within Io’s interior as it is pulled between Jupiter and the other Galilean moons—Europa, Ganymede and Callisto. Several volcanoes produce plumes of sulfur and sulfur dioxide that climb as high as 500 km (300 mi) above the surface. Io’s surface is also dotted with more than 100 mountains that have been uplifted by extensive compression at the base of Io’s silicate crust. Some of these peaks are taller than Mount Everest, the highest point on Earth’s surface.  Unlike most moons in the outer Solar System, which are mostly composed of water ice, Io is primarily composed of silicate rock surrounding a molten iron or iron sulfide core. Most of Io’s surface is composed of extensive plains with a frosty coating of sulfur and sulfur dioxide.

Io’s volcanism is responsible for many of its unique features. Its volcanic plumes and lava flows produce large surface changes and paint the surface in various subtle shades of yellow, red, white, black, and green, largely due to allotropes and compounds of sulfur. Numerous extensive lava flows, several more than 500 km (300 mi) in length, also mark the surface. The materials produced by this volcanism make up Io’s thin, patchy atmosphere and Jupiter’s extensive magnetosphere. Io’s volcanic ejecta also produce a large plasma torus around Jupiter.

Io played a significant role in the development of astronomy in the 17th and 18th centuries; discovered in January 1610 by Galileo Galilei, along with the other Galilean satellites, this discovery furthered the adoption of the Copernican model of the Solar System, the development of Kepler’s laws of motion, and the first measurement of the speed of light. Viewed from Earth, Io remained just a point of light until the late 19th and early 20th centuries, when it became possible to resolve its large-scale surface features, such as the dark red polar and bright equatorial regions. In 1979, the two Voyager spacecraft revealed Io to be a geologically active world, with numerous volcanic features, large mountains, and a young surface with no obvious impact craters. The Galileo spacecraft performed several close flybys in the 1990s and early 2000s, obtaining data about Io’s interior structure and surface composition. These spacecraft also revealed the relationship between Io and Jupiter’s magnetosphere and the existence of a belt of high-energy radiation centered on Io’s orbit. Io receives about 3,600 rem (36 Sv) of ionizing radiation per day.

Further observations have been made by Cassini–Huygens in 2000, New Horizons in 2007, and Juno since 2017, as well as from Earth-based telescopes and the Hubble Space Telescope.

Credit : Wikipedia 

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WHAT WAS THE MERCURY SEVEN MISSION?

On May 15, 1963, the last mission of Project Mercury got under way. Astronaut Gordon Cooper closed out things in style as his flight stretched the capabilities of the Mercury spacecraft to its limits.

The Mercury Seven, also referred to as the Original Seven, were a group of seven astronauts selected to fly spacecraft for Project Mercury – the first human space flight program by the U.S. Even though there were some hiccups, the project, initiated in 1958, was largely successful in its three goals of operating a human spacecraft. investigating an astronaut’s ability to work in space, and recovering spacecraft and crew safely.

Youngest of the Mercury Seven

The final flight of Project Mercury took place in May 1963. The youngest of the Original Seven, astronaut Gordon Cooper, went on to become the first American to fly in space for more than a day during this mission.

Leroy Gordon Cooper Jr. was born in 1927 and served in the Marine Corps in 1945 and 1946. He was commissioned in the U.S. Army after attending the University of Hawaii.

He was called to active duty in 1949 and completed pilot training in the U.S. Air Force. He was a fighter pilot in Germany from 1950 to 1954 and earned a bachelor’s degree at the Air Force Institute of Technology in 1956. He served as a test pilot at Edwards Air Force Base in California until he was selected as an astronaut for Project Mercury. Cooper flew Mercury-Atlas 9, the last Mercury mission, which was launched on May 15, 1963. He called his capsule Faith 7, the number indicating his status as one of the Original Seven astronauts.

Conducts 11 experiments

Longer than all of the previous Mercury missions combined. Cooper had enough time in his hands to conduct 11 experiments. These included monitoring radiation levels, tracking a strobe beacon that flashed intermittently, and taking photographs of the Earth.

When Cooper sent back black-and-white television images back to the control centre during his 17th orbit, it was the first TV transmission from an American crewed spacecraft. And even though there were plans for Cooper to sleep as much as eight hours, he only managed to sleep sporadically during portions of the flight. After 19 orbits without a hitch, a faulty sensor wrongly indicated that the spacecraft was beginning re-entry. A short circuit then damaged the automatic stabilisation and control system two orbits later. Despite these malfunctions and the rising carbon dioxide levels in his cabin and spacesuit. Cooper executed a perfect manual re-entry.

Lands without incident Cooper had clocked 34 hours and 20 minutes in space, orbiting the Earth 22 times and covering most of the globe in the process. This meant that he could practically land anywhere in the globe, a potential pain point that the U.S. State

Department was nervous about. In fact, on May 1, 1963, the country’s Deputy Under Secretary fuel, venting gas that made the spacecraft roll, and more in what felt like a never-ending series during their eight-day mission. They, however, completed 122 orbits, travelling over 5.3 million km in 190 hours and 56 minutes, before safely making their way back to Earth.

After accumulating more than 225 hours in space, Cooper served as the backup command pilot of Gemini 12, which was launched in November 1966, and the backup command pilot for Apollo 10 in May 1969. By the time Cooper left NASA and retired from the Air Force in July 1970, human beings had set foot on the moon, further vindicating the Mercury and Gemini projects that Cooper had been involved with.

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