My Science School

On November 3, 1957, less than a month after they inaugurated the Space Age, the Soviet Union took the next big step with the launch of Sputnik 2.  Hurriedly prepared to take advantage of the propaganda value of the first satellite, Sputnik 2 utilized an animal habitat and carried the dog Laika, the first animal to orbit the Earth.

Sputnik 2 weighed 508 kg, significantly more than its simpler predecessor, and remained attached to its booster rocket after achieving orbit.  Due to the lack of adequate development time, no provisions were made to recover Laika.  Engineers had not designed the environmental control system for a lengthy mission and it is likely that Laika only survived for a few hours after reaching orbit.  On November 10, the satellite’s batteries expired, and receipt of data from the science experiments also ceased.  Sputnik 2 burned up on reentry on April 14, 1958.  It would be nearly three years before the Soviet Union orbited more animals, this time returning the entire “crew” safely to Earth, the first steps in preparation for human space flight.

Laika was a young, mostly-Siberian husky. She was rescued from the streets of Moscow. Soviet scientists assumed that a stray dog would have already learned to endure harsh conditions of hunger and cold temperatures. Laika and two other dogs were trained for space travel by being kept in small cages and learning to eat a nutritious gel that would be their food in space.

The dog's name was originally Kudryavka, or Little Curly, but she became known internationally as Laika, a Russian word for several breeds of dog similar to a husky. American reporters dubbed her Muttnik as a pun on Sputnik.

Unfortunately, Laika's trip into space was one-way only. A re-entry strategy could not be worked out in time for the launch. It is unknown exactly how long Laika lived in orbit — perhaps a few hours or a few days — until the power to her life-support system gave out. Sputnik 2 burned up in the upper atmosphere in April 1958.

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Yuri Gagarin was the first person to fly in space. His flight, on April 12, 1961, lasted 108 minutes as he circled the Earth for a little more than one orbit in the Soviet Union's Vostok spacecraft. Following the flight, Gagarin became a cultural hero in the Soviet Union. Even today, more than six decades after the historic flight, Gagarin is widely celebrated in Russian space museums, with numerous artifacts, busts and statues displayed in his honor. His remains are buried at the Kremlin in Moscow, and part of his spacecraft is on display at the RKK Energiya museum.

More than 200 Russian Air Force fighter pilots were selected as cosmonaut candidates. Such pilots were considered optimal because they had exposure to the forces of acceleration and the ejection process, as well as experience with high-stress situations. Gagarin, a 27-year-old senior lieutenant at the time, was among the pilots selected.

On April 12, 1961, at 9:07 a.m. Moscow time, the Vostok 1 spacecraft blasted off from the Soviets' launch site. Because no one was certain how weightlessness would affect a pilot, the spherical capsule had little in the way of onboard controls; the work was done either automatically or from the ground. If an emergency arose, Gagarin was supposed to receive an override code that would allow him to take manual control, but Sergei Korolev, chief designer of the Soviet space program, disregarded protocol and gave the code to the pilot prior to the flight.

Over the course of 108 minutes, Vostok 1 traveled around the Earth once, reaching a maximum height of 203 miles (327 kilometers). The spacecraft carried 10 days' worth of provisions in case the engines failed and Gagarin was required to wait for the orbit to naturally decay. But the supplies were unnecessary. Gagarin re-entered Earth's atmosphere, managing to maintain consciousness as he experienced forces up to eight times the pull of gravity during his descent.

Vostok 1 had no engines to slow its re-entry and no way to land safely. About 4 miles (7 km) up, Gagarin ejected from the spacecraft and parachuted to Earth. In order for the mission to be counted as an official spaceflight, the Fédération Aéronautique Internationale (FAI), the governing body for aerospace records, had determined that the pilot must land with the spacecraft. Soviet leaders indicated that Gagarin had touched down with the Vostok 1, and they did not reveal that he had ejected until 1971. Regardless, Gagarin still set the record as the first person to leave Earth's orbit and travel into space.

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On June 16, 1963, aboard Vostok 6, Soviet Cosmonaut Valentina Tereshkova becomes the first woman to travel into space. After 48 orbits and 71 hours, she returned to earth, having spent more time in space than all U.S. astronauts combined to that date.

In 1963, Tereshkova was chosen to take part in the second dual flight in the Vostok program, involving spacecrafts Vostok 5 and Vostok 6. On June 14, 1963, Vostok 5 was launched into space with cosmonaut Valeri Bykovsky aboard. With Bykovsky still orbiting the earth, Tereshkova was launched into space on June 16 aboard Vostok 6. The two spacecrafts had different orbits but at one point came within three miles of each other, allowing the two cosmonauts to exchange brief communications. Tereshkova’s spacecraft was guided by an automatic control system, and she never took manual control. On June 19, after just under three days in space, Vostok 6 reentered the atmosphere, and Tereshkova successfully parachuted to earth after ejecting at 20,000 feet. Bykovsky and Vostok 5 landed safely a few hours later.

After her historic space flight, Valentina Tereshkova received the Order of Lenin and Hero of the Soviet Union awards. In November 1963, she married fellow cosmonaut Andrian Nikolayev, reportedly under pressure from Soviet leader Nikita Khrushchev, who saw a propaganda advantage in the pairing of the two single cosmonauts. The couple made several goodwill trips abroad, had a daughter, and later separated. In 1966, Tereshkova became a member of the Supreme Soviet, the USSR’s national parliament, and she served as the Soviet representative to numerous international women’s organizations and events. She never entered space again, and hers was the last space flight by a female cosmonaut until the 1980s.

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Venus is often referred to as Earth’s twin. Both the planets are almost alike in size, density and gravity. Despite similar physical makeup, like most siblings we know of, the two worlds turned out to be drastically different from each other. While Earth is a heaven for life, Venus is a blistering hellscape. Venus has a thick, toxic atmosphere filled with carbon dioxide and at 850 degrees Fahrenheit, it is the hottest planet in the solar system. It has a crushing air pressure and is perpetually shrouded in thick, yellowish clouds of sulphuric acid.

Though Venus was the first ever planet to be explored by a spacecraft (Russia’s Venera 1 in 1961), space agencies have largely ignored Venus in the last few decades and focussed on other planets, especially Mars.

But that’s set to change with NASA, the U.S. Space Agency, announcing two robotic missions to Venus as part of the Discovery Program. Recent studies, one suggesting that the planet's surface was habitable for several billion years, and another suggesting presence of microbes in Venusian skies, have reinvigorated an interest in Venus.

Set to be launched in 2028-2030 time period, the NASA missions will include an orbiter called VERITAS and an atmospheric probe known as DAVINCI+. The price tag of each mission is capped at around $500 million. Read on to know more about these missions...

What is DAVINCI+?

• Probe DAVINCI+, which stands for Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging, will gather more detail on the composition of Venus' atmosphere to learn how it formed and evolved.
• The mission also seeks to determine whether the planet once had an ocean.
• A descent sphere will plunge through the dense atmosphere which is laced with sulphuric acid clouds. It will precisely measure the levels of noble gases and other elements to learn what gave rise to the runaway greenhouse effect we see today.
• DAVINCI+ will also beam back the first high resolution images of the planet's ‘tesserae,’ geological features roughly comparable with Earth's continents whose existence suggests Venus has plate tectonics.
• The results could reshape scientists' understanding of terrestrial planet formation.

What is the objective of VERITAS?

• The other mission is called VERITAS, an acronym for Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy.
• This will aim to map the Venusian surface from orbit and delve into the planet's geologic history.
• Using a form of radar that is used to create three-dimensional constructions, it will chart surface elevations and confirm whether volcanoes and earthquakes are still happening on the planet.
• It will also use infrared scanning to determine rock type, which is largely unknown, and whether active volcanoes are releasing water vapour into the atmosphere.
• While the mission is NASA led, the German Aerospace Center will provide the infrared mapper. The Italian Space Agency and France's Centre National d'Etudes Spatiales will contribute to the radar and other parts of the mission.

What are some of the previous missions to Venus?

• Russia (former Soviet Union) launched a number of missions to Venus under its Venera program between 1961 and 1984. Its Venus program achieved some of the greatest successes of human space exploration—including the first landing of spacecraft on another planet and the first photos from another world’s surface.
• The first one to launch was Venera 1, which made a flyby in May 1961, however no data returned due to communication failure. Subsequently, ten probes successfully landed on the surface of the planet, including the two Vega program and Venera-Halley probes, while thirteen probes successfully entered the Venusian atmosphere.
• Venera 13 survived the intense heat and crushing pressure of Venus’ surface for more than two hours, while others survived only for a few minutes. Most atmospheric information and surface data from Venus were collected by the Soviet Union.
• NASA's Mariner 2 successfully flew by and scanned the cloud-covered world in 1962. NASA’s last Venus orbiter was Magellan, which arrived in 1990, and mapped the planet's surface with radar. Since then, numerous spacecraft from the U.S. (and other space agencies) have flew by Venus as part of their missions to other destinations. These include Galileo to Jupiter in 1990, Cassini-Huygens to Saturn in 1998/99 and NASA's MESSENGER mission to Mercury in 2006 and 2007.
• European Space Agency’s Venus Express Orbiter entered Venus orbit on April 2006 and the communication was lost in November 2014. Japan’s Akatsuki space probe tasked to study the atmosphere of Venus entered Venus orbit in 2015 and is still operational.

Why is there a renewed interest in Venus?

• Scientists think that Venus was once a balmy, temperate world with oceans, rivers and streams. Recent research suggests that Venus was habitable for life for several billion years, until greenhouse effect took hold around 700 million years ago.
• Another research suggests that Venus may be habitable today. Scientists theorise microbes might exist high in the clouds where it’s cooler and the pressure is similar to Earth’s surface. Detection of phosphine, a chemical released by microbes, suggested that life was possible in the clouds of Venus. The apparent phosphine find has not been confirmed by other teams, however, and remains a topic of considerable discussion and debate.
• So Venus has become an attractive target for extraterrestial study.
• Scientists studying exoplanets are trying to understand the Venus-Earth difference to know about how planets evolve in general, and how habitable conditions evolve.

How does future look like for Venus exploration?

• India is developing a potential Venus mission. Shukrayaan-1 is a proposed orbiter to Venus to be launched in 2024 or 2026. The project would include an orbiter and an atmospheric balloon probe and study the surface and atmosphere of the planet.
• Russia aims to go back to Venus with an ambitious mission called Venera-D that would feature an orbiter, a lander and atmospheric balloons. Venera-D will launch in 2029, if all goes according to plan.
• Rocket Lab, a private space agency, plans to launch a Venus mission in 2023 using its Electron rocket and Photon satellite bus.
• EnVision is an orbital mission to Venus being developed by the European Space Agency and proposed to be launched in 2023.

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On July 17, 1984 Savitskaya launched aboard Soyuz T-12, together with Commander Vladimir Dzhanibekov and research cosmonaut Igor Volk. On July 25, 1984, Savitskaya became the first woman to spacewalk, conducting EVA outside the Salyut 7 space station for 3 hours and 35 minutes, during which she cut and welded metals in space along with her colleague Vladimir Dzhanibekov. The importance of their mission was to test the Universal Hand Tool or Universalry Rabochy Instrument (URI). This tool created at the Paton Instituite in Kiev, Ukraine could be used to cut, solder, weld, and braze in space. During the EVA, Savitskaya performed a total of 6 cuts of titanium and stainless steel, 2 coatings of anodized aluminum, 6 tests of tin and lead solder, and test cuts of a 0.5 mm titanium sample. Of the 57 Soviet/Russian spacewalkers through 2010, she is the only woman, and as of April 2020 is still the only Soviet/Russian woman to walk in space. The return to Earth took place on July 29, 1984.

Savitskaya recalled that, during her second mission, she expressed concern about the extravehicular welding exercises, as "I did not understand the point of it. We might burn our spacesuits or the exterior of the station." but her overall excellent performance on both flights silenced critics who questioned a woman's capability to perform space missions. Savitskaya’s and Dzhanibekov’s training and tests allowed for Dzhanibekov to direct two members of the Salyut 7 crew, Kizim and Solovyov, who had performed multiple EVA’s to repair the ship, in the techniques to operate the URI in order to fully repair the fuel line. The total duration of their mission lasted 11 days, 19 hours, and 14 minutes

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Alexei Arkhipovich Leonov was a Soviet and Russian cosmonaut, Air Force major general, writer, and artist. On 18 March 1965, he became the first person to conduct a spacewalk, exiting the capsule during the Voskhod 2 mission for 12 minutes and 9 seconds. He was also selected to be the first Soviet person to land on the Moon although the project was cancelled.

He was one of the 20 Soviet Air Forces pilots selected to be part of the first cosmonaut training group in 1960. As most cosmonauts, Leonov was a member of the Communist Party of the Soviet Union. His walk in space was originally to have taken place on the Voskhod 1 mission, but this was cancelled, and the historic event happened on the Voskhod 2 flight instead. He was outside the spacecraft for 12 minutes and nine seconds on 18 March 1965, connected to the craft by a 4.8-metre (16 ft) tether. At the end of the spacewalk, Leonov's spacesuit had inflated in the vacuum of space to the point where he could not re-enter the airlock. He opened a valve to allow some of the suit's pressure to bleed off and was barely able to get back inside the capsule. Leonov had spent eighteen months undergoing weightlessness training for the mission.

From 1976 to 1982, Leonov was the commander of the cosmonaut team ("Chief Cosmonaut") and deputy director of the Yuri Gagarin Cosmonaut Training Center, where he oversaw crew training. He also edited the cosmonaut newsletter Neptune. He retired in 1992.

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Extravehicular Activity (EVA), are activities performed by space-suited astronauts outside their spacecraft in orbit above the Earth. This collection of 20 framed photographs and corresponding captions include those activities performed during an EVA, which may include satellite capture and repair, assembly/connection of exterior spacecraft components, or performing special experiments or tests.

EVAs may be either tethered (the astronaut is connected to the spacecraft; oxygen and electrical power can be supplied through an umbilical cable; no propulsion is needed to return to the spacecraft), or untethered. Untethered spacewalks were only performed on three missions in 1984 using the Manned Maneuvering Unit (MMU), and on a flight test in 1994 of the Simplified Aid For EVA Rescue (SAFER), a safety device worn on tethered U.S. EVAs.

The Soviet Union/Russia, the United States, Canada, the European Space Agency and China have conducted EVAs.

China became the third country to independently carry out an EVA on September 27, 2008 during the Shenzhou 7 mission. Chinese astronaut Zhai Zhigang completed a spacewalk wearing the Chinese-developed Feitian space suit, with astronaut Liu Boming wearing the Russian-derived Orlan space suit to help him. Zhai completely exited the craft, while Liu stood by at the airlock, straddling the portal.

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He along with a large number of fellow candidates went through many tests first at the Institute of Aerospace Medicine in Bangalore and then to Moscow. The large batch was gradually reduced to a shortlist of four candidates, before a final round of medical tests left just two candidates – Rakesh Sharma and Ravish Malhotra – both of them being IAF pilots. It was made clear at the outset that even though only one of them would finally make the grade for the space odyssey, the other one would be a standby for any eventuality. However, the identity of who exactly would be the lucky one would be taken only towards the last stage before the actual space flight.

AS part of the rigorous training they underwent for nearly two years at the Yuri Gagarin Cosmonaut Training Center at Star City in the outskirts of Moscow, the duo of Sharma and Malhotra were even locked inside a closed room at an IAF facility in Bangalore for 72 hours to detect if they suffered from claustrophobia. Sharma performed yoga for 10 minutes daily to maintain better fitness in space, as well as zero gravity yoga to combat space sickness. On April 2, 1984, Sharma become the first Indian to go into space when he flew aboard the Soviet rocket Soyuz T-11 that was launched from the Baikonur Cosmodrome in the Kazakh Soviet Socialist Republic. The rocket docked and transferred the three member Soviet-Indian international crew which included the spaceship commander Yury Malyshev and flight engineer Gennadi Strekalov, to the Salyut 7 Orbital Station. Over the years, he rose up the ranks and, in 1984, was appointed squadron leader in the IAF. He retired as wing commander and, in 1987, joined the Hindustan Aeronautics Limited (HAL) wherein he was the chief test pilot at the HAL Nashik and Bangalore divisions, respectively, until 1992. He was also associated with the project involving the Light Combat Aircraft Tejas.

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Rakesh Sharma was the first Indian to reach outer space in April 1984. A former IAF pilot, he flew abroad the Soviet rocket Soyuz T-11 as part of a joint programme between the ISRO and the Interkosmos. During a joint television news conference from space, when the then Prime Minister Indira Gandhi asked Sharma about how India looked from outer space, he said “Sare Jahan Se Achcha” (the best in the world).

The honour Hero of the Soviet Union was conferred upon Sharma on his return from space, making him the lone Indian recipient. India’s highest peacetime gallantry award, the Ashoka Chakra, was also conferred on him.

Sharma’s Russian companions aboard enjoyed Indian food in space. The dishes were prepared by the Defence Food Research Laboratory, Mysore which included Pulao, Alu chholey and Sooji halwa.

Sharma carried with him portraits of the then Prime Minister, Indira Gandhi, President Zail Singh, defence minister, Venkataraman and soil from Rajghat, Mahatma Gandhi’s samadhi.

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SPACE TRAVELLERS

Since the first manned space mission in 1961, more than 560 people have journeyed into space - 27 on missions to the Moon and the rest in orbit around Earth. To date, only Russia, China, and the United States have launched humans into space. However, humans are not the only space travellers. Animals such as dogs, monkeys, and spiders have all been sent into space to help with research.

1. Alan Shepard was the second person, and first American, to journey into space.
2. Ulf Merbold, from Germany, became the first European to fly aboard a space shuttle.
3. Jim Voss set the record for longest spacewalk (8 hours 56 minutes) with Susan Helms.
4. Susan Helms.
5. Laika was the first animal to orbit Earth. The Russian dog travelled in Sputnik 2 in 1957.
6. Alexei Leonov made the first spacewalk in March 1965. He spent 10 minutes in space secured to his Voskhod 2 craft.
7. Eileen Collins became the first female shuttle pilot in February 1995, and the first female shuttle commander in July 1999.
8. Yang Liwei was the first Chinese astronaut (taikonaut). China’s first manned space flight was launched in October 2003.
9. Svetlana Savitskaya was the second woman in space and the first woman to spacewalk.
10. Michael Collins was the third member of the Apollo 11 mission in 1969. He orbited the Moon, as Armstrong and Aldrin explored its surface.
11. Dennis Tito was the first space tourist. He paid £14 million ($20 million) for a six-day trip in 2001.
12. Baker, a squirrel monkey, was launched into space on 28 May 1959. She travelled with a rhesus monkey called Able.
13. Eugene Cernan was part of the Apollo 17 mission in December 1972. He was the last person to walk on the Moon.
14. Neil Armstrong was the first person to set foot on the Moon. He spent 2 hours 35 minutes exploring the lunar surface.
15. Yuri Gagarin was the first person to fly into space. His trip in April 1961 took him once round Earth and lasted 108 minutes.
16. Peggy Whitson holds the record for the longest female spaceflight (289.2 days).
17. Mike Melvill was the first commercial astronaut. He piloted SpaceShipOne in June 2004.
18. Valentina Tereshkova was the first woman to fly into space. She made a three-day journey aboard Vostok 6 in June 1963.
19. Gennady Padalka holds the record for the total time spent in space. In his five trips, he has clocked up 878.5 days in space.
20. Sam was a rhesus monkey who was sent into space in 1960 to test equipment that would be used in future manned flights.
21. Valeri Polyakov holds the record for the longest time spent in space during one trip. His record stands at 437.7 days.
22. Bruce McCandless made the first untethered spacewalk in February 1984.
23. John Glenn was the first American to orbit Earth, in 1962. He became the oldest space voyager in 1998, aged 77.
24. Green tree frogs were taken to the Mir space station in 1990.
25. Buzz Aldrin was the second person to set foot on the Moon.
26. Swordtail fish travelled on board the space shuttle Columbia in 1998.
27. Squirrel monkeys and 24 albino rats were taken to Spacelab-3 in 1985.
28. Arabella, a spider, was sent to the Skylab space station in 1973. Once space-adapted, she spun perfect webs.
29. Albino rats.
30. Quail chicks hatched from eggs on the Mir space station in March 1990.
31. Belka and Strelka became the first dogs to go into orbit and survive the journey in 1960.
32. Ham was the first chimpanzee to travel in space. In 1961, he was sent to test equipment that would be used in the first US manned space mission.

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TELESCOPES

A telescope is the astronomer’s basic tool. It makes distant objects appear bigger and reveals their detail. Telescopes work by using a lens or mirror to collect light and bring it to a focus, producing an image. Reflectors, which use a mirror, are the most widely used type of telescope - the bigger the mirror, the more powerful the telescope and the better the view.

• NAKED-EYE VIEW The constellation of Orion is easily visible to the naked eye. On a dark, moonless night, a faint, fuzzy patch of light may be visible below the three stars of Orion’s belt. This is the Orion Nebula.
• THROUGH BINOCULARS The Orion Nebula is a massive star-forming cloud of gas and dust. The nebula becomes more obvious when looked at through binoculars — two low-powered telescopes working together. In standard binoculars the two main lenses are about 5 cm (2 in) wide and the image is magnified seven times.
• IMPROVED VIEW A more powerful telescope improves the view of the nebula. Across the world there are about 50 telescopes with mirrors 2-5 m (6.5-16.5 ft) across and another 20 with mirrors up to 10 m (33 ft) across. These large telescopes are located on mountain-top sites where the air is clear and still. Computerized controls adjust their position, keeping them tracked on their target as Earth turns.
• MEDIUM-SIZED TELESCOPE VIEW The nebula’s shape and form become visible through a telescope with a mirror about 20 cm (7.8 in) across. A camera attached to the telescope collects the light and records the image.
• X-RAY AND INFRARED VIEWS X-rays collected by the Chandra space telescope were used to make this image on the left, which shows the heart of the Orion Nebula. The image on the right shows the same area taken by the Spitzer infrared telescope. Clouds of dust heated by starlight show up in red.
• VIEW FROM SPACE Some telescopes collect forms of energy other than light, such as radio waves, X-rays, and infrared energy. Earth’s atmosphere prevents some of these from reaching Earth so they are collected by telescopes in space. This colour-enhanced image combines data from two space telescopes - Spitzer, which collects infrared waves, and Hubble, which collects both light and ultraviolet waves.
• HEART OF THE NEBULA Hubble’s 2.4-m (7.9-ft) wide mirror collected the light for this detailed view of the Orion Nebula’s bright central area. It includes the Trapezium, a cluster of ten young, brilliant stars that illuminate the nebula with their ultraviolet energy.

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SPACE EXPLORATION

Humans have only been able to send spacecraft to explore space for about 50 years. In that time, more than 100 robotic craft have travelled into the Solar System to reveal what its planets, moons, asteroids, and comets are like. They fly by, orbit, or land on these other worlds. Humans have only been to the Moon, but aim to set foot on Mars in the future.

TIMELINE OF SPACE EXPLORATION

14 October 1957: Sputnik 1, the world’s first artificial satellite, is launched into Earth’s orbit by Russia.

3 November 1957: Laika, a Russian dog aboard Sputnik 2, becomes the first creature to orbit Earth.

2 January 1959: Russian spacecraft Luna 1 is the first to escape Earth’s gravity.

13 September 1959: Luna 2 is the first craft to land on the Moon when it crashes onto its surface.

12 April 1961: Russian Yuri Gagarin is the first person into space. His flight lasts 108 minutes.

16 June 1963: Russian Valentina Tereshkova is the first woman in space.

18 March 1965: Russian Alexei Leonov makes the first EVA (extra vehicular activity), or spacewalk.

3 February 1966: Luna 9 lands successfully on the Moon.

24 December 1968: US spacecraft Apollo 8 is the first manned mission to leave Earth’s gravity and orbit the Moon.

20 July 1969: Neil Armstrong and Buzz Aldrin of Apollo 11 are the first humans to walk on the Moon.

19 April 1971: The first space station, Salyut 1, is launched by the Russians.

3 December 1973 US craft Pioneer 10 is the first to fly by Jupiter.

29 March 1974: US craft Mariner 10 is the first to fly by Mercury.

17 July 1975: US craft Apollo 18 and Russian Soyuz 19 make the first international space rendezvous.

22 October 1975: Russian craft Venera 9 transmits the first images from the surface of Venus.

20 July 1976: US craft Viking 1 is the first to land successfully on Mars.

1 September 1979: Pioneer 11 is the first to fly by Saturn.

12 April 1981: Columbia, the first US space shuttle, is launched.

24 January 1986: US craft Voyager 2 is the first to fly by Uranus.

13 March 1986: European craft Giotto takes the first close-up look at a comet.

24 August 1989: Voyager 2 is the first craft to fly by Neptune.

24 April 1990: The Hubble Space Telescope is launched.

15 September 1990: US craft Magellan starts a three-year mapping programme of Venus.

29 October 1991: US craft Galileo makes the first flyby of an asteroid as it passes Gaspra. 13 July 1995: Galileo arrives at Jupiter and releases a probe to enter its atmosphere.

4 July 1997: US craft Mars Pathfinder and its Sojourner rover touch down on Mars.

20 November 1998: Zarya, the first module of the International Space Station (ISS), is launched.

2 November 2000: The first crew arrives to stay aboard the ISS.

12 February 2001: The NEAR craft lands on asteroid Eros.

25 December 2003: Europe’s first interplanetary craft, Mars Express, orbits Mars.

30 June 2004: US craft Cassini arrives at Saturn to study the planet and its moons. It releases Huygens to land on the moon Titan.

20 November 2005: Japanese craft Hayabusa lands on asteroid Itokawa.

4 August 2007: US craft Phoenix sets off for Mars, arriving in 2008.

18 March 2011: US Messenger spacecraft becomes the first vehicle to orbit around Mercury.

6 August 2012: US Curiosity rover lands in the Gale Crater on Mars.

6 August 2014: European spacecraft Rosetta, carrying the Lander Philae, enters orbit around Comet Churyumov-Gerasimenko.

14 July 2015: US craft New Horizons makes the first flyby of the dwarf planet Pluto.

5 July 2016: US Juno spacecraft enters orbit around Jupiter to survey the planet’s Polar Regions.

15 September 2017: Cassini ends its mission with a deliberate plunge into Saturn’s atmosphere.

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METEORITES

Thousands of tonnes of rocky material enter Earth’s atmosphere each year. Most of it originates from asteroids, but some comes from comets, the Moon, and even Mars. As the rocky pieces close in on Earth they are termed meteoroids. Most burn up, but those that survive and land are known as meteorites. There are three main types: stony meteorites, iron meteorites, and stony-iron meteorites - the rarest kind.

• ESQUEL This stony-iron meteorite was collected in Esquel, Argentina, in 1951. Golden-coloured crystals of the mineral olivine are embedded in the iron-nickel metal.
• THIEL The Thiel Mountains stony-iron meteorite was one of the first found in Antarctica, in 1962.
• METEOR Meteoroids burning up in Earth’s atmosphere produce bright trails. These short-lived streaks of light are termed meteors, or shooting stars. About a million occur every day.
• MURCHISON Stony meteorites are the most common. This one, the Murchison, fell in Australia in 1969. It is one of the most studied meteorites and contains minerals, water and complex organic molecules.
• BARWELL The Barwell meteorite is one of a shower of stones that fell in England in 1965. As it plummeted through Earth’s atmosphere, friction caused the outer surface to heat and melt. This later solidified into a black crust.
• CANON DIABLO This sliced and polished iron meteorite is a piece of the asteroid that produced the Barringer Crater. The pieces found weigh 30 tonnes in total, yet they are only a small fraction of the original asteroid.
• IMPACT CRATER Meteorites can produce craters when they crash into Earth. The Barringer Crater in the Arizona Desert, USA, shown here under a rare blanket of snow, measures 1.2 km (0.75 miles) across and was formed about 50,000 years ago.
• GIBEON Iron meteorites are the second most common type, after stony meteorites. The Gibeon is mainly iron with a small amount of nickel. It is one of many found in Namibia since the 1830s.
• CALCALONG CREEK More than 50 meteorites found on Earth originated on the Moon, blasted off by asteroid impact. The Calcalong creek meteorite, found in Australia, is lunar surface soil that was turned to rock by such an impact.
• NAKHLA This stony meteorite is one of more than 30 found on Earth that originated on Mars. It was blasted off the planet and spent many millions of years in space before landing in Egypt on 28 June 1911.
• TEKTITES Small glassy bodies known as tektites can form when a large meteorite hits Earth. The impact shatters and melts surrounding Earth rock, flinging it upwards. It cools and hardens, falling back to Earth as glassy pieces.

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COMETS

More than a trillion comets surround the planetary region of the Solar System. They follow long orbits around the Sun and together make up a vast sphere called the Oort cloud. Each comet is a lump of dirt and snow, called a nucleus, or “dirty snowball”. Comets are so small that they are only visible when they travel close to the Sun and grow large and bright enough to be seen.

• CHANGING COMET: As a comet approaches the Sun it warms up. The snow turns to gas, which, along with loose dust, flows from the nucleus. When the comet passes closer to the Sun than the orbit of Mars, this material forms a head (called a coma) and two tails, one of gas and one of dust.
• COMET DISPLAY: More than 2,300 comets have been identified as they passed through the Sun’s neighbourhood. About 200 make return visits, but most pass by just once. Three or four times a century, a spectacular one, such as Comet McNaught in January 2007, makes a stunning display.
• PASSING THE SUN: These images from the SOHO spacecraft, track the progress of Comet McNaught as it rounds the Sun. Like most comets, it is named after its discoverer, Robert McNaught, who saw it first on 7 August 2006. It was at its biggest and brightest in January 2007, when closest to the Sun.
• COMET STRUCTURE The nucleus of a comet is a city-sized lump, two-thirds snow and one-third rock dust. Halley’s Comet orbits the Sun every 76 years. When it drew close to it in 1986, the Giotto spacecraft flew into the comet’s coma and captured images of its nucleus.
• BREAKING UP As a comet passes a massive body, such as the Sun or Jupiter, it may be pulled apart by its gravity. Comet Schwassmann Wachmann 3 orbits the Sun every 5.4 years and astronomers have observed that it is disintegrating.

Picture Credit : Google

PLANETS

Hurtling around the Sun are eight planets. Those closest to the Sun - Mercury, Venus, our home planet Earth, and Mars - are made of rock. The vast outer planets - Jupiter, Saturn, Uranus, and Neptune - are called “gas planets” because all we see of them is their gas. All eight travel in the same direction around the Sun. The time taken to make one circuit, or orbit, increases with distance. Mercury takes just 88 Earth days to orbit, while Neptune’s longer journey takes 164.8 Earth years.

1. JUPITER: The largest and most massive planet, Jupiter is also the fastest spinner, rotating once on its own axis in less than 10 hours. This giant world is made mainly of hydrogen and helium, with a central rocky core. A thin faint ring encircles Jupiter, which also has a large family of moons.
2. SATURN: Sixth from the Sun, and second largest, is pale yellow Saturn. Its distinctive feature is its ring system, which is made of billions of pieces of dirty water ice. Saturn is mainly hydrogen and helium with a rocky core. It has a large family of moons.
3. URANUS: Nineteen times the distance of Earth from the Sun, Uranus is a cold, turquoise world bounded by a layer of haze. A sparse ring system encircles the planet’s equator. Uranus is tilted on its side, so that its rings and moons seem to orbit it from top to bottom.
4. MERCURY: Mercury is a dry ball of rock, covered by millions of impact craters. It is the smallest planet, the closest to the Sun, and has the widest temperature range of any planet. During the day it is baking hot, but at night it is freezing cold.
5. VENUS: Second from the Sun, Venus is the hottest planet. This rock world is permanently covered by thick cloud that traps heat and makes it a gloomy planet.
6. NEPTUNE: Neptune is the most distant, coldest, and windiest of all eight planets. Like Uranus, it is made mainly of water-, methane-, and ammonia ices with an atmosphere of hydrogen- rich gas. It is encircled by a thin ring system and has a family of moons.
7. MARS: Sometimes called the “red planet”, Mars is the outermost of the rocky planets and a cold, dry world. It has polar ice caps, giant volcanoes, frozen desert, and deep canyons, formed in the distant past. Mars has also two small moons.
8. EARTH: The only place known to have life is Earth, the largest of the rocky planets and third from the Sun. It is also the only planet with liquid water. Movements in Earth’s crust are constantly changing its surface. Earth has one moon.
9. DWARF PLANETS: The Solar System has five known dwarf planets - small, roundish objects that orbit the Sun amongst other objects. Ceres orbits between Mars and Jupiter within a belt of rocky asteroids, while Pluto, Haumea, Makemake, and Eris are icy worlds that orbit beyond Neptune in a region called the Kuiper Belt.

PLANET SCALES Jupiter, fifth planet from the Sun, is much larger than all the other planets. It measures 142,984 km (88,846 miles) across and is made of about two and a half times as much material as all the other planets put, together. The seven other planets and the dwarf planets are shown here roughly to scale.

Picture Credit : Google