All About Space No. 107의 목차

REPLACING SPACE-TIME String theory Fundamental particles such as electrons are made of tiny strings that vibrate across ten spatial dimensions, plus one time dimension. This picture manages to avoid infinities when combining quantum theory and general relativity, but it cannot currently be tested. Loop quantum gravity (LQG) Space-time is not a smooth fabric, but is made up of a network of tiny stitches instead. This is potentially testable by looking at light reaching us from gamma-ray bursts (GRBs) in the distant universe. Modular space-time Space-time is only a stage when it has actors on it. In other words, interactions between objects create space-time. This can potentially explain the quirks of non-locality and quantum entanglement. Supergravity This is the combination of general relativity with a popular but unproven theory called supersymmetry…

INTERVIEW BIO Dr Nour Raouafi Raouafi is a Tunisian astrophysicist at Johns Hopkins Univerisity’s Applied Physics Laboratory (APL) in Maryland and the project scientist for NASA’s Parker Solar Probe mission. He is an expert in many solar and heliospheric topics, including solar magnetic fields, coronal plumes and jets, coronal mass ejections (CMEs), solar wind, solar energetic particles and many other areas. For the last two years the Parker Solar Probe has been beaming back unique data sets while breaking records when it comes to how close a human-made object has been to the Sun and how fast it travels. Its latest encounter reached within 18.7 million kilometres (11.6 million miles) of the Sun and sped past at 393,000 kilometres (244,225 miles) per hour.…

Alien contact In the event of alien contact Certain protocols have been drawn up by the SETI Institute for if an intelligent signal is found 1 Verification While the discovery of a signal will be exciting, the first step is to make sure that the signal is real, and not from Earth-based interference. To do this the discoverer must repeatedly observe the signal five times, and rule out other sources like satellites or terrestrial radio waves. If the signal is continuously seen from the same region of sky when observing from different locations, then the discoverer can move onto the next step. 2 Get help The discoverer now needs to inform other international observatories and institutions about the discovery. These need to all independently confirm the discovery themselves,…

Apollo highlights: getting mission-ready Planting flags and picking rocks It was perhaps one of the most iconic moments of Apollo 11: Neil Armstrong planting the American flag into lunar soil. And he had to train for it in a simulated moonscape surrounded by ‘lunar rocks’. It was also common practice for all Apollo astronauts to play pretend when it came to collecting samples! Stepping onto the lunar surface It was one small step for [a] man, one giant leap for mankind. Apollo 11 commander Neil Armstrong had to practise climbing up and down the ladder that led from the Lunar Module – dubbed Eagle – to the lunar surface repeatedly a week before he and his crew launched for the Moon. Walking in reduced gravity On the Moon astronauts experienced…

US AIR FORCE X-37B VS NASA SPACE SHUTTLE It’s seen as a miniature version of an iconic spacecraft, but how does the X-37B really measure up? 8 The Space Shuttle could hold eight people. None have flown on the X-37B. 17 Columbia flew for 17 days, 15 hours and 53 minutes on STS-80. X-37B’s fifth mission lasted over 779 days. 4,990KG The launch mass of the X-37B, compared to the 2,040,000 kilograms of the Space Shuttle. 135 The number of Space Shuttle missions, compared to six for X-37B. 1 The X-37B holds the Guinness World Record for being the smallest orbital space plane. 18 METRES (60 FEET) Length of Space Shuttle’s payload bay – ten times that of X-37B’s. © Adrian Mann…

Deep sky challenge Sizzling summer’s clusters and nebulae Glittering star clusters, a dead star’s corpse and a beautiful double star can all be seen this month Source: Wikipedia Commons ©NGS 1535 Many sky-watchers think the summer sky is just too bright to allow for observation of faint and fuzzy deep-sky objects, but if you stay up late enough the sky is just dark enough to let you see some lovely sights through a telescope. Around one or two in the morning – providing the sky you’re under isn’t too marred by the glow of light pollution – a telescope will give you very pleasing views of some of astronomy’s most famous objects. Although the broad, frothy band of the Milky Way dominates the sky, running right through the centre of…

Our contributors include… Colin Stuart Space science writer If we can get a true understanding of how our natural satellite was made, we could uncover how we came to thrive on Earth. Colin has the details on page 14. Nour Raouafi Astrophysicist The project scientist of NASA's Parker Solar Probe reveals the latest results, images and what's next for the craft – and how the next decade is the golden age for solar research. Chris Hadfield Former astronaut Chris Hadfield answers your space questions alongside our expert panel of astronomers, astrophysicists and space exploration experts on page 64. Lee Cavendish Staff writer How big is supergiant Antares? Lee reveals the brand-new images from the Very Large Array that have provided a new look at the red gem that lies in…

Strange ancient ‘failed stars’ found by citizen scientists Citizen scientists recently helped direct astronomers to a pair of objects that straddle the line between planets and stars. These newly spotted substellar objects are brown dwarfs, which share many elements in common with stars. However, unlike stars these gaseous bodies don’t have enough mass to start nuclear fusion in their core, so they resemble planets more than stars. These newfound brown dwarfs have very unusual compositions. They are the most planet-like brown dwarfs to be observed in the Milky Way’s oldest populations of stars. They also might help researchers learn more about planets outside the Solar System. ©NASA/JPL-Caltech The citizen scientists who spotted both objects were part of the ongoing NASA-funded Backyard Worlds: Planet 9 project. They were looking through spacecraft…

NASA human spaceflight chief makes no guarantees on return to Moon Putting astronauts back on the Moon by 2024 will be no small feat, and NASA’s new human spaceflight chief Kathy Lueders has been careful not to make any promises. “I don’t have a crystal ball,” Lueders said when asked about the feasibility of a 2024 Moon landing. “I wish I knew that answer. That’d make my job a lot easier. We’re going to try.” © NASA Lueders, who recently became the associate administrator for NASA’s Human Exploration and Operations Mission Directorate after Doug Loverro’s abrupt resignation, was a bit more pragmatic about the timeline of NASA’s Artemis program than her predecessor. While Lueders seems cautiously optimistic about getting astronauts to the Moon by 2024, Loverro was confident and unwavering…

Moon rock analysis The age of the Moon Analysis of lunar rocks suggests the Moon is almost as old as Earth, meaning the collision happened within Earth’s first 100 million years. Matching oxygen isotopes The relative abundances of the three stable isotopes of oxygen are the same on Earth and the Moon, suggesting a common origin. No sign of water The Moon rocks show no signs of past interaction with water. All the geology can be explained as rocks being under pressure. Differing potassium isotopes There is slightly more of one particular potassium isotope on the Moon, pointing to it being vaporised during a head-on collision. Source: Wikipedia Commons © Bryce Edwards…

WHY CAN’T RELATIVITY AND QUANTUM MECHANICS GET ALONG? QUANTUM MECHANICS Particles are waves and waves are particles This wave-particle duality is central to quantum physics. Light can be thought of as being made of particles called photons, or as a propagating electromagnetic wave. All properties are ‘quantised’ Values in quantum physics are a bit like shoes – they only come in set sizes. Physicists call these ‘quanta’. An electron, for example, can only orbit the atomic nucleus in a limited number of configurations. Objects exist in many states at once Physicists say electrons exist in a ‘superposition’ of states. It’s not in a definite state until we measure it, and beforehand we can only assign probabilities to the likely outcome. Non-locality: spooky action at distance Take a pair of entangled…

Alien contact WHAT HAPPENS WHEN WE CONTACT ALIEN LIFE? Preparing the world for the biggest discovery in the history of humanity Reported by Jonathan O’Callaghan © Shutterstock; Alamy; Getty In August 2016 the entire world was gripped with the news that a possible signal from an intelligent alien race had been received. Picked up by a Russian radio telescope, its discoverers had no explanation for the signal, which appeared to be artificial, and suggested it could be our first sign of alien life. Alas, it was not to be. The signal, like so many before it, turned out to be interference from Earth, most likely a satellite in orbit. But the event highlighted a key point – there is a huge public clamour for finding extraterrestrial (ET) life, and…

How do we know if we’ve made contact? Gerry Harp, director of the Center for SETI Research, reveals what we would expect to see What are we looking for? We’re looking for signals that are clearly artificial. We have lots of ways we communicate using radio on Earth, and in principle ET might use the same. But the interstellar medium – the gas between stars – messes up signals, so we look for narrow-frequency bandwidth signals. How would we verify a signal is real? The signal has to persist. You have to look away and back with telescopes several times, until there have been five cycles. This tells you if it really is from that direction in the sky, or just scattered radiation. Have we ever had a promising signal?…

When will we make contact? 2030 Douglas Vakoch METI International “My best guess for when we’ll detect extraterrestrial life – if, in fact, we make contact in my lifetime – is by 2030, a decade from now.” 2040 Seth Shostak SETI Institute “I’ve bet everyone a cup of coffee that we’ll find a signal within two decades. If not, I’ll have the opportunity to buy a lot of brew.” 2050 John Elliott UK SETI Research Network “In 30 years I think we’ll have the dish capacity, techniques and computing power, as well as the knowledge of where is best to target.” 2070 Andrew Siemion Berkeley SETI Research Center “If we haven’t detected evidence of intelligent life beyond Earth in 50 years, it is likely that we are essentially alone in…

STARGAZER What’s in the sky? Jargon buster Conjunction A conjunction is an alignment of objects at the same celestial longitude. The conjunction of the Moon and the planets is determined with reference to the Sun. A planet is in conjunction with the Sun when it and Earth are aligned on opposite sides of the Sun. Right Ascension (RA) Right Ascension is to the sky what longitude is to the surface of the Earth, corresponding to east and west directions. It is measured in hours, minutes and seconds since, as the Earth rotates on its axis, we see different parts of the sky throughout the night. Declination (Dec) This tells you how high an object will rise in the sky. Like Earth’s latitude, Dec measures north and south. It’s measured in…

STARGAZER The Northern Hemisphere Aquarius and Pegasus grace the skies as we move into September © ESO © NASA/ESA Source: Wikipedia Commons © Adam Evans With the Sun setting not long after 19:00 this month, rich pickings can be had by those with even modest observing equipment. The end of September affords a last chance to catch the likes of Cygnus (the Swan) and Capricornus (the Sea Goat) and their wealth of deep-sky objects. Look out for the ‘Great Square’ of Pegasus (the Winged Horse) rising in the west, while Cepheus (the King) appears in the northwest. In both a selection of binary stars can be split using small telescopes. Aquarius (the Water Bearer), Taurus (the Bull) and Orion (the Hunter) offer globular and open clusters along with glowing star-forming…

HEROES OF SPACE Jedidah Isler Isler’s fervour for blazars led to her becoming the first African American woman to receive a PhD from Yale University © Getty Jedidah Isler is an exceptional astrophysicist and an excellent modern-day role model for any young women of colour, who are pursuing a career in the disciplines of science, technology, engineering and mathematics (STEM). Her studies of the universe in a field that continues to face racial and gender bias are nothing short of truly remarkable. In 2015 Isler presented a TED talk where she spoke eloquently about race and gender within STEM, including her experiences when working towards her doctorate. This talk heavily revolves around metaphorical intersections and the liminal space in which great things happen. Her…

LAUNCH PAD YOUR FIRST CONTACT WITH THE UNIVERSE COMET NEOWISE EDITION NEOWISE blazes brightly over O’Brien’s Castle Photographer: Cormac Coyne This photo was taken from Inisheer, the smallest of the Aran Islands that sits in the middle of Galway Bay on the west coast of Ireland. Just after midnight on 11 July, photographer Cormac Coyne climbed up to one of the highest points on Inisheer that overlooks O’Brien’s Castle. “When I was setting up above the castle, noctilucent clouds were just beginning to form,” he said. To capture NEOWISE, Coyne used a Canon EOS, coupled with a Canon 70-200mm f/2.8 Mark 3 lens. Despite being a naked-eye comet, Coyne also observed NEOWISE through binoculars. “I took the photos into Adobe Camera Raw, processed them and then saved them as a…

Curiosity starts road trip up Martian mountain Words by Elizabeth Howell NASA’s Curiosity rover is embarking on a road trip on Mars. The nearly eight-year-old mission will be guided through a traverse roughly 1.6-kilometres (one-mile) long that will see it climb farther up a mountain to learn more about the planet’s history – and whether it could have been habitable for microbial life in its ancient past. Curiosity is on its way to an area on the 5.5-kilometre (3.4-mile) high Mount Sharp (Aeolis Mons) nicknamed the ‘sulphate-bearing unit’. Sulphates are usually formed around water as it evaporates, and these leftovers could provide more information about how the surface of Mars changed roughly 3 billion years ago when the planet lost most of its atmosphere and running water was no longer…

How the Moon was made © Science Photo Library 1 Theia approaches Earth A Mars-sized object is on an unalterable collision course with the early Earth. 2 Earth gets hit The impactor hits Earth in a head-on collision, vaporising both Theia and Earth’s mantle. 3 Material is thrown out The vaporised material from both bodies mixes and is thrown outwards by the huge impact. 4 Debris gathers Smaller objects begin to condense out of the vapour while continuing to orbit around Earth. 5 The Moon takes shape Many of the smaller objects stick together to form a proto-Moon in orbit around Earth. 6 Our companion is formed Eventually all the pieces come together to form the basis of the Moon…

Interview Dr Nour Raouafi PARKER SOLAR PROBE: TWO YEARS ON “THIS COMING DECADE WILL BE THE GOLDEN AGE OF SOLAR AND HELIOPHYSICS RESEARCH” All About Space catches up with the project scientist for NASA’s incredible Parker Solar Probe mission, Dr Nour Raouafi – a spacecraft continuously breaking records and surpassing all expectations as it orbits the Sun Interviewed by Lee Cavendish © Johns Hopkins APL/Ed Whitman How’s the Parker Solar Probe doing? Are there any updates that we should be aware of? The Parker Solar Probe is doing great. We are going through our fifth encounter and recently we were the closest we’ve ever been to the Sun. After a period of five days where we could not communicate with the spacecraft, it sent us a signal that it’s…

Famous red supergiants Antares © ESO Constellation: Scorpius Distance: 554 light years Age: 11 million years Solar masses: 12 Solar radii: 700 VY Canis Majoris Constellation: Canis Major Distance: 3,820 light years Age: 8.2 million years Solar masses: 17 Solar radii: 1,420 Betelgeuse © ESO Constellation: Orion Distance: 700 light years Age: 10 million years Solar masses: 11 Solar radii: 890 Mu Cephei Source: Wikipedia commons© Sephirohq Constellation: Cepheus Distance: 5,258 light years Age: 10 million years Solar masses: 19 Solar radii: 1,650 CE Tauri Constellation: Taurus Distance: 1,794 light years Age: 14 million years Solar masses: 14 Solar radii: 587…

Alien contact: who will be the first to know? The news will hit a number of individuals before the general public is informed 1 The discoverer An extraterrestrial signal is detected! The discoverer will need to verify the signal several times before revealing to others that it might be a sign of intelligent alien life. 2 Seth Shostak, SETI Institute As director of the SETI Institute, Shostak is likely to be one of the heads of the institutions that are asked to independently verify the signal. 3 The president Once confirmed, national authorities will have to be informed of the signal. In the US that would likely include the president, and in the UK, the prime minister. 4 António Guterres, secretary-general of the UN Broader organisations…

WHAT’S ON BOARD? Hall ion-powered thruster Hall thrusters are electric propulsion devices that create thrust by ionising and accelerating a noble gas. They offer better fuel economy and allow larger payloads and more on-orbit manoeuvring. This thruster is a modified version of those used on Advanced Extremely High Frequency military craft. LightSail The non-profit Planetary Society took advantage of the mission by hitching a ride, putting a small LightSail into Earth orbit. It carries four large, reflective sails that measure 32 square metres (344 square feet). Although too small to sail to the stars, the mirrored sails use the Sun’s energy to generate momentum. Photons within the Sun’s light push on the surface, lending a continuous thrust. CubeSats CubeSats are miniature research satellites, and as well as LightSail, X-37B deployed…

Naked eye targets Naked eye & binocular targets Time to meet some of the summer Milky Way’s treasures 1 Deneb (Alpha Cygni) At magnitude +1.25 Deneb is the 19th-brightest star in the sky. A blue-white supergiant more than 100-times wider than the Sun, it is between 55,000 and 200,000 times more luminous than our own star. It will become the Pole Star around the year 9,800. 2 Great Globular Cluster in Hercules (Messier 13) Messier 13 is an enormous cluster of stars 145 light years wide and 22,180 light years away. This ancient star cluster, which looks like an out-of-focus star in binoculars, contains around 300,000 stars and was discovered by the great astronomer Edmond Halley in 1714. 3 Cygnus X Look below Deneb and you’ll see…