Latest news with #HubbleSpaceTelescope
Scientific American
a day ago
- Science
- Scientific American
Why Do We Launch Space Telescopes?
On April 24, 1990, NASA and the European Space Agency launched an astronomical revolution. When the Space Shuttle Discovery roared into the sky on that day, it carried the Hubble Space Telescope in its payload bay, and the astronauts aboard deployed it into low-Earth orbit soon thereafter. Hubble is not the largest telescope ever built—in fact, with a 2.4-meter mirror, it's actually considered by astronomers to be small—but it has a huge advantage over its earthbound siblings: it's above essentially all of our planet's atmosphere. That lofty perch makes Hubble's views sharper and deeper—and even broader, by allowing the telescope to gather types of light invisible to human eyes and otherwise blocked by Earth's air. And, after 35 years in orbit, Hubble is still delivering incredible science and cosmic vistas of breathtaking beauty. Launching telescopes into space takes much more effort and money than building them on the ground, though. Space telescopes also tend to be smaller than ground-based ones; they have to fit into the payload housing of a rocket, limiting their size. That restriction can be minimized by designing an observatory to launch in a folded-up form that then unfurls in space, as with the James Webb Space Telescope (JWST) —but this approach almost inevitably piles on more risk, complexity and cost. Given those considerable obstacles, one might ask whether space telescopes are ever really worth the hassle. On supporting science journalism If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today. The short answer is: Yes, of course! For astronomical observations, getting above Earth's atmosphere brings three very basic but extremely powerful advantages. The first is that the sky is much darker in space. We tend to think of our atmosphere as being transparent, at least when it's cloudless. But unwanted light still suffuses Earth's air, even on the clearest night at the planet's darkest spot. Light pollution—unneeded illumination cast up into the sky instead of down to the ground—accounts for some of this, but the air also contains sunlight-energized molecules that slowly release this energy as a feeble trickle of visible light. This 'airglow' is dim but, even at night, outshines very faint celestial objects, limiting what ground-based telescopes can see. It's a problem of contrast, like trying to hear a whisper in a crowded restaurant. The quieter the background noise level, the better you can hear faint sounds. It's the same with the sky: a darker sky allows fainter objects to be seen. The second advantage to observing from space is that this escapes the inherent unsteadiness of our air. Turbulence in the atmosphere is the reason stars twinkle. That's anathema to astronomers; the twinkling of a star smears out its light during an observation, blurring small structures together and limiting a ground-based telescope's effective resolution (that is, how well it can distinguish between two closely spaced objects). This also makes faint objects even dimmer and harder to detect because their light isn't concentrated into a single spot and is instead diffused. Above the atmosphere, the stars and nebulas and galaxies appear crisp and unwavering, allowing us to capture far greater detail. The third reason to slip the surly bonds of Earth is that our air is extremely good at shielding us from many wavelengths of light our eyes cannot see. Ultraviolet light has wavelengths shorter than visible light (the kind our eyes detect), and while some of it reaches Earth's surface from space—enough from the sun, at least, to cause sunburns—a lot of it is instead absorbed by the air. In fact, light with a wavelength shorter than about 0.3 micron is absorbed completely. (That's a bit shorter than that of violet light, the shortest we can see, at about 0.38 micron.) So any sufficiently shortwave light—not just ultraviolet, but also even more cell-damaging x-rays and gamma rays—is sopped up by molecules in the air. That's good for human health but not great for observations of astronomical phenomena that emit light in these regimes. This happens with longer wavelengths, too. Carbon dioxide and water are excellent absorbers of infrared light, preventing astronomers on the ground from seeing most of those emissions from cosmic objects, too. As we've learned with JWST, observations in infrared can show us much about the universe that would otherwise lie beyond our own limited visual range. As just one example, the light from extremely distant galaxies is redshifted by the cosmic expansion into infrared wavelengths, where JWST excels. In fact, space telescopes that can see in different wavelengths have been crucial for discovering all sorts of surprising celestial objects and events. X-rays were critical in finding the first black holes, whose accretion disks generate high-energy light as the matter within them falls inward. Gamma-ray bursts, immensely powerful explosions, were initially detected via space-based observations. Brown dwarfs (which are essentially failed stars) emit very little visible light but are bright enough in the infrared that we now count them by the thousands in our catalogs. Observing in these other kinds of light is critical for unveiling important details about the underlying astrophysics of these and other phenomena. It's only by combining observations across the electromagnetic spectrum that we can truly understand how the universe works. Still, launching telescopes into space is a lot of trouble and expense. Official work on Hubble started in the 1970s, but delays kept it on the ground for decades. It also cost a lot of money: roughly $19.5 billion total between 1977 and 2021, in today's dollars. (Operational costs have been about $100 million per year in recent years, but Hubble is facing budget cuts.) JWST was $10 billion before it even launched, and running it adds about $170 million annually to the project's total price tag. Compare that with the European Southern Observatory's Extremely Large Telescope, or ELT, a 39-meter behemoth currently under construction that has an estimated budget of under $2 billion. Building on the ground is simpler, requires less testing and is more fault-tolerant, allowing much more bang for the buck. The capabilities of ground-based versus space-based telescopes are different, however. In general, big earthbound telescopes can collect a lot of light and see faint structures, but except for the ELT, they don't have the resolution of their space-based counterparts and can't see light outside the transparency window of our planet's air. Also, not every observation needs to be done from space; many can be done just fine from the ground, freeing up time on the more expensive and tightly scheduled space telescopes. Pitting these two kinds of facilities against each other—why have one when we can have the other?—is the wrong way to think about this. They don't compete; they complement. Together they provide a much clearer view of the cosmos than either can give by itself. Astronomy needs both.
The Hill
2 days ago
- Science
- The Hill
Uranus changed structure and brightened significantly, study finds
A new study revealed Uranus's structure as a planet changed and brightened significantly over the past 20 years. The study, performed by researchers from the University of Arizona and the University of Wisconsin, observed Uranus four times (2002, 2012, 2015, 2022) in the 20 years using NASA's Hubble Space Telescope. 'Hubble observations suggest complex atmospheric circulation patterns on Uranus during this period, NASA said. 'The data that are most sensitive to the methane distribution indicate a downwelling in the polar regions and upwelling in other regions,' the agency added. Researchers discovered the south polar region of the planet got darker in winter shadow, while the north polar region brightened as it began to come into a more direct view as northern summer approached. Uranus's atmosphere is composed primarily of hydrogen and helium, with a small amount of methane and traces of water and ammonia.
Time of India
3 days ago
- Science
- Time of India
What? There's a Bermuda Triangle in space too and it is expanding day by day
The Bermuda Triangle has been one among the most intriguing mysteries on the earth that remain unsolved till date. This unravelled phenomenon has been centered around the tales of vanishing ships, lost aircraft, and unexplained disappearances. Despite scientific explanations dismissing these as results of natural forces and human error, the lore persists. Interestingly, a similar phenomenon exists above our planet also, not one of vanishing vessels, but of real danger to satellites and astronauts. Called as the 'Bermuda Triangle of space,' the South Atlantic Anomaly (SAA) is a vast region above the Earth stretching from Chile to Zimbabwe where the planet's magnetic field is unusually weak. While spacecraft don't disappear into thin air here, the risk is still high. Satellites that travel through this region experience increased radiation exposure, potentially leading to malfunctions, system failures, and even complete breakdowns. As space research is advancing day by day, understanding this anomaly has become increasingly important. The SAA poses a real hazard to the growing fleet of satellites and manned missions circling our planet. Sponsored Links Sponsored Links Promoted Links Promoted Links You May Like The Most Successful Way of Intraday Trading is "Market Profile" TradeWise Learn More Undo Scientists and engineers are constantly monitoring it, looking for ways to mitigate its effects. What is the South Atlantic Anomaly? The South Atlantic Anomaly (SAA) exists where the inner Van Allen radiation belt dips closest to Earth. This proximity results in an area of intensified radiation, and makes spacecraft vulnerable to charged particles from the Sun. Being different from the other areas where Earth's magnetic field deflects these particles, the SAA allows them to come dangerously close as little as 200 km from the surface. This increased exposure causes serious disruptions. According to John Tarduno, a geophysics professor at the University of Rochester, "The lower geomagnetic field intensity eventually results in a greater vulnerability of satellites to energetic particles, to the point that spacecraft damage could occur as they traverse the area", as reported by All About Space. Satellites passing through the SAA are often put into safe mode to protect sensitive equipment. The Hubble Space Telescope, for instance, crosses the anomaly about 10 times daily and is unable to collect data during these periods, which makes to nearly 15% of its operational time. What is the reason behind this anomaly? The anomaly's origin lies deep within the Earth. A reversed flux patch under Africa is weakening the magnetic field in this region. 'Under Africa, at the core-mantle boundary... the field is reversed,' Tarduno explained. 'It is this patch that seems to be causing most of the weak field and the SAA.' The anomaly is slowly drifting westward and splitting in two. NASA's missions, such as the Ionospheric Connection Explorer, monitor these changes to better predict and protect future missions. As space technology becomes more advanced and dependent on electronics, the SAA presents an ever-growing risk. Incidents like the $273 million failure of Japan's Hitomi satellite highlight how devastating the consequences can be when a spacecraft encounters this zone unprepared.
Yahoo
3 days ago
- General
- Yahoo
Webb Telescope Peers Back in Time Via New 'Deep Field' Image
The James Webb Space Telescope has recently captured some breathtaking shots of individual space bodies, from Neptune and its dreamy auroras to Jupiter's own massive light shows. But the telescope's latest image is going for depth, not focus. In a multi-layered snapshot shared by the European Space Agency (ESA) Tuesday, Webb peers back in time, bringing astronomers one step closer to examining so-called "Cosmic Dawn." This period began when the universe was just a few million years old, and based on what astronomers currently know, that's when the version of the universe we observe today began to take shape. Cosmic Dawn should have quite a bit to say about why our stellar setting is the way it is, making it a vital area of study for space scientists. But imaging Cosmic Dawn is easier said than done, and theory can only go so far. Tuesday's Webb image is as good a starting point as any. The image depicts Abell S1063, a behemoth galaxy cluster 4.5 billion light-years from Earth. While the Hubble Space Telescope captured Abell S1063 nine years ago, the galaxy cluster holds too much potential to be used just once: Its size bends the light of distant galaxies positioned "behind" it, allowing it to serve as a strong gravitational lens. Credit: ESA/Webb, NASA & CSA, H. Atek, M. Zamani In an effort to pick up where Hubble left off, Webb's NIRCam (Near-Infrared Camera) gazed at Abell S1063 and its surroundings. A total of 120 observation hours allowed Webb to take nine snapshots at various near-infrared wavelengths. Stacked together, these snapshots offer what the ESA calls "Webb's deepest gaze on a single target to date." While Abell S1063 dominates the image, the warped streaks of light are gravitational lensing in action. The streaks originate from "faint galaxies from the universe's distant pass," as the ESA puts it, lending scientists the potential to develop our understanding of the emergence of the first galaxies." And on that front, research has already begun. According to two preprint papers published on the arXiv, an international team of astrophysicists has used Webb's data to identify a host of candidate galaxies that could have formed as early as 200 million years after the Big Bang. They've even spotted signs of the first stars in the universe.
Indian Express
3 days ago
- Science
- Indian Express
Scientists uncover new details about Uranus' atmosphere, strange seasons
Uranus, the seventh planet from the Sun, owes its pale blue-green in colour to its atmosphere which absorbs the red wavelengths of sunlight, according to a new study. The study was published by a research group comprising scientists from the University of Arizona in the US as well as other institutions. It sheds light on the atmospheric composition and complex dynamics governing the mystery planet. The researchers were able to provide new information about Uranus after analysing images of the planet captured by NASA's Hubble Space Telescope over the last 20 years. The Hubble images of Uranus were taken between 2002 and 2022. As per the study, Uranus' atmosphere is primarily composed of hydrogen and helium, along with small amounts of methane as well as minute quantities of water and ammonia. Uranus is located between Saturn and Neptune. As the seventh planet from the Sun, Uranus remains one of the least understood planets in our solar system which is why the new research study may be significant. Scientists who authored the study also provided more information about seasonal changes on the planet. Unlike other planets, Uranus' axis of rotation is nearly parallel to its orbital plane. It is likely that Uranus collided with an Earth-sized object, which might be the reason why it is said to be rotating in an 'overturned' position. As a result, it takes 84 years for the planet to complete one revolution around the Sun. This means that the surface of the planet gets sunshine for 42 years and the next 42-year-period is dark. Over the course of the 20-year-long study, researchers were able to observe only a part of the seasonal change of Uranus' atmosphere. The research builds on existing information about Uranus, like the fact that the planet is composed mainly of water and ammonia ice. It is approximately 51,000 kilometres in diameter, making Uranus four times bigger than the Earth with a mass that is 15 times greater than that of Earth's. Uranus also has 13 rings and 28 moons. NASA's Voyager 2 is the only space probe mission that has explored the planet by conducting a flyby in January 1986. However, the group of scientists behind the new study said that they will continue to observe Uranus and gather more information on seasonal changes in its polar regions.
