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Webb telescope to look for first light of cosmic dawn

Publish: 12:04 PM, 12 Dec, 2021


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Peering into deep space and billions of years back in time, the James Webb telescope promises to offer the clearest glimpse yet of the Universe's cosmic dawn, when the earliest galaxies began to form.

The largest and most powerful telescope ever to be launched into space, which will take over from Hubble, will "directly observe a part of space and time never seen before", says NASA.

This is the Universe in its youth, just a few hundred million years after the Big Bang.

With "very lofty science goals in mind", Webb will look back 13.5 billion years to when the first galaxies evolved in the Universe, said Begonia Vila, instrument systems engineer at NASA's Goddard Space Flight Center in a briefing.

It aims to allow us to observe "how they change and evolve to get to the type of galaxy where we live in today," she said, as well as looking at the first stars and trying to detect "the type of elements that we identify as a sign of the life as we know it; water, carbon dioxide, methane".

Looking farther into space means looking farther back in time because of how long it takes for light to travel -- sunlight, for example, takes eight minutes to reach our eyes on Earth.

Hubble reached its limit at 13.4 billion years, with the discovery of the oldest galaxy yet observed, GN-z11.

That ancient galaxy may have been an unprepossessing little dot but it was also "a surprise, with a luminosity that one did not expect at such a distance", said the Swiss astrophysicist Pascal Oesch, who first reported GN-z11.


Hubble, which was launched in 1990, looks mainly at visible light -- but Webb, set to launch on December 22, focuses on infrared.

Light emitted by the very first luminous objects has been "redshifted" by the Universe's continual expansion, according to NASA, arriving today as infrared.

Webb, with its significantly greater sensitivity than Hubble, is expected to provide much more detailed images, which Oesch said "will allow us to explore this era in extraordinary detail".

He is betting that "many, many more galaxies will then be revealed, but they will be much less luminous".

Its infrared capability will also allow Webb to penetrate the interstellar dust clouds that absorb starlight and hide them from Hubble's view.

This "makes it possible to see what is hidden in the clouds, the birth of stars and galaxies", said David Elbaz, an astrophysicist at the French Atomic Energy Commission.

Webb has been jointly developed by NASA, the European Space Agency and the Canadian Space Agency.

The ambition is to help explain a key stage in the evolution of the Universe, when "the lights went on, when the very first stars began to form", said Oesch.

After the Big Bang triggered the expansion of the Universe, it entered a virtually lightless period, the cosmic dark ages, where it was cast in a gaseous fog of hydrogen and helium swirled, making it opaque.

This period continued for hundreds of millions of years until the first stars began to form.

These are thought to have been giants -- up to 300 times more massive than our Sun -- that burnt only for a few million years before exploding as supernovae.

How and when those first stars were formed remains uncertain. One idea is that dark matter -- a substance whose existence is so far still theoretical -- played a role.

This was a crucial time in the Universe's evolution, with the radiation from these massive stars able to split hydrogen atoms back into electrons and protons -- ionising them.

As it ionised, the Universe became more transparent, leading eventually to the "clear" conditions now detected in much of Space.

To study this phenomenon is to investigate the formation of galaxies.

The hope with Webb is to see "the first galaxies, which carry the second generation of stars, which will perhaps teach us things about the first", said Nicole Nesvadba, astronomer at the Lagrange laboratory of the Observatory of the Riviera.

And this, experts hope, will ultimately provide clues to our own existence.

"If we really want to know where our atoms came from, and how the little planet Earth came to be capable of supporting life, we need to measure what happened at the beginning," said John Mather, senior project scientist for the Webb telescope, in comments on the project's website.



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NASA, SpaceX study boosting Hubble to extend its lifespan

Publish: 09:47 AM, 02 Oct, 2022


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NASA and SpaceX have agreed to study the feasibility of awarding Elon Musk's company a contract to boost the Hubble Space Telescope to a higher orbit, with a goal of extending its lifespan, the US space agency said recently.

The renowned observatory has been operating since 1990 about 335 miles (540 kilometers) above Earth, in an orbit that slowly decays over time.

Hubble has no on-board propulsion to counter the small but still present atmospheric drag in this region of space, and its altitude has previously been restored during Space Shuttle missions.

The proposed new effort would involve a SpaceX Dragon capsule.

"A few months ago, SpaceX approached NASA with the idea for a study whether a commercial crew could help reboost our Hubble spacecraft," NASA's chief scientist Thomas Zurbuchen told reporters, adding the agency had agreed to the study at no cost to itself.

He stressed there are no concrete plans at present to conduct or fund such a mission until the technical challenges are better understood.

One of the main obstacles would be that the Dragon spacecraft, unlike the Space Shuttles, does not have a robotic arm and would need modifications for such a mission.

SpaceX proposed the idea in partnership with the Polaris Program, a private human spaceflight venture led by payments billionaire Jared Isaacman, who last year chartered a SpaceX Crew Dragon to orbit the Earth with three other private astronauts.

"This would certainly fit within the parameters we established for the Polaris program," Isaacman said in response to a question about whether reboosting Hubble could be the goal for a future Polaris mission.

Asked by a reporter whether there might be a perception that the mission was contrived in order to give wealthy people tasks to do in space, Zurbuchen said: "I think it's only appropriate for us to look at this because of the tremendous value this research asset has for us."

Arguably among the most valuable instruments in scientific history, Hubble continues to make important discoveries, including this year detecting the farthest individual star ever seen -- Earendel, whose light took 12.9 billion years to reach us.

It is currently forecast to remain operational throughout this decade, with a 50 percent chance of de-orbiting in 2037, said Patrick Crouse, Hubble Space Telescope project manager.

- AFP


NASA   SpaceX   Hubble Telescope  


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NASA's DART spacecraft hits target asteroid in first planetary defense test

Publish: 09:57 AM, 27 Sep, 2022


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NASA's DART spacecraft successfully slammed into a distant asteroid at hypersonic speed on Monday in the world's first test of a planetary defense system, designed to prevent a potential doomsday meteorite collision with Earth.

Humanity's first attempt to alter the motion of an asteroid or any celestial body played out in a NASA webcast from the mission operations center outside Washington, DC, 10 months after DART was launched.

The livestream showed images taken by DART's camera as the cube-shaped "impactor" vehicle, no bigger than a vending machine with two rectangular solar arrays, streaked into the asteroid Dimorphos, about the size of a football stadium, at 7:14 pm EDT (2314 GMT) some 6.8 million miles (11 million km) from Earth.

The $330 million mission, some seven years in development, was devised to determine if a spacecraft is capable of changing the trajectory of an asteroid through sheer kinetic force, nudging it off course just enough to keep Earth out of harm's way.

Whether the experiment succeeded beyond accomplishing its intended impact will not be known until further ground-based telescope observations of the asteroid next month. But NASA officials hailed the immediate outcome of Monday's test, saying the spacecraft achieved its purpose.

"NASA works for the benefit of humanity, so for us it's the ultimate fulfillment of our mission to do something like this - a technology demonstration that, who knows, someday could save our home," NASA Deputy Administrator Pam Melroy, a retired astronaut, said minutes after the impact.

DART, launched by a SpaceX rocket in November 2021, made most of its voyage under the guidance of NASA's flight directors, with control handed over to an autonomous on-board navigation system in the final hours of the journey.

Monday evening's bullseye impact was monitored in near real time from the mission operations center at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland.

Cheers erupted from the control room as second-by-second images of the target asteroid, captured by DART's onboard camera, grew larger and ultimately filled the TV screen of NASA's live webcast just before the signal was lost, confirming the spacecraft had crashed into Dimorphos.

DART's celestial target was an oblong asteroid "moonlet" about 560 feet (170 meters) in diameter that orbits a parent asteroid five times larger called Didymos as part of a binary pair with the same name, the Greek word for twin.

Neither object presents any actual threat to Earth, and NASA scientists said their DART test could not create a new hazard by mistake.

Dimorphos and Didymos are both tiny compared with the cataclysmic Chicxulub asteroid that struck Earth some 66 million years ago, wiping out about three-quarters of the world's plant and animal species including the dinosaurs.

Smaller asteroids are far more common and present a greater theoretical concern in the near term, making the Didymos pair suitable test subjects for their size, according to NASA scientists and planetary defense experts. A Dimorphos-sized asteroid, while not capable of posing a planet-wide threat, could level a major city with a direct hit.

Also, the two asteroids' relative proximity to Earth and dual configuration make them ideal for the first proof-of-concept mission of DART, short for Double Asteroid Redirection Test.

Robotic suicide mission

The mission represented a rare instance in which a NASA spacecraft had to crash to succeed. DART flew directly into Dimorphos at 15,000 miles per hour (24,000 kph), creating the force scientists hope will be enough to shift its orbital track closer to the parent asteroid.

APL engineers said the spacecraft was presumably smashed to bits and left a small impact crater in the boulder-strewn surface of the asteroid.

The DART team said it expects to shorten the orbital path of Dimorphos by 10 minutes but would consider at least 73 seconds a success, proving the exercise as a viable technique to deflect an asteroid on a collision course with Earth - if one were ever discovered.

A nudge to asteroid millions of miles away years in advance could be sufficient to safely reroute it.

Earlier calculations of the starting location and orbital period of Dimorphos were made during a six-day observation period in July and will be compared with post-impact measurements made in October to determine whether the asteroid budged and by how much.

Monday's test also was observed by a camera mounted on a briefcase-sized mini-spacecraft released from DART days in advance, as well as by ground-based observatories and the Hubble and Webb space telescopes, but images from those were not immediately available.

DART is the latest of several NASA missions in recent years to explore and interact with asteroids, primordial rocky remnants from the solar system's formation more than 4.5 billion years ago.

Last year, NASA launched a probe on a voyage to the Trojan asteroid clusters orbiting near Jupiter, while the grab-and-go spacecraft OSIRIS-REx is on its way back to Earth with a sample collected in October 2020 from the asteroid Bennu.

The Dimorphos moonlet is one of the smallest astronomical objects to receive a permanent name and is one of 27,500 known near-Earth asteroids of all sizes tracked by NASA. Although none are known to pose a foreseeable hazard to humankind, NASA estimates that many more asteroids remain undetected in the near-Earth vicinity.

- Reuters


NASA   DART   Asteroid Redirection Test   Planetary Defense  


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Chinese rocket falls to Earth; Nasa says Beijing did not share information

Publish: 09:11 AM, 31 Jul, 2022


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A Chinese rocket fell back to Earth on Saturday over the Indian Ocean but Nasa said Beijing had not shared the "specific trajectory information" needed to know where possible debris might fall.

US Space Command said the Long March 5B rocket re-entered over the Indian Ocean at approximately 12:45 p.m. EDT Saturday (1645 GMT), but referred questions about "reentry's technical aspects such as potential debris dispersal impact location" to China.

"All spacefaring nations should follow established best practices and do their part to share this type of information in advance to allow reliable predictions of potential debris impact risk," Nasa Administrator Bill Nelson said. "Doing so is critical to the responsible use of space and to ensure the safety of people here on Earth."

Social media users in Malaysia posted video of what appeared to be rocket debris.

Aerospace Corp, a government funded nonprofit research center near Los Angeles, said it was reckless to allow the rocket's entire main-core stage – which weighs 22.5 tons (about 48,500 lb) – to return to Earth in an uncontrolled reentry.

Earlier this week, analysts said the rocket body would disintegrate as it plunged through the atmosphere but is large enough that numerous chunks will likely survive a fiery re-entry to rain debris over an area some 2,000 km (1,240 miles) long by about 70 km (44 miles) wide.

The Chinese Embassy in Washington did not immediately comment. China said earlier this week it would closely track the debris but said it posed little risk to anyone on the ground.

The Long March 5B blasted off July 24 to deliver a laboratory module to the new Chinese space station under construction in orbit, marking the third flight of China's most powerful rocket since its maiden launch in 2020. 

Fragments of another Chinese Long March 5B landed on the Ivory Coast in 2020, damaging several buildings in that West African nation, though no injuries were reported.

By contrast, he said, the United States and most other space-faring nations generally go to the added expense of designing their rockets to avoid large, uncontrolled re-entries - an imperative largely observed since large chunks of the Nasa space station Skylab fell from orbit in 1979 and landed in Australia.

Last year, Nasa and others accused China of being opaque after the Beijing government kept silent about the estimated debris trajectory or the reentry window of its last Long March rocket flight in May 2021. 

Debris from that flight ended up landing harmlessly in the Indian Ocean.

- Reuters


Chinese rocket   NASA  


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Meteor impact left 'uncorrectable' damage to the Webb telescope's mirror

Publish: 12:02 PM, 21 Jul, 2022


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Since launching on Dec. 25, 2021, NASA's James Webb Space Telescope (JWST) has been pelted by at least 19 tiny space rocks — including one large one that left noticeable damage on one of the telescope's 18 gold-plated mirrors.

In a sprawling new status report posted to the pre-print database arXiv.org (opens in new tab), NASA researchers have shared the first images showing the extent of that damage. Seen on the C3 mirror in the lower right-hand corner of the image, the impact site appears as a single bright white dent besmirching the golden mirror's surface.

The impact — which likely occurred between May 23 and May 25 this year — left "uncorrectable" damage to a tiny portion of that mirror, the report says. However, this little dent doesn't seem to have inhibited the telescope's performance at all. In fact, the JWST's performance is exceeding expectations "almost all across the board." (Good news for fans of stunning space images.)


Tiny rocks known as micrometeoroids are an all-too-familiar threat to spacecraft in near-Earth orbit. The U.S. Space Surveillance Network keeps track of more than 23,000 pieces of orbital debris measuring larger than the size of a softball — however, the millions of nearby space chunks that are smaller than that are almost impossible to monitor.

Instead, NASA and other space agencies plan for unavoidable impacts.

"Inevitably, any spacecraft will encounter micrometeoroids," the new report says. So far, six micrometeoroids have left noticeable "deformities" on the JWST's mirrors, amounting to about one noticeable impact per month since the telescope launched.

That's all within the realm of the expected. When building the JWST, engineers intentionally hit mirror samples with micrometeoroid-sized objects to test how such impacts would affect the telescope's performance.

What was unexpected, however, was the size of the larger impactor that dented the C3 mirror. This space rock was seemingly larger than the team had prepared for, and researchers are now trying to assess the impact that further strikes like this could have on the JWST.

The new status report, which has not yet been peer-reviewed, was authored by more than 200 scientists working at NASA, the European Space Agency (a collaborator in the JWST's construction and launch, along with NASA and the Canadian Space Agency) and other science institutions around the world. Despite the unexpected impact to the C3 mirror, the researchers found that the telescope is working flawlessly after the 6-month commissioning process, and has a bright future of discovery ahead of it.

"JWST was envisioned 'to enable fundamental breakthroughs in our understanding of the formation and evolution of galaxies, stars, and planetary systems,'" the report says. "We now know with certainty that it will."


JWST   James Webb Space Telescope   Meteor impact  


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Webb space telescope opens door to discoveries still unimagined

Publish: 11:42 AM, 14 Jul, 2022


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The powerful James Webb Space Telescope's inaugural batch of images has opened a new chapter of cosmic exploration, but astronomers say the observatory's most consequential discoveries may well be those they have yet to even imagine.

Distant colliding galaxies, gas-giant exoplanets and dying star systems were the first celestial subjects captured by the multibillion-dollar observatory, putting its wide range of infrared-imaging capabilities on colorful display and proving the telescope works as designed.

Webb's gallery of early photos and spectrographic data, which astronomers likened to the results of mere "target practice" as they readied the telescope for operational science, also previewed several planned areas of inquiry ahead.

The competitively-selected agenda of research includes exploring the evolution of early galaxies, the life cycle of stars, the search for habitable planets orbiting distant suns, and the composition of moons in our own outer solar system.

But the most revolutionary findings by Webb, 100 times more sensitive than its 30-year-old predecessor, the still-operational Hubble Space Telescope, may turn out to be accidental discoveries or answers to questions astronomers have yet to ask.

"Who knows what's coming for JWST. But I'm sure we're going to have a lot of surprises," René Doyon, principal investigator for one of Webb's instruments, the Near-Infrared Imager and Slitless Spectrograph, said Tuesday at NASA's Goddard Space Flight Center in Maryland, where the agency unveiled the observatory's first full-color images.

With Webb open for business seven months after its launch in December, astronomers are preparing for "something that's out there that we never guessed would be there at all," said John Mather, a Nobel Prize-winning senior astrophysicist at NASA whose work during the 1990s helped cement cosmology's 'Big Bang' theory.

DARK MATTER, DARK ENERGY

Mather and other scientists pointed to dark matter, an invisible and little-understood but theoretically influential cosmic scaffolding, as an enigma that Webb might unlock during its mission.

Hubble, likewise, opened a whole new field of astrophysics devoted to another mysterious phenomenon, dark energy, as its observations of supernovas led to the unexpected discovery that the universe's expansion is accelerating.

Taken together, dark energy and dark matter are now estimated by scientists to account for 95% of the known universe. All the galaxies, planets, dust, gases and other visible matter in the cosmos compose just 5%.

"Those were huge surprises," Mather said of early dark matter and dark energy discoveries.

Amber Straughn, a deputy project scientist working with Webb, said: "It's hard to imagine what we might learn with this hundred-times-more-powerful instrument that we really don't know yet."

Dark matter already has figured prominently in Webb's very first "deep field" image, a composite photo of a distant galaxy cluster, SMACS 0723, that offers the most detailed glimpse to date of the early universe thanks to a magnifying effect called a gravitational lens.

The sheer combined mass of galaxies and other unseen matter in the foreground of the image warps the surrounding space enough to amplify light coming from more distant galaxies behind them, bringing into view fainter objects farther away, and thus further back in time.

At least one of the tiny specks of light "photo-bombing" the edge of the picture dates back 13.1 billion years, or nearly 95% of the way to the Big Bang, the theoretical cosmic flashpoint that put the universe in motion 13.8 billion years ago.

But because the calculated combined mass of all the visible matter in the foreground is insufficient by itself to produce the faint circular distortion seen in the image, the lensing effect is firm indirect evidence of dark matter's presence.

"It's the most powerful tool that we have, astrophysically, to do this type of lensing experiment," said Jane Rigby, a Webb operations project scientist. "We can't directly detect dark matter, but we see its impact... we can see its effects in action."

"The universe has been out there, we just had to build a telescope to see what was there," she added.

New light was also shed unexpectedly from Webb's first spectrographic analysis of an exoplanet in a distant solar system, in this case a gas giant roughly the size of Jupiter dubbed WASP-96 b.

Measuring the wavelengths from light filtered through the atmosphere of the exoplanet as it orbited its own sun clearly revealed the molecular signature of water vapor in clouds and haze, features scientists were surprised to find.

"There are discoveries in these data," Webb program scientist Eric Smith said. "We're making discoveries and we really haven't even started trying yet."

- Reuters


James Webb Telescope   Cosmos   NASA  


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