Science
James Webb Space Telescope: The engineering behind a 'first light machine' that is not allowed to fail – Space.com
Randy Kimble will never forget the days in August 2017 when Hurricane Harvey battered Texas. As a project scientist for integration, test and commissioning of the James Webb Space Telescope (JWST), he had no option to hide at home. The giant telescope, at that time already 10 years behind schedule and considerably over budget, was right in the middle of one of its 100-day space simulating test campaigns at NASA’s Johnson Space Center in Houston.
“The main gate was under several feet of water and the rest of the center was shut down,” Kimble told Space.com. “But there was still one route from a hotel strip in that area and you could get in through the back gate at Johnson. Just by a matter of days, we didn’t run out of liquid nitrogen to keep the cooling system going. It was very tense.”
Kimble has worked on JWST since 2009 after spending two decades developing instruments for JWST’s predecessor, the Hubble Space Telescope. Still, he said, the tests of JWST, carried out inside the 40-foot diameter Chamber A (built in the 1960s to test equipment for the moon-bound Apollo missions), were a career highlight. They involved lowering the telescope’s temperature to the minus 390 degrees Fahrenheit (minus 217 degrees Celsius) in which it will operate, and in a vacuum similar to that of space.
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“The cryo-vacuum tests for Webb were long and gruelling,” Kimble said. “It would take weeks just to cool everything down safely and then warm up again safely at the end of the test. And in the middle, when you are cold and stable, that’s when you do your detailed testing.”
Over a six-year period, multiple test campaigns were conducted with teams working on site 24/7, including weekends and holidays, Kimble said. The spacecraft’s four scientific instruments were also tested separately, multiple times, and so was virtually every part of the telescope, the most complex, daring and expensive space observatory ever built.
Some 30 years in the making and with an eventual price tag of $10 billion, the James Webb Space Telescope is simply not allowed to go wrong. The problem is that in the space business, it is rather easy to go wrong.
Lessons from Hubble
When the Hubble Space Telescope launched in 1990, it soon became obvious something was amiss. The images it sent to Earth were disappointing, blurry, nowhere near to what scientists had expected. The problem was traced to the telescope’s great mirror, which was improperly polished during manufacturing. A rescue mission involving a team of astronauts was sent to fix the problem. Hubble received ‘glasses’ to correct its short-sightedness and turned into the astronomical powerhouse that has since generated thousands of iconic and scientifically priceless images.
With the James Webb Space Telescope, rescue missions are impossible and therefore no failures are allowed.
“James Webb Space Telescope is a prototype and with prototypes, you can always have something that goes wrong,” Mark McCaughrean, senior advisor for science and exploration at the European Space Agency (ESA) and interdisciplinary scientist at the JWST science working group, told Space.com. “That’s why JWST is so expensive. Because we’ve spent two decades building and testing every single piece a million ways to do everything to make sure it doesn’t have problems.”
But why does Webb have to be so complex? Wouldn’t a simpler mission work just as well? And why cannot it be serviced by astronauts?
The fact is that serviceability was never an option for Webb. The science it is meant to deliver, the depths of space it is intended to glimpse, simply cannot be accomplished with a spacecraft that astronauts can visit (at least not with currently available spaceships).
The first light machine
The James Webb Space Telescope, sometimes fondly referred to by astronomers as the ‘first light machine,’ was built to see the first stars and galaxies that emerged from dust and gas of the early universe, only a few millions of years after the Big Bang.
Because these stars and galaxies are so far away, the visible light they emitted when the universe was only a few hundred millions of years old has shifted into the near infrared and infrared part of the electromagnetic spectrum. This strange effect, known as the red shift in astronomical jargon, is a result of the expansion of the universe and the ensuing Doppler effect. That’s the same effect that distorts the frequency of a siren of a passing ambulance car.
Infrared radiation is essentially heat, and can be detected with special sensors that are different from those detecting visible light. Since the stars and galaxies that JWST was designed to study are so far away, the incoming signals are also extremely faint. The scientists and engineers behind JWST needed to tackle a range of technical obstacles to make this hoped-for detection possible.
Far from Earth
The Hubble Space Telescope, although originally designed to detect only the visible light of the universe (that in wavelengths that the human eye can process), was in 1997 equipped with then cutting-edge infrared detectors during the second servicing mission; these sensors were later upgraded when new technology became available. But still, infrared astronomy was an obvious afterthought for Hubble, and the telescope clearly wasn’t optimized to feel the warmth of the most distant universe.
Hubble orbits Earth at the altitude of 340 miles (545 kilometers). On top of being regularly blasted by direct sunlight, Hubble also absorbs Earth’s heat. As a result, its infrared detectors are quite dazzled by the telescope’s own warmth and it simply cannot see those faint and distant galaxies.
“If you want a really sensitive infrared telescope, it needs to be really cold,” McCaughrean said. “And to get really cold, you need to get away from Earth.”
And the James Webb Space Telescope will be far away from Earth indeed, about 1 million miles (1.5 million km) away. That’s more than four times farther than the moon. The telescope will orbit the sun, while simultaneously making small circles around the so-called Lagrange point 2 (L2) — a point on the sun-Earth axis constantly hidden from the sun by the planet. At L2, the gravitational pulls of the sun and of Earth keep the spacecraft aligned with the two big bodies.
But even that wouldn’t make Webb cold enough to accomplish its mission.
SPF 1 million
The largest piece of the spacecraft — and one without which the mission would be impossible — is its tennis court-sized deployable sunshield made of five layers of an aluminum-coated space blanket material called kapton.
The sunshield will unfurl in space before the telescope reaches its destination in one of the most nerve-wrecking parts of the spacecraft’s post-launch deployment sequence.
“The sunshield is by far the most mission-critical thing,” said McCaughrean. “If it doesn’t fully deploy, the telescope doesn’t work. We have obviously folded and unfolded it many times on the ground, but nothing like this has ever been flown in space before, and the lack of gravity simply changes things.”
The sunshield is James Webb Space Telescope’s only cooling mechanism. Nestled behind it, the mirrors and the four never-before-flown instruments will remain far below freezing at 390 degrees Fahrenheit (minus 217 degrees Celsius). The sun-facing side, on the other hand, will be incredibly hot — up to 230 degrees F (128 degrees C).
“The sunshield is like sunscreen with an SPF of at least a million in terms of how much it attenuates the solar energy,” said Kimble, then testing and integration project scientist who rode out Hurricane Harvey with JWST. “That allows us to passively cool down cold enough that [the observations] are not limited at all by the glow of the telescope.”
The sunshield is not a simple parasol; a lot of clever engineering went into its design. The five layers of the ultralight kapton material are precisely spaced so that the heat absorbed by each layer is perfectly radiated away from the spacecraft through the gaps. While superthin and ultralight, the material is also incredibly sturdy, enough to survive bombardment by meteorites.
Giant mirror
To do what it has been designed to do, the James Webb Space Telescope really couldn’t be small. The Hubble Space Telescope, with its mirror 7.8 feet (2.4 meters) in diameter, couldn’t detect those distant early galaxies even if it were as cold as Webb.
“If you want to see those distant, faint galaxies, then you need to gather more light,” Kimble said. “And so the simple fact that Webb’s mirror collects six to seven times more photons in a given amount of time [than Hubble], gives you a significant advantage.”
The ability of a telescope to collect light increases with the square of the size of its mirror, explained McCaughrean. With its 21-foot (6.5 m) mirror, Webb will not only be able to take sharper, deeper images of the universe than those that made Hubble famous, it will also do so in a fraction of the time required by Hubble.
“Some of the deep field work that Hubble has done, they would look in a particular field for a couple of weeks,” Kimble said. “Webb can reach that kind of sensitivity limit in seven or eight hours.”
Too big for space?
But here comes another challenge. How do you lift something the size of a tennis court with a 21-foot mirror into space?
The Hubble Space Telescope, which measures 44 feet long (13.2 m) and at most 14 feet (4.2 m) across, fitted quite snugly into the 60-foot long (18.3 m) and 15-foot wide (4.6 m) payload bay of the space shuttle Discovery, from which the telescope was deployed in 1990.
But the widest rocket fairing available when Webb was designed was Europe’s Ariane 5 rocket, and the telescope’s mirror is more than 3 feet (1 m) too wide to fit. So for Webb, getting to space requires folding and unfolding. The mirror and the sunshield, as well as the usual solar arrays and antennas, must all be neatly stowed for the telescope’s launch.
Golden lightweight origami
The mirror, made of 18 hexagonal segments, each 4.3 feet (1.32 m) across, collapses like an origami for the launch. Once in space, these elements unfold, locking together. The jigsaw puzzle is so finely tuned that once the mirror is fully aligned, the seams between the individual segments will be perfectly smooth.
Aligning the mirror once in space will be an intricate endeavour of several months, relying on one of the cameras aboard the spacecraft, the NIRCam instrument.
“Aligning those mirror segments to make a smooth, continuous mirror shape out of them is going to be fascinating,” said Kimble, who will oversee these never-before-conducted operations. “At the beginning, we will produce 18 separate images with NIRCam; at the end, we will have a single beautiful image.”
NIRCam, McCaughrean said, just like many other components of the telescope, is simply not allowed to fail.
“If NIRCam failed, you won’t be able to line up the telescope,” said McCaughrean. “That’s why there is lots of redundancy in it. It has got two completely separate camera systems inside, so if one fails, you have the other one.”
At the backs of the 18 hexagonal mirror segments are small motors that delicately press onto the plates, shifting and bending them with extreme precision until they create one giant, perfectly smooth mirror.
“That means movement at the level of nanometers,” said McCaughrean. There are 25.4 million nanometers in one inch. “It’s incredibly complicated. And that’s why it takes so long for us to actually commission the telescope. We launch it in late December, but the first images won’t come until the summer of 2022 because it takes that long to line everything up.”
The mirror also needed to be extremely lightweight. Had the engineers simply scaled up the 8-foot glass mirror of the Hubble Space Telescope to build the 21-foot mirror of Webb, the telescope would be too heavy for any existing rocket to lift.
As it is, Webb’s mirror is only one 10th of the mass of Hubble’s mirror, with each of the 18 hexagonal segments, made of ultralight metal beryllium, weighing only 46 pounds (20 kilograms). The entire spacecraft, despite its enormous size, weighs only 6.5 metric tonnes compared to the 11.1 metric tonnes of the smaller Hubble.
The surface of the mirror is plated with gold, giving it the signature yellow tint. “The golden color was chosen because it’s the best for reflecting infrared radiation, much better than white or silver,” says McCaughrean.
The light reflected by the giant mirror is then concentrated onto the 30-inch (74 centimeter) secondary mirror that sits opposite the large mirror attached to a foldable tripod that must also deploy in space. From there, the light enters through an opening at the center of the large mirror into the telescope, where a tertiary mirror sends it to the detectors.
Extended thrill
The James Webb Space Telescope launch is currently scheduled for Friday (Dec. 24). Launch day will be a big moment for the thousands of engineers and scientists who have been involved in the mission since its conception in the early 1990s.
But even after launch, the telescope, which has stretched so many people and so many technologies to their limits, will not allow them to rest. The launch will be the beginning of what Kimble described as “extended thrill,” a six-month period of gradual deployments, cooling down, switching on, aligning and testing.
“The first weeks, during our journey to L2, that’s when we will see the major deployments,” said Kimble. “The sunshield, the mirror, the secondary mirror’s support tripod, the solar wings. The telescope will build itself like an origami.”
In a press conference held on Nov. 2, Mike Menzel, Webb lead mission systems engineer at NASA Goddard Space Flight Center, said that 144 release mechanisms must work as intended for the deployment to succeed.
“There are 344 single-point-of-failure items on average,” Menzel said in that press conference. “Approximately 80% of those are associated with the deployment.”
Assuming all its deployments work as intended, Webb will be perched at L2 approximately one month after launch, hidden behind its giant sunshield. Then the telescope will perform the procedure Kimble tested in Houston during Hurricane Harvey — slowly cooling down to its operational temperature while testing its instruments and aligning its mirrors.
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“We can do some rougher alignments on the way down as the system is cooling,” said Kimble. “At that stage, the structures will still be moving a little because of the cooling and shrinking, so the final tweaking can only be done after we reach temperature stability,” 100 to 120 days into the mission.
For Kimble, these months will represent a peak of his career, ensuring that he is “going out with a bang,” he said. After more than four decades working on the most cutting-edge space telescopes, the scientist said he is ready to hand over the magnificent first light machine to others after the end of its nerve-wracking commissioning period.
“It’s going to be very, very intense,” he said.
Follow Tereza Pultarova on Twitter @TerezaPultarova. Follow us on Twitter @Spacedotcom and on Facebook.
If last week’s solar eclipse piqued your interest in astronomy, the Royal Astronomical Society of Canada’s Windsor Chapter plans to show off some of the more dramatic photos and videos members took of the event.
They were stationed along the path of totality along the northern shore of Lake Erie and in the U.S.
“People did take some nice photos with their cellphones, but we have members who took photos and videos with their telescopes,” said member Tom Sobocan. “You’ll see some pretty impressive shots.”
About 100 members are in the local chapter, which meets every third Tuesday of every month.
Thursday’s meeting is at the Ojibway Nature Centre on Matchette Road. It starts at 7:30, and it’s open to the public. Seating is limited, so Sobocan recommends arriving early.
Astronomers are looking ahead to new wonders in the heavens. Right now, the Pons-Brooks Comet, another once-in-a-lifetime opportunity, is approaching Jupiter in the constellation of Aries.
“If you’re in a dark-sky location, you can see it with the naked eye, and from inside the city, you can see it with binoculars,” said Sobocan. “It may get a little bit brighter going towards the fall, but our members have already photographed it with their telescopes.”
It’s a periodic comet which appears in the night sky once every 71 years.
Sobocan said once-in-a-lifetime events, like last week’s eclipse, inspired many of its existing members, but he hopes some new ones will join the group.
“I hope it inspires them to look up at the sky a little bit more often and realize that everything’s in motion in the sky,” he said. “It’s not stationary.”
Science
Giant, 82-foot lizard fish discovered on UK beach could be largest marine reptile ever found – Livescience.com
Scientists have unearthed the remains of a gigantic, 200 million-year-old sea monster that may be the largest marine reptile ever discovered.
The newfound creature is a member of a group called ichthyosaurs, which were among the dominant sea predators during the Mesozoic era (251.9 million to 66 million years ago). The newly described species lived during the end of the Triassic period (251.9 million to 201.4 million years ago).
Ichthyosaurs had already attained massive sizes by the early portion of the Mesozoic, but it was not until the late Triassic that the largest species emerged.
While the Mesozoic is known as the age of the dinosaurs, ichthyosaurs were not themselves dinosaurs. Instead, they evolved from another group of reptiles. Their evolutionary path closely mirrors that of whales, which evolved from terrestrial mammals that later returned to the sea. And like whales, they breathed air and gave birth to live young.
The newly discovered ichthyosaur species was unearthed in pieces between 2020 and 2022 at Blue Anchor, Somerset in the United Kingdom. The first chunk of the fossil was noticed atop a rock on the beach, indicating that a passerby had found it and set it there for others to examine, the researchers explained in the paper. The researchers published their findings April 17 in the journal PLOS One.
The reptile’s remains are made up of a series of 12 fragments from a surangular bone, which is found in the upper portion of the lower jaw. The researchers estimate the bone was 6.5 feet (2 meters) long and that the living animal was about 82 feet (25 m) long.
The researchers named the sea monster Ichthyotitan severnensis, meaning giant lizard fish of the Severn, after the Severn Estuary where it was found. The team believes it is not only a new species but an entirely new genus of ichthyosaur. More than 100 species are already known.
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A number of rib fragments and a coprolite, or fossilized feces, were found in the area as well, but they were not definitively attributed to the same animal.
The sediments in which these specimens were found contained rocks that indicated earthquakes and tsunamis occurred during that time, which suggests that this species lived during a time of intense volcanic activity that may have led to a massive extinction event at the end of the Triassic according to the researchers.
A similar specimen was discovered in Lilstock, Somerset in 2016 and described in 2018. Both were found in what is known at the Westbury Mudstone Formation, within 6 miles (10 kilometers) of each other. This ichthyosaur was estimated to have been as much as 85 feet (26 m) long, although the authors of the latest study believe it was slightly smaller.
The previous contender for the largest marine reptile was another ichthyosaur, Shonisaurus sikanniensis, which was up to 69 feet (21 m) long. S. sikanniensis appeared 13 million years earlier than I. severnensis and was found in British Columbia, making it unlikely that the new discovery represents another specimen of the previously known species.
A similarly massive ichthyosaur called Himalayasaurus tibetensis, which may have reached lengths of 49 feet (15 m), was discovered in Tibet and described in 1972. It dates to the same period, meaning that it probably is not the same species as the new discovery either.
I. severnensis was likely among the last of the giant ichthyosaurs, the researchers claim. Ichthyosaurs persisted into the Cenomanian Age (100.5 million to 93.9 million years ago) of the late Cretaceous period (100.5 million to 66 million years ago). They were eventually supplanted by plesiosaurs — long-necked marine reptiles that went extinct at the end of the Cretaceous, alongside all non-avian dinosaurs.
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The Canadian Space Agency also received a proposed $8.6 million for its lunar program
Nicole Mortillaro (new window) · CBC News
Canada’s space sector received a boost from the federal government in its budget, both in terms of money and vision.
The 2024 budget (new window) included a proposal for $8.6 million in 2024-25 to the Canadian Space Agency (CSA) for the Lunar Exploration Accelerator Program (new window) (LEAP), which invests in technologies for humanity’s return to the moon and beyond.
In addition to the funding, the federal government also announced the creation of a National Space Council, which will be a new whole-of-government approach to space exploration, technology development, and research.
For Space Canada (new window), an organization comprised of roughly 80 space sector companies including some of Canada’s largest, such as Magellan Aerospace (new window), Maritime Launch (new window) and MDA Space (new window), it was a welcome announcement.
We’ve been advocating for it since the inception of our organization, and we were really very happy, and we applaud the federal government’s commitment announced in the budget,
said Brian Gallant, CEO of Space Canada.
Gallant said that investment in space is an investment in Canada.
Two-thirds of space sector jobs are STEM jobs. These are good paying solid jobs for Canadians. And on top of that, we have approximately $2.8 billion that is injected into the Canadian economy because of the space sector,
he said.
The U.S. formed its National Space Council in 1989, but it was disbanded in 1992 and reestablished in 2017.
In the 2023 budget (new window), the government announced proposed spending of $1.2 billion over 13 years, that was to begin in 2024-25, to the CSA’s contribution of a lunar utility (new window) vehicle that would assist astronauts on the moon. The as–yet–developed vehicle could help astronauts move cargo from landing sites to habitats, perform science investigations or support them during spacewalks on the surface of the moon.
It also proposed to invest $150 million over five years for the LEAP program.
MDA Space, the company behind Canadarm, was also pleased with the announcement.
Canada has an enviable global competitive advantage in space and the creation of a National Space Council is critical to Canada maintaining that leadership position,
CEO Mike Greenley said in an email to CBC News.
Space is now a rapidly growing, highly strategic and competitive domain, and there is a real and urgent need to recognize its importance to the lives of Canadians and to our economy and national security.
The next project for MDA is Canadarm3, which will be part of Lunar Gateway, a international space station that will orbit the moon. It will serve as a sort of jumping-off point for astronauts heading to the moon and eventually beyond.
The Lunar Gateway is a great opportunity for Canada and for MDA Space to not only provide the next generation of Canadarm robotics but to clearly plant our flag as a core national and industry participant in the Artemis era,
Greenley said.
Lunar Gateway is set to begin construction no earlier than 2025 (new window), according to NASA.
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