Astronomers have turned their eye towards the future following the US National Academies’ latest decadal survey of astronomy and astrophysics, which recommended a new generation of space telescopes. Keith Cooper explores their prospects, and the lessons learned from the troubled development of the James Webb Space Telescope
Compare and contrast The Pillars of Creation as seen by the Hubble Space Telescope and the James Webb Space Telescope (JWST). On the left is Hubble’s iconic view, taken in visible light in 2014. On the right is the JWST’s new near-infrared view, released in October 2022. (Courtesy: NASA, ESA, CSA, STScI)
Christmas Day 2021 was a happy occasion for most astronomers around the world, as it was when the much-delayed James Webb Space Telescope (JWST) was finally launched. However, the fanfare surrounding its unfurling in space over the next month, as well as the subsequent jubilation over its first images, has masked a troubling problem in observational astronomy – which is that much of the rest of NASA’s fleet of space-based orbiting observatories is ageing. The Hubble Space Telescope has been working since 1990, while the Chandra X-ray Observatory was launched nearly a decade later. Meanwhile, their infrared compatriot, the Spitzer Space Telescope, launched in 2003, is no longer operating, having been shut down in 2020.
That’s why astronomers are worried that should something happen to one or more of these increasingly rickety telescopes, they could be cut off from whole swathes of the electromagnetic spectrum. With the shutdown of Spitzer, the far-infrared (160 μm) is already out of reach as the JWST only ventures into the mid-infrared at 26 μm. Similarly, the JWST is not optimized for observing visible or ultraviolet wavelengths like Hubble does. Sure, the forthcoming Nancy Grace Roman Space Telescope – formerly the Wide Field InfraRed Survey Telescope (WFIRST) – is an optical and near-infrared telescope, but its field of view is much wider than Hubble’s, meaning it is not geared for close-up, detailed work; nor does it have Hubble’s ultraviolet coverage.
Great observatories
To ensure our view of the universe across the spectrum remains bright, US astronomers are currently picking and choosing the next cohort of space telescopes. The prime recommendation of the latest astronomical decadal survey from the US National Academies of Sciences, Engineering and Medicine – the 614-page report Pathways to Discovery in Astronomy and Astrophysics for the 2020s (Astro2020) – is for plans to be put in place for a new generation of “great observatories” to begin launching in the 2040s. This echoes when Chandra, Hubble, Spitzer and the Compton Gamma-Ray Observatory (which operated between 1991 and 2000 and was succeeded in 2008 by the Fermi Space Telescope) were being developed, and which were heralded as the “great observatories”.
Working alongside each other to study the universe, these telescopes have spearheaded NASA’s astrophysics research for decades. The reuse of this phrase “great observatories” in the new decadal survey is deliberate, says the survey’s co-chair, Fiona Harrison of the California Institute of Technology. “It’s to get across the point that panchromatic observations, from X-rays to infrared, are really essential for modern astrophysics,” she says. “A lot of the success of the [original] great observatories is that they were developed and launched one after the other, with overlapping observations.”
Building a successful space telescope is a long process, typically taking 25 years from the start of development to launch. Concept work for Hubble began in the 1960s, while plans for the JWST first came together in 1995, after the Hubble Deep Field images showed that the first galaxies are within reach of a larger telescope. The next generation of such space-based probes therefore won’t launch until the 2040s, at the earliest. But they will include the survey’s number one recommendation: a flagship mission to replace Hubble, drawing inspiration from two concepts – the Habitable Exoplanet Observatory (HabEx) and the Large UltraViolet, Optical and InfraRed (LUVOIR) telescope. Also on the drawing board are an X-ray mission and a telescope that can observe in the far-infrared.
Flagship missions Costs and timescales of past, current and future NASA missions. Cost is at launch, i.e. does not include servicing missions. Development timescale indicates time from survey recommendation to launch. For future missions, the estimated cost is a minimum, assuming immediate start and optimum budget profile. (Data taken from the NASA Astro2020 decadal survey)
But given the precarious health of our current crop of space telescopes, and knowing the new missions won’t launch for another 20 years, shouldn’t astronomers have started planning for new great observatories years ago? “For sure,” says Steven Kahn of Stanford University, who chaired one of the panels in the decadal survey looking at future space telescopes. He cites the Constellation-X observatory – an X-ray space probe that was recommended as a follow-up to Chandra in the 2000 decadal survey, but never came to fruition because of the drawn-out development of the JWST, which sucked up all the astrophysics budget. “The JWST basically dominated the great observatory programme at NASA for two-and-a-half decades,” explains Kahn. “As a result, there wasn’t room to do a follow-on X-ray mission, or the kind of pioneering far-infrared mission that we’re envisaging.”
Winner takes it all
Indeed, the JWST’s development saw many issues, including huge overruns in cost and development time, which almost saw the project cancelled. The memory of these mistakes looms large over the new decadal survey, influencing some of the recommendations made to restore balance to astrophysics in the US. But it wasn’t always like this. Kahn laments how, prior to the 2000 survey, just getting on the list of recommendations in a decadal survey was enough to virtually guarantee that your project or mission would happen. But in the modern era of $10bn telescopes, “you have to be number one or you’re not going to get it done” says Kahn. “The problem is that in this winner-takes-all environment, everybody wants to throw all the bells and whistles they can onto a project because if you think you’re only going to get one shot at a big mission in the next 50 years, you want to make it count.”
It’s this way of thinking that can lead to the problems the JWST both faced and caused. The more complex a mission design becomes, the more instruments and capability that you want it to have to make it worthwhile – which means that it grows more expensive and takes longer to develop. “All of which gets us back into this vicious cycle of winner takes all,” continues Kahn.
Harrison agrees, emphasizing that this new decadal survey is an attempt to try and change US astronomy’s approach. “For a decadal survey to say, this is the number-one thing, we need to do it no matter what, at whatever cost it ends up being, is not a responsible approach,” she says. In an attempt to counter this, the recent survey makes a number of new proposals. Among them is the idea that missions should be designed in tune with specific science priorities, rather than allowing the mission concept to run away with itself, with all the “bells and whistles”, to quote Kahn.
Out with the old The NASA decadal survey concluded that neither the Lynx X-ray Observatory (left) nor the Origins Space Telescope (right) fit the requirements that the panel was looking for. (Courtesy: NASA)
For example, one of the key science questions that Kahn’s panel looked at was the way in which active supermassive black holes in distant, dusty galaxies influence star formation. The accretion of matter onto such black holes would be detectable to a high-angular-resolution X-ray telescope, while a far-infrared spectroscopic mission would be able to peer through the dust and probe specific spectral lines related to star formation and feedback from black-hole winds. The hope is that the two missions could be launched within a few years of one another, and operate in unison. However, what shape those missions will take is still up in the air.
Prior to the decadal survey there were two mission concepts – the Lynx X-ray Observatory and the Origins Space Telescope – that would operate at mid- to far-infrared wavelengths, with a telescope mirror between 6 and 9 m in diameter. Each was estimated to cost about $5bn, but the decadal survey concluded that these costs were being underestimated and that their science capabilities didn’t quite fit into the requirements that the panel was looking for.
Flagship missions
And here enters one of the decadal survey’s other innovations – namely, a new class of space telescope referred to as “probe-class”, with budgets of a few billion dollars. “We have to acknowledge that if things were all going to be as expensive as JWST, it would be difficult to have all the great observatories operating at the same time,” says Marcia Rieke of the University of Arizona, who led the second panel on space telescopes, focusing on the optical and near-infrared regime. “The best way instead might be to have one flagship mission, and then have the other parts of the electromagnetic spectrum covered by probe missions.”
Indeed, any possible X-ray and far-infrared probe-class missions could also be joined by a probe-class ultraviolet telescope. Improvements in mirror coatings and detectors over the last few decades mean that a 1.5 m telescope could actually be more sensitive than Hubble at ultraviolet wavelengths. “That would provide some robustness against Hubble out-and-out failing,” says Rieke.
Projected plan Timeline for the medium and large programmes and projects recommended by the Astro2020 decadal survey. The location of the logos shows the projected start of science operations for a range of missions and observatories – from space- and ground-based observatories across the spectrum, to multimessenger probes as well as telescopes to study key phenomena such as exoplanets and the cosmic microwave background – or the start date of the programme. The survey has three broad science themes, each of which requires a range of facilities and programmes. (Adapted from original by NASA)
To help develop these future space telescopes, whether they proceed as $10bn behemoths or go forward as more modest (but still ambitious) probe missions, the decadal survey recommends that NASA creates a new Great Observatories Mission and Technology Maturation Programme. It would not just develop the technology, but also “mature the mission concepts”, says Harrison. For its part, NASA is already holding workshops as part of this new programme and has produced a draft call for probe missions.
If the X-ray and far-infrared missions – nicknamed “Fire” and “Smoke” for now – are to be probe-class, then the flagship great observatory will be the long-awaited direct replacement for the Hubble Space Telescope. The concept that leads the way is LUVOIR, and two versions of the telescope have been proposed: either a wildly ambitious 15 m telescope, or an 8 m telescope, the latter of which would still be the largest space telescope ever launched.
Other Earths
For cost and practicality reasons, the decadal survey recommended that the 15 m version fall by the wayside, and that the final design meld the best parts of both LUVOIR and HabEx. The key science goal of this telescope, explains Rieke, is that it has to be able to detect Earth-mass planets in the habitable zone of stars. To that end, Rieke’s panel engaged in a discussion with the exoplanet community about how many potentially habitable planets could be detected as a function of the size of the telescope.
Just the one The original 15 m design (A) for the LUVOIR (Large UV/Optical/IR Surveyor) observatory. The Astro2020 decadal survey recommends combining the LUVOIR and HabEx concepts into a single large telescope. (Courtesy: NASA GSFC)
“As a group, you ask: what are the key science goals? What level of sensitivity is needed? What’s the smallest telescope that will do the job?” says Rieke. The answer she got back was that a 6–8 m-aperture telescope is about as small as you dare go if you want to find potentially habitable exoplanets.
Success isn’t just about the size of the telescope though; its instruments have to be up to scratch too. Successfully imaging Earth-sized planets close to their stars will require a coronagraph as part of its design. Exoplanets the size of Earth normally cannot be imaged because the glare of their star is too overpowering. A coronagraph blocks the light of the star, making it easier to see any planets in attendance. They have been a staple of studies of the Sun for decades – their name comes from blocking the Sun’s disc so astronomers can see the solar corona. But devising a coronagraph that can precisely block the bright light of a star, which appears as essentially a point source, while allowing planets just milliarcseconds from the star to be visible by reducing the contrast between the star’s glare and the planets’ light to 10–10, is “quite a step beyond anything that we’ve done before”, says Rieke.
Beyond space, telescopes on the ground
Earth-bound Artist’s concept of the completed Giant Magellan Telescope which will be situated in the Atacama Desert, Chile. (Courtesy: GMTO Corporation)
Not all of the decadal survey’s recommendations are related to giant telescopes in space. Indeed, some of them are giant telescopes firmly rooted on Earth. For example, the controversial Thirty Meter Telescope to be built on Mauna Kea in Hawaii, despite the protests of some native Hawaiians, continues to move forward. So too is the Grand Magellan Telescope, which is under construction in Chile and will feature seven 8.4 m telescopes to give an effective diameter of 24.5 m.
The survey also recommends that the Next Generation Very Large Array – 244 radio dishes of 18 m diameter and 19 dishes of 6 m diameter spread across the US south-west – should start being built by the end of the decade. It will replace the ageing Very Large Array in New Mexico and the Very Long Baseline Array of dishes across the US. Upgrades to the Large Interferometer Gravitational-wave Observatory (LIGO) and plans for an eventual successor are also recommended.
Meanwhile, cosmologists will be heartened to hear that the survey also calls for a new ground-based observatory, dubbed the CMB Stage 4 observatory, to detect polarization in the cosmic microwave background radiation to search for evidence of primordial gravitational waves that resulted from cosmic inflation in the earliest moments of the universe.
Finally, back in space, the highest priority for medium-scale missions is a fast-response time-domain and multimessenger programme to replace NASA’s Swift spacecraft and detect supernovae, gamma-ray bursts, kilonovae and various other kinds of astronomical transients. Crucially, the missions in this new programme need to be able to work with and support the ground-based observations of LIGO, the Cherenkov Telescope Array and the IceCube neutrino detector, for which a “Generation 2” detector has also been recommended.
The next step is to convince politicians to part with the funds that will be needed to make the great observatories possible
Fiona Harrison, California Institute of Technology
“Certainly a focus now for myself and Robert Kennicutt [Harrison’s fellow co-chair from the University of Arizona and Texas A&M University] is to try and articulate to Congress the excitement of the compelling projects recommended by the survey,” she says. “It was a positive response from NASA, and it wants to make the recommendations happen, but the budget has to be there.”
Should that money be forthcoming, then Rieke estimates the funding required to mature the technology for the optical telescope to be about half a billion dollars. “We would then be poised, near the end of this decade, to have all the technology ducks sitting in a row and we’ll be able to enter the construction phase,” she says.
The timescales involved are phenomenal. If Hubble and Chandra are anything to go by, the next-generation telescopes launched in the 2040s could still be operational in the 2070s or beyond. The decadal survey’s recommendations are therefore not just important for the next 10 years of astronomy, but for their impact on much of this century. There was therefore tremendous pressure on the survey to have got it right.
“That’s where it’s important to pick ambitious goals,” says Rieke. “You have to identify something that’s so important that everyone agrees, and is enough of a step forward that something else isn’t going to overtake you while you’re doing it.” History will judge whether this decadal survey got its key decisions correct, but from today’s perspective, the future of astrophysics promises to be an exciting one.
VICTORIA – The British Columbia government is partnering with a bear welfare group to reduce the number of bears being euthanized in the province.
Nicholas Scapillati, executive director of Grizzly Bear Foundation, said Monday that it comes after months-long discussions with the province on how to protect bears, with the goal to give the animals a “better and second chance at life in the wild.”
Scapillati said what’s exciting about the project is that the government is open to working with outside experts and the public.
“So, they’ll be working through Indigenous knowledge and scientific understanding, bringing in the latest techniques and training expertise from leading experts,” he said in an interview.
B.C. government data show conservation officers destroyed 603 black bears and 23 grizzly bears in 2023, while 154 black bears were killed by officers in the first six months of this year.
Scapillati said the group will publish a report with recommendations by next spring, while an independent oversight committee will be set up to review all bear encounters with conservation officers to provide advice to the government.
Environment Minister George Heyman said in a statement that they are looking for new ways to ensure conservation officers “have the trust of the communities they serve,” and the panel will make recommendations to enhance officer training and improve policies.
Lesley Fox, with the wildlife protection group The Fur-Bearers, said they’ve been calling for such a committee for decades.
“This move demonstrates the government is listening,” said Fox. “I suspect, because of the impending election, their listening skills are potentially a little sharper than they normally are.”
Fox said the partnership came from “a place of long frustration” as provincial conservation officers kill more than 500 black bears every year on average, and the public is “no longer tolerating this kind of approach.”
“I think that the conservation officer service and the B.C. government are aware they need to change, and certainly the public has been asking for it,” said Fox.
Fox said there’s a lot of optimism about the new partnership, but, as with any government, there will likely be a lot of red tape to get through.
“I think speed is going to be important, whether or not the committee has the ability to make change and make change relatively quickly without having to study an issue to death, ” said Fox.
This report by The Canadian Press was first published Sept. 9, 2024.
The European Space Agency is fast-tracking a new mission called Ramses, which will fly to near-Earth asteroid 99942 Apophis and join the space rock in 2029 when it comes very close to our planet — closer even than the region where geosynchronous satellites sit.
Ramses is short for Rapid Apophis Mission for Space Safety and, as its name suggests, is the next phase in humanity’s efforts to learn more about near-Earth asteroids (NEOs) and how we might deflect them should one ever be discovered on a collision course with planet Earth.
In order to launch in time to rendezvous with Apophis in February 2029, scientists at the European Space Agency have been given permission to start planning Ramses even before the multinational space agency officially adopts the mission. The sanctioning and appropriation of funding for the Ramses mission will hopefully take place at ESA’s Ministerial Council meeting (involving representatives from each of ESA’s member states) in November of 2025. To arrive at Apophis in February 2029, launch would have to take place in April 2028, the agency says.
This is a big deal because large asteroids don’t come this close to Earth very often. It is thus scientifically precious that, on April 13, 2029, Apophis will pass within 19,794 miles (31,860 kilometers) of Earth. For comparison, geosynchronous orbit is 22,236 miles (35,786 km) above Earth’s surface. Such close fly-bys by asteroids hundreds of meters across (Apophis is about 1,230 feet, or 375 meters, across) only occur on average once every 5,000 to 10,000 years. Miss this one, and we’ve got a long time to wait for the next.
When Apophis was discovered in 2004, it was for a short time the most dangerous asteroid known, being classified as having the potential to impact with Earth possibly in 2029, 2036, or 2068. Should an asteroid of its size strike Earth, it could gouge out a crater several kilometers across and devastate a country with shock waves, flash heating and earth tremors. If it crashed down in the ocean, it could send a towering tsunami to devastate coastlines in multiple countries.
Over time, as our knowledge of Apophis’ orbit became more refined, however, the risk of impact greatly went down. Radar observations of the asteroid in March of 2021 reduced the uncertainty in Apophis’ orbit from hundreds of kilometers to just a few kilometers, finally removing any lingering worries about an impact — at least for the next 100 years. (Beyond 100 years, asteroid orbits can become too unpredictable to plot with any accuracy, but there’s currently no suggestion that an impact will occur after 100 years.) So, Earth is expected to be perfectly safe in 2029 when Apophis comes through. Still, scientists want to see how Apophis responds by coming so close to Earth and entering our planet’s gravitational field.
Breaking space news, the latest updates on rocket launches, skywatching events and more!
“There is still so much we have yet to learn about asteroids but, until now, we have had to travel deep into the solar system to study them and perform experiments ourselves to interact with their surface,” said Patrick Michel, who is the Director of Research at CNRS at Observatoire de la Côte d’Azur in Nice, France, in a statement. “Nature is bringing one to us and conducting the experiment itself. All we need to do is watch as Apophis is stretched and squeezed by strong tidal forces that may trigger landslides and other disturbances and reveal new material from beneath the surface.”
The Goldstone radar’s imagery of asteroid 99942 Apophis as it made its closest approach to Earth, in March 2021. (Image credit: NASA/JPL–Caltech/NSF/AUI/GBO)
By arriving at Apophis before the asteroid’s close encounter with Earth, and sticking with it throughout the flyby and beyond, Ramses will be in prime position to conduct before-and-after surveys to see how Apophis reacts to Earth. By looking for disturbances Earth’s gravitational tidal forces trigger on the asteroid’s surface, Ramses will be able to learn about Apophis’ internal structure, density, porosity and composition, all of which are characteristics that we would need to first understand before considering how best to deflect a similar asteroid were one ever found to be on a collision course with our world.
Besides assisting in protecting Earth, learning about Apophis will give scientists further insights into how similar asteroids formed in the early solar system, and, in the process, how planets (including Earth) formed out of the same material.
One way we already know Earth will affect Apophis is by changing its orbit. Currently, Apophis is categorized as an Aten-type asteroid, which is what we call the class of near-Earth objects that have a shorter orbit around the sun than Earth does. Apophis currently gets as far as 0.92 astronomical units (137.6 million km, or 85.5 million miles) from the sun. However, our planet will give Apophis a gravitational nudge that will enlarge its orbit to 1.1 astronomical units (164.6 million km, or 102 million miles), such that its orbital period becomes longer than Earth’s.
It will then be classed as an Apollo-type asteroid.
Ramses won’t be alone in tracking Apophis. NASA has repurposed their OSIRIS-REx mission, which returned a sample from another near-Earth asteroid, 101955 Bennu, in 2023. However, the spacecraft, renamed OSIRIS-APEX (Apophis Explorer), won’t arrive at the asteroid until April 23, 2029, ten days after the close encounter with Earth. OSIRIS-APEX will initially perform a flyby of Apophis at a distance of about 2,500 miles (4,000 km) from the object, then return in June that year to settle into orbit around Apophis for an 18-month mission.
Related Stories:
Furthermore, the European Space Agency still plans on launching its Hera spacecraft in October 2024 to follow-up on the DART mission to the double asteroid Didymos and Dimorphos. DART impacted the latter in a test of kinetic impactor capabilities for potentially changing a hazardous asteroid’s orbit around our planet. Hera will survey the binary asteroid system and observe the crater made by DART’s sacrifice to gain a better understanding of Dimorphos’ structure and composition post-impact, so that we can place the results in context.
The more near-Earth asteroids like Dimorphos and Apophis that we study, the greater that context becomes. Perhaps, one day, the understanding that we have gained from these missions will indeed save our planet.
Astronomy PhD candidate Veronika Dornan served as the astronomer in residence at Killarney Provincial Park. She’ll be back again in October when the nights are longer (and bug free). Dornan has delivered dozens of talks and shows at the W.J. McCallion Planetarium and in the community. (Photos by Veronika Dornan)
BY Jay Robb, Faculty of Science
July 16, 2024
Veronika Dornan followed up the April 8 total solar eclipse with another awe-inspiring celestial moment.
This time, the astronomy PhD candidate wasn’t cheering alongside thousands of people at McMaster — she was alone with a telescope in the heart of Killarney Provincial Park just before midnight.
Dornan had the park’s telescope pointed at one of the hundreds of globular star clusters that make up the Milky Way. She was seeing light from thousands of stars that had travelled more than 10,000 years to reach the Earth.
This time there was no cheering: All she could say was a quiet “wow”.
Dornan drove five hours north to spend a week at Killarney Park as the astronomer in residence. part of an outreach program run by the park in collaboration with the Allan I. Carswell Observatory at York University.
Dornan applied because the program combines her two favourite things — astronomy and the great outdoors. While she’s a lifelong camper, hiker and canoeist, it was her first trip to Killarney.
Bruce Waters, who’s taught astronomy to the public since 1981 and co-founded Stars over Killarney, warned Dornan that once she went to the park, she wouldn’t want to go anywhere else.
The park lived up to the hype. Everywhere she looked was like a painting, something “a certain Group of Seven had already thought many times over.”
The dome telescopes at Killarney Provincial Park.
She spent her days hiking the Granite Ridge, Crack and Chikanishing trails and kayaking on George Lake. At night, she went stargazing with campers — or at least tried to. The weather didn’t cooperate most evenings — instead of looking through the park’s two domed telescopes, Dornan improvised and gave talks in the amphitheatre beneath cloudy skies.
Dornan has delivered dozens of talks over the years in McMaster’s W.J. McCallion Planetarium and out in the community, but “it’s a bit more complicated when you’re talking about the stars while at the same time fighting for your life against swarms of bugs.”
When the campers called it a night and the clouds parted, Dornan spent hours observing the stars. “I seriously messed up my sleep schedule.”
She also gave astrophotography a try during her residency, capturing images of the Ring Nebula and the Great Hercules Cluster.
A star cluster image by Veronika Dornan
“People assume astronomers take their own photos. I needed quite a lot of guidance for how to take the images. It took a while to fiddle with the image properties, but I got my images.”
Dornan’s been invited back for another week-long residency in bug-free October, when longer nights offer more opportunities to explore and photograph the final frontier.
She’s aiming to defend her PhD thesis early next summer, then build a career that continues to combine research and outreach.
“Research leads to new discoveries which gives you exciting things to talk about. And if you’re not connecting with the public then what’s the point of doing research?”
