The James Webb space telescope: in search of the secrets of the Milky Way | James Webb space telescope

In just a few weeks, the most formidable, expensive robotic probe ever constructed, the £6.8bn James Webb space telescope, will probably be blasted into space on prime of an enormous European Ariane 5 rocket. The launch of the observatory – which has been suffering from many years of delays and large value overruns – guarantees to be the most nervously watched liftoff in the historical past of unmanned space exploration.

The observatory – constructed by Nasa with European and Canadian space company collaboration – has been designed to revolutionise our examine of the early universe and to pinpoint attainable life-supporting planets inside our galaxy. Nonetheless, its planning and development have taken greater than 30 years, with the undertaking struggling cancellation threats, political controversies and additional tribulations. In the course of, a number of different scientific tasks needed to be cancelled to satisfy the large, swelling price ticket of the observatory. As the journal Nature put it, that is “the telescope that ate astronomy”.

Now scientists are about to find if these sacrifices and hovering prices are justified when, in keeping with present schedules, the telescope is fired into space on 22 December. “It’s the launch of a era,” says Daniel De Chambure of the European Space Company (Esa).

The flight mirrors of the telescope undergo cryogenic testing at Nasa’s Marshall Space Flight Center in Huntsville, Alabama.
The flight mirrors of the telescope endure cryogenic testing at Nasa’s Marshall Space Flight Middle in Huntsville, Alabama. {Photograph}: Alamy

Designed as a substitute for the Hubble space telescope – nonetheless in operation after its 1990 launch – the James Webb is a far greater, way more complicated instrument with many extra formidable targets. For a begin, it is not going to examine the seen half of the electromagnetic spectrum – as does the Hubble and most ground-based telescopes – however will collect solely infrared radiation.


“There are lots of causes for this,” says Prof Gillian Wright, director of the UK Astronomy Expertise Centre in Edinburgh. “For a begin, infrared is the good half of the spectrum for wanting by way of mud, and that’s vital as a result of stars and planets kind in areas full of mud. So if you wish to perceive the place and the way different photo voltaic programs are being created, the James Webb ought to present essential knowledge.”

As well as, atmospheres of planets that may include chemical compounds corresponding to methane – a fuel related to organic processes – are additionally finest studied by gathering infrared radiation and will point out if they’re succesful of supporting life.

“Spectroscopy is a vital method of taking a look at the formation of promising planets in our personal galaxy,” provides Wright, who’s the European principal investigator for the staff that constructed one of the Webb’s 4 predominant devices: the MIRI or Mid-infrared instrument. (The different three gadgets may also examine the infrared spectrum however at differing wavelengths.)

This half of the James Webb’s operations is actually a neighborhood affair and can contain taking a look at stars in our personal galaxy. Nonetheless, astronomers additionally need to examine the very early universe in the interval that adopted the beginning of the cosmos in the large bang 13.8bn years in the past. Which means specializing in very, very distant galaxies. And once more finding out infrared radiation offers key benefits.

“A telescope is a time machine. It allows you to see what the universe was like in the previous – as a result of gentle takes a finite time to succeed in us from a distant object,” says Prof Martin Ward of Durham College, who’s a member of the MIRI science consortium. “Nonetheless, gentle will get fainter and redder the additional again you look into the universe till its wavelength reaches the infrared half of the spectrum. So if we need to examine how the first stars, black holes and galaxies fashioned, you additionally want an infrared telescope.”

Floor observatories can function at infrared wavelengths however for prime-quality observations telescopes actually must be lifted above Earth’s heat, moist environment, which blocks a lot of the infrared radiation that reaches us from space. Sadly, placing such a telescope into orbit has been so demanding it has led to numerous delays as 1000’s of scientists and engineers have struggled to beat the technical hurdles thrown up by the James Webb’s formidable design.

One downside has been the easy proven fact that the telescope won’t be able to depend on human help as soon as launched. Hubble nonetheless flies in low Earth orbit, the place astronauts on the space shuttle have been capable of restore and repair it. However the shuttle was grounded a decade in the past and so the James Webb has been designed to function with none prospect of hands-on assist from people.

James Webb

As an alternative, it is going to be fired on a trajectory that may take it into orbit spherical the solar – to a area often known as the second Lagrange level (L2), the place, 1m miles from the Earth, the gravity of our planet and the gravity of the solar cancel one another out. Right here the telescope will be saved stationary in roughly the similar place, the place it will probably function constantly for twenty-four hours a day. As well as, small fuel engines will probably be burned to make sure the craft stays at L2.

At Lagrange 2, it’ll even be simpler to maintain the James Webb chilly. The telescope has been designed to function at round 40C above absolute zero (about -233C) in order that its devices don’t generate spurious warmth alerts that might swamp the faint infrared radiation it receives from the different finish of the universe. Distant from its heat house planet, the telescope will probably be protected by a five-layer-thick protect that may block out radiation from the solar and Earth, and its MIRI may also be chilled by a liquid helium fridge, the James Webb ought to have the ability to maintain its cool for as much as a decade, its designers hope.

However first the observatory should overcome a journey riddled with threat. For a begin there’s the hazard of launcher failure. The Ariane 5 has notched up a complete 111 liftoffs since 1996, 106 of which have been profitable. Extra importantly, its failures occurred early in the rocket’s growth schedule and it’s now rated as a extremely dependable launcher. Nonetheless there’s a probability it might fail because it lifts off from Esa’s space port at Kourou in French Guiana. And given the quantity of cash, effort and time already expended on the undertaking, that’s nonetheless a scary prospect.


And that’s simply the starting. On its months-long journey to its new house at Lagrange 2, the telescope will probably be slowly unfurled because it cruises throughout space. First to be launched will probably be big sheets of wafer-thin foil that may act like large parasols for conserving the telescope cool. Subsequent to look will probably be James Webb’s predominant mirror, the coronary heart of the telescope that may accumulate that infrared radiation from throughout the universe. It’s seven occasions greater than Hubble’s mirror – far too massive to be accommodated as a single merchandise. As Wright says: “It’s a easy proven fact that placing massive objects in space is quite a bit more durable than launching small ones. That has been a key technical problem for the telescope.”

To get spherical the measurement challenge, the James Webb’s designers have constructed a mirror that’s constructed of 18 hexagons of gold-coated beryllium mirror. These will unfurl like a blooming flower and slot collectively routinely to create a 6.5-metre (21ft) mirror.

Every part to do with this unfolding, this unprecedented automated self-assembly, should work flawlessly, a course of that may take round six months to finish. Solely then will astronomers discover out if the James Webb goes to be one of the nice technological triumphs of the twenty first century or a dollar-devouring catastrophe. As Thomas Zurbuchen, Nasa’s affiliate administrator for science missions, places it: “Those that usually are not nervous and even terrified about this usually are not understanding what we are attempting to do.”

The Ariane 5 rocket being prepared for launch in French Guiana.
The Ariane 5 rocket being ready for launch in French Guiana. {Photograph}: NASA

A unique perspective on the warning and delay that has affected the telescope is supplied by Faye Hunter of Airbus, who acted as undertaking supervisor for the MIRI instrument 10 years in the past. “I used to be simply going into secondary college when the concept of the James Webb telescope was agreed,” she says. “Now I’m a mom, and a profitable undertaking supervisor and the telescope nonetheless has not been launched.”

Nonetheless, Hunter stresses the care and a focus that has been taken to verify the observatory operates completely as soon as in orbit, a course of that has concerned greater than 200 engineers and scientists engaged on MIRI alone. “A European consortium supplied the elements and MIRI was assembled from these at the Rutherford Appleton Laboratory in Oxfordshire,” she provides.

“Then it was put in check chambers, which had all air sucked from them, and temperatures have been decreased to ranges that the telescope will expertise in space. After it handed these exams, MIRI was despatched to Nasa, built-in with the telescope’s different three infrared detectors and once more put by way of extra cyrovac exams. It takes a very long time to do that type of factor however it is going to be value the effort.”

The decades-long delay inflicted on the James Webb has had different penalties, nonetheless. Because it was initially named in 2002, politics has moved on. In 2021, many scientists regard the title as inappropriate since they accuse James Webb – a former Nasa administrator – of purging homosexual and lesbian individuals from jobs in Nasa in the Fifties and Nineteen Sixties and have pressed for the telescope to be given one other title. The space company has refused such demands, although the controversy is more likely to linger.

The telescope’s 21 mirrors were packed by Ball Aerospace in canisters before being shipped to Nasa.
The telescope’s 21 mirrors have been packed by Ball Aerospace in canisters earlier than being shipped to Nasa. {Photograph}: NASA

It additionally stays to be seen what the James Webb will uncover. In its three many years of operations, Hubble helped pin down the age of the universe to 13.8bn years in the past; decided the price at which the universe is increasing; and confirmed that almost each main galaxy is anchored by a black gap at its core.

This time, astronomers will probably be anticipating much more. Amongst their hopes is the prospect of imaging the first galaxies to kind after the large bang, understanding how stars are born and evolve, and investigating the potential for all times to look in planetary programs. All this should be executed in a decade, the most probably lifetime of the James Webb. After 10 years, it’s anticipated that it’ll run out of gas and the telescope will now not have the ability to maintain itself situated at L2. Then it’ll drift off beam – to grow to be the costliest piece of space junk ever constructed.

“It’s unlikely an observatory as expensive and complicated as the James Webb will probably be constructed once more for a really very long time,” says Ward. “Large observatories like these are like Christmas timber. They’re fitted with so many various devices which can be hooked up like baubles. In future, we are able to anticipate that smaller and cheaper telescopes with extra particular roles will probably be most well-liked by space businesses. So sure, in a way, this might be the final Christmas for space astronomy.”

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