Hubble and Webb are the Dream Team. Don’t Break Them Up

Many individuals consider the James Webb Area Telescope as a kind of Hubble 2. They perceive that the Hubble Area Telescope (HST) has served us effectively however is now outdated, and overdue for alternative. NASA appears to agree, as they haven’t despatched a upkeep mission in over fifteen years, and are already getting ready to wind down operations. However a current paper argues that this can be a mistake. Regardless of its age, HST nonetheless performs extraordinarily effectively and continues to provide an avalanche of worthwhile scientific outcomes. And on condition that JWST was by no means designed as a alternative for HST — it’s an infrared (IR) telescope) — we might finest be served by working each telescopes in tandem, to maximise protection of all observations.

Let’s not idiot ourselves: the Hubble Area Telescope (HST) is outdated, and is finally going to fall again to Earth. Though it was designed to be repairable and upgradable, there have been no servicing missions since 2009. These missions relied on the Area Shuttle, which might seize the telescope and supply a working base for astronauts. Servicing missions might final weeks, and solely the Area Shuttle might transport the six astronauts to the telescope and home them throughout the mission.

With out these servicing missions, failing parts can now not get replaced, and the general well being of HST will preserve declining. If nothing is finished, HST will finally cease working altogether. To keep away from it turning into simply one other piece of area junk, plans are already being developed to de-orbit it and ship it crashing into the Pacific Ocean. However that’s no purpose to surrender on it. It nonetheless has as clear a view of the cosmos as ever, and mission scientists are doing a wonderful job of working round technical issues as they come up.

The James Webb Area Telescope was launched into area on Christmas dat in 2021. Its system of foldable hexagonal mirrors give it an efficient diameter some 2.7 occasions bigger than HST, and it’s designed to see down into the mid-IR vary. Inside months of deployment, it had already seen issues that clashed with present fashions of how the Universe fashioned, making a mini-crisis in some fields and main unscrupulous information editors to write down headlines questioning whether or not the “Huge Bang Principle” was beneath menace!

The explanation JWST was in a position to seize such historic galaxies is that it’s primarily an IR telescope: Because the Universe expands, photons from distant objects get red-shifted till stars that initially shone in seen gentle can now solely be seen within the IR. However these IR views are proving extraordinarily worthwhile in different scientific fields other than cosmology. In reality, lots of the most hanging photographs launched by JWST’s press crew are IR photographs of acquainted objects, revealing hidden complexities that had not been seen earlier than.

It is a key distinction between the 2 telescopes: Whereas HST’s vary overlaps barely with JWST, it could actually see all the best way up into ultraviolet (UV) wavelengths. HST was launched in 1990, seven years late and billions of {dollars} over price range. Its 2.4 meter major ingredient wanted to be one of the exactly floor mirrors ever made, as a result of it was supposed to be diffraction restricted at UV wavelengths. Famously, avoidable issues within the testing course of led to it being very exactly figured to a barely mistaken form, resulting in spherical aberration stopping it from coming to sharp focus.

Fortuitously the telescope was designed from the begin to be serviceable, and even returned to Earth for repairs by the Area Shuttle if vital. In the long run although, NASA opticians had been in a position to design and construct a set of corrective optics to resolve the issue, and the COSTAR system was put in by astronauts on the primary servicing mission. Through the years, NASA despatched up three extra servicing missions, to improve or restore parts, and set up new devices.

HST could possibly be one of the profitable scientific devices ever constructed. Since 1990, it has been the topic of roughly 1200 science press releases, every of which was learn greater than 400 million occasions. The greater than 46,000 scientific papers written utilizing HST information have been cited greater than 900,000 occasions! And even in its present degraded state, it nonetheless supplied information for 1435 papers in 2023 alone.

JWST additionally ran over time and over price range, however had a much more profitable deployment. Regardless of having a a lot bigger mirror, with greater than six occasions the gathering space of HST, your complete observatory solely weighs half as a lot as HST. Due to its larger sensitivity, and the truth that it could actually see historic gentle redshifted into IR wavelengths, it could actually see far deeper into the Universe than HST. It’s these observations, of galaxies fashioned when the Universe was extraordinarily younger (100 – 180 million years), that created such pleasure shortly after it was deployed.

As worthwhile as these telescopes are, they won’t final perpetually. JWST is positioned deep in area, some 1.5 million kilometers from Earth close to the L2 Lagrange level. When it will definitely fails, it’ll turn out to be simply one other piece of Photo voltaic System particles orbiting the Solar within the huge vacancy of the Photo voltaic System. HST, nevertheless, is in Low Earth Orbit (LEO), and suffers very slight quantities of drag from the faint outer reaches of the ambiance. Over time it’ll steadily lose velocity, drifting downwards till it enters the ambiance correct and crashes to Earth. Due to its measurement, it is not going to deplete fully, and huge chunks will smash into the floor.

As a result of it can’t be predicted the place precisely it’ll re-enter, mission planners at all times supposed to seize it with the Area Shuttle and return it to Earth earlier than this occurred. Its closing resting place was alleged to be in show in a museum, however sadly the shuttle program was cancelled. The present plan is to ship up an uncrewed rocket which is able to dock with the telescope (a particular attachment was put in on the ultimate servicing mission for this objective), and deorbit it in a managed manner to make sure that its items land safely within the ocean.

You could find the unique paper at https://arxiv.org/abs/2410.01187