The James Webb Space Telescope will replace the Hubble Telescope. Find out how it will reveal hidden galaxies that Hubble couldn’t detect.
It was one of those dull weekends on the road. One of my favourite ways to pass the time as a travelling consultant was to take in the local museums.
Having been to the excellent Glenbow Museum many times, I resolved to take in the downtown west end’s original Calgary Science Centre. What I remember most about that outing was a spectacular slide show in the planetarium.
The presentation came from NASA. It was mostly a public relations exercise, rehabilitating NASA’s reputation by coming clean about a big mistake they’d made building the Hubble Space Telescope.
Shaped the Primary Mirror to the Wrong Specification
It was a big mistake in terms of performance, but a minuscule one in terms of workmanship. Technicians had shaped the primary mirror to the wrong specification.
It was off by about one-fiftieth of the width of a human hair, but that was enough to distort the clarity of Hubble’s first test images sent back to Earth. Astronauts eventually fixed it by installing a new set of corrective lenses in 1993.
Now, almost thirty years later, nobody remembers what science reporters called the “Hubble Trouble” at the time. Today they reflect on the thousands of spectacular images Hubble has captured and the contribution the space telescope has made to science.
Hubble is Showing Its Age After Three Decades of Service
Like the rest of us, Hubble is showing its age after three decades of service. Its handlers at the Space Telescope Science Institute think it will have to shut down in about five years.
A replacement is in the works that NASA calls the James Webb Space Telescope. It’s named after the former Administrator of NASA during the space race back in the 1960s. The planned launch date is October 31, 2021.
We always see considerable improvements in performance and features when we upgrade our smartphones or our flat screens TVs. Similarly, the James Webb Space Telescope will offer a new generation of improvements over Hubble. Even though it will weigh roughly half as much as Hubble, its primary mirror will have six times more light-gathering area.
Objectives of the James Webb Space Telescope
The four main objectives of the James Webb Space Telescope will be to:
1. Search for light from the first stars and galaxies that formed in the Universe after the Big Bang
2. Study the formation and evolution of galaxies
3. Understand the formation of stars and planetary systems
4. Study planetary systems and the origins of life.
Last week, the Astrophysical Journal published two new studies by researchers at the University of Melbourne. Ph.D. candidate Madeline Marshall led simulations showing that the James Webb Telescope will see very distant galaxies outshone by quasars that Hubble couldn’t make out.
Quasars, or quasi-stellar objects, are very bright objects at the centre of galaxies. They consist of a supermassive black hole surrounded by a disk of gas and debris.
Observe Very Distant Host Galaxies for the First Time
Ms. Marshall explained, “Webb will open up the opportunity to observe these very distant host galaxies for the first time.” She conducted her research at Australia’s centre of excellence known as All Sky Astrophysics in 3 Dimensions, or ASTRO 3D for short.
Based on previous work in collaboration with countries worldwide, the team at ASTRO 3D developed a leading-edge simulation application called BlueTides. The purpose of BlueTides is to study how galaxies and quasars formed during the first billion years after the Big Bang.
Team member Yueying Ni of Carnegie Mellon University explained that BlueTides is revolutionary because “Its large cosmic volume and high spatial resolution enables us to study those rare quasar hosts on a statistical basis.”
What Hubble Can’t Distinguish, Webb Will Make Out
The researchers took advantage of BlueTides’ Big Data power. It let them replicate what the James Webb Space Telescope would see if astronomers pointed it at one of these early galaxies with quasars. They concluded that what Hubble can’t distinguish, the James Webb Space Telescope, will make out, although it won’t be easy.
Even with the James Webb Space Telescope’s massive primary mirror, these galaxies would be tiny images compared to the whole sky’s representation. On top of that, as Ms. Marshall put it, “The host galaxies are surprisingly tiny compared to the average galaxy at that point in time.”
These galaxies contain the same mass as our Milky Way Galaxy. Yet, they’re only about one-thirtieth of our galaxy’s diameter, making them hard to spot.
“Will Help Us to Understand How a Black Hole Could Grow”
Stuart Wyithe of the University of Melbourne co-authored the study. He explained, “The data it gathers will help us understand how a black hole could grow to weigh a billion times as much as our Sun in just a billion years. These big black holes shouldn’t exist so early because there hasn’t been enough time for them to grow so massive.”
The Hubble Space Telescope taught us a great deal about our place in the Universe. It’s told us the age of the Universe and the rate at which it’s expanding.
Peering into what astronomers call “deep fields,” Hubble has taken us back in time to see stars already forming just 500 million years after the Big Bang. Hubble also enabled scientists to confirm the existence of supermassive black holes.
Confirmed the Existence of Supermassive Black Holes
We no longer had to launch spacecraft and wait for years for them to send back flyby pictures of the planets in our solar system. Beyond that, Hubble enabled planetary scientists to discover and learn about planets orbiting other stars.
The new James Webb Space Telescope will tell us the answers to some even more profound questions. Ms. Marshall concluded by saying, “That can help us answer questions like: How can black holes grow so big so fast? Is there a relationship between the mass of the galaxy and the mass of the black hole, like we see in the nearby Universe?”
We always have more to learn if we dare to know.
NASA’s James Webb Telescopes will reveal hidden galaxies
Limits to Rest-frame Ultraviolet Emission from Far-infrared-luminous z 6 Quasar Hosts
The host galaxies of z = 7 quasars: predictions from the BLUETIDES simulation
NASA Discovery Program – 4 Bids to Explore the Solar System
Dimming of Betelgeuse Explained by Hubble Telescope
Quasar Discovery Challenges Black Hole Theories