65 years of space exploration
I’ve been an astronomy geek most of my life, always intrigued by what’s going on in the night sky and eating up every bit of information I can find about the latest research. Like many, I was blown away by the first images NASA released from the James Webb Space Telescope on July 12, 2022, and what they revealed. The telescope is truly a triumph for NASA and humanity generally. As someone who has witnessed space exploration from its earliest days, I am impressed how far we have come in the last 65 years.
I was 11-years-old in October of 1957 when the Soviet Union (USSR) launched Sputnik, the first artificial satellite to orbit the Earth. It was a small metal sphere (58 cm [23 in.] in diameter) with four wire-like antennas. It was launched into what is now called “low-Earth orbit,” where it made several orbits of the Earth before falling back into the atmosphere and burning up in January of 1958. In those few weeks, Sputnik changed the world.
When the television and radio news media began broadcasting Sputnik’s radio signal—a steady series of “beeps” that transmitted nothing more than the satellite’s existence, my older brother, a ham radio operator, went to work to find the signal. I remember him triumphantly calling the rest of the family into his bedroom, packed with radio equipment, to listen to the incessant beeping until the satellite left our side of the Earth. I also remember a 45-RPM vinyl record of Sputnik’s signal being bought and played in the house. That was all that was on both sides of the record: the steady beep…beep…beep. But that was enough to make it a family keepsake.
Man on the Moon
Things happened quickly after Sputnik’s launch, as the USA and the USSR raced to see who would be first to put a man in space (USSR) and eventually land a man on the Moon (USA). The latter was accomplished in 1969, just 12 years after Sputnik’s launch. None of these projects were cheap and all were risky. NASA always had to be marketing the space program to the public to keep funding coming from the US Congress. But once President John Kennedy’s promise to put a man on the Moon by the end of the 1960s was accomplished, the public fervor for the program dampened down. When the Apollo 13 mission almost ended in disaster, the US Congress cut back funding and NASA concentrated on missions closer to home, such as space stations, shuttles and unmanned explorations of the planets in our solar system.
Hubble Space Telescope
Astronomers have used ground-based optical telescopes to explore the stars for over 400 years. They revealed a lot about our solar system and the stars closest to us but were limited by the atmosphere and weather. That’s why many observatories were placed on high mountains to get above as much of the atmosphere as possible, and near deserts (as in Chile) where there is a better chance of clear skies. Nevertheless, the atmosphere still filters out certain low-frequency wave-lengths of light that limit what can be observed. It was a long-held dream of astronomers, even before the space program, to have a telescope in space, unencumbered by the vagaries of the atmosphere.
Named after astronomer Edwin Hubble, the Hubble Space Telescope was not the first space telescope, but it was the largest when it was launched in 1990. It has a 2.4 m (7.9 ft.) diameter mirror and five instruments to observe a wide range of the electromagnetic spectrum, from ultra-violet through visible to near-infrared. It circles the Earth in a low-Earth orbit and is the only telescope designed to be regularly serviced by astronauts. Astronomers from around the world book time on Hubble through the Space Telescope Science Institute (STScI) that selects the telescope’s targets. Being outside the Earth’s atmosphere, Hubble produces spectacular high-resolution images that have greatly increased our knowledge of the universe and its origin.
James Webb Space Telescope
That said, Hubble cannot detect certain infrared bands of the electromagnetic spectrum because its mirror is too warm, itself emitting infrared energy. The infrared bands are important because their radiation comes from objects in space that are very far away and are moving away from us as the universe expands (light from rapidly receding objects morphs from the visible range to the lower frequency infrared range via the Doppler effect). What was needed was a telescope that had a large enough mirror to gather sufficient faint infrared light and was capable of staying cool enough so as not to distort the infrared images.
Thus the “Next Generation Space Telescope” was conceived and the initial design process began in 1996. The complexity of the project led to cost overruns, many delays and design overhauls. A major redesign in 2005 led the way to the final configuration. At the time, it was renamed the James Webb Space Telescope, after the NASA administrator in the 1960s who oversaw much of the race to the Moon. The construction of the telescope was completed in 2016 at a cost of US$10 billion. The project was led by NASA in partnership with the Canadian and European space agencies.
The Webb’s mirror is 6.5 m (21 ft.) in diameter, providing 25 square meters of light-gathering surface, about six times that of Hubble. The mirror is made of 18 hexagonal, gold-plated segments, the gold providing good infrared reflection.
Along with the mirror and various instruments, there is a large sun shield designed to keep the telescope cool by shielding it from solar radiation and reflected sunlight from the Earth and Moon. All of these components are large, making the Webb a very large space telescope indeed. The challenge was designing it so that it could be compactly placed on a rocket, and once in space, be assembled without astronaut assistance. A tall order.
When the Webb was finally launched on December 25, 2021, all who had worked on its development and construction were on pins-and-needles, hoping that all the complicated tasks the telescope had to do would line up as planned and be completed. There was a lot that could go wrong and the possibility of a catastrophic error was large. But work it did. The launch from French Guiana was flawless, and on January 24 it arrived at its final location, being placed in a halo orbit around the Sun-Earth Second Lagrange Point, fully deployed and ready to go to work.
Second Lagrange Point
In order to keep the Webb mirror as cold as possible to detect very faint infrared radiation from afar, it had to be placed in an orbit where its temperature could remain below 50 K (-223 ºC, -370 ºF). Such an orbit is found at the Second Lagrange Point or L2, a “celestial mechanical location,” where the Webb would be equally affected by the gravitational pull of the Sun and Earth.
L2 is about 1.5 million km (~1 million mi.) from Earth (about four-times further than the Moon). At that location, Webb orbits the Sun but in lockstep with the Earth. To ensure the telescope can see in all directions while blocking light from the Sun, Earth and Moon, it makes a “halo orbit” around L2 that allows it to view in all directions, over a six-month period. As with Hubble, astronomers book time on Webb through the Space Telescope Science Institute (STScI).
The First Images
Perhaps the most interesting of the Webb images released in July by NASA was that of a portion of the Carina Nebula—a large region of dust and gas in the constellation Carina, visible on Earth only from the southern hemisphere. It is about 8,000 light years from Earth. Astronomers had earlier used Hubble to investigate this large nebula to look at the regions where stars are created. The images produced were spectacular. However, because Webb can detect more bands of infrared, it was able to peer through the dust to reveal individual stars actually in the process of being formed—further sharpening the lens on creation itself.
All that said, however, perhaps the most intriguing image released—at least for an amateur astronomy geek like me—is of a cluster of galaxies (SMACS 0723) that are not visible here on Earth. NASA pointed Webb into a piece of the sky that the agency described as about the size of “a grain of sand held at arm’s length” from someone standing on Earth. The Webb revealed that piece of seemingly black sky to be actually teeming with galaxies, many as they were when the universe was less than a billion years old. In other words, those never-before-seen galaxies are about 13 billion light years away. Not a bad find for the first trial images of the telescope. But hang-on. Web is capable of so much more than that. It is designed to see back as far as 180 million years after the Big Bang or the creation of the universe. It is thought that the very first stars were formed about 100-180 million years after the Big Bang. So, there’s a lot more to be discovered and a lot more questions to be asked.
Also intriguing about the incredibly complex SMACS 0723 image is the light of galaxies arcing and bending around other galaxies. This is caused by the gravitational pull of the forward galaxies bending the light coming from galaxies behind them, as predicted by Einstein.
Webb is not just about looking at the beginning of time. It can also look at planets in our solar system as well as exoplanets—outside our solar system. For example, by analyzing the light passing through the atmospheres of those planets, it can determine the chemical composition of those atmospheres and perhaps conditions suitable for life as we know it here on Earth. In one of its initial trials, it looked at exoplanet WASP-96 (1,150 light years away) and found evidence of water in its atmosphere.
Webb was designed to last 10 years, but NASA has indicated that because of the efficiency of its launch and deployment it has enough fuel to last maybe 20 years. That’s a lot of time to look at the many mysteries of our universe. As well, any astronomer from around the world may apply to use it for their research, and all data collected will be put in the public domain for anyone to use. In these days of upheaval and uncertainty over climate change, pandemics, war and divisions, the success of the James Webb Space Telescope demonstrates what can be done when people come together and work for a common goal. It is truly a human triumph and I can’t wait to see what Webb is going to show us next.
Text: Copyright © 2022 Don H. Meredith, All Rights Reserved
Photos courtesy of NASA.
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