The James Webb Space Telescope (JWST) captivated the world when it recently began transmitting images of breathtaking beauty and scientific import. This long-awaited telescope is equipped with advanced technology that enables it to discover faint galaxies formed just after the Big Bang.
Keep reading for an overview of 7 key reasons why the JWST represents such a monumental feat of engineering and signals a new era of astronomy.
1. Its Infrared Instruments Can Detect Extremely Faint Galaxies
The JWST specializes in infrared light which allows it to see very old, extremely distant celestial objects much better than its predecessor the Hubble Space Telescope. Hubble detects primarily visible light, like the human eye.
Here‘s why JWST‘s infrared instruments are so crucial:
| Telescope | Wavelength Detected | Importance |
|---|---|---|
| Hubble | Visible light | Great for images of nearby objects like planets + bright galaxies |
| JWST | Infrared light | Allows seeing first ancient galaxies formed after Big Bang |
The universe is expanding. So very old galaxies have their light redshifted – meaning the wavelengths get stretched out over billions of years. Ancient visible light gets shifted into the infrared spectrum.
JWST was specifically designed to detect these infrared wavelengths to see the first, most distant galaxies that emitted light just a few hundred million years after the Big Bang!
Fun Fact: The oldest galaxy observed so far by JWST dates to just 300 million years after the Big Bang!
2. It Boasts the Largest Mirror Ever Put in Space
Bigger mirrors equal better image resolution and light gathering power. So the JWST designers engineered a massive beryllium mirror spanning over 6.5 meters (21 feet) wide – the biggest telescope mirror ever put into space!
For comparison, take a look:
| Telescope | Mirror Diameter | Light Gathering Area |
|---|---|---|
| Hubble | 2.4 meters | 4.5 m2 |
| JWST | 6.5 meters | 33 m2 |
By having over 7 times more light gathering area, JWST can detect extremely faint objects better than Hubble. Its advanced instruments and huge mirror work together to capture unprecedented views of early galaxy formation.
3. It Must Operate at Extremely Low Temperatures
To detect the infrared light from ancient celestial objects, the JWST needs to nearly eliminate interference from infrared heat sources in its field of view. This includes heat from:
- Solar radiation
- Warm telescope optics
- The Earth itself
So an incredible 5-layer tennis court sized sunshield passively cools the JWST optics and instruments down to below -370°F / -223°C.
At this extreme cryogenic temperature, the telescope can register the tiny amounts of infrared energy from the most distant galaxies without interference. This allows it to essentially see all the way back to just 100 million years after the Big Bang!
4. The Mirror and Sunshield Fold Up Origami-Style
The JWST is an orbiting satellite, so all its components had to fold up inside a rocket for the journey to space.
The team designed:
- 18 hexagonal beryllium mirror segments that unfold and self-align after launch
- 5-layer sunshield membranes that tension and separate to the size of a tennis court
This complex origami-style engineering allows the giant optics and heat shields to launch in a compact form.
Seeing the successful deployment of all these intricate components come together flawlessly weeks after launch had engineers around the world cheering!
5. It Orbits Far From Earth for Ideal Conditions
While Hubble orbits the Earth itself, engineers determined the best location for infrared observations was the Sun-Earth Lagrange point 2 (L2) – almost 1 million miles (1.5 million km) from Earth.
Benefits include:
- Thermally stable environment
- No interference from Earth‘s infrared radiation
- Can use single sunshield to shade optics
This is crucial real estate for JWST‘s optimal performance. The position also keeps its sunshield perfectly oriented between the telescope and the Sun at all times.
6. JWST Started Strong by Exceeding Early Performance Expectations
After launch, JWST‘s mirror segments had to all fold out, self-calibrate, and align nearly perfectly with tolerances measured in microns (1/1000 mm).
Additionally, the onboard instrument calibration took about 6 months for Hubble compared to just 2 weeks for JWST!
JWST‘s first images released showed it could already easily beat most of Hubble‘s key benchmarks. This incredible performance after just a few weeks in space astonished astronomers.
7. It Will Revolutionize Our Understanding of the Early Universe
The JWST mission timeline is designed for 5-10 years of operation. But the telescope has no consumables, so the lifetime will be set by orbital degradation of equipment.
In its first year, JWST already captured images of:
- Previously unseen early galaxies
- Star clusters forming
- Giant exoplanet atmospheres
These observations will help answer questions about:
- How did the first stars and galaxies form?
- How do galaxies evolve over time?
- What are the atmospheres of exoplanets like?
JWST represents a giant leap for astronomy. Let‘s hope it continues exceeding expectations so we can uncover more key insights about the origins of the universe in the years ahead!
