Jakarta –
After being delayed several times, James Webb Space Telescope finally made it slide on Christmas Day. But scientists haven’t been able to breathe a sigh of relief. There are still many stressful stages to go through until the telescope “sit” in position and function properly.
The US national space agency NASA has high hopes for the telescope, which was launched Saturday (25/12) from the Guiana Space Center, Kourou, French Guiana this local time to reveal the secrets of the universe that is still mysterious.
“The James Webb telescope is the most advanced technology. If the launch is successful, it will unlock the secrets of an extraordinary, even almost extraordinary, universe,” said NASA Administrator Bill Nelson.
Here are amazing facts about NASA’s most advanced and most expensive device, as quoted from Big Think.
1. The James Webb telescope is lighter than the Hubble
Compared to its predecessor, the Hubble Telescope, the James Webb is lighter even though it is much larger. In comparison, Hubble is 2.4 meters in diameter, with a sturdy main mirror, and a collecting area of 4.0 square meters. Whereas James Webb Telescope 6.5 meters in diameter, made of 18 different mirror segments, with a collecting area of 25.37 square meters.
If we put them both on a scale on Earth, Webb has a mass of 6,500 kg. When Hubble launched, by comparison, it weighed 11,100 kg. With the upgraded instrument, it now weighs approximately 12,200 kg.
This is a remarkable engineering feat, as nearly every component in James Webb is, if applicable, lighter than its Hubble analogue.
2. The lightest large telescope mirror of all time
Each of the 18 main mirror segments, when first produced, took the form of a curved disc, having a mass of 250 kg. By the time it was completed, it had reduced to only 21 kg or a weight loss of 92%.
This weight is achieved in an interesting way. First, the mirror is cut into its hexagonal shape thereby reducing the weight slightly. But then, almost all the mass on the “back side” of the mirror is removed by machine.
Altogether, these 18 mirrors will form a mirror-like plane with an accuracy of 18 to 20 nanometers. This mirror is the best and lightest ever produced.
3. Looks like gold but is made of beryllium
Yes, there is a layer of gold applied to each mirror, but it would be a great disaster for James Webb if the mirror was made entirely of gold.
Not because gold has a very high density, nor is it because of the malleability of gold. The big problem it will face is thermal expansion. Even at very low temperatures, gold expands and contracts substantially with small temperature changes.
After the telescope has been manufactured and worked into its final shape, then the gold coating is applied. The total gold content in the mirror James Webb Telescope only 48 grams.
4. When it runs out of fuel it will be sent to “graveyard orbit”
Hubble, with help from four service missions, is still functioning more than three full decades after launch. Webb, however, needs to use up his fuel whenever he wants to do something that involves movement.
When it runs out of fuel, the science operation will end. However, we can’t let it drift wherever it goes, because doing so could potentially jeopardize future missions in Lagrangian 2 (L2), a place where Earth’s gravity and Sun’s gravity cancel each other out.
Instead, as was done in the spacecraft sent to L2, Webb will be sent to a “graveyard orbit”, where he will orbit the Sun as long as there is an orbiting Sun.
5. Life span can be extended
While not designed for service, the James Webb could potentially be robotically recharged to extend its life. It would seem a pity that Webb’s life span, after painstakingly building it, would be so limited.
In the mission that will run for 10 years, we will get a supply of many things that can be learned about the universe. But after that, James Webb looks set to have a cumulatively shorter lifespan than his entire time on Earth.
But there is still hope. There’s a refueling port which, if humans developed the right unmanned technology, would allow James Webb to access it.
If the technology can get to L2 and dock with James Webb, the telescope’s fuel can be refilled so that its life span can be extended by a decade or more with each refueling.
Watch Videos “Exoplanet Discovery Becomes Target of James Webb’s Telescope“
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