Top 5 things to know about the James Webb super telescope

After decades of waiting, the most powerful space telescope ever built went into orbit on December 25, just in time for Christmas.

Designed to replace the Hubble telescope, the iconic instrument of NASA and ESA for more than three decades in orbit, James Webb is expected to usher in a new era in space exploration. space with the ability to "look back" to explore all the historical stages of the universe, since the Big Bang about 13.8 billion years ago. Here are 5 things to know about the James Webb megaproject.

Giant main mirror

At the center of the telescope is the 6.5 m-wide main mirror - a concave structure made up of 18 smaller hexagonal mirrors, made of gold-coated beryllium and optimized to reflect infrared light from remote regions of the universe. James Webb's primary mirror is 2.7 times larger than Hubble's with a 100-fold improved sensitivity.

Main mirror of the James Webb telescope.

Mirrors and scientific instruments will be protected from solar radiation by a 5-layer sunshade, shaped like a kite and about the size of a tennis court.

Its membranes are made of kapton, a material known for its high heat resistance and stability over a wide temperature range. This is important because the side facing the Sun will be as hot as 230°F (110°C), while the other side will be as hot as -394°F (-235°C).

1.5 million km . journey

The James Webb telescope will be placed in orbit 1.5 million km from our planet, nearly four times farther than the distance to the Moon. Unlike Hubbe, which orbits the Earth, James Webb will orbit the Sun. Its active site is near the second Lagrange point (L2) of the Earth-Sun system, where the gravitational forces of the two celestial bodies and the centrifugal forces balance each other.

Normally, objects orbiting the Sun farther than Earth would take more than a year to complete one orbit, but because of their proximity to the L2 point, the combined force would allow the satellite to orbit the Sun in a short period of time. a year like the Earth.

It will take about a month for the telescope to move to the L2 point. To date, no astronauts have flown to James Webb's intended operating location. Meanwhile, NASA once sent a crew to the Hubble telescope to repair the device.

Origami inspired folding technology

Due to his huge size, James Webb had to be folded in an Origami style to fit inside the cone of the rocket. Once launched into space, the telescope will automatically unfold and deploy the scientific instruments. NASA emphasizes that this is the most complex and difficult deployment they have ever performed.

About 30 minutes after takeoff, the communication antenna and solar panels will open first, followed by the sunshade on day 6 (after the Moon pass). Its thin films will be guided by a complex mechanism consisting of 400 pulleys and 400 m of cable.

The telescope's main mirror will be deployed to the end in the second week. In the final configuration, the devices need more time to cool down and calibrate. After 6 months, James Webb will be ready to go.

Main Science Quest

James Webb has two main science missions (which account for more than 50% of its observation time). The first mission is to explore the early stages of the history of the universe. Astronomers want to see how the first stars and galaxies formed and evolved after the Big Bang.

The second major goal is to search for exoplanets or extrasolar planets. It will study their atmospheres to check for the possibility of existence or support of life.

Unlike Hubble, which relies mainly on visible and ultraviolet light, James Webb can observe longer wavelength infrared light, which easily penetrates dense clouds of dust, allowing discovery of distant objects. hidden regions in the distant universe.

Infrared rays also allow scientists to "look back in time" to the further past thanks to a phenomenon known as redshift, in which light from distant objects is stretched as the universe expands. and become redder. Of course, James Webb can also make closer observations right into our own solar system.

Decades of delay

Development of James Webb began in 1996 with the first launch scheduled for 2007. However, the project has been repeatedly delayed for decades, increasing the cost to $9.66 billion. , which is almost double the 2009 estimate by the US Government Accountability Office (GAO).

NASA last week announced it would launch the telescope on December 24, but bad weather delayed the mission by at least a day.

James Webb is the result of a large international collaborative effort involving dozens of countries, led by NASA, the European Space Agency and the Canadian Space Agency. More than 10,000 people have worked on the project so far. James Webb's career is expected to last at least 10 years.