Artist's concept of the fully-deployed James Webb Space Telescope (JWST).
(Image Source: NASA)
By Glenn A. Walsh
Reporting for SpaceWatchtower
Finally! After years of delays including launch delays this month, the next great space telescope is scheduled for launch no earlier than Christmas morning: Saturday, 2021 December 25 at 7:20 a.m. Eastern Standard Time (EST) / 12:20 Coordinated Universal Time (UTC). NASA's James Webb Space Telescope, what is described by scientists as the successor to the Hubble Space Telescope, will be launched using an Ariane 5 launch vehicle from the Guiana Space Centre, northwest of Kourou in French Guiana, on the north Atlantic Ocean coast of South America.
NASA will provide Live-Stream coverage of the launch on NASA-TV, beginning Christmas morning at 6:00 a.m. EST / 11:00 UTC. NASA-TV will carry a post-launch news conference on Christmas morning at 9:00 a.m. EST / 14:00 UTC (assuming the launch occurs as scheduled). Internet link to NASA-TV is located near the end of this blog-post.
The James Webb Space Telescope (JWST), which is much larger than the Hubble Space Telescope, is designed to seek stars and galaxies shortly after the “Big Bang”, the creation of our Universe approximately 13.8 billion years ago. The Hubble Space Telescope (HST), along with most traditional terrestrial telescopes, observe using visible light. The JWST is designed to use the infrared portion of the electromagnetic spectrum to search where visible light telescopes cannot.
JWST will be the largest space telescope ever launched. With a primary mirror size of 21.3 feet / 6.5 meters, it is much larger than the HST primary mirror: 7.8 feet / 2.4 meters.
The JWST mirror is comprised of 18 gold-plated beryllium, hexagonal segments. A 5-layer Sun-shield, the size of a tennis court, protects the mirror from any heat radiated by the Sun, Earth, or Moon. Made of silicon and aluminum-coated Kapton, this Sun-shield should keep the JWST primary mirror and related instruments at a temperature no higher than 50 degrees Kelvin / -370 degrees Fahrenheit / -223 degrees Celsius. To search for the earliest galaxies and stars in the Universe, using infrared, the telescope mirror must be extremely cold and shielded from heat.
After the launch of JWST, the telescope will travel 930,000 statute miles / 1.5 million kilometers from Earth to a point in Deep Space known as L2. L2 is the second Lagrange Point of the Earth – Sun system. A Lagrange Point is a site where the gravity between two large bodies, in this case the Earth and the Sun, is relatively balanced; satellites can stay at such a point with minimum energy usage. It is a point in Deep Space where the JWST can remain, somewhat easily, in an orbit and away from the heat of the Earth and the Sun.
Why launch from French Guiana? There are several reasons:
The Guiana Space Centre is operated by the European Space Agency (ESA) and the French space agency (National Centre for Space Studies: CNES); along with the Canadian Space Agency (CSA), the ESA is part of the international collaboration with NASA on this mission. The launch site and launch vehicle are ESA contributions to the mission.
The launch site is near the Equator, which means less energy is needed for launches, particularly to maneuver a spacecraft into equatorial, geostationary orbit. The closer to the Equator a launch occurs, the greater energy from the rotation of the Earth can be utilized in the launch; and, hence, less rocket fuel is needed. As Florida is the closest U.S. state to the Equator, this is why the Kennedy Space Center was sited in Florida.
French Guiana has open sea to the east. As with the Kennedy Space Center, this allows lower rocket stages and other launch debris to fall harmlessly in the Atlantic Ocean, without risking life or property.
The JWST mission has four key goals:
Search for light from the very first stars and galaxies that formed in our Universe, shortly after the Big Bang. The Universe is estimated to be about 13.8 billion years old; JWST is expected to find light from stars and galaxies approximately 13.5 billion years in the past (13.5 billion light-years from Earth).
Study the formation and evolution of galaxies.
Study the formation of stars and planetary systems..
Further study planetary systems, looking for the origins of life.
The Hubble and James Webb space telescopes are different in mission duration. The Hubble Space Telescope has had the advantage of being in a close Earth orbit, where Space Shuttle astronauts have been able to service and upgrade the telescope. With the conclusion of the Space Shuttle program, the ability to service and upgrade the HST seems to have ended. As the HST is now, it is expected to last until some tine in the 2030s.
The JWST, being placed much further away from the Earth, cannot be serviced or upgraded by current space technology. To stay at the L2 orbital site, which is a somewhat unstable orbit, rocket propellant must be used. JWST has 10 years of rocket propellant on-board, to maintain the L2 configuration of the telescope. So, 10 years is the upper limit of the mission duration.
The nominal science mission is officially 5 years, with the hope that the telescope can continue to be used for research for 10 years. Once the JWST spacecraft reaches L2, there will be a 6-month commissioning phase, before the official science mission begins. The commissioning phase includes the careful, and very risky, unfolding of the huge telescope mirror, very crucial Sun-shield, and related instruments.
The JWST is named after James Webb, the second Administrator of NASA. James Webb ran NASA from February of 1961 until October of 1968, for seven years retiring just before the first manned flight of the Apollo spacecraft..He was in charge of NASA during all Mercury and Gemini flights. And, he was Administrator during the investigation of the tragic fire, which killed three astronauts, during a ground test of the Apollo 1 spacecraft on Friday, 1967 January 27.
The James Webb Space Telescope, originally designed to cost $1 billion to $3.5 billion, had many cost over-runs, throughout the many years of development and delays. With the launch of JWST, the final cost of the project will be $10 billion.
More than 30 years ago, even before the 1990 launch of the Hubble Space Telescope, planning had begun on JWST. Construction of JWST began in 2004, after having been named to honor James Webb in 2002.
In 1993, when the U.S. Congress killed the Superconducting Super Collider project for particle physics in Texas, scientists had feared the same thing would happen to JWST. But, former U.S. Senator Barbara Mikulski (D-Md.) helped to save JWST at that time.
The launch of JWST had been expected some time between 2007 and 2011. Due to continual cost over-runs, the launch kept being delayed. In 2011, the U.S. House of Representatives voted to cancel the JWST project, due to the continual cost over-runs. Scientists and space enthusiasts, including teachers and school children, successfully rallied to save the project.
As it took many years to develop and
construct the JWST, planning for the next great space telescope has
just begun. In November, a committee convened by the independent
National Academies of Sciences, Engineering, and Medicine has
recommended that another huge space telescope should be designed and
built to study exo-planets (planets orbiting stars other than our
Sun) and search for signs of life. It is projected that this new
telescope would be launched some time in the 2040s.
NASA-TV Live-Stream Coverage of the Launch of the James Webb Space Telescope:
Link >>> https://www.nasa.gov/nasalive
Internet Links to Additional Information ---
James Webb Space Telescope (JWST) -
Link 1 >>> https://jwst.nasa.gov/
Link 2 >>> https://www.nasa.gov/mission_pages/webb/main/index.html
Link 3 >>> https://en.wikipedia.org/wiki/James_Webb_Space_Telescope
Ariane 5 rocket (to launch JWST): Link >>> https://en.wikipedia.org/wiki/Ariane_5
Guiana Space Centre (launch site for JWST): Link >>> https://en.wikipedia.org/wiki/Guiana_Space_Centre
L2 - Second Lagrange Point in Earth - Sun System: Link >>> https://en.wikipedia.org/wiki/Lagrange_point#L2
Source:
Glenn A. Walsh Reporting for SpaceWatchtower,
a project of Friends
of the Zeiss
Friday, 2021 December 24.
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