NASA begins painstaking four-month process of bringing the James Webb Space Telescope into focus so it can start taking pictures of the universe by May
美国宇航局 has begun a four month-long process of bringing the James Webb Space Telescope into focus so it can start taking pictures of the universe by May.
The painstaking task is due for completion in time for the $10 billion observatory to begin peering into the cosmos by early summer.
詹姆斯韦伯太空望远镜, which blasted off from Guiana Space Centre on 圣诞 天, fully deployed its 21-foot, gold-coated primary mirror, NASA said last week, following deployment of its sunshield and smaller, secondary mirror.
Deployment of the primary mirror marked the final stage of all major spacecraft deployments to prepare for science operations, but now NASA engineers needs to fine-tune its individual optics into one huge, precise telescope.
Once this is done, James Webb is expected to capture its first science images in May, which would then be processed over about another month before they can be released to the public in June.
This artist’s conception of the James Webb Space Telescope in space shows all its major elements fully deployed. The telescope was folded to fit into its launch vehicle, and then was slowly unfolded over the course of two weeks after launch
James Webb’s primary mirror consists of 18 hexagonal segments of gold-plated beryllium metal, and measures 21 脚 4 英寸 (6.5 米) 在直径上. It is supported by three shallow carbon fiber tubes, or struts, that extend out from the large primary mirror, which is comprised of 18 hexagonal segments
JAMES WEBB REACHES MAJOR MILESTONE AS MIRROR UNFOLDS
James Webb Space Telescope fully deployed its 21-foot, gold-coated primary mirror, successfully completing the final stage of all major spacecraft deployments to prepare for science operations, NASA said on January 8.
After more than a week of other critical spacecraft deployments, the Webb team began remotely unfolding the hexagonal segments of the primary mirror, the largest ever launched into space. This was a multi-day process, with the first side deployed January 7 and the second January 8.
A joint effort with the European Space Agency (这个) and Canadian Space Agency, Webb will explore every phase of cosmic history, from within our solar system to the most distant observable galaxies in the early universe.
The telescope is currently on its way to the second Lagrangian point (L2), an area of balanced gravity between the Sun and Earth, where it will spend more than a decade exploring the universe in infrared.
To focus the telescope, mission control engineers at NASA’s Goddard Space Flight Center in Greenbelt, 马里兰州, began by sending their initial commands to tiny motors called actuators that slowly position and fine-tune the telescope’s principal mirror.
These actuators have been built to move incrementally at temperatures as low as -400°F (-240摄氏) in the vacuum of space.
James Webb’s primary mirror consists of 18 hexagonal segments of gold-plated beryllium metal, and measures 21 脚 4 英寸 (6.5 米) in diameter – a much larger light-collecting surface than Hubble, Webb’s predecessor.
的 18 segments, which had been folded together to fit inside the cargo bay of the rocket that carried the telescope to space, were unfurled with the rest of its structural components during a two-week period following Webb’s December 25 发射.
Those segments must now be detached from fasteners that held them in place for the launch and then moved forward half an inch from their original configuration – a 10-day process – before they can be aligned to form a single, unbroken, light-collecting surface.
The alignment will take an additional three months, Lee Feinberg, the Webb optical telescope element manager at Goddard, 告诉路透社.
The five-layered sunshield will protect the telescope from the light and heat of the sun, Earth and moon, but keeping its scientific instruments below -380 华氏度
Aligning the primary mirror segments to form one large mirror means each segment ‘is aligned to one-five-thousandth the thickness of a human hair’, Feinberg said.
The telescope’s smaller, secondary mirror, designed to direct light collected from the primary lens into Webb’s camera and other instruments, must also be aligned to operate as part of a cohesive optical system.
If all goes as planned, the telescope should be ready to capture its first science images in May, which would be processed over about another month before they can be released to the public in June.
The James Webb Space Telescope Mirror is seen during a media unveiling at NASA’s Goddard Space Flight Center at Greenbelt, Maryland prior to launch on December 25. The big gold hexagons make up its primary mirror
的 18 segments making up the primary mirror had to be folded together to fit inside the cargo bay of the rocket that carried the telescope to space
An artist’s impression of the James Webb Space Telescope folded in the Ariane 5 rocket after launch from Europe’s Spaceport in French Guiana
Described by NASA as the premier space-science observatory of the next decade, Webb will mainly view the cosmos in the infrared spectrum, allowing it to gaze through clouds of gas and dust where stars are being born.
Instruments on the James Webb Space Telescope
近红外摄像头 (近红外相机) 从可见光边缘到近红外线的红外成像仪
近红外光谱 (近红外光谱仪) 还将在相同的波长范围内进行光谱分析.
美里 (中红外仪器) 将测量中长红外波长范围从 5 至 27 千分尺.
FGS/NIRISS (精细制导传感器和近红外成像仪和无缝隙光谱仪), 用于在科学观测时稳定天文台的视线.
相比下, predecessor Hubble has operated primarily at optical and ultraviolet wavelengths since its 1990 发射.
Webb is about 100 times more powerful than Hubble, enabling it to observe objects at greater distances, thus farther back in time, than Hubble or any other telescope.
This will bring into view a glimpse of the cosmos never previously seen – dating to just 100 大爆炸后百万年, the theoretical flashpoint that set in motion the expansion of the observable universe an estimated 13.8 十亿年前.
The new space telescope has been developed at a cost of $8.8 十亿 (£6.6 billion), with operational expenses projected to bring its total price tag to about $9.66 十亿 (£7.2 billion), according to Reuters.
The orbiting infrared observatory is designed to be about 100 times more powerful than its predecessor, the Hubble Space Telescope.
NASA likes to think of James Webb as a successor to Hubble rather than a replacement, as the two will work in tandem for a while.
The JWST project, which started in 1996, is an international collaboration led by NASA in partnership with the European and Canadian space agencies.
NASA ‘s revolutionary James Webb Space Telescope has successfully lifted off to start its long flight into space to replace the Hubble telescope after decades of planning and delays
James Webb’s primary mirror is a much larger light-collecting surface than Hubble, Webb’s predecessor. Webb will look back to almost the beginning of time, to when the first stars and galaxies were forming
James Webb began development in 1996 and was originally envisaged to launch in 2007, but a major redesign in 2005 put this back.
Construction was finally completed in 2016 and an extensive period of testing work began, but this was delayed by the Covid-19 pandemic.
Launch had been scheduled for March 2021 before being delayed to October, and then again until December.
It was previously scheduled to launch on December 18, 2021, 但 ‘an incident‘ during launch preparations pushed this back.
The launch was lastly rescheduled for Christmas Eve, before finally being moved to December 25.
NASAs Hubble Space Telescope is still working and has made more than 1.5 million observations since its mission began in 1990
The Hubble telescope was launched on April 24, 1990, via the space shuttle Discovery from Kennedy Space Centre in Florida.
It is named after famed astronomer Edwin Hubble who was born in Missouri in 1889.
He is arguably most famous for discovering that the universe is expanding and the rate at which is does so – now coined the Hubble constant.
The Hubble telescope is named after famed astronomer Edwin Hubble who was born in Missouri in 1889 (图为)
Hubble has made more than 1.5 million observations since its mission began in 1990 and helped publish some 18,000 scientific papers.
It circles the Earth at a speed of about 17,000mph (27,300公里/小时) in low Earth orbit at about 340 miles in altitude.
Hubble has the pointing accuracy of .007 arc seconds, which is like being able to shine a laser beam focused on Franklin D. Roosevelt’s head on a dime roughly 200 英里 (320公里) 远.
The Hubble telescope is named after Edwin Hubble who was responsible for coming up with the Hubble constant and is one of the greatest astronomers of all-time
Hubble’s primary mirror is 2.4 米 (7 脚, 10.5 英寸) across and in total is 13.3 米 (43.5 脚) 长 – the length of a large school bus.
Hubble’s launch and deployment in April 1990 marked the most significant advance in astronomy since Galileo’s telescope.
Thanks to five servicing missions and more than 25 years of operation, our view of the universe and our place within it has never been the same.