NASA's Spitzer Space Telescope's mission has come to an end on Thursday, after more than 16 years studying the universe in infrared light, revealing new wonders in the solar system, galaxy and beyond.

According to a release of NASA's Jet Propulsion Laboratory (JPL), mission engineers confirmed on Thursday afternoon that the spacecraft was placed in safe mode, ceasing all science operations.

After the decommissioning was confirmed, Spitzer Project Manager Joseph Hunt declared the mission had officially ended.

Launched in 2003, Spitzer was one of NASA's four Great Observatories, along with the Hubble Space Telescope, the Chandra X-ray Observatory and the Compton Gamma Ray Observatory. The Great Observatories program demonstrated the power of using different wavelengths of light to create a fuller picture of the universe, according to JPL.

"Spitzer has taught us about entirely new aspects of the cosmos and taken us many steps further in understanding how the universe works, addressing questions about our origins, and whether or not are we alone," said Thomas Zurbuchen, associate administrator of NASA's Science Mission Directorate in Washington.

"This Great Observatory has also identified some important and new questions and tantalizing objects for further study, mapping a path for future investigations to follow. Its immense impact on science certainly will last well beyond the end of its mission," Zurbuchen said.

Among its many scientific contributions, Spitzer studied comets and asteroids in the solar system and found a previously unidentified ring around Saturn, according to JPL.

It studied star and planet formation, the evolution of galaxies from the ancient universe to today, and the composition of interstellar dust. It also proved to be a powerful tool for detecting exoplanets and characterizing their atmospheres.

Spitzer's best-known work may be detecting the seven Earth-size planets in the TRAPPIST-1 system -- the largest number of terrestrial planets ever found orbiting a single star -- and determining their masses and densities, according to JPL.

China plans to launch more space science satellites in the coming three to four years, according to the Chinese Academy of Sciences (CAS).

The satellites will be used to detect electromagnetic signals associated with gravitational waves, solar eruption activities, astronomy and the interaction between solar wind and the Earth's magnetosphere.

Four new missions include the Gravitational Wave Electromagnetic Counterpart All-sky Monitor, the Advanced Space-borne Solar Observatory, the Einstein-Probe and the Solar Wind Magnetosphere Ionosphere Link Explorer.

Previously, CAS has successfully launched several space science satellites including the Dark Matter Particle Explorer, the Quantum Experiments at Space Scale, the Hard X-ray Modulation Telescope and the Taiji-1, China's first satellite to conduct in-orbit experiments on key technologies related to space-based gravitational wave detection.

Spacewalking astronauts worked to complete repairs to a cosmic ray detector outside the International Space Station on Saturday and give it new life.

It was the fourth spacewalk since November for NASA's Andrew Morgan and Italy's Luca Parmitano to fix the Alpha Magnetic Spectrometer. They installed new coolant pumps last month to revive the instrument's crippled cooling system and needed to check for any leaks in the plumbing.

Parmitano quickly discovered a slight leak and tightened the fittings. "Our day just got a little more challenging," Mission Control observed.

Provided everything goes well, the $2 billion spectrometer — launched to the space station in 2011 — could resume its hunt for elusive antimatter and dark matter next week, according to NASA.

NASA has described the spectrometer spacewalks as the most complicated since the Hubble Space Telescope repair missions a few decades ago. Unlike Hubble, this spectrometer was never intended for astronaut handling in orbit, and it took NASA years to devise a repair plan.

Despite their complexity, the first three spacewalks went well. Morgan and Parmitano had to cut into stainless steel pipes to bypass the spectrometer's old, degraded coolant pumps, and then spliced the tubes into the four new pumps — no easy job when working in bulky gloves. The system uses carbon dioxide as the coolant.

Besides checking for leaks Saturday, the astronauts had to cover the spectrometer with thermal insulation.

"Good luck out there, have a lot of fun," astronaut Jessica Meir radioed from inside. "We are very excited for you to be finishing off all of the amazing work that you've already put into this AMS repair, and I think everyone's excited to the prospects of what AMS has to offer once you guys finish off the work today."

The massive 7 1/2-ton (6,800-kilogram) spectrometer was launched to the space station on NASA's next-to-last shuttle flight. Until it was shut down late last year for the repair work, it had studied more than 148 billion charged cosmic rays. The project is led by Samuel Ting, a Nobel laureate at the Massachusetts Institute of Technology.

The repairs should allow the spectrometer to continue working for the rest of the life of the space station, or another five to 10 years. It was designed to operate for three years and so already has surpassed its expected lifetime.

Saturday's spacewalk got started a little late. A strap on a bag accidentally got caught in the seal when one of the inside hatches was closed and the air lock had to be reopened and repressurized before the astronauts could go out.

NASA's two other astronauts on board, Meir and Christina Koch, performed two spacewalks over the past 1 1/2 weeks to upgrade the space station's solar power system.

Altogether, this station crew has gone out on nine spacewalks.

China announced that it will launch its first Mars mission probe in July this year, China Youth Daily reported Thursday, adding that this is the first time the country disclosed the launch month of its Mars exploration program.

The Mars probe will be sent by the Long March-5 Y4 carrier rocket, said the newspaper, citing sources from the China Aerospace Science and Technology Corporation (CASC).

The Long March-5 Y4 rocket has recently completed a 100-second test for its high thrust hydrogen-oxygen engine, which is the last engine examination before the final assembly.

According to the CASC, China will send a probe to orbit and land and deploy a rover on Mars.

In 2020, the Long March-5 rocket will carry out several missions, including the Mars probe launch and the lunar sample return.

A total of 24 high thrust hydrogen-oxygen rocket engine tests will be conducted this year for these missions.

NASA's Spitzer Space Telescope, having been exploring the universe in the infrared for over 16 years, will conclude its mission on Jan. 30, said NASA's Jet Propulsion Laboratory (JPL) on Wednesday.

Launched in 2003, Spitzer revealed previously hidden features of known cosmic objects and led to discoveries and insights spanning from the solar system to nearly the edge of the universe, said the JPL in a press release.

"Spitzer taught us how important infrared light is to understanding our universe, both in our own cosmic neighborhood and as far away as the most distant galaxies," said Paul Hertz, director of astrophysics at NASA Headquarters.

"The advances we make across many areas in astrophysics in the future will be because of Spitzer's extraordinary legacy," Hertz said.

Spitzer was designed to study "the cold, the old and the dusty," three things astronomers can observe particularly well in infrared light. The telescope has studied some of the most distant galaxies ever detected.

Spitzer also has a keen eye for interstellar dust, which is prevalent throughout most galaxies, said the JPL, adding that some infrared wavelengths of light can penetrate dust when visible light cannot, allowing Spitzer to reveal regions that would otherwise remain obscured from view.

"It's quite amazing when you lay out everything that Spitzer has done in its lifetime, from detecting asteroids in our solar system no larger than a stretch limousine to learning about some of the most distant galaxies we know of," said Michael Werner, Spitzer's project scientist.