
© Subaru-Asahi Star CameraGreen Lasers over Hawaii
Late last month, mysterious green laser beams were spotted from Hawaii's tallest peak. Experts initially said the burst of laser beams was emitted by a NASA spacecraft though
that was proven incorrect this week -- with evidence pointing to a Chinese satellite.
Space experts at the National Astronomical Observatory of Japan (NAOJ) initially
tweeted on Jan. 30 that the Subaru-Asahi Star Camera
"captured green laser lights in the cloudy sky over Maunakea, Hawai'i. The lights are thought to be from a remote-sensing altimeter satellite ICESAT-2/43613."But on Feb. 6, one week later,
NAOJ issued a correction on YouTube that specified the laser beams weren't from a US spacecraft but
the "most likely candidate" was a "Chinese Daqi-1/AEMS satellite."Here's the video of the Chinese satellite firing bursts of lasers toward Earth:
"According to Dr. Martino, Anthony J., a NASA scientist working on ICESat-2 ATLAS, it is not by their instrument but by others." [a correction note on the YouTube video explains]
"His colleagues, Dr. Alvaro Ivanoff et al., did a simulation of the trajectory of satellites that have a similar instrument and found a most likely candidate as the ACDL instrument by the Chinese Daqi-1/AEMS satellite.
"We really appreciate their efforts in the identification of the light. We are sorry about our confusion related to this event and its potential impact on the ICESat-2 team."
Even though the Daqi-1 satellite is supposedly an atmospheric environment monitoring spacecraft, there are many concerns after the
spy balloon incident last week of space-base and even high-altitude surveillance equipment monitoring the US and allies.
Comment: China describes Daqi-1 and its intended activities:
China's Daqi-1 satellite was launched in April last year and similar to ICESat-2, it's an atmospheric environment monitoring satellite. That means it's in orbit around Earth in order to monitor global carbon levels, as well as atmospheric pollution.
Daqi-1 contains five instruments to help it do this, including ACDL, which stands for Aerosol and Carbon dioxide Detection Lidar. Lidar is an acronym for laser imaging, detection, and ranging, and it works a little like sonar. But instead of sending out sound waves to map an area, it sends out laser beams.
And it's these lasers that are believed to have lit up the sky over Hawaii at the end of January.
In the case of ACDL, it can send out dual-wavelength lasers at specific wavelengths in order to detect various molecules in Earth's atmosphere.
The time it takes for these laser beams to bounce back provides information on the composition of the atmosphere and ground below.
For example: ACDL can work out how much CO2 is in Earth's atmosphere by emitting two alternating lasers around the 1572 nanometer wavelength range.
"Daqi-1 can monitor fine particle pollution like PM2.5, pollutant gasses including nitrogen dioxide, sulfur dioxide and ozone, as well as carbon dioxide concentration," a March 2021 press release from the China Aerospace Science and Technology Corporation, which developed Daqi-1, explained.
It's early days for Daqi-1 so we're still waiting for results from its scans. But if all goes to plan, the satellite is just the start of China's plans to keep tabs on air pollution.
"China will produce a series of Daqi satellites in the future, which will be used to monitor atmospheric pollution, provide remote sensing data support for environment authorities, and also support scientific research into global climate change."
"Daqi-1 will be networked with other satellites, including Daqi-2, to realize greenhouse gas monitoring and help China achieve reduction of carbon emissions."
It's yet to be seen whether these green atmospheric detecting lasers may become more common as China achieves this goal.
Comment: China describes Daqi-1 and its intended activities: