There were so many "cool" science things that happened this week:
- Scientists revealed a "first-of-its-kind" image of a black hole and its event horizon.
- A novel observation about lightning formation was reported in the scholarly literature.
- SpaceX launched its new Falcon Heavy rocket from NASA’s Kennedy Space Center after sending up a Roadster in a test launch about a year ago.
I want to focus on that last cool thing. Falcon Heavy is the world's most powerful rocket system with 27 engines. This week's launch lofted a Saudi Arabian satellite into space then SpaceX successfully landed two of the rocket boosters at Cape Canaveral. The "cool factor" didn't stop there for me. The GOES-East weather satellite operated by the National Oceanic and Atmospheric Administration (NOAA) captured this awesome image below.
The National Weather Service (NWS) posted the image on its Facebook page and said:
#GOESEast captured the streak of #FalconHeavy shortly after liftoff from Kennedy Space Center this evening. This is the 6.2 µm - "Upper-level Water Vapor" Band with a 2 km resolution and is used for tropospheric water vapor tracking. More imagery here.
In the image, white and and cooler colors represent very amounts of moisture (water vapor and clouds). Green colors indicate the presence of high water vapor and/or ice crystals). Red and yellow areas show that very little water vapor is present.
How did the satellite see the rocket contrail (see the arrow in the image)? GOES-East has an imager that "sees" the atmosphere at many different wavelengths. Our eyes only see things in the visible portion of the electromagnetic spectrum. The Advanced Baseline Imager aboard this satellite uses 16 different wavelength or spectral bands: Two visible channels, four near-infrared channels, and ten infrared channels. Infrared (IR) channels essentially detect heat. These bands are chosen to observes different things like clouds, smoke, volcanic ash plumes, pollution, vegetation, atmospheric motion and more.
The image above used the 6.2 micron channel. It is in the IR portion of the spectrum and is very useful for tracking atmospheric water vapor in the middle part of the atmosphere. Many gases in our atmosphere are "selective" absorbers at certain wavelength. For example, ozone in the stratosphere selectively absorbs ultraviolet (UV) radiation. A tutorial by CIMSS at the University of Wisconsin explains why the 6.2 micron channel is useful for detecting water vapor. Its website points out:
Water vapor comprises only 1-4% (by volume) of the atmosphere, yet it plays a critical role (along with carbon dioxide, ozone, and other so-called "greenhouse gases") in the Earth's energy balance. Water vapor absorbs and reradiates electromagnetic radiation in various wavelength bands, most notably the infrared 6-7 micron band. Such infrared radiation -- emitted by the Earth/atmosphere and intercepted by satellites -- is the basis for remote sensing of tropospheric water vapor.
Like many airplanes in the sky, rockets leave condensation trails ("contrails"). The GOES-East imager can detect the rocket-generated cloud line at the 2-km resolution. Scott Baxhmeier of CIMSS added a bit more insight in a Tweet:
The Water Vapor bands are essentially Infrared spectral bands - so the "warm" feature seen on Water Vapor imagery is actually a signature of air that was superheated by the booster rockets.
He also compared the water vapor image with a shortwave IR image and the heat trail was apparent.
Meteorologists like me know about GOES-East but perhaps you do not. GOES-East is a part of the U.S. fleet of geosynchronous weather satellites. In a geosynchronous orbit 22,000 miles above the Earth, these satellite orbit at a rate matching the Earth's rotation. This fact is important because it allows these types of weather satellites to "remain" over the same location. Many communication, television, and radio satellites are in similar orbits. According to a NOAA website operated by its satellite division:
NASA launched the first GOES for NOAA in 1975. The GOES-N series includes GOES-15, which was launched in 2010. The latest generation of GOES is the GOES-R series. The satellites in the GOES-R Series are: GOES-R (now GOES-16) launched on November 19, 2016. GOES-16 is currently operating as GOES East.
There is also a satellite designated as GOES-West. Other satellites in the series are scheduled for launch through 2024.
