Lets talk about science. Not just any science but the science and research that is currently underway at NASA (National Aeronautics and Space Administration). One of the most enjoyable experiences of Awesome Con is the addition of real science to the program and having NASA scientists discuss their latest research. This year I had the opportunity to learn more about the Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2) mission, the upcoming solar eclipse on August 21, and sat in on a panel all about space lasers. The space lasers tied into the ICESat-2 mission but other mission were also discussed.
This is all part of Future Con. Smithsonian Magazine and Awesome Con debuted Future Con, June 16th – 18th in Washington, D.C. This event, held as part of the overall Awesome Con experience, brought together entertainment, science, and technology. Future Con included guest speakers, scientist panels, and booths where attendees got hands on demos and asked questions from the experts. At the NASA booth Awesome Con attendees got to see a 200-year-old ice core sample from Greenland. Within the core was preserved air bubbles, witnessing a moment in time captured within the ice. These ice cores can tell us what climate conditions were like not only hundreds of years ago but also hundreds of thousands of years.
Awesome Con overall may be a celebration of pop-culture but that doesn’t mean we can’t learn the science of our planet and solar system, the universe, and NASA’s missions to study them all. There were even discussions on the science behind our favorite sci-fi and superhero movies.
ICESat-2 and Space Lasers
While at Awesome Con I attended the “NASA’s Space Lasers” panel. This panel was comprised of scientists and engineers from NASA’s Goddard Space Flight Center. The guests were Luis Ramos-Izquierdo (optical engineer), Erwan Mazarico (planetary scientist), Evan Hoffman (laser remote sensing), Jennifer Sager (engineer), Brooke Medley (cryospheric scientist), and Kate Ramsayer (outreach specialist).
What is a Laser? The term laser stands for Light Amplification by Stimulated Emission of Radiation. Lasers use a diode, lens, crystal, and reflecting mirror to create a narrow, strong, and unbroken beam of light. Unlike white light that contains all the colors of the spectrum a laser produces a beam consisting of one color and wavelength. Though lasers have many purposes from cutting hard substances to delicate surgery at NASA lasers are being used in instruments for mapping, determining elevation and volume, geodesy, and even downloading data from the moon.
When talking about mapping, lasers are used to gather data about elevation and changes in terrain. It can also be used for mapping tree canopies and atmospheric conditions. One of the most commonly used forms of laser mapping technology is lidar, Light Detection and Ranging. The majority of lidar products available come from onboard aircraft sensors that fly over a region emitting laser pulses. These pulses bounce off the ground and measure elevation. The elevation of the ground, vegetation, buildings, and depending on the sensor water and other harder to map areas is measured by recording how long it takes for the light to hit the sensor. From there the sensor measures the time to determine distance traveled getting the elevation of the object. Once all the data is collected it is processed into a point cloud, millions of points each with an elevation, and then processed into a readable map of the terrain or topography.
Though NASA uses aircraft based lidar systems they also have satellite based laser systems that do the same thing on a larger scale. Whereas aircraft can only do small swaths of earth at a time, satellites can map entire planets or in the case of ICESat-2 large Earth landmasses.
Besides ICESat-2 there are other onboard laser systems measuring the moon and other planets. Launched in 2004, MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) was launched to observe and map the surface of Mercury. In order to map the topography of the planet a laser altimeter onboard MESSENGER is used. A laser altimeter, used for mapping topography from orbit, measures the altitude of an object to get elevations.
NASA is also using a laser altimeter to map the moon with the LRO (Lunar Reconnaissance Orbiter). Onboard the LRO is LOLA (Lunar Orbiter Laser Altimeter) that uses a single laser pulse split into five beams. When the beams hit the surface they are backscattered. The return pulse is then measured by LOLA using the time of flight. That time is factored with the speed of light for a precise measurement of the range from spacecraft to lunar surface resulting in a topographic map of the lunar surface. Lasers don’t just map topography but can also be used for the study of Earth’s atmosphere. For instance, CATS (Cloud-Aerosol Transport System) is a lidar system on the International Space Station, which is used to take profile measurements of atmospheric aerosols and clouds. This can give scientists a better understanding of atmospheric aerosols and used to improve climate change models.
This gets us to ICESat-2 and the measurements of the polar ice sheets to determine sea level rise. Launching in 2018, ICESat-2 will replace ICESat-1 flying over Antarctica and Greenland. During the panel we learned that knowing the volume of the polar ice sheets would allow scientists to better understand how much the sea level could rise. For example, the Antarctica ice sheet is the largest in the world and two times the size of the contiguous United States. The volume of this massive ice sheet can contribute to a 200 ft. sea level rise if it were all to melt. From the South Pole we move far north to Greenland and the largest ice sheet in the Northern Hemisphere. If all the ice on Greenland were to melt it would contribute 20 ft. of sea level rise.
It is important to understand the current volume of ice on both landmasses so we know how much ice is currently on the surface and how much is melting. With satellites NASA can map the entire Antarctic or Greenland ice sheets because no two areas will be the same thickness or volume and ice won’t melt the same everywhere. ICESat-2 will be used to get an accurate volume by measuring the surface elevation as it tracks over the ice sheet. To get the volume it will fly over the same path again getting another measurement for height change. Height change when integrated over the entire ice sheet produces volume change. According to the panel ICESat-2 will be able to get six elevation measurements on one pass.
Even though there is the mission of measuring ice sheet volume, ICESat-2 will be able to measure heights of tree canopies, buildings, mountain ranges, and other surface features as it crosses over the Earth.
Beyond mapping lasers can be used for Geodesy. Geodesy is the study of the geometric processes of the Earth, Earth’s orientation, and gravitational field. NASA is using satellite laser ranging to determine space Geodesy. It is also used to track satellites and also lunar orbiting satellites like the LRO. ICESat-2 will also have mirrors on board for laser ranging as it makes its passes around the Earth. For laser ranging a laser is shot from the surface of the earth to an orbiting satellite hitting arranged mirrors. The time in which it takes the light to return to Earth determines the range of the satellite. It’s a way for NASA to know the location of its satellites to accurately map the surface of the moon or the ice sheets.
Our last look at how NASA is using lasers was the Lunar Laser Communication Demonstration (LLCD) in 2013. LLCD was onboard the Lunar Atmosphere and Dust Environment Explorer (LADEE), which was launched to explore the Lunar atmosphere and determine if dust is causing the glow observed during the Apollo missions. It used a pulsed laser beam to transmit data from the moon back to Earth at a speed of 622 Mbps. This was also the first time NASA used lasers in two-way communication instead of radio waves. We were also told at the panel that this technology would revolutionize how we get Internet, so look out for laser Internet coming over the next decade or two.
To find out more on ICESat-2 visit NASA’s official mission web page.
The Total Solar Eclipse of 2017
Moving away from space lasers we go to one of the biggest events of 2017 for residents of North America, the total solar eclipse. This will occur on August 21st and all residents, weather permitting, will be able to view the eclipse. Though only a portion of the continent will have totality, from Oregon to South Carolina, everyone else will have some form of partial eclipse. Totality is expected to last up to two minutes and forty seconds but depends on your location. Those living in or plan to be in North America this will be the last total solar eclipse until April 8, 2024.
More information on the path of the eclipse and how to view it safely can be found on NASA’s Total Solar Eclipse web page.