NASA sees a paradigm shift in Earth observing missions, which will increasingly rely on small satellite technologies but provide big results.
NASA has announced what it hopes will mark a new era for Earth observation missions using small satellites. Also known as CubeSats, nanosatellites and microsatellites, small satellites have for quite some time been a cost-effective and agile method of testing technology destined for larger missions. NASA officials say small satellites are now poised to serve as vehicles for serious scientific research in space. Varied in size, CubeSats can be small enough to hold in your hand and microsatellites can be as large as a small washing machine, according to NASA. They can fly solo or in a constellation or swarm.
Thomas Zurbuchen, associate administrator of NASA’s Science Mission Directorate in Washington, explained at a news conference, “NASA is increasingly using small satellites to tackle important science problems across our mission portfolio. They also give us the opportunity to test new technological innovations in space and broaden the involvement of students and researchers to get hands-on experience with space systems.”
The first CubeSats were developed in 1999 by Jordi Puig-Suari at California Polytechnic State University and Bob Twiggs at Stanford University, but it took time to develop safe launching mechanisms and convince agencies like NASA to allow these devices on board missions carrying billions of dollars’ worth of technology. The first CubeSat was launched in 2003.
Often carried as secondary payloads on larger missions, small satellites offer a unique platform for students to develop and build technologies from start to finish. Full-scale satellite missions often take decades to develop and launch into space, which makes it difficult for students to witness the process in its entirety. Small satellites can be completed and launched in the span of a few years. For a high school or college student, the experience can be transformative.
In 2006, Rohan Punnoose was a student at Thomas Jefferson High School for Science and Technology in Alexandria, Virginia. Punnoose was the student project leader for TJ3Sat, the first CubeSat designed and launched by high school students. The project took seven years to complete. But according to the students’ teacher Adam Kemp, many stayed in touch and followed the project to launch in 2013 at NASA’s Wallops Flight Facility. Punnoose is now interning at SpaceX, working on avionics systems integration and expects to graduate from the University of Michigan in 2018 with a bachelor of science in engineering.
In 2014, Punnoose told Earthzine, “To work on a project on such a huge scale is so inspiring. Nobody actually thought we would actually get a satellite that would go up in space, everybody doubted and we did it.”
Small satellites will not replace larger and more robust satellite missions any time soon. Large-scale missions will continue to have benefits such as size, number of instruments, and the ability to carry out longer-duration missions. But NASA officials say missions with small satellites will allow for increased capacity in Earth observations and shed new light on important phenomena including hurricanes, climate, and cloud transport systems.
According to the National Oceanic and Atmospheric Administration’s National Weather Service, forecasting for cyclones and hurricanes has improved by about 50 percent since the 1990s, but scientists still lack reliable measurements for winds inside the storms. In the past, very large satellites like NASA’s QuickSCAT provided valuable data about ocean winds, but these missions are costly and take many years to develop. In 2009, QuickSCAT ceased functioning and was replaced with a temporary solution called ISS-RapidSCAT on the International Space Station (ISS). RapidSCAT was used to calibrate scatterometers on international satellites and provided valuable insights to scientists and forecasters before being decommissioned in November 2016.
The Cyclone Global Navigation Satellite System (CYGNSS) from the University of Michigan, in development under NASA’s Earth System Science Pathfinder (ESSP) Program, is expected to deliver improved accuracy and weather prediction as well as observations about the relationship between near-surface winds, the atmosphere and developing storms.
The principal investigator for CYGNSS is Chris Ruf – professor of atmospheric science and electrical engineering at University of Michigan. In an interivew with NASA, Ruf said, “If CYGNSS works well, it will provide a new paradigm for doing lower cost missions that are managed outside of the traditional NASA field centers. It has the potential to become a long-lasting new option for how to do missions, and it is really exciting to be a part of that.”
Aaron Ridley, mission constellation scientist for CYGNSS, describes the mission, which incorporates eight small satellites carrying modified Global Positioning System (GPS) receivers, all pointed at the oceans. According to Ridley, the satellites piggyback on signals coming from existing commercial and government-operated GPS satellites currently in orbit. These satellites provide signals to the small CYGNSS satellites 24 hours a day, seven days a week. When a GPS signal hits smooth water, the returning signal bounces back uniformly, but if the water surface is rough, the returning signal is distorted, indicating wind. The researchers liken the signal transmisssion to that of a reflection of the moon on still waters versus a choppy pond.
CYGNSS is scheduled for launch from Cape Canaveral, Florida, on an Orbital ATK Pegasus rocket on Dec. 12, 2016.
William Blackwell is principal investigator for the Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of Smallsat (TROPICS) mission at the Massachusetts Institute of Technology’s Lincoln Laboratory, another NASA ESSP mission. Blackwell points to dramatic advances in miniaturization technology, which have served as major boons to the scientific instruments and the spacecraft bus over the last five years. Because of these advancements, each satellite in the TROPICS mission weighs just eight pounds and is about the size of a loaf of bread.
The TROPICS constellation will include 12 CubeSats traveling above a band of Earth between 40 degrees latitude North and South. When launched in 2020, the satellites will produce microwave measurements every 30 minutes. According to Blackwell, these measurements can be used to derive a number of physical properties of the storm and surrounding atmosphere, including temperature and water vapor profiles, precipitation and cloud properties.
“There are a number of currently unanswered questions that can be addressed with TROPICS rapid, cloud-penetrating observations,” he said. “For example, there is warming in the core of a hurricane, and this warming and its relationship to storm intensification has led to numerous studies spanning decades of research.”
Blackwell explained that the frequency and type of data collected will paint a more dynamic picture of often-dangerous storms and how they are developing. Each satellite includes instruments providing “scans across Earth’s surface once every two seconds to provide three-dimensional information on the storm’s structure, like a CAT-Scan.”
Given the increasing number of billion dollar hurricanes in the United States and elsewhere, small satellite missions like TROPICS and CYGNSS in development under NASA’s Earth System Science Pathfinder (ESSP) Program could provide invaluable information to scientists hoping to understand these complex weather patterns – this information could aid in the decision-making process before, during and after disasters strike.
With all the excitement about small satellites in the public and private sector, managing air traffic and space debris in the future is likely to become a major undertaking. According to Steve Jurczyk, associate administrator for the Science Mission Directorate at NASA Headquarters, “It’s going to be critical to manage small spacecraft traffic as we move forward.”
Efforts are underway to move monitoring space debris and traffic from the purview of the U.S. Air Force to the Federal Aviation Administration. In September, Andy Pasztor wrote in The Wall Street Journal, “With roughly 1,400 commercial satellites currently flying and several thousand more expected to be launched into popular low-altitude orbits over the next 10 years, Pentagon brass are ready to hand over the painstaking task to civilian authorities.”
Regardless of future obstacles and work to do, the excitement about small satellite emerging technology is tangible. Ellen Stofan, chief scientist at NASA Headquarters, sees small satellites as drivers of innovation that will produce partnerships between public and private sectors to advance scientific and human exploration in space. The technology can reduce risks inherent in demonstrating new technologies and act as pathways for future large-scale missions, all while providing access for universities and students hoping to pursue scientific discoveries.
To Stofan, “Sometimes smaller is bigger.”
Jenny Woodman is a science writer and Writing Club coordinator for IEEE Earthzine. Follow her on Twitter @JennyWoodman.