Each day, new and innovative space technologies are being developed in countries around the world, and with that, a steady stream of satellites, rockets, cargo ships, and crew vehicles are being launched into the Earth's orbit and beyond.
So what happens to these systems when they come to the end of their functional life, or malfunction and break?
Some are programmed to re-enter the Earth's atmosphere where, if all goes well, they incinerate safely upon entry. Some are programmed to use their last bit of fuel to launch further into outer space, into so-called graveyard or disposal orbits. Other chunks of space debris are left to float in Earth's orbit, and as a result, estimates indicate that millions of pieces of space junk circulate our planet, traveling at tens of thousands of miles per hour. It's not hard to imagine how, at that speed and velocity, any kind of collision with a working satellite or spacecraft could mean instantaneous destruction.
To help address this real and ever-growing concern, in 2019 the World Economic Forum launched the Space Sustainability Rating (SSR), and held a competition to select teams to design the tool. The organizations selected were the European Space Agency along with a U.S. team led by Assistant Professor Danielle Wood, director of the the Media Lab's Space Enabled group, in collaboration with Minoo Rathnasabapathy of Space Enabled, Professor Moriba Jah at the University of Texas at Austin, and Simon Potter of the space analytics and engineering company BryceTech.
The rating system under development by this team over the past two years has been designed to score the sustainability of manufacturers and operators, and is based on factors such as plans to de-orbit systems upon completion of missions; choice of orbital altitude; ability of systems to be detected and identified from the ground; collision-avoidance measures; size and number of objects left in space from the launch vehicle; and sharing of data. By voluntarily participating in the SSR system, missions will earn a certification and rating that verifies their level of sustainability.
"The development and deployment of the SSR comes at a crucial time in the ongoing efforts to encourage responsible behavior among a growing and increasingly diverse group of space actors," says Potter. "Satellites are being launched in dramatically greater numbers, increasing the threat to the long-term sustainability of the space environment. The SSR aims to incentivize space actors to consider sustainability as a critical component of mission design and operations, in the same way that ESG [Environmental, Social & Governance] considerations are becoming increasingly embedded in activities on Earth."
Now, with the progress made by this foundational team, the SSR is poised to move from the design stage to prepare for operations, and the école Polytechnique Fédérale de Lausanne (Swiss Institute of Technology of Lausanne) Space Center — known as eSpace — has been tapped to lead the SSR rollout following a competitive selection process.
For this next chapter in space debris mitigation, the original SSR design team, including Wood, Rathnasabapathy, Jah, Potter, Stijn Lemmens and Francesca Letizia of ESA, and Nikolai Khystov of the World Economic Forum, will serve on the SSR's Advisory Council. This role includes serving on the team that makes recommendations and approves changes to the SSR definition, helps to communicate the value and benefits of the rating, and advises countries on how they can incorporate SSR guidelines into their national policies.
"The transition of the SSR from design to operations is an exciting milestone, and just the start of a new era of space sustainability research at MIT and with our collaborator Moriba Jah at the University of Texas at Austin," notes Wood.
Wood and her research team are building new alliances to expand research impact in space sustainability. Both Jah and Kevin O'Connell are newly announced affiliated researchers with Space Enabled. O'Connell served as the director of space commerce in the U.S. Department of Commerce and is a recognized expert on the global space economy. In addition, a research collaborative has been formed together with Jah and Richard Linares at MIT's Department of Aeronautics and Astronautics to design next-generation methods that support space traffic management.
Wood explains, "At Space Enabled, future research will continue our work to create models to estimate how challenging it is to detect, identify, and track an object in space; build tools that invite new countries and firms to help shape sustainable space operations; study economic, social, and legal trends that influence the accessibility of space; and develop new methods to ensure that human activity — in our own orbit, on the moon, Mars, and beyond — is environmentally, socially, and economically sustainable."
To celebrate this new season of research on space sustainability, Wood hosted Jah to discuss his views on space environmentalism in a public, virtual event on June 24 as part of the MIT Media Lab Perspective series.
The collaboration between Space Enabled and Jah leverages the capabilities of the Advanced Research Collaboration and Application Development Environment (ARCADE), a digital commons that Jah developed with the Texas Advanced Computing Center and IBM. ARCADE provides a platform to perform analysis related to SSR while leveraging ASTRIAGraph, a free tool that enables and encourages scientific and policy inquiries regarding space safety, security, and sustainability.
"The SSR is one of several pillars required to solve the wicked problem of uncoordinated space traffic activities," says Jah. "Space operations knowledge is uneven across space actors, and thus the practice is also uneven as a consequence. The SSR aims, in part, to harmonize the currently existing gap between knowledge and practice in the space operations community. The University of Texas tool ASTRIAGraph contributes to this endeavor by creating a public platform to visualize and analyze estimates of the locations of human-generated space objects."
Wood notes that with the leadership role that Space Enabled has played in designing the SSR, the group has established a collaborative research portfolio in space sustainability, and collaborations with key experts in the field. "We can build upon this in exciting ways," she concludes, "and MIT will continue to innovate new ways of thinking and designing to preserve the environment in space and on Earth for generations to come."