Draper's Role in the Past and Future of VLEO
There is a common expression – "what's old is new again" – that can be interpreted as outdated things can be recycled and become relevant once again. Although often associated with things like fashion or language, the expression can be used to describe Draper's role in support of spacecraft operations in Very Low Earth Orbit (VLEO).
Draper's experiences with VLEO extend back to the early days of spaceflight—to the once-classified Corona program, which ran from 1959-1972 as an intelligence gathering tool monitoring Soviet military capabilities. Supported in part by the orbital calculations provided by Draper's team of subject matter experts, the Corona family of flight vehicles achieved a perigee (point of closest approach) of around 100 miles.
The program ultimately produced more than two million feet of film for the intelligence community and significantly contributed to the avoidance of nuclear conflict through the program's unique and then state-of-the-art intelligence gathering capability.
To operate in VLEO, one only requires a basic understanding of the unique orbital regime that bridges the respective air and space domains it saddles. The VLEO layer can be characterized by its physical parameters of increased and highly uncertain atmospheric density, higher atmospheric drag because of the increased density profile, and the widespread presence of atomic oxygen. These three factors all present significant challenges to the long-term mission operation and performance of satellites in VLEO.
Notionally recognized as an orbital altitude below 450 kilometers or 280 miles, prolonged VLEO requires the use of either continuous propulsion or novel technologies to counteract the impact of these operational challenges and maintain orbit.
Despite these technical challenges, VLEO offers several valuable benefits, most notably the potential for cheaper launch costs to reach this lower altitude and the enhanced resolution enabled by these orbits. A few simple calculations highlight that a two-fold decrease in altitude from Low Earth Orbit to VLEO (i.e. decreasing from 600 km to 300 km) leads to a significant decrease in the size of optical payload, a four-fold decrease in radio frequency (RF) power for communication, a sixteen-fold decrease in radar RF power, and a significant reduction of communications latency.
Recent improvements in satellite communication links have further reduced the size, mass, and power requirements of these satellites. And VLEO's increased atmospheric drag inherently solves the problem of space debris with the eventual de-orbit and disposal of the satellite through reentry into the Earth's atmosphere.
The recognized benefits and advancement of satellite technology have reinvigorated the exploration of VLEO as an operational domain. The availability of high-resolution imagery, novel propulsion systems, and enhanced survivability technologies for VLEO platforms promise to make this orbit a continued area of interest for both commercial and military operators alike.
As an engine of innovation with more than 60 years of experience in VLEO, Draper's Space Systems team continues to work at the crossroads of academia, industry, and government, contributing to international conferences, delivering technical talks with government agencies, and pursuing technology development programs.
The last decade has seen great advancement for VLEO technologies across the space ecosystem, and Draper stands poised once again to leverage our expertise to solve real-world problems and lead the continued advancement of future VLEO missions.