Kerstyn Auman, a space situational awareness analyst with the Aerospace Corporation, highlights the role LEO plays in various sectors. "LEO is frequently used for communications and imaging due to its lower latency compared to other orbits. For time-sensitive applications like voice communications or internet surfing, this near-instantaneous connection is paramount."

LEO-based satellites, due to their proximity to Earth, require less signal power for transmission and can be considerably compact-some are as petite as a Rubik's cube and weigh a mere three pounds. However, to ensure constant coverage of a specific terrestrial area, a substantial number of these satellites are needed due to their rapid orbit cycle. A typical LEO satellite orbits Earth 16 times in 24 hours, necessitating hundreds or even thousands of satellites for persistent global coverage. Fortunately, these smaller satellites are more cost-effective to manufacture and can be launched in batches on a single rocket, an approach often referred to as a "ride share."

Maintaining course in LEO requires satellites to travel at a speed of around 17,000 miles per hour to achieve equilibrium between momentum and gravity. Insufficient momentum can result in gravitational pull veering the satellite off course. Auman explains, "If the satellite's momentum drops, gravity can pull it off-course, resulting in an eventual decline in the satellite's orbit."

Another significant challenge for LEO satellites is atmospheric drag, comparable to running against a robust wind. This friction can reduce satellite speed, compelling them to burn fuel more often than those in other orbits to maintain their position. If neglected, their orbit can decay, leading to reentry into Earth's atmosphere.

"Solar weather is another influencing factor as it changes the Earth's atmospheric composition and subsequently the drag experienced by a satellite," adds Auman. "Predicting the solar weather and thus the satellite's precise location and trajectory is an intricate task that can be assisted by GPS satellites located in higher orbits."

The Space Systems Command (SSC) is developing new missile warning, tracking, and defense sensors targeting LEO and Medium Earth Orbit (MEO), marking a radical departure from the current practice of deploying large satellites in the Geostationary Orbit (GEO), located 22,236 miles above Earth. According to Col. Heather Bogstie, senior materiel leader for the Resilient Missile Warning, Tracking, and Defense Acquisition Delta at SSC, diversifying orbits and placing sensors closer to Earth would enhance missile detection and tracking accuracy.

Bogstie elaborates, "By deploying our sensors across varied orbits, we can scrutinize the same area and targets from multiple viewpoints, improving our detection capabilities due to additional look angles and range."

The next generation missile warning, tracking, and defense approach is aligned with the Space Warfighting and Analysis Center's (SWAC) force design, devised to address emergent missile threats, like hypersonics that are harder to detect from GEO. Bogstie affirms, "Our design hinges on advanced sensor technology and the profusion of commercial space vehicles, enabling affordable placement of more sensors closer to the targets we aim to detect and track."

Consequently, the Space Systems Command is leveraging every available orbital path, from LEO to GEO, to bolster space capabilities provided to combatant commands, offering a nuanced and strategic approach to national defense.

This article is based on a press release from Space Systems Command.

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