T009 // Space Debris and Armageddon

If you have an interest in these subjects, please bear with me. Feel free to challenge numbers, ideas, and assumptions (though I try not to assume anything about space operations) on LinkedIn.

Virtually everyone in every sector of the space community has witnessed the blood-in-the-water shark frenzy developing around the imminent ‘Armageddon’ of orbital debris. Leaving aside the infinitesimally small number of verified damage incidents attributable to debris strikes—with little, if any, information on what caused the strike (artificial debris, meteorites, monatomic oxygen, intense radiation bursts, natural or artificial weapons)—I thought it might be interesting to neutrally examine some numbers and scenarios. I served on the original MIT Lincoln Labs Haystack Observatory Satellite Collison Avoidance Working Group. The working group’s research and findings were initially classified as SECRET, as was the observatory itself.

Several members investigated generic debris issues; however, the principal function of the working group was to track and identify intentional encroachments, such as ‘bumping’ and deliberate collisions, ‘attacks’ on US GEO satellites. We found many of them. The Haystack radars could ‘skin paint’ at 24,000 miles. At the time, there were less than 300 GSO satellites—now there are about double that number. The ITU spacing requirements were set at 1.5 degrees but in practice, some satellites operated within 50 miles of each other, granted at the much slower GSO velocities of 2 to 4 kilometers per second. Okay, let’s assign a BLENDED ‘parking space’ size of 5 cubic miles per satellite, averaging spacing in SLEO/LEO/MEO/GEO and 1 cubic mile each for every one of the 30,000 pieces of debris.

Call this 10,000 functional satellites; that would be 50,000 cubic miles for satellites and 30,000 cubic miles for debris. 80,000, call it 100,000 cubic miles for every single object, all operating in defined, predictable trajectories. That leaves 259,990,000,000 cubic miles of free, empty space. That ratio is 10-100 times greater than the space between the nucleus and electron shell of an atom. So, using that very generous number, we could put up 100,000,000 or more satellites without risking a single collision with each other or debris.

The spacing of GEO satellites is approximately 1.5 degrees nominally. Practically, it’s often as little as a fraction of a degree. While there are good rationales for preventing collisions (there are many more deliberate collisions than are talked about), the real technical reason for the nominal space is to reduce or eliminate frequency and power interference. With a single, cheap, old-style lifter like an Atlas or Delta, it’s possible to loft 10 tons of beach sand into a retrograde orbit and say goodbye to 20-40 GEO satellites. No nukes, no ultra-velocity missiles, no particle beams, lasers, etc. A $20M launch vehicle and $100 worth of sand. This isn’t science fiction. We used to war game these doomsday scenarios.

From my years in defense aerospace, we became mired in, and trapped by, traditional rubrics such as 'threat definition', 'threat analysis', 'mission and scope creep'. Weapons were gauged 'PK and CEP' measures of the probability of kill. The 'systems acquisition process' was built around the nascent but maturing Systems Engineering and Integration discipline. When working for defense contracts, one learned that given all options, it was imperative that the threat always be overestimated, if not outright exaggerated, and that budget estimates always include generous room for expansion, including the infamous cost-plus contract. Within the span of two years, space debris has emerged as a 'looming threat to national security'. Beware of such warnings, and before committing billions to 'study contracts', let’s define the putative threats in quantitative terms. That was the purpose of starting this dialog. What is the real threat, where is the evidence, and to what extent are we conflating imaginary doomsday scenarios with real world, scientifically documented, and validated threats to national security, and to government and commercials space assets?