A Density Scale

Density

Server Sky will deploy at 6411 km altitude. Gas density at that altitude is 6E-18 kg/m², mostly hydrogen. That is 5E-18 times smaller than air density at the surface; it is difficult to comprehend just how tenuous the exosphere is, so here is a density scale. The densities below assume average solar activity, F107 = 150 , averaged over the day, on the equator, at the equinox .

"zone"	density kg/m³	pressure
zepto	2e-21			interstellar space "average"
zepto	1e-20			interplanetary space 1 A.U.
atto?	?		35786 km altitude	geosynchronous orbit
atto	6e-18		6411 km altitude	m288 server sky
atto	3e-17			beamline Large Hadron Collider
femto	1e-15		1250 km altitude	lowest sustainable solar sail
pico	2e-12		410 km altitude	International Space Station
nano	1.2e-09		160 km altitude	useful low earth orbits
micro	6.8e-07		100 km altitude	"edge of space", suborbitals
micro	8.5e-06		85 km altitude	drag zone for suborbital
milli	1.1e-03		50 km altitude
	1.2	1.01 Bar	0 km altitude	Sea level
Kilo	≈ 1e3	1.1 KBar		Deepest Ocean
Mega	≈ 1e6	3.6 MBar	Center of Earth	ideal gas density at pressure

The air is too dense at ISS altitudes (in the pico zone) to experiment with server sky - thinsats must be in orbit long enough to test maneuvering and to be observed from the earth, in the femto circular orbit zone or higher. Low earth orbits in the nano zone have a million times as much drag, and a suborbital in the micro zone has a billion times as much density as the femto zone.

A suborbital falling for 100 seconds plunges at more than 900 meters per second, and descends almost 50 kilometers, into the "milli zone". A single turn and stop thinsat maneuver takes 300 seconds. Quite impractical for thinsat testing, even inside a vacuum chamber inside the suborbital.