Ron Reedy, the CEO of Skeyeon, recognized that flying satellites at the low altitudes could reduce the expense of a constellation. He had no idea if there would be any show-stoppers. “I pushed the team to prove it wouldn’t work,” Reedy explained, “which is sort of backward for an entrepreneur.” “After over a year, they stated, ‘We can’t prove it won’t work, but we think we can prove it will work.'” That was in the year 2017. Skeyeon (pronounced sky-on) of San Diego has been designing and testing essential components for the constellation of tiny satellites that will offer high-resolution daily Earth pictures from an altitude of around 250 kilometres since then.
Skeyeon isn’t the only one who sees the potential of orbits considerably below those used by standard Earth-imaging satellites. Earth Observant, situated in San Francisco, and Albedo, based in Austin, Texas, are soliciting funds to launch satellites into very low Earth orbit (VLEO). Meanwhile, the European Union has allocated $6.7 million to Discoverer, which is a Horizon 2020 research project aimed at “radical redesigning” Earth observation satellites for the low-altitude missions.
What’s the big deal about VLEO? The cost of a satellite frequently rises in tandem with its altitude.
The price of telescope optics is reduced when you get nearer to an item of interest. Traveling close to the ground stations lowers radio power demand, reducing the need for huge solar panels. Lower orbits mean faster data delivery for communications missions. VLEO also reduces the number of radiation satellites is exposed to, allowing for additional off-the-shelf spacecraft components. “None of this is straightforward, but if you can get these concepts to work, the payoff could be huge,” said Peter Roberts, who works as the Discoverer scientific coordinator as well as space theme lead at the University of Manchester Aerospace Research Institute.
Thales Alenia Space clarified in a 2016 paper on the Skimsats, that lowering a satellite’s altitude from 650 kilometres to 160 kilometres results in “a 64x reduction in the radar RF power, a 16x reduction in communications RF power, and 4x reduction in the optical aperture diameter to be able to achieve the same performance.” “The only way to have higher resolution while at the same time still playing in a smallsat environment is to descend lower,” stated Scott Herman, CEO of Cognitive Space and former chief technical officer of BlackSky.
NEED A BOOST?
VLEO does, after all, come with its own set of difficulties. Atmospheric drag will reduce a satellite’s lifespan below 450 kilometres unless an external source or onboard propulsion propels it higher. (Cargo trucks and onboard thrusters assist the ISS (International Space Station) in maintaining its height, which is roughly 400 kilometres.) VLEO satellites have already been launched. With the help of xenon-fuelled electric thrusters, the European Space Agency’s Gravity field as well as steady-state Ocean Circulation Explorer spaceship, known as GOCE, remained at heights of 240-280 kilometres from 2009 to 2013.