The Perils and Promise of LEO Constellations

Article by Sandra Erwin                                 July 4, 2020                              (spacenews.com)

• Mike Griffin, the Undersecretary of Defense for Research and Engineering, says that the Pentagon must reduce its dependence on large, billion-dollar satellites in geosynchronous orbit that are vulnerable to anti-satellite weapons. As an alternative, the DoD’s Space Development Agency plans to deploy satellites in ‘proliferated low Earth orbit’ constellations, or ‘PLEO’, to put up a communications transport layer and a surveillance and tracking layer of satellites for hypersonic missile defense.

• The smaller satellites comprising the PLEO constellations provide a resilient space infrastructure that is cheaper and easier to replace than geostationary systems, should they be destroyed by anti-satellite weapons. A key question is whether satellites and launch vehicles can be made cheap enough to make the cost of taking down a LEO system not worth it. “Changing the “cost equation” for an enemy will be a key challenge for DoD and the U.S. Space Force,” said Michael Martindale, the Director of Space Education for Space Force.

• ‘Low Earth orbit’ (LEO) satellites are easier to hit from ground-based anti-satellite weapons. Sophisticated in-space weaponry is not required for LEO satellites, as it would be to take down satellites in geostationary orbit (GEO).

• A recent study by Todd Harrison of the Center for Strategic and International Studies shows that China and Russia, despite their rhetoric about wanting to ban weapons in space, are building arsenals of ground-based anti-satellite weaponry. This sends a message to other countries that ground-based anti-satellite weapons are fair game. Says Harrison, “With its 2019 ASAT test, India made clear that it believes kinetic Earth-to-space ASAT weapons are a legitimate means of self-defense by deterrence.”

• In their respective space-arms control proposals, China and Russia do not prohibit ground-based weapons. “Their behavior says they’re only interested in banning the capabilities that they don’t already have,” says Martindale. With more LEO systems about to be deployed by the DoD, which are vulnerable to the ground-based anti-satellite missiles, American space superiority is now being contested.

• Space Force can’t possibly protect every satellite in Earth’s orbit, so it must figure out ways to deter countries from even attempting to take one down. The United States has more to lose than anyone else if satellites become targets in a war. The key is to make it too costly for an enemy to mount an attack. “You have to reduce the value of each individual target.” Says Martindale, “[I]f there are hundreds of targets, and the enemy knows that the U.S. can replenish those assets quickly, the cost equation changes and using missiles is not as effective.”

• Such a deterrent strategy would require a ready supply of replacement satellites and rapid access to launch services so constellations can be replenished quickly and inexpensively. Right now, it generally takes years to get a DoD satellite off the ground. Space Force needs to bring this equation down to days or weeks to launch and replace a LEO positioned satellite.

The Pentagon has already created an acronym — PLEO — for its plans to deploy satellites in proliferated low Earth orbit constellations.

DoD’s Space Development Agency is leading the way as it prepares to put up a communications transport layer and a surveillance and tracking layer for hypersonic missile defense.

The Pentagon’s staunchest proponent of PLEO, undersecretary of defense for research and engineering Mike Griffin, has argued that the Pentagon must reduce its dependence on large, billion-dollar satellites in geosynchronous orbit that are vulnerable to anti-satellite weapons.

The case for proliferated constellations in low Earth orbit is based on the idea that it provides a resilient space infrastructure. Smaller satellites would be cheaper and easier to replace than geostationary systems if they were destroyed by anti-satellite weapons. That approach should work in theory. A key question is whether satellites and launch vehicles can be made cheap enough to make the cost of taking down a LEO system not worth it.

Changing the “cost equation” for an enemy will be a key challenge for DoD and the U.S. Space Force, says Michael Martindale, a former U.S. Air Force space operator and currently the director of space education for the Space Force Association.

As much as DoD worries about GEO satellites becoming targets of China’s orbital weapons, LEO systems are much easier to hit — no sophisticated in-space weapons required. So-called direct-ascent weapon such as ordinary surface-to-air missiles and anti-ballistic missile interceptors are far more likely to be used against low-orbiting satellites than space-based weapons, Martindale says.

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