Why does the Department of Defense engage in space situational awareness? Simple: to deter conflict.

"Since our military is so reliant on space, we have to know what is going on in space," John Hill, principle director for space policy within the Office of the Under Secretary of Defense for Policy, said March 7 at a panel discussion during the Satellite 2017 conference in Washington.

Space situational awareness, or SSA, fundamentally boils down to deterring conflict, he said, hyperbolically, yet somewhat seriously, adding that this is also a discussion about world peace.

For the DoD, SSA is essential for deterring conflicts and denying adversarial attacks in the space domain, he said. And if that's an impossibility, he said, the U.S. must win, and protecting space assets is critical to that.

Space might be where conflict starts because all modern militaries — and even others that aren't modern like the Islamic State group, which utilizes satellite communications — use space in some way, shape or form, Hill said.

This discussion dates back to the 1990s in the wake of the Gulf War. The U.S. decided to heavily invest in space so that by the Bosnian and Kosovar conflict, the U.S. observed the benefits afforded by space for multi-theater operations.

Following these developments, other countries began to build counter-space capabilities, Hill said.

Deny, don't impose

Rather than applying the model of deterrence by cost imposition — a model of the nuclear deterrence era that sought to deter adversaries with the threat of overwhelming effects — the model of deterrence by denial is more applicable to the space environment, said Hill. This model of denying the adversary of the benefit of attack, he added, is what the Pentagon needs to consider when thinking about space.

Deterrence by cost imposition in the space realm could be difficult, Douglas Loverro, former deputy assistant secretary of defense for space policy, said last year. It can be difficult to justify an attack by the U.S. on another nation's territory when that nation attacks a satellite that the U.S. does not even admit exists, he noted.

Loverro similarly asserted that deterrence by denial is the best model. He wondered whether an attacker would risk international condemnation for creating debris in space, in reference to a 2007 event in which China conducted an anti-satellite missile test that caused a great amount of threatening debris. He also rhetorically wondered whether adversaries would risk the ire of U.S. partners if they have to attack a French satellite in order to deny the U.S. the ability to image its territory.

Denying the benefit of attack — while making it politically difficult to wage an attack — and perhaps utilizing economic sanctions or retaliatory actions at a lower level is a better way to deter attacks in space than completely depending on retaliatory strikes, he said.

The DoD has invested in measures and partnerships for SSA, Hill said, such as radar data to support observations and upgrading command and control systems.

However, the agency can never have enough computational power to understand that data because, simply put, space is really big. Hill noted that there are trillions of cubic miles that are part of this battlespace, highlighting the immense challenge of SSA and thus deterrence.

Mark Pomerleau is a reporter for C4ISRNET, covering information warfare and cyberspace.