Reporting about the U.S. nuclear posture in national media tends to focus mainly on the weapons—the ballistic missiles and bombers that deter aggression by threatening retaliation.

However, there is more to a nuclear posture than the weapons.

There needs to be an industrial complex for supplying items like plutonium and tritium.

There needs to be a resilient command network that can manage the weapons in wartime and peacetime.

And there needs to be an early-warning system so that U.S. leaders know when the nation is under attack.

This commentary is about the latter need.

Without timely, reliable missile warning, the whole posture breaks down, because U.S. leaders may have only minutes to respond in a crisis, and the information on which they will act must be accurate.

Ever since Russia first fielded a large force of intercontinental ballistic missiles, the United States has relied on a constellation of satellites high above the Earth’s surface in what is called geostationary orbit to alert national authorities of nuclear attack.

Experts often refer to geostationary orbit as “GEO.”

In that orbit, 22,300 miles above the Earth’s surface, satellites circle the planet at the speed at which it turns, so they appear to hover above the same spot.

They can see a vast preponderance of the Earth’s surface, thus if the infrared sensors on the satellites are sensitive enough, they will detect the heat of missile launches almost anywhere (a separate group of polar-orbiting satellites covers extreme northern regions).

Given the locations from which hostile launches would likely originate—either in the Eurasian interior or in the vast expanses of the world’s oceans—these satellites would likely provide the first warning that an attack is underway.

In recent years, as sensor and processing technologies have advanced, the satellites have proven useful in also providing situational awareness for conventional forces and technical insights for the intelligence community.

But there isn’t much doubt what the primary mission is: providing indication of nuclear missile launches so that the U.S. can either prepare to retaliate or try to defend against the incoming warheads.

This system seemed to work well until the second decade of the new century, when the threat began to change.

At that point, Russia and China started to field capabilities that threatened the survivability and functionality of the missile warning constellation.

Then they commenced development of hypersonic glide weapons that were harder to track and characterize than the ballistic missiles of the past.

Many of the details are classified, but the bottom line is that Pentagon planners began to fear U.S. missile-warning satellites were not robust or resilient enough to address emerging challenges.

In fact, they became so alarmed that during the Trump years, a crash program was begun to construct something more survivable and sensitive.

The cornerstone of the next-generation missile warning system is called Overhead Persistent Infrared, or OPIR, which will replace the existing constellation of geostationary and polar-orbiting satellites with a more resilient, affordable system.

Lockheed Martin

LMT
was awarded a contract to develop three next-gen geostationary satellites, and Northrop Grumman

NOC
got the nod to build two polar satellites.

The companies will also deliver software and other services necessary to control the satellites from the ground and exploit their collections for diverse military purposes.

However, this is just the beginning of next-gen missile warning, because the nation faces a growing array of threats that may not be so easily tracked or characterized as Russia ICBMs.

A classified report delivered to Congress last October laid out a more ambitious orbital architecture for detecting and tracking every conceivable type of strategic weapon that might be fielded by future adversaries.

A key feature of the proposed architecture, as revealed in a subsequent unclassified summary, is that it must be layered.

In other words, while the geostationary and polar satellites under development are critically important, other spacecraft in different orbits will also be needed.

The biggest reason why is that the closer you are to a threat, the easier it is to understand its precise nature.

Some emerging threats will be too faint, or too fleeting, to quickly characterize from 22,300 miles away, even with world-class sensors and advanced computing capabilities.

So there has been talk of additional missile-warning layers in lower orbits.

The orbits that have garnered the most discussion are low-earth orbits, where satellites are so close to the Earth they can track and characterize phenomena that would be nearly invisible from geostationary distances.

LEO, as it is called, is definitely going to play a role in any articulated architecture, but it is dogged by two problems.

First, satellites in LEO are so close to the surface that they have a limited field of view.

Second, satellites in LEO are traveling so fast relative to the Earth’s surface that they only spend a few minutes within view of any particular location before they disappear over the horizon.

Combine those two limitations, and it turns out that hundreds of satellites in low-earth orbit might be needed to provide continuous coverage in areas of interest.

Fortunately, small-satellite technologies have been developed that allow for inexpensive construction of the needed systems, but there are all sorts of other problems such as maintaining connectivity among different layers in the architecture.

One other option discussed in the architecture report that has gotten scant public attention is medium-earth orbits—in other words, the array of potential orbital planes between LEO and GEO.

Satellites in MEO, as it is called, could generate better understanding of some threats than satellites in high orbits, while still having a wide field of view and requiring relatively few spacecraft to complete a constellation.

One non-traditional company exploring the MEO option, Millennium Space, says it has developed low-cost satellite technology that would function equally well in any orbital regime.

Millennium is owned by Boeing

BA
, which has other irons in this fire.

Unfortunately, the Space Force’s budget request for fiscal 2022 eliminated a demonstration project that would have tested the potential of medium orbits for supplementing the missile-warning system.

That decision seems to have been driven mainly by budget constraints.

But it’s hard to imagine a military mission more important than warning of nuclear-missile attack, so there’s something to be said for not eliminating architecture options before they have been fully assessed.

The Space Force might want to revisit the decision to cancel a MEO demonstration in its fiscal 2023 budget request.

Boeing and Lockheed Martin contribute to my think tank.