WASHINGTON — Key Pentagon officials met this week to make critical decisions on the future of the Army's air and missile defense architecture, and while the service is not making recommendations in favor of any one radar for the system, the way forward must include an ability to target threats from 360 degrees — something the current Patriot system can't do.

Raytheon's Patriot has been the Army's cornerstone air-and-missile defense system for 40 years. But the service wants to replace the stovepipe system over time with a more integrated one.

It's clear from Army slides outlining findings from an analysis of alternatives conducted over the past year, that the preference is to develop a newer 360-degree radar that meets emerging requirements and would keep pace with the more challenging threat environment expected in the future.

But the cost of developing a new radar, rather than upgrading the Raytheon-made Patriot, would cost more than the Army has in its budget for such an effort, according to the slides — marked "for official use only" and obtained by Defense News -- indicate. The full analysis of alternatives is classified as secret, according to the documents.

The Army can afford to modernize Patriot and give it 360-degree capability, the slides show, but it is predicted it that the missile wouldn't won't be able to keep up against a wide range of modern and future threats even with a baseline upgrade.

The Office of the Secretary of Defense (OSD) would have to give the Army more money if the Pentagon reaches a consensus that it should develop a newer radar instead of upgrading its Patriots with Raytheon's game-changing Ggallium Nnitride (GaN) active electronically scanned array (AESA) radar, currently in development.

An OSDffice of the Secretary of Defense study advisory group met on Nov. 12 to determine the right path. The decisions made this week and in the coming months will decide the fate of the Patriot system and could open the door for other defense contractors to play a major role in the Army's future missile defense architecture.

The Army is budgeted in its five-year plan to start a competition for the radar in fiscal year 2017.

The analysis considered the baseline option of a Patriot system with an AESA radar, a Patriot AESA radar with three antenna arrays (enabling Patriot to see behind itself), a multi-function fire control radar (MFCR), an MFCR with a surveillance radar, and the Marine Corps' Ground/Air Task Oriented Radar (G/ATOR) made by Northrop Grumman.

According to the slides, the analysis set out to study the life-cycle costs, performance, schedule, technology, operational impacts and affordability of each alternative compared to the baseline Patriot system and examined what trades existed.

The Army looked at the risk and the cost associated with each alternative in order to fully integrate them into its future Army Integrated Air and Missile Defense (AIAMD) Integrated Battle Command System (IBCS). Northrop Grumman is developing and will field IBCS — the brains of the future missile defense system — in fiscal year 2019.

And the analysis considered the growth potential for each option to defend against an evolving lower-tier threat, according to the slides.

To focus the study, the Army made several assumptions. For one, it assumed that any alternative could be fully integrated into the AIAMD network. Raid vignettes were designed to represent a single battery's capability.

The Army also evaluated the cost based on 91 procured radars — four prototypes and 87 production assets — and 485 launchers consisting of four prototypes and 481 production assets.

The service figured the program schedule would reach initial operational capability ideally by fiscal year 2026 and procurement quantities would stay at 15 battalions as described in a Nov. 7, 2014, materiel development decision.

To assess capabilities, alternatives were weighed against the most stressing tactical ballistic missile threat to the front, according to the document.

Overall, the Army determined the baseline Patriot option had the highest cost in terms of operations and maintenance costs. However, the Patriot upgrades stay within the Army's cost target and would show improvements over the baseline option in addressing threats.

Replacement alternatives with X-band interceptor communication arrays were determined to be the most costly, exceeding Army cost targets. But they "have the most improvement" over the baseline Patriot, according to the slides read.

G/ATOR's average procurement unit cost is priced anywhere between $147 million and $254.6 million, MFCR is predicted to cost $223.9 million per copy and the MFCR with a surveillance radar is estimated to cost $326.4 million.

Every option analyzed received "high risk" rankings overall of not meeting the anticipated program schedule.

The baseline Patriot and the upgraded Patriot, according to a chart within the slides, ranks them both rank as "high risk" for not meeting the schedule in the engineering and manufacturing development (EMD) phase and the production and deployment (P&D) phase. Both would need 88 months of schedule and might need another year or two to further reduce risk.

The Patriot baseline risk in the EMD phase is driven by the time required to build three radars and P&D risk is driven by the production and calibration time for the radars and launchers. The chart notes that three to four production quality systems are needed for operational test and evaluation.

The upgraded Patriot's EMD risk is based on software development to move from a sectored field of view to a 360-degree capability.

The G/ATOR system — which would need 118 months to move through the acquisition cycle — was assessed as having high schedule risk in both the technology maturation and risk reduction phase (TMRR) and the EMD phase. The program could see schedule slippage, the Army predicts, anywhere from 14 to 18 months.

The TMRR and EMD risk for G/ATOR is due to the need to develop and integrate adjunct equipment to allow it to detect missile threats in the lower tier, the slides show.

Both the multi-fire control radar and the MFCR paired with a surveillance radar presented low risk in both the TMRR and P&D phases, but moderate risk in the EMD phase. Both options would need 118 months to get through all three phases and could be delayed from one to five months to drive out risk.

EMD risk for the MFCR is driven by production of radars with GaN technology and also by integrating the radar into the AIAMD network.

The Army concluded that upgrades and replacement radar options take nearly the same amount of time to field. The baseline Patriot would reach initial operational capability in fiscal year 2027, upgraded Patriot in early fiscal FY-2028, MFCR and MFCR with surveillance capability in late fiscal FY-'28. G/ATOR would take the longest to reach initial operational capability, according to the slides, reaching the milestone past fiscal FY-2029.

The study also found the Patriot AESA radar designs represent the lowest failure and reliability risk. While Raytheon is well on its way to delivering a robust Ggallium Nnitride radar, the Army notes that there's a steep learning curve in GaN technology for some vendors.

While the analysis was primarily focused on options for a radar, it devoted some thought to a new near-vertical launcher to replace the currently fielded Patriot launcher.

The study determined that performance would be better with a near-vertical launcher (set at a 70-degree launch point) but that the baseline Patriot launcher (with a 30-degree launch point) can fit more interceptors. The slides indicate that a new launcher could be adjusted to fit more interceptors, but added that the missile load-out capacity is the "key driver" in terms of launcher performance.

The Army also noted that the performance issues are threat-dependent and can be mitigated by the positioning of the launcher and that future improvements could include remote slewing.

Lockheed Martin's Medium Extended Air Defense System's near-vertical launcher was also included on the chart addressing schedule risk and received low risk ratings in the TMRR phase and the P&D phase, but high risk ratings in the EMD phase.

"EMD risk is driven by possible interface redesign if new prime mover is utilized," the slide reads.

According to the slides, a final report on the analysis of alternatives is due in mid-December and an AIAMD assessment white paper is expected to be delivered in mid- to late December.

If the Army decides to hold a competition for a new radar, Raytheon's competition will likely be Lockheed Martin, which has spent the last 15 years developing the Medium Extended Air and Missile Defense System (MEADS) that includes a 360-degree radar with the United States, Germany and Italy.

The U.S. decided against buying MEADS, and after closing out the technology-development phase of the program decided not to even harvest the technology coming from the program for use in its missile defense programs. But Germany is planning to continue developing MEADS with Lockheed and MBDA Deutschland. Italy is waiting for Germany to mint its development deal before getting on board.

Twitter: @JenJudson