Did the Divert Thrusters Fail in the CTV-02+ Test?  (January 18, 2017)

On January 28, 2016 the Missile Defense Agency (MDA) conducted its most recent flight test of its Ground-based Midcourse Defense (GMD) national missile defense system.  One of the key objectives of this test, designated CTV-02+, was to test a new alternate divert thruster (ADT) system.  Following the test, officials described it as completely successful.  However, in July 2016, The Los Angeles Times reported that, in fact, the ADT system failed in the test.  Following the Times report, MDA officials continued to insist that the test was completely successful.  So what’s going on here?  The 2016 Annual Report of the Pentagon’s Director of Operational Test and Evaluation, released to the public earlier this month, shows how, with some creative use of wording, both claims can be true.

The kill vehicle of the Ground-Based Interceptor (GBI) uses four rocket divert thrusters to maneuver as it homes in on its target.  However, the divert thruster system used both in previous tests and on the currently deployed GBIs produces vibrations that can interfere with the kill vehicle guidance system.  These vibrations caused the failure of intercept test FTG-06a in December 2010.

Following the FTG-06a failure, deliveries of further GBIs was suspended until the problem that caused the failure could be identified and corrected.  Following the successful demonstration in intercept test FTG-06b in June 2014 of a repair to the guidance system to reduce the effect of the vibrations, deliveries of GBIs resumed.  However, these new GBIs still had the original divert system, and the vibrations produced by this system were still apparently enough of a concern that MDA decided to replace the original divert system in the last ten GBIs it planned to deploy.

These last ten GBIs to be deployed will be equipped with the new CE-II Block I kill vehicles, and will bring up the total number of deployed GBIs up to the total of 44 that MDA announced in 2013 would be deployed by the end of 2017.  These new kill vehicles will have the ADT system in place of the original divert system, and the most important objective of CTV-02+ was to demonstrate the effective performance of the ADT system before the first intercept test of the CE-II Block I kill vehicle.  This intercept test, designated FTG-15, was originally scheduled for the last quarter of calendar year 2016 but has not yet taken place.  The MDA has stated that it will not begin the deployment of the ten CE-II Block I interceptors until this test is successfully completed.

In CTV-02+, the kill vehicle did not attempt to intercept the target. Instead its modified CE-II kill vehicle was intended was intended to fly past it while making preplanned maneuvers to test the ADT system.  According to an MDA press release following the test: “Upon entering terminal phase, the kill vehicle initiated planned burn sequence to evaluate the alternate thruster diverters until fuel was exhausted, intentionally precluding an intercept.[1]

Following the test, all official sources indicated that the test had been a complete success.  The MDA press release went on to say that the test had succeeded in “successfully evaluating performance of alternate divert thrusters for the system’s Exoatmospheric Kill Vehicle.”  In a  prepared Congressional statement from April 2016, MDA Director Vice Admiral James Syring stated that: “This past January we successfully executed GM CTV-02+, a non-intercept flight test involving the launch of a GBI from Vandenberg Air Force Base and an air-launched IRBM target over the Pacific Ocean. We were able to exercise fully the new Alternate Divert Thruster in the CE-II EKV in a flight environment…”[2]

However, a July 6, 2016 article by David Willman in The Los Angeles Times, based on interviews with several unidentified Pentagon scientists, reported that the ADT system actually had failed in the test.[3]  One of the scientists stated that “The mission wasn’t successful.” “Did the thruster perform as expected? No, it did not provide the control necessary for a lethal impact of an incoming threat.”  The scientists further stated that the fly-by distance from the target was twenty times greater than planned.

The day after the The Los Angeles Times article was published, the Missile Defense Advocacy Alliance (MDAA) posted a report criticizing it.[4]  The MDAA report was largely based on a May 2016 classified MDA report to Congress and on additional information released by the MDA (the MDAA report did specify when and how this additional information was released).  According to the MDAA report, the classified MDA report stated that CTV-02+ had a 100% success rate on all of its primary objectives and 99% on its secondary objectives.  It also stated that one anomaly occurred, but that none of the test objectives were affected by it. The additional material released by MDA stated that “Performance data for all four thrusters has been evaluated and falls with expected parameters” and that the kill vehicle carried out “scripted burns as planned until the fuel was depleted.

Can these conflicting  reports be reconciled?

The 2016 Annual Report from the Pentagon’s Director of Operational Test and Evaluation provides more specific information about CTV-02+ and in particular on the performance of the ADTs in the test.  It states that:

“The ADTs turned on and off as commanded and performed nominally.  One controller circuit board associated with one of the ADTs experienced a short and did not command the ADT to turn on for the latter part of the test.  This controller circuit board is contained within the GBI Guidance module and is not considered to be part of the ADT subsystem.”[5]

So this makes it clear that one of the ADTs did not fire as expected.  This would have caused the kill vehicle to deviate from its planned trajectory, consistent with the LA Times article.  However, the component that caused the failure was not considered by the MDA to be part of the new ADT system, and hence there was no failure of the ADT system.  Apparently the proper performance of the component that failed was not an objective of the test (unless it is the 1% secondary objective failure cited in the classified MDA report).  However, had this been an intercept test, it seems very likely that the failure would have caused a miss.


[1] Missile Defense Agency, “Ground-based Midcourse Defense System Conducts Successful Flight Test,” News Release, January 28, 2016.  Online at: https://www.mda.mil/news/16news0002.html.

[2] Unclassified Statement of Vice Admiral J.D. Syring, Subcommittee on Strategic Forces of the House Armed Services Committee, April 14, 2016.  Online at: https://www.mda.mil/global/documents/pdf/FY17_Written_Statement_HASC_SF_Admiral_Syring_14042016.pdf.

[3] David Willman, “A test of America’s homeland missile defense system failed. Why did the Pentagon call it a success?” The Los Angeles Times, July 6, 2016.  Online at: http://www.latimes.com/projects/la-na-missile-defense/

[4] Missile Defense Advocacy Alliance, “Veering Off,” July 7, 2016.  Online at: http://missiledefenseadvocacy.org/alert/veering-off/.

[5] Director of Operational Test and Evaluation, “Ground-based Midcourse Defense (GMD),” FY 2016 DOT&E Annual Report, December 2016, pp. 421-422.  Online at: http://www.dote.osd.mil/pub/reports/FY2016/pdf/bmds/2016gmd.pdf.