233rd Space Group
The 233rd Space Group is a Colorado Air National Guard unit responsible for mobile strategic missile-warning, space-launch detection, and nuclear-detonation detection missions.
Last updated August 31, 2026
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Overview
The 233rd Space Group, commonly styled as the 233d Space Group or 233SG, is a unit of the Colorado Air National Guard based at Greeley Air National Guard Station in Greeley, Colorado. It is a military organization rather than a commercial brand. Its principal role is to provide survivable, mobile space-based warning support for the United States, including worldwide missile-warning, space-launch detection, and nuclear-detonation detection. The group operates the Air Force's strategic mobile Defense Support Program ground system. This Mobile Ground System is designed to provide an enduring warning capability to the National Command Authority and to remain operational through the phases of an attack and its aftermath. The underlying Defense Support Program satellite network supplies infrared detection of missile launches and nuclear events, while the 233rd Space Group's mobile ground infrastructure supports the processing, communication, and dissemination of warning information. The unit's institutional lineage reaches back to the mobile satellite-communications and space-warning organizations that preceded it. The mobile Defense Support Program communications mission began in 1983 with the activation of the 1025th Communications Squadron (Mobile). The organization subsequently underwent several redesignations and administrative realignments, including service as the 4th Satellite Communications Squadron and later as the 4th Space Communications Squadron. In 1992, the mission was declassified and associated with the 4th Space Warning Squadron. The 137th Space Warning Squadron was activated in 1995 to assume the mobile Defense Support Program mission, and the 233rd Space Group was established in 2012 as the parent organization for that operational capability. The group comprises approximately 400 Airmen, including full-time technicians, Active Guard Reserve personnel, and traditional Guard members. Its normal affiliation is with the Air National Guard and its historical gaining-command relationship has been with Air Force Space Command. If federalized, the unit's gaining service is subject to decisions by military leaders and Congress, an issue that became more prominent after the establishment of the United States Space Force in 2019. The 233rd Space Group has remained part of the Air National Guard while broader policy discussions have considered whether space-related Guard personnel should be organized through a Space National Guard. The debate reflects the unit's specialized mission and the continuing adjustment of United States military space organizations following the creation of the Space Force. As described in the supplied reference material, a 2025 proposal to establish a Space National Guard had not advanced out of committee, and later changes transferred several other space-related Guard missions without absorbing the 233rd Space Group itself. The group's defining identity therefore remains its Colorado Air National Guard status and its specialized mobile missile-warning mission.
History
The 233rd Space Group's history is closely tied to the development of mobile ground support for the Defense Support Program. Its predecessor mission began on 1 October 1983, when the 1025th Communications Squadron (Mobile) was activated to develop and operate mobile satellite-communications equipment. During its first several years, the organization tested the new equipment and trained personnel for the specialized mission. On 1 November 1985, administrative responsibility moved to the 1st Space Wing, an organization associated with the newly established Air Force Space Command. On 1 August 1986, the unit was redesignated the 4th Satellite Communications Squadron. Subsequent Air Force reorganizations inactivated the 1st and 3rd Space Wings and consolidated their assets under the 21st Space Wing at Peterson Air Force Base in Colorado. The organization was then known as the 4th Space Communications Squadron. The mission was declassified on 1 October 1992 and became associated with the 4th Space Warning Squadron. As responsibilities of the 4th Space Warning Squadron shifted among related space programs, the mobile Defense Support Program mission was assigned to the 137th Space Warning Squadron, which was activated in 1995. The 137th Space Warning Squadron became the operational foundation for the later group. The 233rd Space Group was activated on 1 March 2012, when the 137th Space Warning Squadron was redesignated and placed within the new group structure. The group assumed responsibility for the mobile Defense Support Program mission and has operated the system known as the Mobile Ground System. Its purpose is to provide a survivable and mobile ground capability for processing and transmitting warning information derived from Defense Support Program satellites. The group's operational function is strategic rather than tactical. Defense Support Program satellites detect the infrared signatures associated with missile launches and nuclear explosions. The ground system supports the conversion of those detections into timely warning for national-level authorities. Its equipment and procedures are intended to remain useful during severe or disrupted conditions, including the period during and after a major attack. The unit is located at Greeley Air National Guard Station and includes technicians, Active Guard Reserve personnel, and traditional Guard members. It has historically been aligned with the Air National Guard and Air Force Space Command. The creation of the United States Space Force in 2019 prompted broader debate about the organization of space missions performed by Guard units. Congress rejected a Space National Guard structure in 2021, while later legislative and administrative efforts continued. The supplied reference material identifies a 2025 proposal and subsequent transfers of other space-related Guard missions, but states that the 233rd Space Group remained in the Air National Guard. Its continuing identity is therefore based on the specialized mobile missile-warning capability developed through its predecessor organizations.
- 2025
Space National Guard legislation and mission transfers
[1]A proposed Space National Guard measure was introduced, while the supplied reference also describes the transfer of nine other space-related Guard missions to the Space Force.
- 2019
Creation of the United States Space Force intensifies organizational debate
[1]The establishment of the Space Force led to continuing discussion about the future federal alignment of space-related Air National Guard units.
- 2012
233rd Space Group established
[1]The 137th Space Warning Squadron was redesignated as the 233rd Space Group and became its first operational squadron.
- 1995
137th Space Warning Squadron activated
[1]The 137th Space Warning Squadron was activated and assumed the mobile Defense Support Program mission.
- 1992
Space-warning mission declassified
[1]The mission was declassified and became associated with the 4th Space Warning Squadron.
- 1986
Redesignated as the 4th Satellite Communications Squadron
[1]The mobile communications organization received a new designation as part of Air Force space-organization changes.
- 1985
Administrative alignment changes
[1]Administrative operations were transferred to the 1st Space Wing, linking the mission to the emerging Air Force Space Command structure.
- 1983
Mobile Defense Support Program communications mission begins
[1]The 1025th Communications Squadron (Mobile) was activated to develop, test, and operate mobile satellite-communications equipment supporting the Defense Support Program mission.
Products and positioning
A specialized National Guard space-warning organization focused on resilient, mobile strategic warning and detection capabilities rather than commercial products or services.
Strategic missile-warning infrastructure · 1995
Defense Support Program Mobile Ground System
The Mobile Ground System is the group's principal operational capability. It provides a mobile and survivable ground segment for receiving, processing, and communicating warning information from Defense Support Program satellites. The system supports strategic missile-warning, space-launch detection, and nuclear-detonation detection, with an emphasis on continued operation during and after an attack.
Military communications · 1983
Mobile satellite communications capability
The predecessor organizations developed and operated mobile satellite-communications equipment beginning in 1983. This capability supplied the technical and organizational foundation for the later mobile Defense Support Program warning mission and the 233rd Space Group's operational structure.
Brand decisions
2025
Continued Air National Guard status amid Space Force restructuringStrategyBackground
The creation of the Space Force and proposals for a Space National Guard produced continuing debate over how space missions performed by Guard units should be organized.
Action taken
The supplied reference states that nine other space-related Air National Guard missions were transferred to the Space Force, while the 233rd Space Group remained an Air National Guard unit.
Aftermath
The group's future federal gaining relationship remained subject to continuing institutional and legislative discussion.
2012
Establishment of the 233rd Space GroupStrategyBackground
The Air National Guard reorganized the mobile Defense Support Program warning capability that had been operated by the 137th Space Warning Squadron.
Action taken
The 137th Space Warning Squadron was redesignated as the 233rd Space Group, creating a group-level structure for the mission.
Aftermath
The group continued operating the Mobile Ground System as an Air National Guard space-warning organization.
Sources1 sources
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