– The Pentagon expects to settle this summer on the primary payload for TacSat-5, the latest in a series of experimental satellites designed to demonstrate low-cost, quick-reaction space capabilities that are highly responsive to the needs of tactical military commanders.


Industry responses to a Dec. 1 request for information on potential TacSat-5 payloads are due at the end of January, said Chris Olmedo, TacSat-5 program manager at the U.S. Air Force Research Laboratory’s Space Vehicles Directorate at Kirtland Air Force Base, N.M. Once the Air Force settles on a payload concept it will solicit bids from prospective builders, he said.


According to the request for information, the Air Force is interested in three broad application areas: communications, battle-space characterization and space situational awareness. In the battle-space characterization category, the Air Force is interested in such payloads as radar, visible, ultraviolet or infrared sensors for gathering various types of data, including terrestrial and space weather information, according to the solicitation. Navigation- and timing-type payloads for augmenting the Air Force’s GPS constellation will not be considered, the document said.


Olmedo said promising concepts that do not make the cut for TacSat-5 will be considered for the planned TacSat-6 mission.


The Air Force launched TacSat-2, the first in a series of so-called Operationally Responsive Space demonstrations, in December. The military plans to launch two more TacSats this year: TacSat-1, which has been delayed primarily due to issues with its launcher, the Falcon-1 rocket built by Space Exploration Technologies Corp. (SpaceX) of
El Segundo
; and TacSat-3.


TacSat-4, to carry an all-telecom payload, is expected to launch in 2008, with TacSat-5 following as early as fall 2009, Olmedo said.


As envisioned, TacSat-5 would weigh no more than 400 kilograms, cost no more than $20 million, and have an operating life of one to three years, according to the request for information.


If program officials stay within the cost cap, TacSat 5 would be significantly cheaper than three of its four predecessors. A Government Accountability Office report released in early 2006 estimated the cost of TacSat-1 at $9.3 million, TacSat-2 at $37 million, TacSat-3 at $35 million, and TacSat-4 at $41 million.


Other goals for the TacSat-5 mission include completing checkout of the satellite during its first orbit, according to the request for information.


TacSat program officials are hoping to take advantage of recent military efforts to develop common components and interfaces for responsive satellite platforms as they design TacSat-5, Olmedo said. In early 2006, for example, the Air Force awarded Ball Aerospace & Technologies Corp. of
, a contract to develop the Space Test Program-Standard Interface Vehicle, a flexible satellite platform designed to launch on virtually any type of rocket and host a wide variety of payloads.


Launch is not included under TacSat-5’s cost cap, Olmedo said. The program office is looking at a variety of options, he said, including the Minotaur rocket that launched TacSat-2 and is slated to loft TacSat-3 and TacSat-4; SpaceX’s Falcon-1, the QuickReach vehicle under development by AirLaunch LLC of Kirkland, Wash., and possibly even a modified Trident missile.


The payload concepts submitted in response to the request for information will be evaluated by officials from each of the services at the 0-6 (the colonel or Navy captain level) and general officer level before a collective decision is made on the path forward this summer, Olmedo said. A contract award to build the payload could come as early as September, he said.


In addition to representatives from each of the services, officials from the Defense Advanced Research Projects Agency and the intelligence community are involved in the mission selection process as well, he said. NASA also might participate on a non-voting basis, he said.


The Marine Corps will review the industry concepts for communications payloads, the Army and the Navy will review battle-space characterization concepts, while the Air Force will evaluate space situational awareness concepts, Olmedo said.


A Panel of senior military officials will then discuss the concepts and choose a mission for TacSat-5, Olmedo said.


The program office elected not to solicit proposals for navigation and timing payloads after the Air Force Space and
said it was developing a future GPS strategy and would prefer not to work with that type of payload at this time, Olmedo said.


After choosing a payload for TacSat-5, selection officials also may rank other proposed concepts, possibly enabling the military to accelerate work on TacSat-6, Olmedo said. The idea for doing this came out of a military study on Operationally Responsive Space that is expected to be submitted to Congress in February, he said.