SMALL SATELLITE PROGRAM
 

Our Past
This page overviews the mission and satellite design of two past satellite programs: USUsat I and USUsat II.

 

USUsat I

The Department of Defense, NASA, and industry jointly sponsored the development and launch of ten university nanosatellites to demonstrate miniature bus technologies, formation flying, and distributed satellite capabilities. Utah State University (USU), the University of Washington (UW), and Virginia Polytechnic Institute and State University (Virginia Tech, VT) designed and developing a system of three 15 kg spacecraft to investigate satellite coordination and management technologies, and perform distributed ionospheric measurements. The three universities coordinated in the areas of satellite design, formation flying, mission development, and scientific instrumentation. The mission was called ION-F for Ionospheric Observation Nanosatellite Formation.

ION-F Mission Timeline

Figure 1 illustrates the ION-F mission architecture from launch through individual spacecraft deployment. The three ION-F spacecraft are initially assembled in a stack, and mounted on the Multi Satellite Deployment System (MSDS) provided by the Air Force.

The MSDS will carry two stacks of satellites on a given launch [1], and will be deployed from the Shuttle Hitchhiker Experiment Launch System (SHELS) developed at the NASA Goddard Space Flight Center (NASA-GSFC) Shuttle Small Projects Payload Project (SSPP) [2].

After the MSDS has been released from the Space Shuttle [3] and the Orbiter is a safe distance away, the two stacks are separated from the MSDS simultaneously [4]. After separation, the stack’s attitude is stabilized and initial systems checkouts are performed. Finally, the individual spacecraft are deployed from the stack [5]. Once the individual spacecraft have been deployed, the mission begins.

ION-F Science Missions

Formation Flying Mission

The ION-F formation flying mission will investigate a variety of distributed control and estimation algorithms for coordinating the satellites. Separations for spacecraft formations range from 10 m to 50 km. “Two or more spacecraft in similar orbits with no active control by either to maintain a relative position” is a satellite constellation. In contrast, formation flying is “two or more spacecraft that use an active control scheme to maintain the relative positions of the spacecraft.” Formations can vary in number of members, relative distances, and shapes.

Formation flying objectives have been broken down as follows: primary goals include demonstrating intersatellite communications, autonomous formation keeping, and autonomous formation maneuvering; secondary goals are to demonstrate more than one formation, and to fly all three satellites in one coordinated formation.

Ionospheric Science

The electron density of the ionosphere varies significantly with altitude, latitude, longitude, and many time constants. As such, detailed global measurements over a period of several months are of great importance for the validation of quantitative models. Structures of irregular electron density exist in a wide range of sizes, and affect communications, navigation, satellite ocean altimetry, surveillance, and GPS systems. A plasma impedance probe flown on each ION-F satellite will measure the absolute electron density, as well as plasma structures and waves ranging in size from 200 m to 100 km. Measurements of the ionosphere will be collected during the entire mission; by taking three-point measurements in time at controllable relative distances, a detailed, qualitative picture of the ionosphere can be developed, greatly surpassing the quality of current models. This effort is being supported by NASA’s Office of Space Science.

USUsat II (under construction)

Figure 1: ION-F Mission Scenario Overview

 

 

 

 

 

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