>> Another Step in the Light Direction

Spacecraft structure is a major part of spacecraft mass. Making large masts ultra-lightweight can reduce the structure's contribution to the overall spacecraft mass, reducing both mass and the corresponding cost of launch.

Solar sailing, which requires very large structures, is an ideal use for ultra-lightweight structures. Much of the spacecraft's mass is required for the structure to deploy and stabilize the reflecting sail. Thus, using ultra-lightweight structures for this purpose will help greatly. Furthermore, the propulsive acceleration to the spacecraft provided by the solar sail is inversely proportional to the spacecraft mass, so that less mass means faster acceleration and shorter times to complete missions

However, before these ultra-light masts can be used on scientific missions, several of their key technologies must be matured and validated sufficiently to bring to an acceptable level the risk associated with their first use in space. Among these technologies are the deployment mechanisms, techniques for making sure the deployed mast is securely in place, control of the deployment motion and forces, and the effects of attachments and loads on both the static and dynamic performance of the structures.

Engineers at ATK Space Systems test solar sail deployment in the laboratory.

The ultra-lightweight deployable mast technology called SAILMAST will be validated on ST8. The name SAILMAST is derived from Scalable Architecture for the Investigation of the Load Managing Attributes of a Slender Truss. For the ST8 validation experiment, a 40-m gossamer mast will be built, empirically characterized both during deployment and as a load-carrying member, and exercised to validate analytical models of its deploying and load-carrying behavior and performance. These experiments and modeling will resolve major uncertainties associated with using the ultra-lightweight SAILMAST in space and will facilitate its infusion as a fully functional deployable system.