g-negation support system must not compromise the electrostatic sensitivity or contamination  requirements of the spacecraft and must be compliant with use on the GPM spacecraft. The GPM Solar Arrays consist of two Solar Array Wings with one installed to each of the +Y and -Y sides  of the GPM Spacecraft. Each Solar Array has a boom that extends approximately 3 m (10 ft) and attaches to the center of four panels. Each panel is approximately 1.5 m (5 ft) by 2.75 m (9 ft) aluminum  honeycomb with carbon fiber face sheets. Separately, each Solar Array wing weighs about 177 kg (390 lb). Compared to its predecessor satellite TRMM, GPM’s Solar Arrays have about two times the mass. 

     Figure 3. Solar Array Wings on Spacecraft At the time of publication the SADDS has been shipped to Japan on the GPM Spacecraft for a 2014  launch. Prior to shipment, each wing underwent environmental testing, multiple walk outs, and four official  deployment tests. Through the process of developing the g-negation system and working through issues as they arose during deployment testing valuable lessons learned were discovered which are described  herein.  Background Each of the GPM solar array wing assemblies deploys in the same relative sequence. As such, and  because only one wing would be deployed at any given time for testing, only one g-negation system  needed to be developed. Initial concepts for the g-negation system included a table system which supported the wing assembly from below and an overhead gantry system which supported the wing assembly from above. Previous GSFC projects TRMM and X-ray Timing Explorer (XTE) had successfully employed table systems that supported the deployable subsystem using air pads. As a result of these  prior efforts, air system advantages and disadvantages were fairly well known and additionalconsideration was given to an overhead gantry system. Gantry research and development was short-lived  however, due primarily to the multi-directional deployment sequence and path of the wing assembly panels as shown in Figure 4.  The solar array panel deployment sequence and path would demand a relatively elaborate overhead  tracking system. Additionally, that system could neither introduce significant deployment friction nor influence the wing’s deployment path in either an inhibitive or assistive manner. Thus, the need for an  uninfluenced deployment path eliminated the early gantry concepts and refocused the development on  table systems. Furthermore, minimal system friction was more likely to be achieved on the table surface  by using an air pad system. Due to the long moment arm created by each Solar Array’s wing span, even the small amount of friction created by a castor-supported system could have overwhelmed the solar array wing hinge springs.  Once the decision was made to pursue an air pad table system, the natural progression was to adapt and  refine the table system used by the aforementioned spacecraft’s TRMM and XTE. Custom tables and air  pads were developed for XTE and these would also be employed by GPM. While the table system  +Y Solar Array Wing  -Y Solar Array Wing GPM Main Structure  Boom  -Y Panel 1  -Y Panel 2  -Y Panel 4  -Y Panel 3  336