Abstract: The present invention provides a heterogeneous spacecraft network including a network management architecture to facilitate communication between a plurality of operations centers and a plurality of data user communities. The network management architecture includes a plurality of network nodes in communication with the plurality of operations centers. The present invention also provides a method of communication for a heterogeneous spacecraft network.

Abstract: A closed tonometer for subcutaneous insertion is disclosed having a small closed equilibrating bath. Three noble metal electrodes, preferably platinum (Pt), communicate through electrical conductors to the bath at spacings exceeding 0.2 mm. Each noble metal electrode is typically exposed to the bath by embedding the noble metal in a dielectric and cutting both dielectric and electrode so that the exposed electrode is flush with and a part of the closed bath wall. The bath is contained within an oxygen permeable membrane -- preferably Silastic.RTM. a registered trademark of Dow Corning Corporation of Midland, Michigan. The bath contains a sodium chloride (NaCl) solution, preferably 0.9%, and small amounts of a hydroquinone such as a tenth of a gram of pure ascorbic acid per 30 ml of NaCl solution. One of the noble metal electrodes becomes a quinhydrone reference electrode preserving a precise voltage differential with respect to the electrolyte bath.