The Multi-user Droplet Combustion Apparatus (MDCA) is a multi-user facility designed to accommodate different droplet combustion science experiments.  The MDCA will conduct experiments using the Combustion Integrated Rack (CIR) of the NASA Glenn Research Center’s Fluids and Combustion Facility (FCF).  The payload is planned for the International Space Station.  The MDCA, in conjunction with the CIR, will allow for cost effective extended access to the microgravity environment, not possible on previous space flights.  It is currently in the Engineering Model build phase with a planned flight launch with CIR in 2007.   

The MDCA contains the hardware and software required to conduct unique droplet combustion experiments in space.  It consists of a Chamber Insert Assembly (CIA), an Avionics Package, and a multiple array of diagnostics.  Its modular approach permits on-orbit changes for accommodating different fuels, fuel flow rates, soot sampling mechanisms, and varying droplet support and translation mechanisms to accommodate multiple investigations.  Unique diagnostic measurement capabilities for each investigation are also provided.  Additional hardware provided by the CIR facility includes the structural support, a combustion chamber, utilities for the avionics and diagnostic packages, and the fuel mixing capability for PI specific combustion chamber environments.  Common diagnostics provided by the CIR will also be utilized by the MDCA.  Single combustible fuel droplets of varying sizes, freely deployed or supported by a tether are planned for study using the MDCA.  Such research supports how liquid-fuel-droplets ignite, spread, and extinguish under quiescent microgravity conditions.  This understanding will help us develop more efficient energy production and propulsion systems on Earth and in space, deal better with combustion generated pollution, and address fire hazards associated with using liquid combustibles on Earth and inspace.  

As a result of the concurrent design process of MDCA and CIR, the MDCA team continues to work closely with the CIR team, developing Integration Agreements and an Interface Control Document during preliminary integration activities.  Integrated testing of hardware and software systems will occur at the Engineering Model and Flight Model phases.  Because the engineering model is a high fidelity unit, it will be upgraded to a flight equivalent Ground Integration Unit (GIU) when the engineering model phase is completed.  The GIU will be available on the ground for troubleshooting of any on-orbit problems.  Integrated verification testing will be conducted with the MDCA flight unit and the CIR flight unit.  Upon successful testing, the MDCA will be shipped to the Kennedy Space Center for a post-shipment checkout and final turn-over to CIR for final processing and launch to the International Space Station.  

Once on-orbit, the MDCA is managed from the GRC Telescience Support Center (TSC).  The MDCA operations team resides at the TSC.  Data is transmitted to the PI’s at their home sites by means of TREK workstations, allowing direct interaction between the PI and operations staff to maximum science.  Upon completion of a PI’s experiment, the MDCA is reconfigured for the next of the three follow-on experiments or ultimately removed from the CIR, placed into stowage, and returned to Earth.

MDCA/CIR Testing and Integration 

Integrated testing between the MDCA hardware and CIR carrier will be performed on the engineering units of both pieces of hardware.  Both units are hi-fidelity, flight-like units.  Testing, planned for December 2002 will include a full array of sub-package testing, leading to a full end-to-end functional test.  Upon completion, the MDCA Engineering Model (EM) will undergo vibration & microgravity testing, EMI/EMC, and acoustical testing.  In parallel with EM environmental testing, the MDCA flight hardware will be procured and assembled.  Testing will be conducted on the flight unit in early summer 2005 in preparation for a turn-over of the hardware to CIR for flight integrated testing in August 2005.    

Launch of the MDCA Hardware

The MDCA hardware will be launch as stowed hardware on the same incremental flight launch as the CIR.  This hardware will include the MDCA common hardware and experiment unique hardware for the first droplet investigation, Flame Extinguishment Experiment (FLEX).  The Chamber Insert Assembly, MDCA Avionics Package, and experiment unique hardware will be separate stowed items.  Once on-orbit, the CIA and Avionics Package will be removed from stowage.  The avionics package will be installed on the CIR rack and the CIA will be inserted into the CIR combustion chamber.  Experiment unique diagnostics for the first experiment will be installed on the CIR optics bench.