EMIT: Delivering a Complex Payload for the International Space Station

Abstract— EMIT (Earth Surface Mineral Dust Source InvesTigation) was selected in February 2018 as part of the Second Stand Alone Mission of Opportunity Notice (SALMON-2), Program Element Appendix (PEA): Earth Venture Instrument-4. From the start, the EMIT integration and test program was going to be complicated by the complexity of the payload and restrictions on being able to do the dynamics qualification in the full flight configuration. During formulation phase (Phase B), the team elected to separate the instrument into three structurally independent elements – one for the optics, one for the avionics, and one for enclosure and radiators. Taking this approach greatly complicated the planning for the assembly phase, but offered several potential advantages in planning the integration and test program.After the EMIT project preferred flow was defined for the EMIT PDR, those plans were upended by the arrival of COVID. The EMIT team faced a situation where most, but not all, components were going to be delivered late – with large uncertainties on the relative delays. This uncertainty led to review of the assembly flow and finding ways to decouple the three primary integration flows. Other considerations included building additional ground support equipment to permit work to continue on much of the system in the event critical flight parts arrived even later than expected. In hindsight, this fixation on finding schedule resiliency should have been part of the original plan. This paper will provide an overview of the instrument design, how the three major assemblies were designed to be tested independently, and specific decisions made to ensure maximum flexibility to make progress and reduce technical risk should key elements be delivered late. Examples will include early decisions to build extra copies of engineering models, to create temporary facilities to optimize the test flow, and to rearrange the test orders to find ways to reduce risks on partial assemblies while waiting for late deliveries.