In 2012, the Mars Curiosity Rover landed on the surface of our closest planetary neighbor in the Milky Way Galaxy. Undeniably, this was a momentous achievement, and the tremendous amount of data gathered has advanced our understanding of Mars, especially that it once had conditions favorable for sustaining life, and may serve as an environment for life to thrive in the future. Valuable data like this is indispensable for the planning and success of future trips to Mars, such as the Mars 2020 Rover Mission.
Landing on Mars has historically been a perilous exercise. Of the 45 attempts to date, 23 have been unsuccessful. Although the success rate has increased significantly over the last couple of decades, even successful attempts encounter tense moments before the final touchdown. This final leg of the journey is infamously known as the “7 minutes of Terror”.
After entering Mars’ atmosphere, the landing of the spacecraft is monitored and controlled by the Entry, Descent, and Landing (EDL) system. However, there is a delay of approximately 14 minutes for signals to travel from Mars back to earth, while the descent takes roughly half as long. This means that the rover has to make any necessary corrections or adjustments independently, without any help from the controllers on the ground. This blackout is quite stressful as any unexpected contingencies could damage the rover or even end the mission; including overheating or slamming into Mars’ surface or some other object too fast.
For Mars 2020, the rover will include a camera system to film the descent and landing stages. The Jet Propulsion Laboratory (JPL) was tasked with the development of the EDL camera system.
Before being selected to work with any aerospace industry organization, a contract manufacturer (CM) must pass a higher level of scrutiny than what is required to manufacture PCBs for most other industries. JPL, however, has even stricter standards and has set a high bar for fabrication and assembly quality.
Tempo Automation is well known in the PCB industry for providing fast, high-quality PCB manufacturing services. Tempo specializes in precise turnkey prototyping and utilizes an advanced software-driven process, the digital thread, to not only expedite the manufacturing process but also enable in-process monitoring. These capabilities, coupled with support by DFM engineers, contribute to Tempo’s agile manufacturing service, which is able to identify and respond to changes quickly.
The development of the electronics systems for the Mars 2020 Rover EDL camera system is a multi-year project. However, to ensure that quality standards are met within the allotted schedule, CMs must be able to build boards fast, respond to and resolve adjustments quickly, and meet IPC 610 Class 3 or J-STD-001 with Space Addendum standards. By demonstrating the capability to meet these requirements, Tempo was selected for the Mars 2020 project.
The high level of quality required by JPL can be challenging to achieve; however, precision limits are defined by the CM’s equipment capabilities. During the course of working with Tempo, JPL optimized the fast design/build/test prototype iteration cycle to resolve minor issues and ensure that board design parameters were within Tempo’s fabrication and assembly capabilities.
Tempo’s standard services involve performing several inspections at strategic steps of the assembly stage to ensure secure component mounting. This proved to be invaluable and led to the identification of a design issue that, if left uncorrected, could have negatively impacted board quality and yield rate. A component assembly problem was detected during an automated optical inspection (AOI) and traced to a problem with the silkscreen design. This discovery and Tempo’s suggested solution led to an improvement in the design with minimal impact on the product development schedule. Additional feedback from Tempo also led to minor changes to enhance board quality.
Depending on the size of the system or platform, some JPL projects can take up to five years for development. In this case, the boards developed are additions to the previous EDL system, commercial-off-the-shelf (COTS) components are used, and the development schedule is substantially shorter. However, the PCBs built by Tempo required several iterations before the final flight-level design was achieved.
Tempo’s turnaround time on the initial non-flight, prototype boards for the EDL camera system was a week or less, even with adjustments. For flight boards, required documentation and coordination with vendors necessitated minimal addition time. Fast turnaround on boards, coupled with support from Tempo’s design for manufacturing (DFM) engineers, provided JPL with ample time to refine the design and achieve the flight-level quality boards necessary. Furthermore, Tempo provided traceability documentation, as mandated by aerospace standards.
The rover launch is scheduled for the summer of 2020. And with the EDL capability upgrade camera system developed by JPL with Tempo’s critical system PCB manufacturing assist, this landing should go a long way towards ending any future instances of the “7 Minutes of Terror.”
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