Product Assurance approach for New Space environment
by Eladio Montoya (eladio.montoya@altertechnology.com)
Current exuberance of the New Space market is characterised among other factors by the use of COTS (Commercial Off-The-Shelf) components and minimized requirements in product assurance and testing policy. These results ultimately in relatively high failure rates of the missions (although decreasing year by year, still above 20% excluded launch failures ) which has been allowed by the relatively low maturity of the New Space sector and the just-for-demonstration purpose of many of the missions. However, recent and planned strong investments in smallsat constellations require a mastered reliability of the platforms and payloads and a risk management strategy. This means that smallsat builders need to develop a capability in risk management, contrarily to the risk avoidance of traditional space sector. At Alter Technology, based on our experience of more than 30 years in the Space Sector, we have identified several key activities in product assurance and small satellite testing that need to be addressed for a successful commercial mission.
1. Develop a Product Assurance Plan adapted to your mission
Product assurance plans are aimed at choosing components, manufacturing procedures and testing strategies at all levels that will assure the required reliability for the project. In the space sector these plans need to assess lifetime of the components under harsh conditions:
- Thermal vacuum cycling due to day/night cycles,
- Gamma radiation hardness (at least 10-20krad for LEO, more for MEO, GEO and deep space missions),
- Proton, neutron and heavy ion radiation hardness for MEO, GEO and deep space missions.
Specific standards such as IEC-TR-62380, FIDES 2009, MIL-HDBK-217 or Siemens SN 29500 exist to calculate MTTF (Mean Time To Failure) based on environmental conditions and component grade. In these models, the failure rate of each component of the BOM is known by experience (or estimated) and this allows for the calculation of a global MTTF of a piece of equipment. Of course, the higher the component grade, the lower the failure rate for a given set of environmental conditions. The component grade selection can benefit of a large panoply of grades, such as space, military, automotive, enhanced COTS or plain COTS.
A specific testing strategy needs also to be developed in the Product Assurance plans, and this can be a combination of testing at component, subsystem or system levels. It is also strongly advised to make use of HALT (Highly Accelerated Life Tests) that allow reducing risks. Alter Technology is currently developing Product Assurance plans for New Space companies based on their specific mission requirements and hardware.
2. Component engineering
Selection of the right grade of electronic components is critical to ensure the reliability of the mission. The current trend in New Space is to choose plain COTS components, but it must be said that plain COTS cannot assure lifetimes of the whole subsystem beyond 20 months even in LEO due to radiation effects. On the other hand, not all the components need to have the same grade and for example, key components such as sensors, FPGAs, DC-DC converters, ADC, can be chosen with a higher grade than, passive components, in order to increase the overall reliability of the system.
Alter Technology, based on its 30 year experience in component procurement and testing, has developed the DOEEET platform (www.doeeet.com) which contains more than 20 million references of space and other grade components, with information abouts technical specifications, obsolescence, heritage, testing, etc.
3. Component testing
New Space actors are typically very reluctant to test components because of budget constraints. To help solve this and increase reliability in New Space, the DOEEET platform includes a tool called “Crowdtesting” with which different parties can share the costs of testing key component by Alter Technology. Again, an appropriate selection of the tests to be done to components can decrease dramatically the technological risks without too much extra cost.
4. Adapted packaging
In many cases, COTS or automotive components can be valid but need to be repacked in ceramic enclosures in order to make them clean or resistant to high temperature. Alter Technology has in-house packaging and manufacturing facilities such as wafer dicing, flip-chip, wire & bump bonding, encapsulation and sealing, fiber bonding or Laser diode assembly.
5. Equipment testing
New Space companies frequently limit testing to the full satellite level and only a structural model (SM) and a proto-flight model (PFM) are manufactured. The testing is frequently limited to the minimum requirements of the launcher, consisting on vibration and thermal vacuum. However, our proposal is that for commercial missions, the following testing guidelines should be applied:
a. Design your hardware to get highest test observability: include sensors and ports that may allow to monitor the variable that allow a full diagnosis of the equipment.
b. Include spare units for the testing campaigns.
c. Do not limit the testing to the launcher’s requirements, but to the mission requirements.
d. The test plan should incorporate:
- Radiation test at component/system level when needed
- Thermal assessment, including extreme temperatures coverage, thermal cycles, and under vacuum when possible
- Mechanical integrity, comprising vibration, SRS and another mechanical stresses with a final physical analysis
- Highly Accelerated Life Test (HALT)
- EMC and communications test
The testing can be performed in house, but it implies important investments in testing equipment and costs of trained staff, and in implementation time; or rather by independent third parties like Alter Technology that can mutualise these costs and are have facilities readily available. We believe New Space sector will gradually upgrade equipment reliability as investments and insurance will require a risk management strategy to ensure the return on investments.
6. Adopt a third-party certification scheme.
Traditional space sector is not a serial manufacturing industry, but new space is when constellation of tens of satellites are involved. All related serial manufacturing sectors (automotive, electronics, aeronautics, military…) use third-party certification schemes and small satellite constellations should not be an exception. When manufacturing tens of satellites, full testing of each unit can be too expensive, and therefore, the generally adopted strategy is to fully qualify the first unit and to ensure that the AIV is consistent. To do this, the owner of the constellation, who is not necessarily a space specialist, can engage a third independent party. The task of this third-party certifier is to ensure that:
• the configuration of the design is updated, complete and no inconsistencies exist
• the supply chain is robust: all suppliers are qualified
• all assembly and integration processes are followed
• testing procedures are followed and testing equipment is calibrated.
Conclusion
In conclusion, the New Space sector is characterized by budget constraints and fast development times that lead to an industrial concept of “mastered” reliability, as opposed to a “total” reliability of the traditional space sector.
This mastered reliability translates into all quality aspects (component grade, packaging, design, assembly, integrations and testing) in order to ensure final profitability of New Space projects. We have presented here several ways that we think may help New Space actors tailor their production processes to achieve their quality goals.
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