Lowering thermal insulation costs, improving reliability for SmallSats

Constellations of small, narrow bandwidth satellites (SmallSats) are steadily replacing larger, conventional, wider-bandwidth satellites as the preferred spacecraft in communications, Earth monitoring, and defense and commercial applications.

The costs to manufacture and assemble component parts, launch, and operate SmallSats are all dramatically lower than with conventional satellites. And, SmallSats operate in low Earth orbits (LEO), offering advantages in transmission latency, the time it takes for signals to be relayed from the spacecraft to Earth.

Initiatives among contractors hope to deploy broadband Internet planet-wide, with SmallSats functioning as orbiting cell phone towers.

The transformation from large satellites to inexpensive LEO SmallSats is significantly impacting how manufacturers perceive mission-critical components. The burgeoning number of smaller satellites requires multiple shapes and layers of insulation to guard the spacecraft from heat. SmallSat manufacturers are recognizing the ability of precision formatters to achieve this consistency with multi-layer insulation (MLI) blankets. Add in cycle time reduction and inventory advantages, and co-sourcing MLI has the potential to become a long-term trend in satellites.

Blanket shops

Traditionally, satellite manufacturers have completed the design and production of MLI blankets, almost always as the last item on their to-do lists. Insulation blanket manufacturing personnel use templates to hand-cut MLI materials into odd shapes that may be as asymmetrical as amoebas. Hand-cut pieces are then planerized, or flattened, with their dimensions input to a computer that adds them to the satellite design.

Part-to-part consistency presents challenges with templates. Hand cutting introduces human error, and templates will wear and distort from their original specs. The process also requires logistics and inventory mandates that can result in unacceptable cycle times if not expertly managed.

After years of designing and manufacturing a satellite’s more complex components, designers must ensure that the more pedestrian, soft-goods MLIs are available before launch, as well. Without proper insulation, it’s a no-go for all systems.

Rethinking MLI production

SmallSat constellations can consist of scores of individual spacecraft, each protected by dozens of MLI shapes, or pieces. These shapes must be precisely replicated from one SmallSat to another for optimum performance – something achievable with CAD-CAM controlled material formatting and CNC materials manufacturing.

The key to optimizing the CAD-CAM and CNC equipment and achieving part-to-part MLI shape consistency is anticipating its use early in the satellite’s design stage and working closely with technology partners who can direct the design to its peak processing on the machinery. SmallSat makers benefit by working with businesses that specialize in formatting soft-goods parts according to precision specifications and delivering them to the satellite manufacturer close to launch time.

Co-sourcing

A co-source scenario might work like this:

The satellite manufacturer’s material and process (M&P) engineers will select a precision formatter of flexible materials and bring its specialists into the satellite’s design process early – usually before the bus, or body of the satellite, has reached final design. The satellite manufacturer typically supplies data to the formatter via .STP, .DWG, .DXF, and .PDF CAD-CAM files. Everything is done digitally, including creating and working with 3D to 2D flat patterns. The data enables expert formatters to produce MLI shapes consistently among satellites, free of hand-cutting, and without the need to redesign shapes that are out-of-spec due to worn templates.

Other components that should be identified early in the satellite’s design are the insulation’s black MLI films that keep reflections down, and grommets, fasteners, snaps, grounding straps, hook-and-loop fasteners, and sewing patterns that keep the insulation in place. At the job’s completion, these parts can be supplied to the launch pad with the insulation layers as a complete package to save installation time.

Side-by-side with their technical expertise, MLI formatting partners can save satellite makers factory space and provide inventory and delivery advantages with offsite manufacturing.

For example, certain base polyamide films that survive up to 500°F are essential for creating MLIs. Lead times for them can reach six months. M&P engineers overseeing satellite design and manufacture need to factor these distant-horizon lead times into their production cycles and budget dollars and space for in-house inventory. Precision formatters can co-source the manufacturing task, freeing blanket shop factory space, while accepting responsibility for inventory monitoring and having product available for on-time delivery.

Streamlining MLI production via faster manufacturing methods and providing on-time delivery can cut cycle time. Co-sourcing also frees a satellite manufacturer’s engineering resources for other, more appropriate tasks.

Materials efficiency

It’s essential to include materials efficiency when discussing co-sourcing MLI.

Materials used in MLI construction can cost upward of $200 per linear foot. Hand-cutting the layers’ shapes inevitably leaves unused material remnants.

Formatters using CAD-CAM can nest shapes to maximize material use. CAD-CAM takes the often oddly shaped designs and angles them, jigsaw-puzzle like, within the material footprint to reduce waste and ultimately contribute to greater materials use and more efficient processing.

Web Industries Inc

About the author: Lee Smith is Web Industries Inc.’s business development manager. He can be reached at lsmith@webindustries.com .