Each month, Batteries Digest Newsletter includes feature stories relating to:

batteries, fuel cells and solar power.

The following is a feature from the March 1998 issue on solar cells. Reprints are available on the OrderInfo.html page.

TRW Meets 21st Century Space Solar Panel

Demands with Terrestrial Automation

With great excitement battery producers eye the recent growth and projections for worldwide communications, which include cellular phones, pagers, computers, and PDAs. Any one of these markets would give business developers of many companies sleepless nights considering all the requirements needed to be in the game and yet to be competitive as the new systems become available. These global communications are moving to space, along with the satellites, which form the vertices of these networks. This dynamic and growing business is becoming fraught with all the problems of competitiveness, including costs, reliability and deliverability. In space not only is the battery critical, but so are the solar panels to power the bird and recharge the batteries. Power management in space is rocket science. This concept is well expressed by Sherman Jobe, who heads the Science and Engineering Directorate at NASA Huntsville. In a spacecraft, if you dont have power, theres an awful lot of other things that dont really matter. (see BD #22, p.1)

 Eugene F. Silkowsky is TRWs Power Sources Manufacturing Factory Manager for the Space and Electronics Group. He says, By standardizing on the automation components we can take advantage of a high volume operation and apply it to low volume. This approach has proven to be fruitful. Quality is improved; yields have increased; scrap and rework are reduced, and the span time is shortened. We are pleased with the results of automation, and as a result, our budget grows each year to do more. Prior to joining the Space and Electronics Group, Gene was responsible for high volume manufacturing of airbag crash sensors within TRW.  

There was a time was when the insertion in orbit of a single satellite was heralded, but now the excitement lies with talk of constellations consisting of multiple low earth orbiting (LEO) satellites building the framework of global telephone networks as in the case of the Iridium constellation of 66 satellites with reserves in place. Anticipations are that this will be a high volume business requiring lower costs and improved reliability marching side by side with technological improvement. TRW Inc., with over $10 billion in sales, has realized both the market growth and these new competitive pressures. Not being a newcomer to space, TRW designed and built Pioneer 1, which launched just 11 days after NASA was formed. Another TRW spacecraft, Pioneer 10, was the first to leave the solar system over 20 years ago and amazingly, still returns data to earth although being more than 5 billion miles away.

At first glance, the view of robotic/automation advances at TRW as just another high tech innovation might be viewed as an expected step, but it should receive more individual recognition. As mentioned previously, the quantities are rising astronomically, and the outlook in the first decade of the next millennium is for more demand. Hand in hand with the greater quantity is the time and cost penalties of reliability failures. Spacecraft have to become less costly, have greater availability in shorter time windows and have fewer failures. Businesses in the western world have learned lessons in manufacturing. Earth bound devices, from autos to toasters, have been pressured by monetary constraints and availability because the Japanese showed the world that production quantities could be achieved with lower costs and improved reliability. This has been accomplished because one of modern technologys tools, robotic automation, employs machines to perform tasks accurately and repeatably with checks and balances at each step to make sure that the construction is correct.

 
 A full scale model of the Space-Based Infrared System-Low (SBIRS-Low) Flight Demonstration System (FDS) Spacecraft with one of its two solar panels attached stands in TRWs high bay in Redondo Beach, CA. In the same high bay, the actual FDS spacecraft are in the process of being assembled, integrated and tested. TRWs teammate, Raytheon, is providing the infrared sensor payload and mission data processing. The FDS spacecraft will be launched in 1999 and operated on orbit for one year, demonstrating the systems capability to detect and track strategic and tactical ballistic missiles and perform other missions.

BD visited TRWs new solar array production facility, which opened in April of 1998, to view the state-of-the-art custom designed automation equipment for assembling, interconnecting, testing and inspecting solar cells, panels and arrays. Guiding the tour was Sally Koris, TRWs Public Relations Manager. She and Eugene F. Silkowski, the Power Sources Manufacturing Factory Manager for the Space and Electronics Group, described what was happening at their new facility.
Gene noted that the new facility dealt with three main production areas.
1. Solar arrays-where stack production testing, panel assembly and electrical testing are performed
(Further testing such as
environmental testing and
temperature cycling is done on
the main campus.)
2. Spacecraft DC harnessing and wiring (not the rf harnessing)
3. Assembly for battery packs

TRW does not make the solar cells or batteries, but it does assemble them into modules and adds the power electronics to utilize the combination of solar power capture and battery energy storage to maintain a healthy satellite power system in space for a decade and a half . Current technologies use either silicon or gallium arsenide chemistries. The efficiency of the lower cost silicon is about 16%, but the gallium arsenide/germanium can increase to over 20% along with a skyrocketing increase in price.

 
  In the Solar Cell Glassing Workstation shown here, a TRW systems engineer can change the program to build different solar cell configurations in just hours instead of the 7 days previously required. The robotic arm is able to apply adhesive to a solar cell, then accurately locate and place a piece of cover glass on the cell without spillage, cure it and then place the cell in a cassette storage device - and do it repeatedly 90 times an hour. Glassing can be performed on any size and type of solar cell.

Currently TRW has work in their shop concerning three system satellites. All come under an umbrella label, EOS COM, which means they have a standardized spacecraft bus, solar array, and power system. However, each one is designed to perform a different suite of experiments. The projects which are currently being worked on in the shop include:

1. EOS PEM - Experiments are being designed for oceanographic/ land research. (In the plant, Battery Assembly is being done for this EOS project.)
2. EOS Chemistry The suite of experiments will look at worldwide pollution, including the atmosphere (Solar array work is being done in the plant.)
3. SBIRS (Space Based Infrared System) boost based detection system is being built for the government.
(Solar panels are being construced.)

The good news of automation lowering assembly costs and increasing reliability tells only half of the story. The other half of the benefit allows for tailoring in cell fabrication which will most likely have to be varied for the next job. Again automation comes to the rescue.If the robotic tools have been designed properly, a combination of hardware and software can make the same assembly stations ready to produce the new recipe within a few hours. Think of it as the equivalent of having a kitchen utensil which would automatically make a pizza tonight and roast duck tomorrow.

Gene stated, The automation equipment is unique to TRW. Our systems engineers developed the hardware and software to automate this process, so no one else has these machines. Within the department, we have automation designers, and depending on our workload, we will develop the specifications and do the liaison work with an outside house which will build our equipment. About half the time we design and build it ourselves. Our people are technically current and can do a good liaison job when needed. Everything built is totally state-of-the-art. My biggest thrill is going down at lunchtime to the darkened automation room to see the robots work. (The room is dark because motion sensors turn the overhead lights off while the employees are out of the room.) Gene almost views the machines as toys to be enjoyed for their intricate performance.

When asked if TRW becomes involved in land based solar arrays, Gene said, We ...

 

For the rest of the story, order issue #36 from the order form at: OrderInfo.html