Honeywell engineers enhance Space Station computers

By John McHale

CLEARWATER, Fla. - Engineers at Honeywell Space Systems in Clearwater, Fla., enhanced the flight Multiplexer/Demultiplexer (MDM) computers previously used on NASA`s fleet of space shuttles, for the use on International Space Station.

The main difference between the Shuttle and Space Station MDMs is the central processor. The Space Station devices use a commercial 386SX processor from Intel Corp. in Santa Clara, Calif., says Bob Davis, senior staff engineer for Honeywell`s Data Control Products department.

Supportability for the 386 will not be a problem, Davis says, because Intel supplied Honeywell with spare parts, and if the spare parts run out, Intel will sell the 386 die, Davis explains. "Intel`s software also is backward compatible and will work with the 386," he says

The 386 came in a high-reliability, hermetically sealed package and passed Honeywell`s radiation testing, Davis adds.

The technology evolved to include distributed processing capabilities to enable each remote-terminal MDM to execute commands independently of a central computer, Davis says.

Under the $240 million development contract with the Boeing Co. in Seattle, engineers from the Honeywell Space Systems Satellite Systems Operation in Phoenix built and delivered 51 MDM flight hardware units; 74 MDM ground hardware units; 66 Multiplexer/ Demultiplexer Application Test Environment (MATE) units; and various test units and miscellaneous spares.

The MDMs, which have a modular computer architecture with a high-speed interface, will control core systems - power, environmental control, guidance, and navigation - as well as sensors, and effectors. They will also manage payload operations and handle the station`s most critical commands from ground control.

"The modular architecture adds flexibility," Davis says. "Any channel is configurable."

The Space Station uses two types of Honeywell MDMs: the Space Station Multiplexer/Demultiplexer (SSMDM) and the Enhanced Space Station Multiplexer/ Demultiplexer (ESSMDM).

The SSMDM collects signals from sensors and effectors, astronauts, or subsystems. It processes the information and transmits signals and commands such as steering the solar arrays and channeling the power necessary to operate scientific experiments.

An SSMDM consists of a chassis, power supply, I/O control unit, I/O backplane, SX backplane, and I/O circuit cards. Astronauts can replace circuit cards on orbit, which simplifies maintenance and reduces downtime and operating costs, Davis says.

The I/O control unit includes the processor, memories, I/O circuit card control logic, and analog-to-digital converter.

Communication is via independent dual-redundant MIL-STD-1553B data bus channels, which enables the device to operate as a bus controller, bus monitor, or in remote terminal mode. Also, the SSMDM`s built-in hardware and software self-test capabilities can detect and report 94 percent of all possible failure modes, Davis says.

The enhanced version

The enhanced MDM is the command-and-control resource, and serves as the Space Station`s master bus controller of all SSMDMs, Davis explains.

In addition to the SSMDM, the enhanced version uses a 2.2-million-instructions-per-second central processor, a math coprocessor, and expanded RAM, he says. It also has enhanced computing speed and a high-rate data link to communicate and control the mass storage unit and scientific payloads. It is software and hardware self-diagnostic.

The high-rate data link circuit cards communicate with the Mass Storage Unit - a ruggedized military re-writable hard disk - and the Space Station`s scientific payloads for 10 megabit- per-second fiber optic data transfer and receipt.


The MATEs enable engineers involved in the Space Station program to develop and test their application software in preparation for in-flight operation. MATE performs verification and debug testing for Space Station flight software.

The MATE system includes Digital VAX and Sun Sparc 5 development workstations, dual tape drives, a real-time software tool set from Integrated Systems Inc. of Sunnyvale, Calif., internal and external Ethernet, utilities platform (bus analyzer), and a real-time input/output platform.

Honeywell engineers also developed mechanisms such as a Power Data Transfer Assembly (PDTA), which transfers the energy from the solar panels to the spacecraft`s payload. In addition to the PDTAs, they will deliver two bearing assemblies, two utility transfer assemblies, and seven beta gimbals for the solar arrays.

The International Space Station is an international orbiting laboratory to be used for the advancement of a wide range of scientific and technical research. The 16 nations involved are: the United States, Brazil, Canada, Italy, Belgium, Netherlands, Denmark, Norway, France, Spain, Germany, the United Kingdom, Sweden, Switzerland, Japan, and Russia. The first element of the International Space Station, the Russian-built Functional Cargo Block, will be launched in June 1998 and the first U.S.-built hardware will be launched in July 1998.

Click here to enlarge image

NASA officials say supporting the Intel 386-based space station computers, pictured above, will not present a problem.

Military & Aerospace Photos

Most Popular Articles

Related Products

CHAMP-FX4 6U OpenVPX Virtex-7 FPGA Processor Card

The CHAMP-FX4 is the flagship 6U product in Curtiss-Wright Defense Solutions’ family of user-prog...

PMC-E2001 Audio/Acoustic Waveform Generating PMC Card

PMC-E2001 Delta-sigma PMC features 16-bit resolution with 8 Analog Outputs and 4 Analog Inputs wi...

VPX3-453 3U VPX Virtex-6/8640D Digital Signal Processor

The Curtiss-Wright VPX3-453 is a high performance 3U VPX DSP and FPGA processor card that combine...

SBC-K7 Embedded PC for Instrumentation and Control

The SBC-K7 is an ideal platform for embedded instrumentation that combines an Atom PC running Win...

CPU-PPC460EX-VME Processor Board

The CPU-PPC460EX-VME PowerPC processor board is designed for rugged, conduction and convection co...

PC/104 SBC and Peripherals

Kontron PC/104 Standalone Single Board Computers (SBCs) serve in every format, even with consiste...

General Micro "Horizon" C299

The C299 Horizon is a third generation, 6U cPCI SBC module based on GMS’ upgradable CPU technolog...

Rugged Mobile Communications Server

Advanced communications server designed to be deployed in environments where it needs to meet cer...

RR2P Removable Canister RAID System

Transportable data storage for mobile field use aboard planes, ships and ground transport. 2U, du...

API DC Link Power Film Capacitors

High reliability DC link capacitors for power inverter applications which require superior life e...

Related Companies

Curtiss-Wright Defense Solutions

About Curtiss-Wright Defense Solutions Curtiss-Wright Defense Solutions (CWDS) is a long established techno...

Innovative Integration

  Since 1988, Innovative Integration has grown to become one of the world's leading suppliers of DSP and data ac...

Beyond Electronics Corp

Beyond Electronics(BEC) provides Rugged COTS board and system level solutions in various small form factor products c...


Driving the world’s embedded computing platforms Kontron is a global leader in embedded computing technology.&n...

General Micro Systems Inc

Since 1979, General Micro Systems has been providing the most diverse line of single-board computers in the industry....

Elma Electronic Inc

Who we are...   About Elma Electronic Systems   The Systems division of Elma Electronic Inc. supplies the

Winchester Systems Inc

At its founding in 1981, Winchester Systems introduced its first 5 MB disk system for Intel development system users....

API Technologies Corp

Who We Are API Technologies is a dominant technology provider of RF/microwave, microelectronics, and security technol...

Extreme Engineering Solutions Inc (X-ES)

 Extreme Engineering Solutions, Inc. (X-ES) is a leader in the design, manufacture, and support of standard and ...

Falcon Electronics

Distributes military, hi-rel and space-grade semiconductors including ARINC 429/1553 databus products, power supplies...
Wire News provided by   

Press Releases

Low Viscosity, One Part Cyanoacrylate Is Non-Toxic and Meets ISO 10993-5 Specifications

Master Bond MB250NT is widely used for a variety of applications ranging from repair to high speed producti...

Thermally Conductive, Two Component Epoxy Passes USP Class VI Tests and ISO 10993-5 Specifications

With biocompatibility and cytotoxicity certifications, Master Bond EP21AOLV-2Med is often selected for bond...

One Component, Snap Cure Epoxy Features High Strength Properties

Suitable for a variety of applications in the electronic, aerospace and OEM industries, Master Bond EP3SP5F...

One Part Epoxy Resists up to 500°F and Meets NASA Low Outgassing Specifications

Master Bond Supreme 12AOHT-LO is a one component epoxy for a variety of bonding and sealing applications in...

VICTORY Shared Processing, Fire Control Computer, and Switch for Ground Vehicles Introduced by Curtiss-Wright

Curtiss-Wright Corporation today announced that its Defense Solutions division has introduced a new fully i...


Curtiss-Wright Corporation’s Defense Solutions division applauds Northrop Grumman Corporation (NYSE: NOC) o...

Curtiss-Wright’s New Rugged Mobile IP Router Subsystem Features an Integrated Cisco® 5915 ESR Router

Curtiss-Wright Corporation today announced that its Defense Solutions division, a Cisco® Systems Solution T...

GE Announces First Sub-Credit Card-Sized Multi-Function High Definition (HD) Video Tracker

HUNTSVILLE, AL.— OCTOBER 13, 2014—GE’s Intelligent Platforms business today announced at AUSA (October 13-...


Meeting the Gen3 backplane challenge with OpenVPX and COTS

Tight Pentagon budgets mean military systems must stay in the field for longer than ever before. This doesn't mean obsolete technology, however. Today's military electronics are being upgraded constantly, an...
Sponsored by:

Design Strategy Considerations for DO-178C Certified Multi-core Systems

Join Wind River to learn how system architecture and design choices can minimize your DO-178C certification challenges.

Sponsored by:

Flying, Sailing or Driving - The Rugged, Embedded Intel-based Server that goes where you need it!Flying Sailing or Driving

Leveraging the power of server-class processors is no longer relegated to the confines of data centers. Through several innovations, Mercury Systems has ruggedized Intel’s server-class chips for deployment. ...
Sponsored by:

All Access Sponsors

Mil & Aero Magazine

April 2015
Volume 26, Issue 4

Download Our Apps




Follow Us On...


Military & Aerospace Electronics

Weekly newsletter covering technical content, breaking news and product information

Cyber Security

Monthly newsletter covering cyber warfare, cyber security, information warfare, and information security technologies, products, contracts, and procurement opportunities

Defense Executive

Monthly newsletter covering business news and strategic insights for executive managers

Electronic Warfare

Quarterly newsletter covering technologies and applications in electronic warfare, cyber warfare, optical warfare, and spectrum warfare.

Embedded Computing Report

Monthly newsletter covering news on embedded computing in aerospace, defense and industrial-rugged applications

Unmanned Vehicles

Monthly newsletter covering news updates for designers of unmanned vehicles