NSSC-1

The NASA Standard Spacecraft Computer-1 (NSSC-1) is a

Floating point

arithmetic was not supported.

Usage

The NSSC-1 was used on the

Solar Maximum Mission
Hubble Space Telescope (for spacecraft control, not image data handling which initially used the DF-224)
Landsat-D,D' Missions, renamed Landsat 4 and Landsat 5

and other missions that were mostly limited to the solar system, eg Gamma Ray Observatory, and UARS.^[1]^: 910

The prior OBP hardware was developed by

medium-scale integration) TTL chips from Harris.^[1]

^: 904

The NSSC-1 was implemented by IBM using TRW versions of the Harris chips.[1]^: 905

Programming and support

The NSSC-1 had an

flight dynamics simulator hosted on a PDP-11/70 minicomputer.^[2]

A purpose-built NSSC-1 Flight Executive was developed for use on the Solar Maximum Mission (SMM) and subsequent flights. It switched tasks at intervals of 25 ms and included a stored

relative time commands. It had a status buffer that could be transferred back to a ground receiver station and thus required a lot of memory, typically more than half of that available, leaving the rest for applications and spare.^[3]

Historical context

Prior to NSSC-1

The Advanced Onboard Processor (AOP) was used on Landsat B & C, International Ultraviolet Explorer (IUE), and OSS-1. It used

transistor-transistor logic (TTL).^[1]

Subsequent to NSSC-1

In the 1980s the RCA 1802 was used for many missions—like Galileo. This mission and other missions started the trend away from custom built NASA CPUs in spacecraft. The exploration of the inner and outer parts of the solar system would have to be done with existing (civilian and military-aerospace) CPUs.

Before the RAD family of 32 bit CPUs were used in space missions, the MIL-STD-1750A (a CPU that could run modern applications) saw substantial use.

Since the arrival of the IBM RAD6000 in the 2000s and the RAD750 in the 2010s, using the NSSC-1 has become unthinkable. Its computing power was not great, and most modern space missions require flight computers to have substantial and substantive computing power.

References

^
S2CID 9237533.{{cite journal}}: CS1 maint: multiple names: authors list (link
)

^ Styles, F., Taylor, T., Tharpe, M. and Trevathan, C. “A General-Purpose On-Board Processor for Scientific Spacecraft,” NASA/GSFC, X-562-67-202, July 1967.
^ Stakem, Patrick H. The History of Spacecraft Computers from the V-2 to the Space Station, 2010, PRB Publishing, ASIN B004L626U6