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September 13th, 2016 ~ by admin

OSIRIS-REx: Bringing Back Some Bennu

OSIRIS-Rex: RAD750 to Bennu

OSIRIS-Rex: RAD750 to Bennu

The Apollo Group  carbonaceous asteroid Bennu is a potential Earth impactor, with a 0.037% likelihood of hitting earth somewhere between 2169 and 2199.  Bennu is thought to be made of materials left over from the very early beginnings of our solar system, making researching them a very tantalizing proposition.  Rather than wait for the small chance of Bennu delivering a sample to Earth in 150 years the thoughtful folks at NASA decided to just go fetch a bit of Bennu.  Thus is the mission of OSIRIS-REx which was launched a few days ago (Sept 8, 2016) aboard an Atlas V 441 as an $850 Million New Frontiers mission.

Somewhat surprisingly there is scant details about the computer systems that are driving this mission to Bennu.  OSIRIS-REx is based on the design of the Mars Reconnaissance Orbiter (MRO), MAVEN and Juno, and thus is based on the now ubiquitous BAE RAD750 PowerPC processor running the redundant A/B side C&DH computers.  This is the main ‘brain’ of the Lockheed Martin built spacecraft.  Of course the dual RAD750s are far from the only processors on the spacecraft, with communications, attitude control, and instrumentation having their own (at this point unfortunately unknown) processors.

REXIS Electronics: Virtex 5QV - Yellow Blocks are Off the Shelf IP, Green Blocks are custom by the REXIS Team. Powered by a Microblaze SoftCore.

REXIS Electronics: Virtex 5QV – Yellow Blocks are Off the Shelf IP, Green Blocks are custom by the REXIS Team. Powered by a Microblaze SoftCore.

One instrument in particular we do know a fair amount about though.  Regolith X-ray Imaging Spectrometer (REXIS) is a student project from Harvard and MIT. REXIS maps the asteroid by using the Sun as an X-ray source to illuminate Bennu, which absorbs these X-rays and fluoresces its own X-rays based on the chemical composition of the asteroid surface. In addition REXIS also includes the SXM, to monitor the Sun’s X-Rays providing context to what REXIS is detecting as it maps Bennu.  REXIS is based on a Xilinx Virtex-5QV Rad-Hard FPGA.  This allows for a mix of off the shelf IP blocks, and custom logic as well. The 5QV is a CMOS 65nm part designed for use in space.  Its process, and logic design are built such as to minimize any Single Event Upsets (SEU), and other radiation induced errors.  It is not simply a higher tested version of a commercial part, but an entirely different device.   Implemented on this FPGA is a 32-bit RISC softcore processor known as Microblaze.  The Microblaze has ECC caches implemented in the BRAM (Block RAM) of the FPGA itself and runs at 100MHz.

It will take OSIRIS-REx 7 years to get to Bennu, sample its surface, and return its sample to Earth.  By the time it gets back, the RAD750 powering it may not be so ubiquitous, NASA is working on determining what best to replace the RAD750 with in future designs.  Currently several possibilities are being evaluated, including a QuadCore PowerPC by BAE, a QuadCore SPARC (Leon4FT), and a multi-core processor based on the Tilera architecture.  As with consumer electronics, multi-core processors can provide similar benefits in space of hogher performance and more flexible power budgeting all with the added benefit (when design for such) of increased fault tolerance.

July 3rd, 2016 ~ by admin

Juno Joins Jupiter: And Brings Some Computers For The Trip

Juno - RAD750 Powered Mission to Jupiter

Juno – RAD750 Powered Mission to Jupiter

NASA’s Juno mission to Jupiter arrives in just about a day, after a 5 year journey that began in August of 2011 aboard an Atlas V rocket.  The Juno mission is primarily concerned with studying the magnetic fields, particles, and structure of Jupiter.  Finding out how Jupiter works, and what its core is made of are some of Juno’s goals.  None of the experiments need a camera, but NASA decided, in the interest of public outreach and education, that if you are going to spend $1 billion to send a probe to Jupiter, it probably should have a camera.  Energetic particle detectors, Magnetometers, and Auroral Mappers are great for science, but what the public is inspired by is pretty pictures of wild and distant worlds.

Juno is powered by a now familiar computer, the BAE RAD750 PowerPC radiation hardened computer.  It operates at up to 200MHz (about the processing power of a mid 1990’s Apple Computer) and includes 256MB of Flash memory and 128MB of DRAM.  It (and the other electronics) are encased in a 1cm thick titanium radiation vault.  Flying in a polar orbit around Jupiter, Juno will experience intense radiation and magnetic fields.  The probe is expected to encounter radiation levels in the order of 10Mrads+.  The vault limits this to 25krads, within what the electronics can handle.  It should be noted that a dose of 10krads is fatal in most cases.  This intense of radiation will degrade the prober, even with shielding, resulting in a mission life of only 37 orbits (a little over a year) before the probe will be gracefully crashed into Jupiter.

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November 19th, 2013 ~ by admin

MAVEN To Mars: Another BAE RAD750 CPU

MAVEN to Mars - RAD750 Powered

MAVEN to Mars – RAD750 Powered

NASA has successfully launched the $671 million MAVEN mission to Mars for atmospheric research.  Like the Mars Reconnaissance Orbiter it is based on, it’s main computer is a BAE RAD750,  a radiation hardened PowerPC 750 architecture.  This processor first flew on the Deep Impact Comet chaser and is capable of withstanding up to 1 million rads of radiation.  The entire processor sub-system can handle 200,000 rads.  To put this in perspective, 1000 rads is considered a lethal dose for a typical human.  Likely much higher then a Apple Mac G3 that the PowerPC 750 was originally used in back in 1998 as well.   The processor can be clocked at up to 200MHz though often will run slower for power conservation.

The MAVEN should reach Mars within a few days of the Indian Space Agency’s $71 million Mangalyaan Orbiter launched earlier this month.  MAVEN is taking a faster route, at the expense of a heavier booster and larger fuel consumption.  The Mangalyaan Orbiter’s main processor is the GEC/Plessey (Originally produced by Marconi and now Dynex) MAR31750, a MIL-STD-1750A processor system.