Battery Radiation Protection on OSIRIS-REx

The ancient Egyptians imagined a universe populated by deities in control of their world. Their god Osiris was in charge of fertility, agriculture, the afterlife, the dead, resurrection, life, and vegetation. Bennu, on the other hand, managed sun, creation and earth. But if the asteroid bearing that name struck our planet, technology might need more than battery radiation protection to survive.

Sampling Bennu Under Battery Radiation Protection

Asteroid 101955 Bennu is a carbonaceous asteroid, some 51 million miles from earth in the Apollo group. The lump of rock approximately 1,800-feet across, is the most likely hazardous object to strike earth between 2178 and 2290, although this would be a long-shot. Notwithstanding this, NASA decided to collect a physical sample to analyze its composition at the micro level.

But the sample-return-mission would need battery radiation protection for its delicate systems to survive sun’s constant bombardment beyond earth’s atmosphere. The power system they designed for the mother-craft comprised two solar power arrays delivering energy to two identical 28-volt, 30-ampere-hour batteries.

However, the return capsule needed to be trimmed down to the basics. And so the final success of the mission arguably depended on two, 8-cell lithium batteries. All that effort, and all mission control’s hopes relied on their ability to survive, and faithfully help bring the samples safely to earth 2572 days after original mission lift-off.

The OSIRIS-REx Batteries Had Impressive Lineage

The report by NASA we link to below, details how the OSIRIS-REx batteries evolved from earlier 30Ah, 28V versions. This time, however, they required a radiation enclosure around the electronics leading to a modified installation footprint. NASA shock-tested these extensively, so they knew they would withstand the critical touch-grab-and-go impact on Bennu.