RELATED: Curiosity Kicks Off Next Mars Odyssey With a Selfie
"We are in the process of defining a set of diagnostic tests to carefully assess the drill feed mechanism," said Steven Lee, Curiosity's Deputy Project Manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "We are using our test rover here on Earth to try out these tests before we run them on Mars.
"To be cautious, until we run the tests on Curiosity, we want to restrict any dynamic changes that could affect the diagnosis. That means not moving the arm and not driving, which could shake it."
As Curiosity lowers its robotic arm to the surface to commence drilling, the drill feed mechanism extends the drill bit to make contact with the ground. According to mission engineers, it appears that either a physical brake on the feed didn't disengage fully, or Curiosity detected some abnormality with the feed's motor's electrical encoder. Both scenarios would have caused Curiosity to disengage.
Interestingly, this isn't the first time problems have occurred with the instrument. The drill offers two modes of operation; the first is purely rotary, where the drill piece rotates like the hand drill you have in your toolbox and the mode that it attempted on Dec. 1. The second mode provides a percussion drilling method that has an action like a tiny pneumatic drill or a chisel. Either or both drilling methods can be employed depending on the rocky material being sampled. Since February 2015, the percussion mechanism has been experiencing intermittent short circuits, so mission managers decided to use this mode sparingly.