NASA Mars Perseverance Rover: Ejecting Martian Pebbles

Before and After Perseverance Sample Tube Shake

Before and After Perseverance Sample Tube Shake: An animated GIF depicts the Martian surface below the Perseverance rover, showing the results of the January 15, 2022, percussive drill test to clear cored-rock fragments from one of the rover’s sample tubes. Credit: NASA/JPL-Caltech

The team has made good progress implementing the initial recovery steps outlined last week. Our first success: The upper two pebbles were ejected from the bit carousel during a test. This is great news, as these small chunks of debris are believed to be the cause of the unsuccessful transfer of the drill bit and sample tube into the carousel back on December 29. Our second success: We appear to have removed most – if not all – of the cored rock that remained in Sample Tube 261.

Here is the latest…

Pebbles in Bit Carousel

On Monday, January 17, the WATSON camera imaged the bit carousel and its pebbles – and also took images underneath the rover to establish just what was down there before any recovery strategies were applied. Later that same Martian day, we rotated the bit carousel about 75 degrees before returning it back to its original position. WATSON imaging showed the two upper pebbles were ejected during the process. Tuesday night we also received the second set of under-rover images, which show two new pebbles on the surface, indicating the ejected pebbles made it fully through bit carousel and back onto the surface of Rotating Perseverance's Bit Carousel

Rotating Perseverance’s Bit Carousel: An annotated GIF depicts a rotational test of Perseverance’s bit carousel in which two of four rock fragments were ejected. The five images that make up the GIF were obtained by the rover’s WATSON imager on January 17, 2022. Credits: NASA/JPL-Caltech/MSSS

The other two pebbles, located below the bit carousel, remain. It is interesting to note that some of the initial trials performed on our testbed here on Earth indicate that the location of the two leftover pebbles may not pose a significant problem with bit carousel operation, but we are continuing analysis and testing to confirm this.

Remaining Sample in Tube

On Saturday, January 15, the team performed an experiment using Perseverance’s rotary-percussive drill. After the robotic arm oriented the drill with Sample Tube 261’s open end angled around 9 degrees below horizontal, the rover’s drill spindle rotated and then extended. Our remarkable Mastcam-Z instrument (which has video capability previously used to document some of Ingenuity’s flights) captured the event. The imagery from the experiment shows a small amount of sample material falling out of the drill bit/sample tube. Later that same Martian day, the bit was positioned vertically over “Issole” (the rock that provided this latest core) to see if additional sample would fall out under the force of gravity. However, Mastcam-Z imaging of 261’s interior after this subsequent maneuver showed it still contained some sample.

Perseverance Expels Rock Fragments

Perseverance Expels Rock Fragments: A portion of a cored-rock sample is ejected from the rotary percussive drill on NASA’s Perseverance Mars rover. The imagery was collected by the rover’s Mastcam-Z instrument on January 15, 2022. Credit: NASA/JPL-Caltech/ASU/MSSS

Given that some of the sample had already been lost, the team decided it was time to return the rest of the sample to Mars and hopefully completely empty the tube to ready it for potentially another sampling attempt. On Monday, January 17, the team commanded another operation of the rotary percussive drill in an attempt to dislodge more material from the tube. With the tube’s open end still pointed towards the surface, we essentially shook the heck out of it for 208 seconds – by means of the percussive function on the drill. Mastcam-Z imagery taken after the event shows that multiple pieces of sample were dumped onto the surface. Is Tube 261 clear of rock sample? We have new Mastcam-Z images looking down the drill bit into the sample container that indicate little if any debris from the cored-rock sample remains. The sample tube has been cleared for reuse by the project.

Perseverance's Sample Tube Looks Clean

Perseverance’s Sample Tube Looks Clean: This image, taken by the Mastcam-Z camera aboard NASA’s Perseverance Mars rover on January 20, 2022, shows the rover successfully expelled the remaining large fragments of cored rock from a sample tube held in its drill. Credits: NASA/JPL-Caltech/ASU/MSSS

Future Moves

The team is still reviewing the data and discussing next steps. Like all Mars missions, we’ve had some unexpected challenges. Each time, the team and our rover have risen to the occasion. We expect the same result this time – by taking incremental steps, analyzing results, and then moving on, we plan to fully…

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