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Strings in Perseverance’s drill?

String in Perseverance's drill
Click for full image.

Since August 5th, the Perseverance science team has been trying to figure out the origin as well as the consequences of “two string-like pieces” of foreign object debris (FOD as used by today’s acronym-happy scientists) that they have spotted next to one of the rover’s coring drill bits.

The photo to the right, cropped and reduced to post here, looks directly down at that core drill bit and shows one of those strings both to the side of the bit as well in full resolution in the inset. From today’s update:

Since first identified Aug. 5 in imagery of the rover’s sample collection system after a 12th rock core sample was taken, the FOD has been the focus of several methodical diagnostic activities in an attempt to better understand the nature of the debris.

We’ve commanded the rover to move, rotate, or vibrate components we think could harbor FOD. And we’ve obtained multiple sets of images of the components from different angles and in different lighting conditions from rover cameras: Mastcam-Z, Navcam, Hazcam, Supercam, and even the WATSON (Wide Angle Topographic Sensor for Operations and eNgineering) camera located on the rover’s turret. Finally, a thorough review of recent coring and bit-exchange activities confirm that they all executed nominally with no indication of interference from the FOD.

Analysis of the latest round of imaging, downlinked earlier today, indicates that while the two small pieces remain visible in the upper part of the drill chuck, no new FOD has been observed. In addition, imagery taken of the ground beneath the robotic arm and turret, as well as the rover deck, also showed no new FOD.

Because these strings do not appear to interfere in any way with the drill’s operation, the science team has decided neither is a cause for concern, and will therefore command the rover to leave this just-completed drill site and move on to the southwest to a location at the base of the delta the rover visited about three months ago.

The strings themselves are likely pieces from the equipment released during the rover’s landing, and might even have come from the tangled string the rover imaged on the nearby ground in July, and that was gone just four days later. The wind had blown it away, and may have even at that time blown pieces into the drill.

Conscious Choice cover

Now available in hardback and paperback as well as ebook!


From the press release: In this ground-breaking new history of early America, historian Robert Zimmerman not only exposes the lie behind The New York Times 1619 Project that falsely claims slavery is central to the history of the United States, he also provides profound lessons about the nature of human societies, lessons important for Americans today as well as for all future settlers on Mars and elsewhere in space.

Conscious Choice: The origins of slavery in America and why it matters today and for our future in outer space, is a riveting page-turning story that documents how slavery slowly became pervasive in the southern British colonies of North America, colonies founded by a people and culture that not only did not allow slavery but in every way were hostile to the practice.  
Conscious Choice does more however. In telling the tragic history of the Virginia colony and the rise of slavery there, Zimmerman lays out the proper path for creating healthy societies in places like the Moon and Mars.


“Zimmerman’s ground-breaking history provides every future generation the basic framework for establishing new societies on other worlds. We would be wise to heed what he says.” —Robert Zubrin, founder of founder of the Mars Society.


All editions are available at Amazon, Barnes & Noble, and all book vendors, with the ebook priced at $5.99 before discount. The ebook can also be purchased direct from my ebook publisher, ebookit, in which case you don't support the big tech companies and I get a bigger cut much sooner.


Autographed printed copies are also available at discount directly from me (hardback $24.95; paperback $14.95; Shipping cost for either: $5.00). Just email me at zimmerman @ nasw dot org.


  • GaryMike

    From a pre-retirement spacecraft tech’s beard? Earth on Mars!

    It has begun!

  • Ohhh. ‘String Theory’; too tempting. And, cheap.

  • pawn

    “FOD” has been around a long time.

    Now it’s spread to other planets!!!

    They’ll probably find a tennis ball somewhere out there.

  • Wind blowing stuff around except when you need it to clear the solar panels.

  • Col Beausabre

    “FOD” normally refers to a jet engine ingesting something that damages the engine. Aboard aircraft carriers, before any engines are started for the day, the entire flight deck crew walks the length of the deck to find if anything that shouldn’t be there is cleared from the deck. We’re talking about a serious matter. “The crash of a Concorde, Air France Flight 4590, at Charles de Gaulle Airport near Paris on 25 July 2000 was caused by FOD; in this case a piece of titanium debris on the runway which had been part of a thrust reverser that had fallen from a Continental Airlines McDonnell Douglas DC-10 during takeoff about four minutes earlier. All 100 passengers and nine crew on board the flight, as well as four people on the ground, were killed.”

  • Edward

    Col Beausabre wrote: “Aboard aircraft carriers, before any engines are started for the day, the entire flight deck crew walks the length of the deck to find if anything that shouldn’t be there is cleared from the deck. We’re talking about a serious matter.

    In spacecraft construction, FOD is also a concern, which has caused expensive problems. The Russians had some bizarre debris in one of their ISS module tanks, which may have delayed its launch by years. I once worked in a large cleanroom in which we also had morning FOD walks, inspired by the ones performed on the U.S. Navy’s aircraft carriers. Another facility where I worked had a big search for a dropped small washer, just to make sure that it had not fallen into the waveguide, helping to justify such FOD walks and other “stow as you go” policies, because being clean made it easier to know that any washer found was the dropped washer.

    FOD and other contaminants is why we “old-school” engineers are so shocked that SpaceX builds their Starship test units in open buildings. They seem to store their Raptor engines in tents that are open to birds, bugs, and bats and whatever droppings, feathers, debris, other contamination they may leave behind. (Humidity and temperature control were also considered important for the safety of the flight hardware as it was being constructed and tested.)

    Despite Perseverance having been designed to operate in a dusty environment, look at the concern and trouble raised by a mere thread or two. Why the concern? They need to be sure that they aren’t from the rover (it isn’t falling apart or being damaged by something) and that neither will jam up some part of the mechanism or cause other trouble.

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