Retrieving Clean Samples From Mars

Welcome to 2020! A new year and a new decade that’s ripe with possibility and opportunity. A time to take stock, change life up a little (or a lot), and refocus on priorities. Maybe for you it’s a renewed commitment to better health? More conscious curation of your social media stream? Or perhaps it’s that perennial favorite – quitting smoking? And for one major player in the space exploration field, this means so much more than giving up a personal habit: it’s a matter of policy – IEST-RP-CC027, to be precise. With the Mars 2020 Rover about to begin its coast-to-coast journey to Cape Canaveral ahead of launch this summer, scientists at NASA’s Jet Propulsion Laboratory in Pasadena, CA, are taking additional precautions to ensure sterility. And this includes contamination from second-hand smoke…

Looking endearingly similar to Pixar’s animated rover ‘Wall-e’, the Mars 2020 rover is scheduled for launch towards the Red Planet in July of this year. Embarking on what will be a mission of at least one Mars year (equivalent to 687 of our Earth days), the machine will land at the Jezero Crater on February 18, 2021 with the aim of gathering data on the planet’s geology, environment, atmosphere, and potential biosignatures. Based on the same configuration as the Mars Science Laboratory’s Curiosity rover, Mars 2020 is around 10 feet in length, 9 feet wide, and around 7 feet tall. At just 2,314lbs, it weighs a little less than a compact car and, over the course of the whole mission, will get even better mileage! But don’t let the diminutive size fool you – this machine incorporates state-of-the-art instrumentation including SHERLOC, PIXL, RIMFAX, and MOXIE. Who? Let’s take a quick look…

MOXIE and PIXL are a dynamic duo that together examine the chemical composition of Mars’ atmosphere and surface.

Developed at MIT by Principal Investigator Michael Hecht, MOXIE is the ‘Mars Oxygen In-Situ Resource Utilization Experiment’ and it is charged with creating oxygen from carbon dioxide. Currently the approximate size of a car battery, MOXIE will convert some of the ~96% CO₂ in the Martian atmosphere to oxygen to help propel human exploration of the planetary surface. PIXL – the ‘Planetary Instrument for X-ray Lithochemistry’ – uses an X-ray spectrometer to analyze the chemical composition of surface rocks, identifying up to 20 chemical ‘fingerprints’ and seeking evidence of past microbial life. The ‘Radar Imager for Mars’ Subsurface Experiment’ – aka RIMFAX – was developed by a team in Norway and leverages ground-penetrating radar to chart geological features below the planet’s surface including ice, liquid water, or salt brines. RIMFAX is especially unusual insofar as it is the first tool of this kind to be sent on a Mars mission and will be able to detect evidence of water up to a depth of 30 feet. And let’s not forget SHERLOC: the ‘Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals.’ With a distinct hands-off approach SHERLOC uses a fluorescence spectrometer, cameras, and a 248.6nm Deep UV laser to identify minerals, organics, and possible biosignatures. According to Luther Beegle, the Principal Investigator heading the SHERLOC team in Pasadena, SHERLOC’s mission is to address ‘[K]ey, driving questions [of] whether Mars is or was ever inhabited, and if not, why not? The SHERLOC investigation will advance the understanding of Martian geologic history and identify its past biologic potential.’(1)

A fundamental mission indeed.

And clearly, with this level of specialized equipment aboard, contamination control is absolutely imperative.

Moreover, as we know from our Learning Center article, ‘What are the most common sources of Contamination in a Cleanroom?’ human vectors – personnel and visitors – are the most likely source of potential cleanroom contamination. And this is why JPL’s Mars 2020 assembly, test and launch operations manager, David Gruel, held a firm line with media representatives invited to visit the rover prior to its journey to Florida. On December 27th, JPL opened the doors – metaphorically – to the Spacecraft Assembly Facility’s High Bay 1, a large cleanroom in the heart of a facility known as ‘the cradle of robotic space exploration.’(2) High Bay 1 and High Bay 2 are the best known of the areas within the facility and are both Class 10,000 cleanrooms, meaning they permit fewer than 10,000 particles sized 0.5 microns or larger per cubic foot of air. According to JPL, within High Bay 1 air cycles about 70 times per hour, temperature is controlled at a relatively chilly 68 degrees, and staff keep themselves warm by regularly cleaning surfaces with isopropyl alcohol, microfiber mops, and HEPA vacuums.

Components entering the area must first be unpackaged in an airlock on the ‘dirty’ side of the divide before being cleaned and moved into the sterilized environment.

And of course, there is a correct protocol to follow even in the method of cleaning. According to PharmTech, airflow visualization studies – ‘smoke studies’ – are an important tool in designing how the air should flow to ensure decontamination of items and the surfaces upon which they rest within a controlled environment. As writer Manuel M. Garza notes: ‘Dynamic studies should document that airflow […] is unidirectional and sweeping down and away from sterile equipment surfaces, container/closure systems, and product. Dynamic studies work to confirm that facility and equipment design, equipment operation, and personnel aseptic manipulations (i.e., interventions) do not disrupt the “first air” (i.e., air exiting the high-efficiency particulate air filters […] essentially particle free, in a unidirectional manner) to critical areas where sterile surfaces, materials, and products are exposed.’(3)

And decontamination protocols based on smoke studies like these apply not only to components and tools, but also to personnel and visitors as Jacob Margolis of National Public Radio (NPR) discovered: ‘Before you can get even a little close to the rover, you’ve got to prepare yourself to visit it in the clean room – no notepads and pencils with shavings that can fly off.’(4) And then it’s time to dress the part. JPL’s guidelines are strict: ‘Automated shoe brushes and sticky mats remove debris from [visitors’] shoes before they enter a locker room. Once their feet are covered with booties, they step over a line onto the clean side of the room.

Then it’s time to don a bunny suit, face mask, hair cover and latex gloves before taping sleeves closed. (A mannequin called High Bay Bob stands on the floor of High Bay 1, demonstrating proper attire and giving visitors a sense of scale.) Finally, they step into an “air shower” that blows stray particles off the outside of their garments.

Static electricity can interfere with electronics, so personnel wear an antistatic cord around one wrist, with a clip on the other end to attach to hardware in the clean room. As added precautions against static electricity, humidity in the room is kept at about 45% and the concrete floor has a special epoxy coating to bleed static charge that builds up in garments as people move about the room.’(5)

But this level of contamination control was not always so strictly enforced.

During the Ranger unmanned space programs of the 1960s, smoke played a very different role within the facility and engineers were permitted to smoke even within High Bay 1, something unthinkable today. In fact, as JPL historian Erik Conway notes, ‘The whole idea of a clean room for spacecraft assembly comes out of the Ranger program.’(6) And while we will never again see engineers lighting up in a sterile environment, smoke can still present a problem…

The Institute of Environmental Sciences and Technology (IEST), an association and reference point dedicated to contamination control, writes the standards for the entire cleanroom/sterile facilities arena. And one of these standards, IEST-RP-CC027: Personnel Practices and Procedures in Cleanrooms and Controlled Environments, specifically covers the establishment of personnel procedures and training programs for cleanroom environments.(7) Although, of course, good manufacturing practices (GMPs) mandate the prohibition of actively smoking within a contamination controlled environment, second-hand smoke is a contaminant that might not be so obvious. According to IEST-RP-CC027, personnel should refrain from smoking onsite for at least 30 minutes before entering a cleanroom in order to ensure they are not unwitting vectors of particulate matter within the smoke. And it’s obvious when it’s pointed out – after all, we are well aware that cosmetics, lotions, hairsprays, perfumes, and any other number of chemically-based unctions and potions are prohibited within sterile or aseptic environments. But given that the mandate came as a surprise to the invited media, we do also wonder how many new employees are surprised to be informed that smoking during a lunchbreak is detrimental to more than just their own physical health…

But why should NASA be concerned about something as miniscule as second-hand smoke particulates?

Contamination of any size is fundamentally antithetical to the 2020 mission both in terms of transmitting contamination to Mars and of spoiling samples that will be brought home in future missions. For the definitive last word on this, let’s return to the Mars 2020 rover, at time of writing still sitting in the JPL cleanroom. In his interview with NPR’s Jacob Margolis, David Gruel explained in stark terms the aim of the strict decontamination procedures that both personnel and visitors undergo in order to maintain a pristine environment for the craft: ‘It would be a real bad day for us in the future if those samples come back from Mars and – guess what? – they’ve got my whisker in that sample. [Or a] Kardashian perfume is sensed in the sample. That would be a bad day for us.’(8)

We can only agree. And more than that, even the thought of anything Kardashian-related on Mars would be a ‘bad day’ for many of us too…

What’s your take on this? Do you believe we’ll be able to retrieve clean samples from Mars? Or do you have concerns about the potential for contamination? We’d love to know your thoughts!

References:

1. https://mars.nasa.gov/mars2020/mission/instruments/sherloc/
2. https://www.jpl.nasa.gov/news/news.php?feature=7565
3. https://www.pharmtech.com/how-plan-smoke-studies
4. https://www.npr.org/2019/12/28/792022287/up-close-with-the-mars-rover
5. https://www.jpl.nasa.gov/news/news.php?feature=7565
6. ibid
7. https://www.iest.org/Standards-RPs/Recommended-Practices/IEST-RP-CC027
8. https://www.npr.org/2019/12/28/792022287/up-close-with-the-mars-rover