The Guided Wave HPV analyzer is a simple turnkey solution for the measurement of hydrogen peroxide and water (H₂O₂ and H₂O) concentrations in vapor phase. These are both measured together because they are codependent. The analyzer operates in real-time, which takes the guesswork out of determining the H₂O₂ and H₂O concentrations during cycle development and throughout the actual sterilization cycle. NASA will gain continuous, accurate data for documentation and validation by using Guided Wave’s HPVA.

Why Choose Vapor Hydrogen Peroxide (VHP) Sterilization

Thermally sensitive electronics and hardware on modern spacecraft are not compatible with heat microbial reduction (HMR).  As a result, various low temperature vapor phase sterilization methods were considered. Ethylene oxide with Methyl bromide and Formaldehyde with Paraformaldehyde leave organic residue. Consequently, these alternatives are not ideal for organic sensitive hardware. On the other hand, Hydrogen peroxide (H₂O₂) does not leave organic residue. Oxygen and water are the only by-products. VHP is also cheaper, ideal for heat-sensitive parts, more efficient and takes less time to process than HMR.

The Jet Propulsion Laboratory (JPL) at the Biotechnology and Planetary Protection Group conducted literature review and research work to define process specifications in order to pursue vapor phase hydrogen peroxide (VHP) as an alternative sterilization technique. Quoted from their site,

“During research work, microbes were selected to test the lethality of the technique, including Bacillus stearothermophilus, Bacillus subtilis var. niger, Bacillus pumilus and Bacillus circulans.”

The microbes were deposited on different materials including aluminum, polymer, paint, and epoxied graphite. Following the research work and results, NASA PPO granted approval to use this technique for spacecraft subsystems and systems.

The initial stage for VHP sterilization involves a vacuum chamber where water is evacuated from the environment. In the next stage, H₂O₂ is injected into the chamber. In the third stage, sterile filtered air is injected into the chamber, which allows H₂O₂ vapor to penetrate the packaging and diffusion restricted areas to enhance the efficacy of the sterilization process. In the final stages of the process, the chamber is evacuated once more, followed by venting with sterile filtered air: the concentration of hydrogen peroxide vapor returns to ambient levels and the enclosure can be opened to retrieve contents.

NASA PPO has approved the use of VHP as a low-temperature sterilization modality, for simple surfaces, with specifications for time, rate, and H₂O₂ concentration levels. Complex geometries (e.g., vented boxes and electronic chassis inside the warm electronics box of a rover), however, require further directions. Thus, an additional study aims to describe the effect of VHP on electronic materials, materials with different configurations, solder joints, etc. Work has also begun for developing a portable VHP system that can be used locally (e.g., at the site of hardware integration in a cleanroom or on the launch pad).

Collecting Samples from Mars and the Consequences

For the first time, the Mars 2020 rover, carries a drill that can collect core samples of the most promising rocks and soils. The rover will set them aside in a “cache” on the surface of Mars. A future mission could potentially return these samples to Earth. That would help scientists study the samples in laboratories with special room-sized equipment that would be too large to take to Mars.

The question of “is there life on another planet?’ is an ancient thought. However, the consideration of protecting that life – is a relatively new one.  If life does exist on other planets, such as Mars, then we need to consider the consequences of what might occur when material is accidentally or inadvertently transferred between plants. Addressing these consequences is at the forefront of NASA’s Planetary Protection Policy.

NASA’s Planetary Protection Policy and Contamination

NASA, Jet Propulsion Laboratory, California Institute of Technology states,

“Planetary Protection addresses microbial contamination of the solar system by spacecraft that we launch from Earth (forward contamination). This contamination must be prevented in order to preserve the integrity of exploring the solar system; celestial bodies that may have once held an environment suitable for life (e.g., Mars and outer planet icy bodies) are especially vulnerable. Likewise, extraterrestrial contamination of the Earth and Moon (backward contamination), by way of sample return missions, must be prevented. We must approach with caution and preparedness in bringing unknown and potentially dangerous biological materials back to Earth.

While searching for life on the surface of a solar system body (via life-detection instruments) or in future samples returned to Earth, contamination could result in the “false-positive” indication of life. Thus, Planetary Protection’s primary strategy to prevent contamination is to confirm that spacecraft launched from Earth is clean. This precaution ensures that planets, and any life that might be there, remain in their original pristine state for scientific analysis. After the hardware is treated with various forms of microbial reduction, technicians assembling the spacecraft frequently wipe hardware surfaces with an alcohol solution to keep the spacecraft clean. Planetary Protection engineers carefully sample the surfaces and perform microbiology tests to show that the spacecraft meets the specified requirements for biological cleanliness.

In addition to this mission implementation role, the Biotechnology and Planetary Protection Group seeks to develop or adapt modern molecular analytical methods to rapidly detect, classify, and/or enumerate the widest possible spectrum of Earth microbes carried by spacecraft (on surfaces and/or in bulk materials, especially at low densities) before, during, and after assembly, test, and launch operations. Additionally, the group aims to identify new or improved methods, technologies, and procedures for spacecraft sterilization that are compatible with spacecraft materials and assemblies”

From the white paper “The Evolution of Planetary Protection Implementation on Mars Landed Missions “ 

….”Cleaning and sterilization are distinctly different operations. Sterilization is the process to kill live microbes, while cleaning is a process that physically removes live and dead microbes and debris from hardware surfaces. The most commonly used current spacecraft hardware cleaning methods are precision cleaning and alcohol wiping. While these methods are efficient for cleaning massive contamination, they are not effective for removing micron and submicron-sized microbes and debris from hardware surfaces.

NASA planetary protection regulations state that a surface may be considered “sterile” if a microbial burden of less than 300 aerobic bacterial spores per meter² can be treated to achieve a 104-fold reduction in viable endospores (spores).”  To read the entire paper link here

Count Down to NASA’ Mars 2020 Launch
The launch window for NASA’s Mars 2020 Rover named Perseverance is between July 17 – August 5, 2020. This time frame is the best landing opportunity as Earth and Mars are in good positions relative to each other. Consequently, it will take less power to travel to Mars in comparison to other dates when Earth and Mars are in different positions in their orbits. Landing is estimated for February 18, 2021. The mission duration is approximately 687 Earth days which is at least one Mars year. Guided Wave is excited to have our HPVA equipment be a part of this historic event.

NASA is determined to get its life-hunting Mars rover off the ground this summer despite the coronavirus outbreak.

For example, terephthalic acid (TPA) and dimethyl terephthalic acid (DMT) can both be synthesized by reacting P-xylene with cobalt–manganese–bromide catalyst, acetic acid, and air. Realtime quantitative monitoring of this caustic reaction is possible with the Guided Wave ClearView db analyzer along with an SST probe. The SST probe can be installed directly into the reaction vessel for continuous process monitoring and optimization. Additionally, in an extremely corrosive environment, the sample probe can be constructed out of Hastelloy C276.

In batch polymerization, DMT reacts with ethylene glycol in esterification to form monomer alcohol, which then polymerizes with TPA. The continuous method, on the other hand, involves a polymerization between TPA and ethylene glycol, so DMT is not necessary. Both methods involve heating either DMT or TPA with ethylene glycol to about 536 ºF for 30 minutes at atmospheric pressure, and then the mixture spends 10 hours under vacuum. near-infrared analyzers such as the ClearView db and NIR-O Process analyzers can be used to provide in-situ monitoring of the cross-linking under vacuum conditions. Out of specification product can be detected with a high temperature shuttle probe and near-infrared monitoring during melt transfer. By monitoring the molten polymer stream for acid number, cost savings can be realized by preventing the off-spec product from reaching the extrusion or pelletizer.

Rugged sample interface designs built to withstand harsh polymer process conditions, as well as the low maintenance requirements make Guided Wave probes and flow cells a cost effective, smart choice to help optimize polymer production, improve yields, ensure consistent product quality and enhance profitability. While Guided Wave’s probes and flow cells are optically matched for use with Guided Wave NIR or UV-VIS analyzers to provide top system performance, they are also compatible with many other analyzer brands.