Before dawn broke over the skies of Cape Canaveral on the morning of October 15, 1997, Cassini began its 7 year, 2.1-billion-mile journey to explore the Saturn system. Onboard, the shellfish-like Huygens probe would attempt the first-of-a-kind landing on Titan, one of Saturn’s icy moons. The aim of that mission: to gather information about the mysteries of Saturn’s rings and their moons and, perhaps, take a glimpse into the origins of our solar system.
Hidden deep within Cassini and the Huygens probe were small, spherical beads of carbon technology, ready to collect and concentrate gases for analysis. The Carboxen® astronauts from the Supelco® portfolio were ready to bravely go where no adsorption technology had gone before and the insights they would gather would change the fundamental theories of how our solar system came to be.
The Huygens probe nestled in its descent module. Image Credit and Copyright: European Space Agency
“This wasn’t our first NASA project and it wouldn’t be our last,” explains William ‘Bill’ R. Betz, Head of the Particle Design Group at Merck. “Our Carbosieve technology was used on the Voyager missions and gained enormous insight into the chemistry of planetary atmospheres. But this mission required us to take carbon adsorption technology to another level.”
“NASA needed to detect a range of gases and elemental isotopes with technology that was robust enough to withstand high g-forces and the chemical onslaught of Titan´s methane and organic-rich atmosphere. Of course, we jumped at the chance and the whole team was determined to create a solution that would meet all of NASA’s needs.”
Supelco® product technology would be used in two analyzers. The ion and neutral mass spectrometer (INMS) on Cassini featured Carboxen® 1004 – a highly engineered, meticulously uniform, multi-porous layer of carbon spheres to analyze hydrogen isotopes and small chain hydrocarbons. These results would be used to refine the Big Bang theory and look for indicators of lifeforms.
The gas chromatography-mass spectrometer (GC-MS) on the Huygens probe included Carboxen® 1017- a graphitized carbon molecular sieve. This technology would make the 2.5-hour descent to the surface of Titan, gathering and concentrating samples as it fell before spending 72 minutes collecting data on Titan’s surface.
“The energy in the room was palpable when we heard the results,” Betz remembers. “Huygens established that the primary gases in Titan’s atmosphere were nitrogen and methane. By detecting ratios of carbon and nitrogen isotopes and noting the absence of noble gases, other than Argon, the evolution of Titan’s atmosphere could be modeled. This revealed contrary data to that measured in Venus and Jupiter and played into bigger conversations around planetary creation.
“It’s astonishing to think that the data from Titan might shape the way we view our solar system,” states Betz. “We know now that methane and ethane rains from clouds and gathers in rivers and lakes at the poles and the solid surface consists of water ice covered with sands of hydrocarbons that fall from the atmosphere. This paints a pretty accurate picture of the early days of Earth’s formation.”
Cassini completed its final mission looping in and out between Saturn and its rings before plummeting into the planet, continuing to transmit data before burning up like a meteor and becoming part of the planet itself.
But this wasn’t the end of Carboxens in space. In 2018, NASA called again, this time with a mission in miniature atmosphere monitoring onboard the International Space Station (ISS). Working with NASA´s Jet Propulsion Laboratory, Merck was asked to provide the preconcentrator for the micro-electrical mechanical systems preconcentrator gas chromatograph (MEMS PCGC). This future-proofed technology would provide critical major constituent and trace gas analysis onboard the ISS, on extra-vehicular activities and inside spacesuits.
“This development required a huge technological leap,” remembers Dr Leidy Peña Duque, Senior Scientist, Adsorption Technologies. “NASA wanted to improve current air monitoring systems in nearly every way: smaller and lighter units, more frequent monitoring and continuous operation. The astronauts depend on the data from these systems, even slight imbalances in atmospherics ratios can have fast and serious consequences. Our technologies needed to be failsafe but also deliver against a whole range of performance targets.”
The team used Carboxen 1000, a monolayer of high-purity, synthetic carbon spheres each measuring between 177 – 250 µm with a pore diameter of just 10 – 12 Å. This tiny monolayer, provided on a chip no bigger than a small coin, concentrates gases by a factor of 4000, a huge leap from the previous system’s capabilities.
“This new system measures major gases every two minutes, providing a near real-time view on the atmosphere entering the astronauts’ lungs,” explains Duque. “Previous systems could only manage 3-5 hourly readings and on top of this, NASA can now test trace gases every week. This reliable companion is one-third of the mass of its predecessor and churns out data automatically. The astronauts know exactly what they are breathing and should any parameter change, they can take immediate action.”
“These little carbon beads pack so much potential and they have equally important roles here on Earth,” continues Duque. “Since they are synthesized in the laboratory, they have a purity and morphological profile that is much superior to naturally sourced activated carbon so they can be used in the most difficult purification processes.”
Carboxens are now being used in cutting-edge biologics production, most recently in purifying monoclonal antibodies (mAbs) to treat cancers and autoimmune diseases. Host cell proteins (HCPs) are a bioproduct of mAb production but they can cause an adverse immune response in patients if they aren’t removed from the final treatment. Low molecular weight HCPs are particularly difficult to remove due to their physicochemical properties and non-specific association with antibodies. Added to this, upstream processing creates highly variable conditions of pH and conductivity, rendering many purification processes unsuitable.
“With the highly customizable nature of Carboxens, purification can take place in extremes of pH and in hydrophilic and hydrophobic conditions and they are so effective that downstream ion exchange processes may not be necessary. This could be game-changing in improving the safety and efficacy of mAbs.”
“This is just the start of the journey for Carboxens and they are just one part of a wide portfolio of carbon technology from Supelco® brand,” continues Duque. “We are currently investigating their use in battery capacity applications to support precious metal catalysts. With the precision of Carboxens, we can reduce the amount of precious metals needed. This will be critical as we use these finite sources to journey towards more sustainable transportation and energy storage.”
Carboxens have served us well in space, now swirling within Saturn and diligently measuring the air that astronauts breathe. But as they continue their mission here on Earth, purifying life-saving cancer treatments and powering the sustainable energy revolution we know that these are just steps on their journey. Where might these little carbon spheres take us next?