To explore space is to defy the dust
As the world’s space agencies prepare to return to the Moon and explore the planets, space materials engineers have come to grips with a formidable enemy: dust. The talc-like abrasive dust that shrouds the Moon and other planetary surfaces can darken surfaces, wear down coatings, and clog space mechanisms.
For ESA, dust contamination is a pressing issue for upcoming missions such as the International Lunar Gateway – a planned station in lunar orbit comprising European modules, which will serve as a base camp for stays on the surface of the Moon – and the Argonaut European Large Logistics Lander, EL3, intended to carry cargo for lunar settlers, who would stay on the Moon for long periods of time.
ESA is also responsible for the sample transfer robotic arm of the International Mars Sample Return Campaign – with the crucial role of taking samples from Mars rovers to place on an ascent rocket for return. on earth. The dust could potentially interfere with the mechanisms of the 2.5m long arm.
Materials engineers from the Agency met their international counterparts at the recent ISMSE-13/ICPMSE-15 Materials in the Space Environment conference in Leiden, the Netherlands, with dust control being one of the main topics in discussion.
They presented research, including a dedicated planetary dust simulation facility – currently under development at ESA’s ESTEC Technology Center in the Netherlands – which will be used to study charging effects and thermal displacements and optics induced by dust in surfaces. They also evaluated the effects of dust on spacesuit textiles and, with actual moon dust being worth more than its weight in gold, they are evaluating the most suitable lunar simulants for testing purposes.
From dust to dust – on the Moon and beyond
James Gaier, a retired NASA scientist who worked on the Apollo program, chaired a dedicated panel discussion at the conference. He noted that “lunar dust is present everywhere on the Moon, created by the constant bombardment of micrometeorites pulverizing the rocky surface into fine particles. Unlike earth dust, it has never been weathered by water or wind, so even microscopic particles still retain razor-sharp edges. And the unfiltered energy of the lunar sun can give dust a strong static cling.
Looking further afield, the same is true for the Martian surface – with the wind to move it around the planet – as well as the rocky atmosphere-devoid moons and numerous asteroids.
Apollo astronauts who encountered lunar dust first-hand during Apollo’s day-long landings on the surface of the Moon highlighted the challenge it presents for longer stays in their mission debriefs.
Apollo 12 Commander Pete Conrad noted, “I think one of the most aggravating and limiting facets of lunar surface exploration is dust and its clinging to anything, no matter what. type of material, whether skin, suit material, metal, whatever. what it is and its restrictive rubbing action on whatever it gets. He added that even the outer layers of spacesuits were beginning to be worn.
Apollo 17 Commander Gene Cernan agreed, “I think dust is probably one of our biggest inhibitors to nominal operation on the Moon. I think we can overcome other physiological or physical or mechanical problems except dust. »
More recently, China’s Yutu-1 rover was reportedly grounded on its second day on the Moon by lunar dust clogging its moving parts.
Dusty Lunar Landings
Calling lunar dust contamination Apollo’s unfinished business, Carlos Soares of NASA’s Jet Propulsion Laboratory (JPL) contamination control engineering team explained that the problem begins during landing – depending on the size of the lander involved, its rocket boosters could dislodge tons of lunar dust. regolith upon touchdown, which could then become lodged on the lander’s surfaces and cover the entire landing area.
JPL therefore developed a complex modeling-based framework to simulate lunar landing events, starting with recreating Apollo landings, to help enable degradation assessments. To help validate these simulations, propellant plume testing was performed using the German Aerospace Center’s STG-CT high-vacuum plume test facility. The framework has also been applied to other planetary landing scenarios, including a landing on Europa, Jupiter’s ice-encrusted moon.
A team led by the Italian National Center for Aerospace Research (CIRA) also presented their work on the development of a specially designed anti-dust polymer, with modified surface properties to form “non-stick” surfaces.
New environments and spatial problems
Co-hosted with the French space agency CNES, the French aerospace laboratory Onera and the Integrity Testing Laboratory Canada, ISMSE-13/ICPMSE-15 from September 18-23 marked the first time that the international l Space Materials Engineering had been meeting in person for four years, joined by participants from Japan Aerospace Exploration Agency JAXA and China National Space Administration (CNSA) as well as national space agencies.
Materials engineer and ESA co-organizer Adrian Tighe explains: “In one form or another, this event has been going on for four decades now, where we come together to discuss many of the issues currently facing the space sector. in terms of spatial environment. and its effect on materials.
“So, in addition to the subject of dust, we have seen for example a focus on the problems associated with satellites flying very close to the Earth – at so-called ‘very low Earth orbit’ altitudes – where the highly erosive atomic oxygen is encountered at the top of the atmosphere.could be a problem for planned constellations as well as the challenge of simulating material-level damage from orbital debris, which is proving to be an increasingly important factor in orbits with heavy traffic.
“Then there is the growing trend around commercialization, including the desire to use more ‘off-the-shelf’ parts for cheaper and faster space missions, in place of traditional components and materials. qualified for space – but needing a balance in terms of performance, radiation tolerance and so on.This is followed by discussions of brand new manufacturing and testing methodologies based on concepts such as scanning and modeling, l intelligence and machine learning, opening up many new possibilities!
ISMSE-13/ICPMSE-15 was hosted at the Naturalis Biodiversity Center in Leiden, allowing for a fascinating discussion of the process of preserving dinosaur bones before they were put on display, and giving context to a discussion on the ” biomimetic” for space – mimicking natural systems and lifespans for engineering purposes.