Connect with us

Science

Dealing with dust: A back-to-the-moon dilemma – SpaceNews

Published

 on


If the political, technical and budgetary stars align for NASA and its partners in coming years, the moon could be the go-to place as the century unfolds. Astronauts would again explore Earth’s celestial next-door neighbor, perhaps setting in motion future mining endeavors to extract ices likely lurking in sunlight-shy craters for processing into water, oxygen, and rocket propellant. Humans that “settle in” on the moon could well be a future prospect.

Earth’s moon is a dusty denizen of deep space. View from the International Space Station. Credit: NASA/Jeff Williams

The next chapter in the U.S. human exploration of the moon, the Artemis Project, will dispatch crews there for extended periods of time, building upon Apollo’s heritage. Between 1969 and the end of 1972, a dozen astronauts kicked up the powdery regolith, the topside dirt of the moon. But there’s one flash back message from the Apollo moonwalkers worth heeding: the place is a Disneyland of dust.

During their landings, dust blown up into the thin lunar atmosphere impacted astronaut visibility. Once crews were out and about on the moon, the dust had deleterious effects on their spacesuits, helmets, equipment and instrumentation. Apollo expedition members could not escape tracking lunar material inside their lunar landers. After doffing their helmets and gloves, moonwalkers could feel the abrasive nature of the dust, even experiencing an “Apollo aroma” — a distinctive, odoriferous smell.

As explained by Apollo 17’s moon landing crew:

“I think dust is probably one of our greatest inhibitors to a nominal operation on the moon. I think that we can overcome other physiological or physical or mechanical problems except dust,” said mission commander Eugene Cernan. “One of the most aggravating, restricting facets of lunar surface exploration is the dust and its adherence to everything no matter what kind of material, whether it be skin, suit material, metal, no matter what it be and its restrictive friction-like action to everything it gets on,” said lunar module pilot and geologist, Harrison Schmitt.

AGENCY, INDUSTRY CONCERN

Study groups and technologists are assessing ways to lessen the negative impact of lunar dust on the astronauts, their equipment, and surface operations.

Apollo 17 commander Eugene Cernan prepares to doff dust-covered moonwalking spacesuit. Credit: NASA

Joel Levine, a research professor in applied science at The College of William and Mary in Williamsburg, Virginia, was convener and chair of a NASA workshop on lunar dust and its impact on human exploration. The message from that workshop held in February was clear. “Prior to the first Artemis human landing on the moon, we must better understand the particle size distribution, structure, chemical composition, potential toxicity, magnetic and electrical properties and the dynamics and distribution of lunar dust,” he said.

The workshop findings were published Sept. 24 as a NASA Engineering and Safety Center Technical Assessment Report, stating that the dust problem “is an agency and industry concern affecting most mission subsystems and it must be addressed.” The report also said that it is crucial that measurements and experiments be taken and carried out on the lunar surface by precursor landers to find out dust characteristics “that will influence hardware design, and provide toxicology data to safeguard crew health.”

PROTECTING LUNAR GEAR

Future machinery on the moon will be presented challenges, said Gerald Sanders, an expert on in-situ resource utilization (ISRU) for NASA’s Space Technology Mission Directorate at Johnson Space Center in Houston. Unlike other equipment and instruments that operate on the moon, ISRU systems and hardware need to operate continuously and in direct contact with lunar regolith and dust for very long periods of time. It is vital, he said, to develop techniques and technologies to resist abrasion, to safeguard optical coatings, as well as protect rotating mechanisms. In the end, easily replaceable components in lunar-situated gear will be critical.

Apollo 17 helmets and dusty spacesuits stuffed inside a lunar lander following the last human treks on the moon in December 1972. Credit: NASA

“While the Apollo missions and samples returned to Earth have provided a wealth of information, it will not be until the VIPER rover enters a permanently shadowed region that we will get a true sense of what the regolith is like to design future ice mining equipment,” Sanders said. NASA’s Volatiles Investigating Polar Exploration Rover, or VIPER, is a mobile robot that will go to the moon’s south pole, perhaps as early as December 2022 under NASA’s Commercial Lunar Payload Services program.

Philip Metzger, a planetary physicist with the Planetary Science faculty at the University of Central Florida, has focused his research on dust transport and its effects due to landing spacecraft on the moon.

“Lunar lander engine exhaust blows dust, soil, gravel, and rocks at high velocity and will damage surrounding hardware such as lunar outposts, mining operations, or historic sites unless the ejecta are properly mitigated,” said Metzger.

Decades of research have developed a consistent picture of the physics of rocket exhaust blowing lunar soil, “but significant gaps exist,” Metzger added. “No currently available modeling method can fully predict the effects. However, the basics are understood well enough to begin designing countermeasures.”

Metzger is principal investigator for the Ejecta Sheet Tracking, Opacity, and Regolith Maturity (STORM) instrument, set to fly on a Masten Space Systems Xodiac vertical takeoff and vertical landing system. The upcoming flight in Mojave, California, will gauge the density and sizes of particles that churn up during terrestrial simulations of lunar landings.

INTEGRATED DUST MITIGATION STRATEGY

NASA wants to place the first woman and next man at the lunar south pole in 2024. That location is advocated as a future base camp given possible access to ice and other mineral resources. However, still unknown are the true physical properties of the lunar dust and regolith in the polar regions.

Dust being displaced by engine exhaust from the Apollo 15 mission’s lunar lander, Falcon. Credit: NASA

Jorge Núñez of the Planetary Exploration Group at Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland, said a host of questions need to be tackled. “We can approximate and extrapolate based on the data we already have, but we will not really know until we land in those regions,” he said.

“As we learned from the Apollo missions, lunar dust can cause a wide range of issues, including being a hazard to astronaut health, sticking to all kinds of surfaces like spacesuits, visors and windows, solar panels, and radiators,” Núñez said. Lunar dust also degrades seals, fabrics, and mechanisms. Dealing with dust is going to require an “integrated dust mitigation strategy,” he added, such as using slow, methodical movements and allow adequate time for dust cleaning protocols, as well as keeping spacesuits outside of the pressurized habitat or lunar rover, to utilizing an electrodynamic dust shield to repel dust off materials.

Núñez said that NASA’s Lunar Surface Innovation Initiative is accelerating the development of many of these dust mitigation technologies that are important for enabling human missions on the surface of the moon.

MOON SIMULANTS

The reactive nature of lunar dust to humans is another area flagged by APL’s Karl Hibbitts, lead facilitator for the ISRU focus group of the Lunar Surface Innovation Consortium. The lunar dust has been known to be troublesome in this area since the Apollo era. The particles are chemically very reactive, he said, thus the potential health concern (although various passivation techniques to make them less reactive are being explored).

Apollo 11 Lunar Module Pilot Buzz Aldrin’s bootprint. Aldrin photographed this bootprint about an hour into their lunar extra-vehicular activity on July 20, 1969, as part of investigations into the soil mechanics of the lunar surface. This photo would later become synonymous with humankind’s venture into space. Credit; NASA

“We have attempted to study the reactivity of lunar soils in the lab,” Hibbitts said, “but the studies I know of have all been on samples already altered by the Earth’s atmosphere. The new studies on carefully curated lunar soils will hopefully shed some new insights.” Furthermore, as far as “simulants” go — concoctions of made-on-Earth material to imitate the properties of the lunar regolith — one has to choose which properties one needs the simulants to mimic. “It’s not possible to create literally tons of lunar soil, or possibly even a small amount. Facilities are just now learning how to make realistic agglutinates,” he added, and yet to be reproduced is the nanophase metallic iron that’s resident in the moon’s regolith.

“We’re getting better at approximating the shape and size distribution function, but the reactivity could only be mimicked by production in a vacuum chamber and will always be limited to tiny quantities,” Hibbitts told SpaceNews.

So far, human contact with tiny, very sharp, glassy lunar dust particles only occurred briefly during the Apollo missions, said Peter Sim, an emergency medicine specialist in Newport News, Virginia. But in returning to the moon and establishing a long-term presence, lunar dust, in sufficient doses, represents a “toxic threat” to human health, he said.

The respiratory system is particularly susceptible, Sim said, but the eyes, skin, and possibly the gastrointestinal tract and other organs may also be affected. Primary prevention of human exposure to lunar dust “should be our number one goal,” he advised.

He added that NASA’s new Exploration Extravehicular Mobility Unit (xEMU) spacesuit will help keep the dust at bay. It has a group of dust-tolerant features, to prevent inhalation, or contamination of the suit’s life support system. Still, keeping habitats dust-free by minimizing incursions, and using effective atmospheric filtration systems, will be a major challenge. “Monitoring of the dust that is present inside lunar habitats will be crucial, since the hab is the place where astronauts are most likely to be exposed. Because of this, the quantity, size, and potential toxicity of the ‘hab dust’ is of paramount importance,” he said.


SpaceNews contributor Leonard David is the author of “Moon Rush: The New Space Race” published by National Geographic in May 2019.

This article originally appeared in the Dec. 14, 2020 issue of SpaceNews magazine.

Let’s block ads! (Why?)



Source link

Continue Reading

Science

The Olduvai Gorge gives up two-million-year-old secrets – Varsity

Published

 on


Few archaeological sites can claim to be famous, but the Olduvai Gorge in northern Tanzania is chief among them. With the word ‘olduvai’ coming from a misspelling of the Maasai word, ‘oldupai,’ a name for a plant that grows in the area, the fossil-rich region is famous for offering up some of the first evidence of fossil remains and stone tools used by early hominins, ancestors of today’s humans.

In the 1930s, Louis and Mary Leakey were working in Olduvai when they uncovered stone tools from early humans. Since then, it has become a popular archaeological site. The gorge lent an even older name — the Oldoway Gorge — to the paleolithic culture discovered there before the Abbevillian culture and, subsequently, their tools. Oldowan tools are often either large hammering stones or smaller, sharper flake stones used for cutting. They were used by precursors to modern Homo sapiens, such as Homo habilis.

Now, an international research team comprised of scientists from around the world, including from U of T, have conducted a thorough search of the Olduvai Gorge and concluded that hominins were living and building tools in the site as early as two million years ago. Moreover, their continual occupation of the gorge, extending over a 235,000-year period, shows how early hominins could adapt to changing environments — a skill that might have aided in their expansion out of Eastern Africa.

A wide source of information

The researchers combed through a wide array of sources to reach their findings. They took samples from previously excavated fossils and tools and compared them against samples of pollen, plants, and charcoal from wildfires, which were all deposited into the soil millions of years ago. The result was a pattern of human activity in the same place across time.

The prehistoric Olduvai landscape contained a variety of environments, such as streams, floodplains, woody forest, dry steppe, and even patches of land covered by ash from volcanic activity. Early hominins were able to exploit all of these environments, partly by bringing materials they needed for tools with them. Some of the rocks used to make tools originated 12 kilometres from where they were found. Others were made using what was at hand.

However, it is not clear which hominin species made these tools, largely because no new fossils were found. One possible candidate is Homo habilis because their fossils have been excavated nearby.

Rethinking the past

Oldowan tools have been excavated in nearby Ethiopia dating back to 2.6 million years ago, so this study does not represent the earliest discovery of stone tools. But it does extend the timeline of the Olduvai Gorge specifically. Previously, the oldest use of tools in the region was dated to 1.85 million years ago, so these findings push that start point by about 150,000 years. 

Moreover, these new findings demonstrate that early hominins had a robust ability to adapt to new environments. Julio Mercader Florin, lead author and professor at the University of Calgary, wrote in The Conversation that “This is a clear sign that 2 million years ago humans were not constrained technologically and already had the capacity to expand geographic range.”

The researchers discovered that the tools used remained the same regardless of what environment they were found in. It might have been human adaptability, then, that enabled our ancestors to thrive in the Olduvai Gorge and beyond.

Let’s block ads! (Why?)



Source link

Continue Reading

Science

Test fire of NASA's SLS moon rocket ends prematurely – CTV News

Published

 on


NASA’s Space Launch System rocket ignited its four main engines Saturday on a test stand in Mississippi, but the engines shut down earlier than the agency planned.

The hot fire test was the last of eight tests that make up what NASA calls a “green run,” a series of ground tests aimed at ensuring the vehicle doesn’t have any major structural or engineering issues before it is put on a launch pad. The rocket is the most powerful launch vehicle the space agency has ever constructed.

The SLS was supposed to light its engines for about eight minutes, the length of time the engines will have to fire to propel the rocket on its orbital missions.

It’s not yet clear why the engines powered down after little more than a minute at NASA’s Stennis Space Center near Bay St. Louis, Mississippi. The test was still useful for gathering data and “teams are assessing the data on early engine shutdown,” the space agency tweeted.

During a Saturday night news conference, John Honeycutt, the SLS program manager, said NASA officials will go over the data gathered in the test to identify the issue.

“What we learned was — is that we didn’t have the pressurization valve modeled appropriately,” Honeycutt said.

Officials had hoped to run the test for at least 250 seconds, he said.

During the hot fire test, engineers “power up all the core stage systems, load more than 700,000 gallons of cryogenic, or supercold, propellant into the tanks and fire all four engines at the same time,” according to NASA.

It is unclear if another test will be needed before the rocket is shipped to Florida, the launch site where the rocket is expected to make its first journey into outer space.

Rick Gilbrech, director of the Stennis Space Center, said his site would need at least four to five days to prepare the fuel for another test if the rocket is ready. He and his team aren’t discouraged by Saturday’s test and are proud of what they’ve accomplished this year, especially during the Covid-19 pandemic, he said.

NASA administrator Jim Bridenstine said the test was “not a failure.”

“This is not a failure. This is a test, and we tested today in a way that is meaningful where we’re going to learn … we’re going to make adjustments, and we’re going to fly to the moon,” he said.

“This was a successful day. We didn’t get everything we wanted and yes we’re going to learn, we’re going to have to make adjustments,” he said. “But again, this is a test. And this is why we test.”

 

Yet another delay

 

SLS has been haunted by critiques of long delays and cost overruns, and with the premature end of the critical hot fire test, its launch may be delayed once again.

“We got lots of data that we’re going to go through and be able to sort through and get to a point where we can make determinations as to whether or not, you know, launching in 2021 is a possibility or not,” Bridenstine said.

The rocket is a key part of NASA’s Artemis lunar exploration program, which aims to send the first woman and next man to the moon by 2024. NASA officials also hope the SLS will be used to reach Mars and other “deep space destinations.”

SLS has been under development for a decade. Under the Obama administration, NASA was already planning to use SLS to take astronauts back to the moon by 2028, and that remained the plan until Vice President Mike Pence directed the space agency to drastically accelerate its timeline in 2019.

Boeing was contracted in 2012 to build SLS’s main components, and the rocket was originally expected to start flying in December 2017. But Boeing has been blasted in several government oversight reports for “poor performance,” costly schedule slips and ballooning expenses. That made SLS a touchy political talking point, and many in the space industry remain suspicious that a 2024 moon landing is possible.

At one point, Bridenstine reportedly considered skipping the green run test to expedite SLS’s development. But more recently he has asserted that the tests are essential to ensuring the rocket is safe enough to carry humans into space and to work out any potential engineering problems before attempting an orbital launching.

Bridenstine is expected to step down when President-elect Joe Biden is inaugurated next week. It’s not clear if NASA will stick with the 2024 timeline under the new administration, though the official Democratic platform calls for “continuity” in NASA’s space programs between presidential administrations.

The SLS rocket stands taller than the Statue of Liberty and has about 15% more thrust at liftoff than the Saturn V rockets that powered the Apollo missions about 50 years ago.

NASA’s Artemis I mission is expected to launch by the end of 2021 with two test flights around the moon without astronauts.

A crewed test mission, Artemis II, is set to launch in 2023 in preparation to have the Artemis III mission return astronauts to the surface of the moon in 2024 for the first time since the 1970s.

Artemis is named after the Greek goddess of the moon and is the twin sister of Apollo, which was name NASA used for the missions and spacecraft that first took Americans to the moon in 1969.

Let’s block ads! (Why?)



Source link

Continue Reading

Science

US: NASA cuts short ground test of its giant moon rocket – Al Jazeera English

Published

 on


US space agency NASA ignited all four engines of its giant Space Launch System (SLS) for the first time on Saturday, but the “hot fire” test ended much earlier than expected.

Mounted in a test facility at NASA’s Stennis Space Center in the state of Mississippi, the SLS’s 65-metre-tall (212-foot) core stage roared to life at 4:27pm local time (22:27 GMT) and burned for more than a minute before the exercise was aborted.

The test was supposed to last for eight minutes to simulate the rocket’s climb to orbit.

NASA said in a statement that its teams were “assessing the data to determine what caused the early shutdown”.

The fiery show on Saturday is a vital step for the space agency and its top SLS contractor, Boeing, before the SLS’s planned debut launch later this year.

The success of that unmanned mission, called “Artemis I”, will set the stage for the first landing on the Moon by humans since the Apollo 17 mission in 1972. US President Donald Trump has pushed for that trip – which will also see the first woman on the Moon – to take place by 2024.

‘Important milestone’

It was unclear whether Boeing and NASA would have to repeat Saturday’s test, a prospect that could push the SLS’s debut launch into 2022.

Speaking to reporters following the test, SLS Program Manager John Honeycut said it was hard to detect what exactly went wrong. He said they had seen a flash in a thermal protection blanket on one of the engines and were analysing the data.

And despite the test being cut short, NASA Administrator Jim Bridenstine said the firing of the RS-25 engines had provided valuable information for the planned missions.

“I know not everybody is feeling as happy as we otherwise could because we wanted to get eight minutes of a hot fire and we got over a minute, but I just want to remind people where we’ve been and where we’re going and what an important milestone this is,” he told reporters.

He added: “We got lots of data that we’re going to be able to sort through,” to determine if a do-over is needed and whether a November 2021 debut launch date is still possible.

In addition to Artemis I, two other missions are planned. The first mission will test the SLS and an unmanned Orion spacecraft, while Artemis II will take astronauts around the Moon in 2023 but it will not land. Astronauts will only be sent to the Moon during the third mission in 2024.

The SLS, in its configuration for Artemis I, will stand 98 metres (322 feet), taller than the Statue of Liberty, and is more powerful than the Saturn V rockets used in the Apollo missions.

The rocket is now three years behind schedule and nearly $3bn over budget.

Critics have long argued for NASA to retire the rocket’s shuttle-era core technologies, which have launch costs of $1bn or more per mission, in favour of newer commercial alternatives that promise lower costs.

By comparison, it costs as little as $90m to fly the massive, but less powerful, Falcon Heavy rocket designed and manufactured by Elon Musk’s SpaceX, and some $350m per launch for United Launch Alliance’s legacy Delta IV Heavy.

While newer, more reusable rockets from both companies – SpaceX’s Starship and United Launch Alliance’s Vulcan – promise heavier lift capacity than the Falcon Heavy or Delta IV Heavy, potentially at a lower cost, SLS backers have argued it would take two or more launches on those rockets to launch what the SLS could carry in a single mission.

NASA’s eventual goal is to establish an Artemis Base Camp on the Moon before the end of the decade, an ambitious plan that would require tens of billions of dollars in funding and a green light from President-elect Joe Biden and Congress.

A manned return to the Moon is the first part of the Artemis programme to set up a long-term colony and test technologies for a crewed mission to Mars in the 2030s

Let’s block ads! (Why?)



Source link

Continue Reading

Trending