A Day on Earth Used to Only Be 19 Hours

Meteosat
A full disk view of the Earth, courtesy of Meteosat-I 1. Credit: ESA/Meteosat

On Earth, a single solar day lasts 24 hours. That is the time it takes for the Sun to return to the same place in the sky as the day before. The Moon, Earth’s only natural satellite, takes about 27 days to complete a single circuit around our planet and orbits at an average distance of 384,399 km (~238,854.5 mi). Since time immemorial, humans have kept track of the Sun, the Moon, and their sidereal and synodic periods. To the best of our knowledge, the orbital mechanics governing the Earth-Moon system have been the same, and we’ve come to take them for granted.

But there was a time when the Moon orbited significantly closer to Earth, and the average day was much shorter than today. According to a recent study by a pair o researchers from China and Germany, an average day lasted about 19 hours for one billion years during the Proterozoic Epoch – a geological period during the Precambrian that lasted from 2.5 billion years to 541 million years ago. This demonstrates that rather than gradually increasing over time (as previously thought), the length of a day on Earth remained constant for an extended period.

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Astronauts Will Be Tracking Dust Into the Lunar Gateway. Is This a Problem?

Artist's impression of astronauts on the lunar surface, as part of the Artemis Program. Credit: NASA
Artist's impression of astronauts on the lunar surface, as part of the Artemis Program. Credit: NASA

Lunar regolith (aka. Moondust”) is a major hazard for missions heading to the Moon. It’s everywhere on the surface – 5 to 10 meters (~16.5 to 33 feet) in depth in some places – not to mention jagged and sticky! During the Apollo missions, astronauts learned how this dust adhered to everything, including their spacesuits. Worse, it would get tracked back into their Lunar Modules (LMs), where it stuck to surfaces and played havoc with electronics and mechanical equipment, and even led to long-term respiratory problems.

This is a major concern for the Artemis Program, which aims to establish a “sustained program of lunar exploration and development.” One of the key elements of this program is the Lunar Gateway, a lunar habitat that will orbit the Moon for a planned 15 years and facilitate long-term missions to the surface. The impact that regolith introduced by astronauts returning from the surface will have is not well understood. In a recent paper, a NASA-led team of researchers created a physics-based model to asses how regolith could impact the habitat over time.

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If We Can Master Artificial Photosynthesis, We Can Thrive in Space

Illustration of a photobioreactor as a means of growing building materials on Mars. Credit: Joris Wegner/ZARM/Universität Bremen

By 2030, multiple space agencies will have sent astronauts to the Moon for the first time since the Apollo Program ended over 50 years ago. These programs will create lasting infrastructure, like the Lunar Gateway, Artemis Base Camp, Moon Village, and the International Lunar Research Station (ILRS). In the ensuing decade, the first crewed missions to Mars are expected to occur, culminating with the creation of the first human outposts on another planet. Commercial ventures also want to establish habitats in Low Earth Orbit (LEO), enabling everything from asteroid mining to space tourism.

One of the biggest challenges for this renewed era of space exploration (Space Age 2.0) is ensuring that humans can remain healthy while spending extended periods in space. Foremost among them is ensuring that crews have functioning life support systems that can provide a steady supply of breathable air, which poses its own technical challenges. In a recent study, a team of researchers led by Katharina Brinkert of the University of Warwick described how artificial photosynthesis could lead to a new type of life support system that is smaller, lighter, easier, and more cost-effective to send to space.

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Airbus Developed a System To Extract Oxygen and Metal From Lunar Regolith

An illustration of a Moon base that could be built using 3D printing and ISRU, In-Situ Resource Utilization. Credit: RegoLight, visualisation: Liquifer Systems Group, 2018
An illustration of a Moon base that could be built using 3D printing and ISRU, In-Situ Resource Utilization. Credit: RegoLight, visualisation: Liquifer Systems Group, 2018

New technologies utilizing material found in space are constantly popping up, sometimes from smaller companies and sometimes from larger ones. Back in 2020, one of the largest companies of them all announced a technology that could have significant implications for the future lunar exploration missions planned over the next ten years. The European aerospace giant Airbus developed the Regolith to OXYgen and Metals Conversion (ROXY) system. 

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NASA Has a Plan to Power the Moon

Artist's impression of astronauts on the lunar surface, as part of the Artemis Program. How will they store power on the Moon? 3D printed batteries could help. Credit: NASA
Artist's impression of astronauts on the lunar surface, as part of the Artemis Program. How will they store power on the Moon? 3D printed batteries could help. Credit: NASA

Despite all the hype surrounding the coming of the commercial space age, NASA and other governmental agencies will still play a vital role in the early stages of getting much of the infrastructure up and running before commercial actors can come in. That role will primarily be filled by being the first (and sometimes only) customer for a wide variety of companies that hope to profit from exploiting space resources. 

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How Much Damage Will Lunar Landings Do to Lunar Orbiters?

Artist rendering of an Artemis astronaut exploring the Moon’s surface during a future mission. Credit: NASA

Multiple missions are destined for the Moon in this decade. These include robotic and crewed missions conducted by space agencies, commercial space entities, and non-profit organizations. The risks and hazards of going to the Moon are well-documented, thanks to Apollo Program and the six crewed missions it sent to the lunar surface between 1969 and 1972. But unlike the “footprints and flags” of yesterday, the plan for the coming decade is to create a “sustained program of lunar exploration and development.”

This means establishing a greater presence on the Moon, building infrastructure (like habitats, power systems, and landing pads), and missions regularly coming and going. Given the low-gravity environment on the Moon, spacecraft kick up a lot of lunar regolith (aka., “Moon dust”) during takeoff and landing. This regolith is electrostatically-charged, very abrasive, and wreaks havoc on machines and equipment. In a recent study, NASA researchers Philip T. Metzger and James G. Mantovani considered how much damage all this regolith could inflict on orbiting spacecraft.

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Researchers Are Building a Simulated Moon/Mars Research Station Deep Underground

These images show the first laboratory in the Bio-SPHERE project. The medical lab is located 1 km under the surface, near one of the UK's deepest mine sites. Image Credit: Dr. Alexandra Iordachescu/University of Birmingham.

In the early days of spaceflight, just getting a satellite into Earth’s orbit was an accomplishment. In our era, landing rovers on other planets and bringing samples home from asteroids is the cutting edge. But the next frontier is rapidly approaching, when astronauts will stay for long periods of time on the Moon and hopefully Mars.

But before we can send people to those dangerous environments, the Artemis partner space agencies have to know how to keep them safe. An important part of that is simulating the conditions on the Moon and Mars.

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The Moon has a Solid Core Like the Earth

A new study suggests that the moon's magnetic field from a dynamo in its liquid metallic core (inner red sphere) lasted 1 billion years longer than thought. (Image credit: Hernán Cañellas (provided by Benjamin Weiss))

Some fifty years ago, the Apollo Program sent the first astronauts to the Moon. In addition to the many science experiments they conducted on the surface, the Apollo astronauts brought back samples of lunar rock for analysis. The Soviet Luna program sent several robotic missions to the Moon around the same time that conducted sample-return missions. The examination of these rocks revealed a great deal about the composition of the Moon and led to new theories about the formation and evolution of the Earth-Moon system.

For example, analysis of the rocks revealed that the Earth and the Moon are similarly composed of silicate minerals and metals. This led to theories that the Moon’s interior is similarly divided into a silicate mantle and crust and a metallic core. However, many aspects of this theory, like the structure of the core (solid or molten?), have been debated for decades. According to new findings by a team of French scientists, it is now a scientific certainty that the Moon’s innermost region consists of a solid inner core surrounded by a molten outer core (just like Earth’s).

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Glass Fibers in Lunar Regolith Could Help Build Structures on the Moon

Electron microscope images of various glass particles identified from China's Chang'e-5 lunar samples. Credit: Laiquan Shen, R.Z. et al. (2023)

Through the Artemis Program, NASA plans to send the first astronauts to the Moon in over fifty years. Before the decade is over, this program aims to establish the infrastructure that will allow for a “sustained program of lunar exploration and development.” The European Space Agency (ESA) also has big plans, which include the creation of a Moon Village that will serve as a spiritual successor to the International Space Station (ISS). China and Roscosmos also came together in June 2021 to announce that they would build the International Lunar Research Station (ILRS) around the lunar south pole.

In all cases, space agencies plan to harvest local resources to meet their construction and long-term needs – a process known as In-Situ Resource Utilization (ISRU). Based on samples returned by the fifth mission of the Chinese Lunar Exploration Program (Chang’e-5), a team of researchers from the Chinese Academy of Sciences (CAS) identified indigenous glass fibers for the first time. According to a paper they authored, these fibers were formed by past impacts in the region and could be an ideal building material for future lunar bases.

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Thirsty on the Moon? Just Throw Some Regolith in the Microwave

A crucible that could be used to extract water from Lunar regolith. Credit: Cole, et al

No matter where we go in the universe, we’re going to need water. Thus far, human missions to Earth orbit and the Moon have taken water with them. But while that works for short missions, it isn’t practical in the long term. Water is heavy, and it would take far too much fuel to bring sufficient water to sustain long-term bases on the Moon or Mars. So we’ll have to use the water we can extract locally.

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