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Mars is Earth’s next-door neighbor in the solar system — two rocky worlds with differences down to their very core, literally.

A new study based on seismic data obtained by NASA’s robotic InSight lander is offering a fuller understanding of the Martian deep interior and fresh details about dissimilarities between Earth, the third planet from the sun, and Mars, the fourth.

The research, informed by the first detection of seismic waves traveling through the core of a planet other than Earth, showed that the innermost layer of Mars is slightly smaller and denser than previously known. It also provided the best assessment to date of the composition of the Martian core.

Both planets possess cores comprised primarily of liquid iron. But about 20% of the Martian core is made up of elements lighter than iron — mostly sulfur, but also oxygen, carbon and a dash of hydrogen, the study found. That is about double the percentage of such elements in Earth’s core, meaning the Martian core is considerably less dense than our planet’s core — though more dense than a 2021 estimate based on a different type of data from the now-retired InSight.

“The deepest regions of Earth and Mars have different compositions —  likely a product both of the conditions and processes at work when the planets formed and of the material they are made from,” said seismologist Jessica Irving of the University of Bristol in England, lead author of the study published this week in the journal Proceedings of the National Academy of Sciences.

The study also refined the size of the Martian core, finding it has a diameter of about 2,212-2,249 miles (3,560-3,620 km), approximately 12-31 miles (20-50 km) smaller than previously estimated. The Martian core makes up a slightly smaller percentage of the planet’s diameter than does Earth’s core.

The nature of the core can play a role in governing whether a rocky planet or moon could harbor life. The core, for instance, is instrumental in generating Earth’s magnetic field that shields the planet from harmful solar and cosmic particle radiation.

“On planets and moons like Earth, there are silicate — rocky — outer layers and an iron-dominated metallic core. One of the most important ways a core can impact habitability is to generate a planetary dynamo,” Irving said.

“Earth’s core does this but Mars’ core does not — though it used to, billions of years ago. Mars’ core likely no longer has the energetic, turbulent motion which is needed to generate such a field,” Irving added.

Mars has a diameter of about 4,212 miles (6,779 km), compared to Earth’s diameter of about 7,918 miles (12,742 km), and Earth is almost seven times larger in total volume.

The behavior of seismic waves traveling through a planet can reveal details about its interior structure. The new findings stem from two seismic events that occurred on the opposite side of Mars from where the InSight lander — and specifically its seismometer device — sat on the planet’s surface.

The first was an August 2021 marsquake centered close to Valles Marineris, the solar system’s largest canyon. The second was a September 2021 meteorite impact that left a crater of about 425 feet (130 meters).

The U.S. space agency formally retired InSight in December after four years of operations, with an accumulation of dust preventing its solar-powered batteries from recharging.

“The InSight mission has been fantastically successful in helping us decipher the structure and conditions of the planet’s interior,” University of Maryland geophysicist and study co-author Vedran Lekic said. “Deploying a network of seismometers on Mars would lead to even more discoveries and help us understand the planet as a system, which we cannot do by just looking at its surface from orbit.”
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A Japanese space start-up will attempt Tuesday to become the first private company to put a lander on the Moon.   

If all goes to plan, ispace’s Hakuto-R Mission 1 lander will start its descent towards the lunar surface at around 15:40 GMT.   

It will slow its orbit some 100 kilometers above the Moon, then adjust its speed and altitude to make a “soft landing” around an hour later.   

Success is far from guaranteed. In April 2019, Israeli organization SpaceIL watched their lander crash into the Moon’s surface.   

ispace has announced three alternative landing sites and could shift the lunar descent date to April 26, May 1 or May 3, depending on conditions.   

“What we have accomplished so far is already a great achievement, and we are already applying lessons learned from this flight to our future missions,” ispace founder and CEO Takeshi Hakamada said earlier this month.   

“The stage is set. I am looking forward to witnessing this historic day, marking the beginning of a new era of commercial lunar missions.”   

The lander, standing just over two meters tall and weighing 340 kilograms, has been in lunar orbit since last month.   

It was launched from Earth in December on one of SpaceX’s Falcon 9 rockets after several delays.   

So far only the United States, Russia and China have managed to put a robot on the lunar surface, all through government-sponsored programs.   

However, Japan and the United States announced last year that they would cooperate on a plan to put a Japanese astronaut on the Moon by the end of the decade.   

SEE ALSO: A related video by VOA’s Alexander Kruglyakov

The lander is carrying several lunar rovers, including a miniature Japanese model of just eight centimeters that was jointly developed by Japan’s space agency with toy manufacturer Takara Tomy.   

The mission is also being closely watched by the United Arab Emirates, whose Rashid rover is aboard the lander as part of the nation’s expanding space program.   

The Gulf country is a newcomer to the space race but sent a probe into Mars’ orbit in 2021. If its rover successfully lands, it will be the Arab world’s first Moon mission.   

Hakuto means “white rabbit” in Japanese and references Japanese folklore that a white rabbit lives on the Moon.   

The project was one of five finalists in Google’s Lunar X Prize competition to land a rover on the Moon before a 2018 deadline, which passed without a winner.   

With just 200 employees, ispace has said it “aims to extend the sphere of human life into space and create a sustainable world by providing high-frequency, low-cost transportation services to the Moon.”   

Hakamada has touted the mission as laying “the groundwork for unleashing the Moon’s potential and transforming it into a robust and vibrant economic system.”   

The firm believes the Moon will support a population of 1,000 people by 2040, with 10,000 more visiting each year.   

It plans a second mission, tentatively scheduled for next year, involving both a lunar landing and the deployment of its own rover. 
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The U.S. Space Force said on Monday that Elon Musk’s SpaceX was granted approval to lease a second rocket launch complex at a military base in California, setting the space company up for its fifth launch site in the United States. 

Under the lease, SpaceX will launch its workhorse Falcon rockets from Space Launch Complex-6 at Vandenberg Space Force Base, a military launch site north of Los Angeles where the space company operates another launchpad. It has two others in Florida and its private Starbase site in south Texas. 

A Monday night Space Force statement said a letter of support for the decision was signed on Friday by Space Launch Delta 30 commander Col. Rob Long. The statement did not mention a duration for SpaceX’s lease. 

The new launch site, vacated last year by the Boeing-Lockheed joint venture United Launch Alliance, gives SpaceX more room to handle an increasingly busy launch schedule for commercial, government and internal satellite launches. 

Vandenberg Space Force Base allows for launches in a southern trajectory over the Pacific Ocean, which is often used for weather-monitoring, military or spy satellites that commonly rely on polar Earth orbits. 

SpaceX’s grant of Space Launch Complex-6 comes as rocket companies prepare to compete for the Pentagon’s Phase 3 National Security Space Launch program, a watershed military launch procurement effort expected to begin in the next year or so. 
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Twitter accounts operated by authoritarian governments in Russia, China and Iran are benefiting from recent changes at the social media company, researchers said Monday, making it easier for them to attract new followers and broadcast propaganda and disinformation to a larger audience. 

The platform is no longer labeling state-controlled media and propaganda agencies, and will no longer prohibit their content from being automatically promoted or recommended to users. Together, the two changes, both made in recent weeks, have supercharged the Kremlin’s ability to use the U.S.-based platform to spread lies and misleading claims about its invasion of Ukraine, U.S. politics and other topics. 

Russian state media accounts are now earning 33% more views than they were just weeks ago, before the change was made, according to findings released Monday by Reset, a London-based non-profit that tracks authoritarian governments’ use of social media to spread propaganda. Reset’s findings were first reported by The Associated Press. 

The increase works out to more than 125,000 additional views per post. Those posts included ones suggesting the CIA had something to do with the September 11, 2001, attacks on the U.S., that Ukraine’s leaders are embezzling foreign aid to their country, and that Russia’s invasion of Ukraine was justified because the U.S. was running clandestine biowarfare labs in the country. 

State media agencies operated by Iran and China have seen similar increases in engagement since Twitter quietly made the changes. 

The about-face from the platform is the latest development since billionaire Elon Musk purchased Twitter last year. Since then, he’s ushered in a confusing new verification system and laid off much of the company’s staff, including those dedicated to fighting misinformation, allowed back neo-Nazis and others formerly suspended from the site, and ended the site’s policy prohibiting dangerous COVID-19 misinformation. Hate speech and disinformation have thrived. 

Before the most recent change, Twitter affixed labels reading “Russia state-affiliated media” to let users know the origin of the content. It also throttled back the Kremlin’s online engagement by making the accounts ineligible for automatic promotion or recommendation—something it regularly does for ordinary accounts as a way to help them reach bigger audiences. 

The labels quietly disappeared after National Public Radio and other outlets protested Musk’s plans to label their outlets as state-affiliated media, too. NPR then announced it would no longer use Twitter, saying the label was misleading, given NPR’s editorial independence, and would damage its credibility. 

Reset’s conclusions were confirmed by the Atlantic Council’s Digital Forensic Research Lab (DFRL), where researchers determined the changes were likely made by Twitter late last month. Many of the dozens of previously labeled accounts were steadily losing followers since Twitter began using the labels. But after the change, many accounts saw big jumps in followers. 

RT Arabic, one of Russia’s most popular propaganda accounts on Twitter, had fallen to less than 5,230,000 followers on January 1, but rebounded after the change was implemented, the DFRL found. It now has more than 5,240,000 followers. 

Before the change, users interested in seeking out Kremlin propaganda had to search specifically for the account or its content. Now, it can be recommended or promoted like any other content. 

“Twitter users no longer must actively seek out state-sponsored content in order to see it on the platform; it can just be served to them,” the DFRL concluded. 

Twitter did not respond to questions about the change or the reasons behind it. Musk has made past comments suggesting he sees little difference between state-funded propaganda agencies operated by authoritarian strongmen and independent news outlets in the west.

“All news sources are partially propaganda,” he tweeted last year, “some more than others.”
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