The most recent lunar occultation of Mars that was visible from the United States occurred on December 7, 2022. A handful of these events occur every few years around each Martian opposition, but they are usually only visible from a small portion of Earth, often over the ocean or in polar regions. The next lunar occultation of Mars visible across most of the United States will happen on the night of February 4–5, 2042. There are similar occultations of Mars in 2035, 2038, and 2039 visible in narrow swaths of South Florida and the Pacific Northwest.
This photo was taken with a handheld Canon 80D and a 600 mm lens. Settings were 1/2000 sec, f/8, ISO 400. The image was cropped and lightly edited in Adobe Lightroom.
The Moon also periodically covers Venus, Jupiter, Saturn, and the Solar System’s more distant planets. A good resource on lunar occultations is In-The-Sky.org, which lists events where the Moon will block out a planet or a bright star. Be sure you choose your location on the upper right corner of the page and toggle year by year to plan out future viewing opportunities.
Viewing these kinds of events can be breathtaking and humbling. In 2012, I was lucky enough to observe the transit of Venus in front of the Sun, something that only happens twice every 121 years.
Seeing Mars, twice the size of the Moon, rising above the lunar horizon like a rusty BB pellet next to a dusty volleyball provided a perfect illustration of the scale and grandeur of the Solar System. Similarly, viewing Venus dwarfed by the Sun was a revealing moment. The worlds accompanying Earth around the Sun are varied in size, shape, color, and composition.
In one glance, an observer can see the barren, airless lunar surface and a cold, desert planet that once harbored rivers, lakes, and potentially life, all while standing on our own planet, an oasis in the cosmos. One thing that connects them all is humanity’s quest for exploration. Today, robots are operating on or around the Moon and Mars. Governments and private companies are preparing to return astronauts to the lunar surface within a few years, then moving on to dispatch human expeditions to the red planet.
Plans to land astronauts on the Moon are already in motion, but significant financial and technological hurdles remain for a crew mission to put humans on Mars. But for a short time Monday night, it looked like there was a direct path.
Starship will test its payload deployment mechanism on its seventh test flight.
SpaceX’s first second-generation Starship, known as Version 2 or Block 2, could launch as soon as January 13. Credit: SpaceX
An upsized version of SpaceX’s Starship mega-rocket rolled to the launch pad early Thursday in preparation for liftoff on a test flight next week.
The two-mile transfer moved the bullet-shaped spaceship one step closer to launch Monday from SpaceX’s Starbase test site in South Texas. The launch window opens at 5 pm EST (4 pm CST; 2200 UTC). This will be the seventh full-scale test flight of SpaceX’s Super Heavy booster and Starship spacecraft and the first of 2025.
In the coming days, SpaceX technicians will lift the ship on top of the Super Heavy booster already emplaced on the launch mount. Then, teams will complete the final tests and preparations for the countdown on Monday.
“The upcoming flight test will launch a new generation ship with significant upgrades, attempt Starship’s first payload deployment test, fly multiple reentry experiments geared towards ship catch and reuse, and launch and return the Super Heavy booster,” SpaceX officials wrote in a mission overview posted on the company’s website.
The mission Monday will repeat many of the maneuvers SpaceX demonstrated on the last two Starship test flights. The company will again attempt to return the Super Heavy booster to the launch site and attempt to catch it with two mechanical arms, or “chopsticks,” on the launch tower approximately seven minutes after liftoff.
SpaceX accomplished this feat on the fifth Starship test flight in October but aborted a catch attempt on a November flight because of damaged sensors on the tower chopsticks. The booster, which remained healthy, diverted to a controlled splashdown offshore in the Gulf of Mexico.
SpaceX’s next Starship prototype, Ship 33, emerges from its assembly building at Starbase, Texas, early Thursday morning. Credit: SpaceX/Elon Musk via X
For the next flight, SpaceX added protections to the sensors on the tower and will test radar instruments on the chopsticks to provide more accurate ranging measurements for returning vehicles. These modifications should improve the odds of a successful catch of the Super Heavy booster and of Starship on future missions.
In another first, one of the 33 Raptor engines that will fly on this Super Heavy booster—designated Booster 14 in SpaceX’s fleet—was recovered from the booster that launched and returned to Starbase in October. For SpaceX, this is a step toward eventually flying the entire rocket repeatedly. The Super Heavy booster and Starship spacecraft are designed for full reusability.
After separation of the booster stage, the Starship upper stage will ignite six engines to accelerate to nearly orbital velocity, attaining enough energy to fly halfway around the world before gravity pulls it back into the atmosphere. Like the past three test flights, SpaceX will guide Starship toward a controlled reentry and splashdown in the Indian Ocean northwest of Australia around one hour after liftoff.
New ship, new goals
The most significant changes engineers will test next week are on the ship, or upper stage, of SpaceX’s enormous rocket. The most obvious difference on Starship Version 2, or Block 2, is with the vehicle’s forward flaps. Engineers redesigned the flaps, reducing their size and repositioning them closer to the tip of the ship’s nose to better protect them from the scorching heat of reentry. Cameras onboard Starship showed heat damage to the flaps during reentry on test flights last year.
SpaceX is also developing an upgraded Super Heavy booster that is slightly taller than the existing model. The next version of the booster will produce more thrust and will be slightly taller than the current Super Heavy, but for the upcoming test flight, SpaceX will still use the first-generation booster design.
Starship Block 2 has smaller flaps than previous ships. The flaps are located in a more leeward position to protect them from the heat of reentry. Credit: SpaceX
For next week’s flight, Super Heavy and Starship combined will hold more than 10.5 million pounds of fuel and oxidizer. The ship’s propellant tanks have 25 percent more volume than previous iterations of the vehicle, and the payload compartment, which contains 10 mock-ups of Starlink Internet satellites on this launch, is somewhat smaller. Put together, the changes add nearly 6 feet (1.8 meters) to the rocket’s height, bringing the full stack to approximately 404 feet (123.1 meters).
This means SpaceX will break its own record for launching the largest and most powerful rocket ever built. And the company will do it again with the even larger Starship Version 3, which SpaceX says will have nine upper stage engines, instead of six, and will deliver up to 440,000 pounds (200 metric tons) of cargo to low-Earth orbit.
Other changes debuting with Starship Version 2 next week include:
• Vacuum jacketing of propellant feedlines
• A new fuel feedline system for the ship’s Raptor vacuum engines
• An improved propulsion avionics module controlling vehicle valves and reading sensors
• Redesigned inertial navigation and star tracking sensors
• Integrated smart batteries and power units to distribute 2.7 megawatts of power across the ship
• An increase to more than 30 cameras onboard the vehicle.
Laying the foundation
The enhanced avionics system will support future missions to prove SpaceX’s ability to refuel Starships in orbit and return the ship to the launch site. For example, SpaceX will fly a more powerful flight computer and new antennas that integrate connectivity with the Starlink Internet constellation, GPS navigation satellites, and backup functions for traditional radio communication links. With Starlink, SpaceX said Starship can stream more than 120Mbps of real-time high-definition video and telemetry in every phase of flight.
These changes “all add additional vehicle performance and the ability to fly longer missions,” SpaceX said. “The ship’s heat shield will also use the latest generation tiles and includes a backup layer to protect from missing or damaged tiles.”
Somewhere over the Atlantic Ocean, a little more than 17 minutes into the flight, Starship will deploy 10 dummy payloads similar in size and weight to next-generation Starlink satellites. The mock-ups will soar around the world on a suborbital trajectory, just like Starship, and reenter over the unpopulated Indian Ocean. Future Starship flights will launch real next-gen Starlink satellites to add capacity to the Starlink broadband network, but they’re too big and too heavy to launch on SpaceX’s smaller Falcon 9 rocket.
SpaceX will again reignite one of the ship’s Raptor engines in the vacuum of space, repeating a successful test achieved on Flight 6 in November. The engine restart capability is important for several reasons. It gives the ship the ability to maneuver itself out of low-Earth orbit for reentry (not a concern for Starship’s suborbital tests), and will allow the vehicle to propel itself to higher orbits, the Moon, or Mars once SpaceX masters the technology for orbital refueling.
Artist’s illustration of Starship on the surface of the Moon. Credit: SpaceX
NASA has contracts with SpaceX to build a derivative of Starship to ferry astronauts to and from the surface of the Moon for the agency’s Artemis program. The NASA program manager overseeing SpaceX’s lunar lander contract, Lisa Watson-Morgan, said she was pleased with the results of the in-space engine restart demo last year.
“The whole path to the Moon, as we are getting ready to land on the Moon, we’ll perform a series of maneuvers, and the Raptors will have an environment that is very, very cold,” Morgan told Ars in a recent interview. “To that, it’s going to be important that they’re able to relight for landing purposes. So that was a great first step towards that.
“In addition, after we land, clearly, the Raptors will be off, and it will get very cold, and they will have to relight in a cold environment (to launch the crews off the lunar surface),” she said. “So that’s why that step was critical for the Human Landing System and NASA’s return to the Moon.”
“The biggest technology challenge remaining”
SpaceX continues to experiment with Starship’s heat shield, which the company’s founder and CEO, Elon Musk, has described as “the biggest technology challenge remaining with Starship.” In order for SpaceX to achieve its lofty goal of launching Starships multiple times per day, the heat shield needs to be fully and immediately reusable.
While the last three ships have softly splashed down in the Indian Ocean, some of their heat-absorbing tiles stripped away from the vehicle during reentry, when it’s exposed to temperatures up to 2,600° Fahrenheit (1,430° Celsius).
Engineers removed tiles from some areas of the ship for next week’s test flight in order to “stress-test” vulnerable parts of the vehicle. They also smoothed and tapered the edge of the tile line, where the ceramic heat shield gives way to the ship’s stainless steel skin, to address “hot spots” observed during reentry on the most recent test flight.
“Multiple metallic tile options, including one with active cooling, will test alternative materials for protecting Starship during reentry,” SpaceX said.
SpaceX is also flying rudimentary catch fittings on Starship to test their thermal performance on reentry. The ship will fly a more demanding trajectory during descent to probe the structural limits of the redesigned flaps at the point of maximum entry dynamic pressure, according to SpaceX.
All told, SpaceX’s inclusion of a satellite deployment demo and ship upgrades on next week’s test flight will lay the foundation for future missions, perhaps in the next few months, to take the next great leap in Starship development.
In comments following the last Starship test flight in November, SpaceX founder and CEO Elon Musk posted on X that the company could try to return the ship to a catch back at the launch site—something that would require the vehicle to complete at least one full orbit of Earth—as soon as the next flight following Monday’s mission.
“We will do one more ocean landing of the ship,” Musk posted. “If that goes well, then SpaceX will attempt to catch the ship with the tower.”
Stephen Clark is a space reporter at Ars Technica, covering private space companies and the world’s space agencies. Stephen writes about the nexus of technology, science, policy, and business on and off the planet.
“We have since determined that while the capsule was dipping in and out of the atmosphere, as part of that planned skip entry, heat accumulated inside the heat shield outer layer, leading to gases forming and becoming trapped inside the heat shield,” said Pam Melroy, NASA’s deputy administrator. “This caused internal pressure to build up and led to cracking and uneven shedding of that outer layer.”
An independent team of experts concurred with NASA’s determination of the root cause, Melroy said.
NASA Administrator Bill Nelson, Deputy Administrator Pam Melroy, Associate Administrator Jim Free, and Artemis II Commander Reid Wiseman speak with reporters Thursday in Washington, DC. Credit: NASA/Bill Ingalls
Counterintuitively, this means NASA engineers are comfortable with the safety of the heat shield if the Orion spacecraft reenters the atmosphere at a slightly steeper angle than it did on Artemis I and spends more time subjected to higher temperatures.
When the Orion spacecraft climbed back out of the atmosphere during the Artemis I skip reentry, a period known as the skip dwell, NASA said heating rates decreased and thermal energy accumulated inside the heat shield’s Avcoat material. This generated gases inside the heat shield through a process known as pyrolysis.
“Pyrolysis is just burning without oxygen,” said Amit Kshatriya, deputy associate administrator of NASA’s Moon to Mars program. “We learned that as part of that reaction, the permeability of the Avcoat material is essential.”
During the skip dwell, “the production of those gases was higher than the permeability could tolerate, so as a result, pressure differential was created. That pressure led to cracks in plane with the outer mold line of the vehicle,” Kshatriya said.
NASA didn’t know this could happen because engineers tested the heat shield on the ground at higher temperatures than the Orion spacecraft encountered in flight to prove the thermal barrier could withstand the most extreme possible heating during reentry.
“What we missed was this critical region in the middle, and we missed that region because we didn’t have the test facilities to produce the low-level energies that occur during skip and dwell,” Kshatriya said Thursday.
During the investigation, NASA replicated the charring and cracking after engineers devised a test procedure to expose Avcoat heat shield material to the actual conditions of the Artemis I reentry.
So, for Artemis II, NASA plans to modify the reentry trajectory to reduce the skip reentry’s dwell time. Let’s include some numbers to help illustrate the difference.
The distance traveled by Artemis I during the reentry phase of the mission was more than 3,000 nautical miles (3,452 miles; 5,556 kilometers), according to Kshatriya. This downrange distance will be limited to no more than 1,775 nautical miles (2,042 miles; 3,287 kilometers) on Artemis II, effectively reducing the dwell time the Orion spacecraft spends in the lower heating regime that led to the cracking on Artemis I.
NASA’s inspector general report in May included new images of Orion’s heat shield that the agency did not initially release after the Artemis I mission. Credit: NASA Inspector General
With this change, Kshatriya said NASA engineers don’t expect to see the heat shield erosion they saw on Artemis I. “The gas generation that occurs during that skip dwell is sufficiently low that the environment for crack generation is not going to overwhelm the structural integrity of the char layer.”
For future Orion spaceships, NASA and its Orion prime contractor, Lockheed Martin, will incorporate changes to address the heat shield’s permeability problem.
Waiting for what?
NASA officials discussed the heat shield issue, and broader plans for the Artemis program, in a press conference in Washington on Thursday. But the event’s timing added a coat of incredulity to much of what they said. President-elect Donald Trump, with SpaceX founder Elon Musk in his ear, has vowed to cut wasteful government spending.
Depending on how you count them, China now has roughly 18 types of active space launchers.
China’s new Long March 12 rocket made a successful inaugural flight Saturday, placing two experimental satellites into orbit and testing uprated, higher-thrust engines that will allow a larger Chinese launcher in development to send astronauts to the Moon.
The 203-foot-tall (62-meter) Long March 12 rocket lifted off at 9: 25 am EST (14: 25 UTC) Saturday from the Wenchang commercial launch site on Hainan Island, China’s southernmost province. This was also the first rocket launch from a new commercial spaceport at Wenchang, consisting of two launch sites a short distance from a pair of existing launch pads used by heavier rockets primarily geared for government missions.
The two-stage rocket delivered two technology demonstration satellites into a near-circular 50-degree-inclination orbit with an average altitude of nearly 650 miles (about 1,040 kilometers), according to US military tracking data.
The Long March 12 is the newest member of China’s Long March rocket family, which has been flying since China launched its first satellite into orbit in 1970. The Long March rockets have significantly evolved since then and now include a range of launch vehicles of different sizes and designs.
Versions of the Long March 2, 3, and 4 rockets have been flying since the 1970s and 1980s, burning the same toxic mix of hypergolic propellants as China’s early ICBMs. More recently, China debuted the Long March 5, 6, 7, and 8 rockets consuming the cleaner combination of kerosene and liquid oxygen propellants. These new rockets provide China with a spectrum of small, medium, and heavy-lift launch capabilities.
So many rockets
So, why bother with yet another Long March rocket? One reason is that Chinese officials seek a less expensive rocket to deploy thousands of small satellites for the country’s Internet mega-constellations to rival SpaceX’s Starlink network. Another motivation is to demonstrate the performance of upgraded rocket engines, new technologies, and fresh designs, some of which appear to copy SpaceX’s workhorse Falcon 9 rocket.
Like all of China’s other existing rockets, the Long March 12 configuration that flew Saturday is fully disposable. At the Zhuhai Airshow earlier this month, China’s largest rocket company displayed another version of the Long March 12 with a reusable first stage but with scant design details.
The Long March 12 is powered by four kerosene-fueled YF-100K engines on its first stage, generating more than 1.1 million pounds, or 5,000 kilonewtons of thrust at full throttle. These engines are upgraded, higher-thrust versions of the YF-100 engines used on several other types of Long March rockets.
Models of the Long March rockets on display at the China National Space Administration (CNSA) booth during the China International Aviation & Aerospace Exhibition in Zhuhai, China, on November 12, 2024. In this image, models of a future reusable version of the Long March 12 (left) and the super-heavy Long March 9 (right) are visible. Credit: Qilai Shen/Bloomberg via Getty Images
Notably, China will use the YF-100K variant on the heavy-lift Long March 10 rocket in development to launch Chinese astronauts to the Moon. The heaviest version of the Long March 10 will use 21 of these YF-100K engines on its core stage and strap-on boosters. Now, Chinese engineers have tested the upgraded YF-100K in flight, with favorable results from Saturday’s launch.
China is also developing a new crew-rated spacecraft and lunar lander that will launch on Long March 10 rockets, eyeing a human landing on the lunar surface by 2030. The Long March 10 will have a reusable first stage like the Falcon 9, and China is now working on a super-heavy fully reusable rocket that appears to be a clone of SpaceX’s Starship. This Long March 9 rocket, which probably won’t fly until the 2030s, will enable larger-scale sustained lunar exploration by China.
And now, the details
The Long March 12 was developed by the Shanghai Academy of Spaceflight Technology, also known as SAST, one of the two main state-owned organizations in charge of designing and manufacturing Long March rockets. Together with the Beijing-based China Academy of Launch Vehicle Technology, SAST is part of the China Aerospace Science and Technology Corporation, the largest government-run enterprise overseeing the Chinese space program.
According to SAST, the Long March 12 is capable of delivering a payload of at least 12 metric tons (26,455 pounds) into low-Earth orbit and about half that to a somewhat higher Sun-synchronous orbit. Two kerosene-fueled YF-115 engines power the Long March 12’s upper stage.
The Long March 12 is also China’s first 3.8-meter (12.5-foot) diameter rocket, which is an optimal match between the width of the booster and lift capability, allowing it to be transported by railway to launch sites across China, according to the state-run Xinhua news agency.
China’s older Long March rocket variants are slimmer and generally require engineers to strap together multiple first-stage boosters in a cluster arrangement to achieve performance similar to the Long March 12. The core of the heavy-lift Long March 5 is around 5 meters in diameter and must be transported by sea.
China’s first Long March 12 rocket on its launch pad before liftoff. Credit: Photo by VCG/VCG via Getty Images
In a post-launch press release, SAST identified several other “technology breakthroughs” flying on the Long March 12 rocket. These include a health management system that can diagnose anomalies in flight and adjust the rocket’s trajectory in real time to compensate for any minor problems. The Long March 12 is also China’s first rocket to use cryogenic helium to pressurize its liquid oxygen tanks, and its tanks are made of an aluminum-lithium alloy to save weight.
The Long March 12 is also the first rocket of its size in the Long March family to be assembled on its side instead of stacked vertically on its launch mount. After integrating the rocket in a nearby hangar, technicians transferred the first Long March 12 to its launch pad horizontally, then raised it vertical with an erector system. This is the same way SpaceX integrates and transports Falcon 9 rockets to the launch pad. SpaceX copied this horizontal integration approach from older Soviet-era rockets, and it offers several advantages, allowing teams to assemble rockets faster without the need for large overhead cranes in tall, cavernous vertical assembly buildings.
A bug or a feature?
We’ve already mentioned the proliferation of different types of Long March rockets, with nine classes of Long March launchers currently in operation. And each of these comes in multiple sub-variants.
This is a starkly different approach from SpaceX, which flies standardized rockets like the Falcon 9 and Falcon Heavy, which almost always fly in the same configuration, regardless of the payload or destination for each mission. The only exception is when SpaceX launches Dragon crew or cargo capsules on the Falcon 9.
Depending on how you count them, China now has roughly 18 different types of active space launchers. This number doesn’t include the Long March 9 or Long March 10, but it counts all the other Long March configurations, plus numerous small- and medium-class rockets fielded by China’s quasi-commercial space industry.
These startups operate with the blessing of China’s government and, in many cases, got their start by utilizing surplus military equipment and investment from Chinese local or provincial governments. However, the Chinese Communist Party has allowed them to raise capital from private sources, and they operate on a commercial basis, almost exclusively to serve domestic Chinese markets.
In some cases, these launch startups compete for commercial contracts directly with the government-backed Long March rocket family. The Long March 12 could be in the mix for launching large batches of spacecraft for China’s planned satellite Internet networks.
Some of these launch companies are working on reusable rockets similar in appearance to SpaceX’s Falcon 9. All of these rockets, government and commercial, are part of an ecosystem of Chinese launchers tasked with hauling military and commercial satellites into orbit.
The Long March 12 launch Saturday was China’s 58th orbital launch attempt of 2024, and no single subvariant of a Chinese rocket has flown more than seven times this year. This is in sharp contrast to the United States, which has logged 142 orbital launch attempts so far this year, 119 of them by SpaceX’s Falcon 9 or Falcon Heavy rockets.
There are around a dozen US orbital-class launch vehicle types you might call operational. But a few of these, such as Northrop Grumman’s Pegasus XL and Minotaur, and NASA’s Space Launch System, haven’t flown for several years.
SpaceX’s Falcon 9 is now the dominant leader in the US launch industry. Most of the Falcon 9 launches are filled to capacity with SpaceX’s own Starlink Internet satellites, but many missions fly with their payload fairings only partially full. Still, the Falcon 9 is more affordable on a per-kilogram basis than any other US rocket.
In China, on the other hand, none of the commercial launch startups have emerged as a clear leader. When that happens, if China allows the market to function in a truly commercial manner, some of these Chinese rocket companies will likely fold.
However, China’s government has a strategic interest in maintaining a portfolio of rockets and launch sites, same as the US government. For example, Chinese officials said the new launch site at Wenchang, where the Long March 12 took off from over the weekend, can accommodate 10 or more different types of rockets.
Stephen Clark is a space reporter at Ars Technica, covering private space companies and the world’s space agencies. Stephen writes about the nexus of technology, science, policy, and business on and off the planet.
Enlarge/ The eruptions that produced the dark mare on the lunar surface ended billions of years ago.
Signs of volcanic activity on the Moon can be viewed simply by looking up at the night-time sky: The large, dark plains called “maria” are the product of massive outbursts of volcanic material. But these were put in place relatively early in the Moon’s history, with their formation ending roughly 3 billion years ago. Smaller-scale additions may have continued until roughly 2 billion years ago. Evidence of that activity includes samples obtained by China’s Chang’e-5 lander.
But there are hints that small-scale volcanism continued until much more recent times. Observations from space have identified terrain that seems to be the product of eruptions, but only has a limited number of craters, suggesting a relatively young age. But there’s considerable uncertainty about these deposits.
Now, further data from samples returned to Earth by the Chang’e-5 mission show clear evidence of volcanism that is truly recent in the context of the history of the Solar System. Small beads that formed during an eruption have been dated to just 125 million years ago.
Counting beads
Obviously, some of the samples returned by Chang’e-5 are solid rock. But it also returned a lot of loose material from the lunar regolith. And that includes a decent number of rounded, glassy beads formed from molten material. There are two potential sources of those beads: volcanic activity and impacts.
The Moon is constantly bombarded by particles ranging in size from individual atoms to small rocks, and many of these arrive with enough energy to melt whatever it is they smash into. Some of that molten material will form these beads, which may then be scattered widely by further impacts. The composition of these beads can vary wildly, as they’re composed of either whatever smashed into the Moon or whatever was on the Moon that got smashed. So, the relative concentrations of different materials will be all over the map.
By contrast, any relatively recent volcanism on the Moon will be extremely rare, so is likely to be from a single site and have a single composition. And, conveniently, the Apollo missions already returned samples of volcanic lunar rocks, which provide a model for what that composition might look like. So, the challenge was one of sorting through the beads returned from the Chang’e-5 landing site, and figuring out which ones looked volcanic.
And it really was a challenge, as there were over 3,000 beads returned, and the vast majority of them would have originated in impacts.
As a first cutoff, the team behind the new work got rid of anything that had a mixed composition, such as unmelted material embedded in the bead, or obvious compositional variation. This took the 3,000 beads down to 764. Those remaining beads were then subject to a technique that could determine what chemicals were present. (The team used an electron probe microanalyzer, which bombards the sample with electrons and uses the photons that are emitted to determine what elements are present.) As expected, compositions were all over the map. Some beads were less than 1 percent magnesium oxide; others nearly 30 percent. Silicon dioxide ranged from 16 to 60 percent.
Based on the Apollo samples, the researchers selected for beads that were high in magnesium oxide relative to calcium and aluminum oxides. That got them down to 13 potentially volcanic samples. They also looked for low nickel, as that’s found in many impactors, which got the number down to six. The final step was to look at sulfur isotopes, as impact melting tends to preferentially release the lighter isotope, altering the ratio compared to intact lunar rocks.
After all that, the researchers were left with three of the glassy beads, which is a big step down from the 3,000 they started with.
Erupted
Those three were then used to perform uranium-based radioactive dating, and they all produced numbers that were relatively close to each other. Based on the overlapping uncertainties, the researchers conclude that all were the product of an eruption that took place about 123 million years ago, give or take 15 million years. Considering that the most recent confirmed eruptions were about 2 billion years ago, that’s a major step forward in timing.
And that’s quite a bit of a surprise, as the Moon has had plenty of time to cool, and that cooling would have increased the distance between its surface and any molten material left in the interior. So it’s not obvious what could be creating sufficient heating to generate molten material at present. The researchers note that the Moon has a lot of material called KREEP (potassium, rare earth elements, phosphorus) that is high in radioactive isotopes and might lead to localized heating in some circumstances.
Unfortunately, it will be tough to associate this with any local geology, since there’s no indication of where the eruption occurred. Material this small can travel quite a distance in the Moon’s weak gravitational field and then could be scattered even farther by impacts. So, it’s possible that these belong to features that have been identified as potentially volcanic through orbital images.
In the meantime, the increased exploration of the Moon planned for the next few decades should get us more opportunities to see whether similar materials are widespread on the lunar surface. Eventually, that might potentially allow us to identify an area with higher concentrations of volcanic material than one particle in a thousand.
Our Moon may appear to shine peacefully in the night sky, but billions of years ago, it was given a facial by volcanic turmoil.
One question that has gone unanswered for decades is why there are more titanium-rich volcanic rocks, such as ilmenite, on the near side as opposed to the far side. Now a team of researchers at Arizona Lunar and Planetary Laboratory are proposing a possible explanation for that.
The lunar surface was once flooded by a bubbling magma ocean, and after the magma ocean had hardened, there was an enormous impact on the far side. Heat from this impact spread to the near side and made the crust unstable, causing sheets of heavier and denser minerals on the surface to gradually sink deep into the mantle. These melted again and were belched out by volcanoes. Lava from these eruptions (more of which happened on the near side) ended up in what are now titanium-rich flows of volcanic rock. In other words, the Moon’s old face vanished, only to resurface.
What lies beneath
The region of the Moon in question is known as the Procellarum KREEP Terrane (PKT). KREEP signifies high concentrations of potassium (K), rare earth elements (REE), and phosphorus (P). This is also where ilmenite-rich basalts are found. Both KREEP and the basalts are thought to have first formed when the Moon was cooling from its magma ocean phase. But the region stayed hot, as KREEP also contains high levels of radioactive uranium and thorium.
“The PKT region… represents the most volcanically active region on the Moon as a natural result of the high abundances of heat-producing elements,” the researchers said in a study recently published in Nature Geoscience.
Why is this region located on the near side, while the far side is lacking in KREEP and ilmenite-rich basalts? There was one existing hypothesis that caught the researchers’ attention: it proposed that after the magma ocean hardened on the near side, sheets of these KREEP minerals were too heavy to stay on the surface. They began to sink into the mantle and down to the border between the mantle and core. As they sank, these mineral sheets were thought to have left behind trace amounts of material throughout the mantle.
If the hypothesis was accurate, this would mean there should be traces of minerals from the hardened KREEP magma crust in sheet-like configurations beneath the lunar surface, which could reach all the way down to the edge of the core-mantle boundary.
How could that be tested? Gravity data from the GRAIL (Gravity Recovery and Interior Laboratory) mission to the Moon possibly had the answer. It would allow them to detect gravitational anomalies caused by the higher density of the KREEP rock compared to surrounding materials.
Coming to the surface
GRAIL data had previously revealed that there was a pattern of subsurface gravitational anomalies in the PKT region. This appeared similar to the pattern that the sheets of volcanic rock were predicted to have made as they sank, which is why the research team decided to run a computer simulation of sinking KREEP to see how well the hypothesis matched up with the GRAIL findings.
Sure enough, the simulation ended up forming just about the same pattern as the anomalies GRAIL found. The polygonal pattern seen in both the simulations and GRAIL data most likely means that traces of heavier KREEP and ilmenite-rich basalt layers were left behind beneath the surface as those layers sank due to their density, and GRAIL detected their residue due to their greater gravitational pull. GRAIL also suggested there were many lesser anomalies in the PKT region, which makes sense considering that a large part of the crust is made of volcanic rocks thought to have sunk and left behind residue before they melted and surfaced again through eruptions.
We now also have an idea of when this phenomenon occurred. Because there are impact basins that dated to around 4.22 billion years ago (not to be confused with the earlier far-side impact), but the magma ocean is thought to have hardened before that, the researchers think that the crust also began to sink before that time.
“The PKT border anomalies provide the most direct physical evidence for the nature of the post-magma ocean… mantle overturn and sinking of ilmenite into the deep interior,” the team said in the same study.
This is just one more bit of information regarding how the Moon evolved and why it is so uneven. The near side once raged with lava that is now volcanic rock, much of which exists in flows called mare (which translates to “sea” in Latin). Most of this volcanic rock, especially in the PKT region, contains rare earth elements.
We can only confirm that there really are traces of ancient crust inside the Moon by the collection of actual lunar material far beneath the surface. When Artemis astronauts are finally able to gather samples of volcanic material from the Moon in situ, who knows what will come to the surface?
Enlarge/ NASA’s Orion spacecraft descends toward the Pacific Ocean on December 11, 2021, at the end of the Artemis I mission.
NASA
NASA officials declared the Artemis I mission successful in late 2021, and it’s hard to argue with that assessment. The Space Launch System rocket and Orion spacecraft performed nearly flawlessly on an unpiloted flight that took it around the Moon and back to Earth, setting the stage for the Artemis II, the program’s first crew mission.
But one of the things engineers saw on Artemis I that didn’t quite match expectations was an issue with the Orion spacecraft’s heat shield. As the capsule streaked back into Earth’s atmosphere at the end of the mission, the heat shield ablated, or burned off, in a different manner than predicted by computer models.
More of the charred material than expected came off the heat shield during the Artemis I reentry, and the way it came off was somewhat uneven, NASA officials said. Orion’s heat shield is made of a material called Avcoat, which is designed to burn off as the spacecraft plunges into the atmosphere at 25,000 mph (40,000 km per hour). Coming back from the Moon, Orion encountered temperatures up to 5,000° Fahrenheit (2,760° Celsius), hotter than a spacecraft sees when it reenters the atmosphere from low-Earth orbit.
Despite heat shield issue, the Orion spacecraft safely splashed down in the Pacific Ocean. Engineers discovered the uneven charring during post-flight inspections.
No answers yet
Amit Kshatriya, who oversees development for the Artemis missions in NASA’s exploration division, said Friday that the agency is still looking for the root cause of the heat shield issue. Managers want to be sure they understand the cause before proceeding with Artemis II, which will send astronauts Reid Wiseman, Victor Glover, Christina Koch, and Jeremy Hansen on a 10-day flight around the far side of the Moon.
This will be the first time humans fly near the Moon since the last Apollo mission in 1972. In January, NASA announced a delay in the launch of Artemis II from late 2024 until September 2025, largely due to the unresolved investigation into the heat shield issue.
“We are still in the middle of our investigation on the performance of the heat shield from Artemis I,” Kshatriya said Friday in a meeting with a committee of the NASA Advisory Council.
Engineers have performed sub-scale heat shield tests in wind tunnels and arc jet facilities to better understand what led to the uneven charring on Artemis I. “We’re getting close to the final answer in terms of that cause,” Kshatriya said.
NASA officials previously said it is unlikely they will need to make changes to the heat shield already installed on the Orion spacecraft for Artemis II, but haven’t ruled it out. A redesign or modifications to the Orion heat shield on Artemis II would probably delay the mission by at least a year.
Instead, engineers are analyzing all of the possible trajectories the Orion spacecraft could fly when it reenters the atmosphere at the end of the Artemis II mission. On Artemis I, Orion flew a skip reentry profile, where it dipped into the atmosphere, skipped back into space, and then made a final descent into the atmosphere, sort of like a rock skipping across a pond. This profile allows Orion to make more precise splashdowns near recovery teams in the Pacific Ocean and reduces g-forces on the spacecraft and the crew riding inside. It also splits up the heat load on the spacecraft into two phases.
The Apollo missions flew a direct reentry profile. There is also a reentry mode available called a ballistic entry, in which the spacecraft would fly through the atmosphere unguided.
Enlarge/ Ground teams at NASA’s Kennedy Space Center in Florida moved the Orion spacecraft for the Artemis II mission into an altitude chamber earlier this month.
The charred material began flying off the heat shield in the first phase of the skip reentry. Engineers are looking at how the skip reentry profile affected the performance of the Orion heat shield. NASA wants to understand how the Orion heat shield would perform during each of the possible reentry trajectories for Artemis II.
“What we have the analysis teams off doing is saying, ‘OK, independent of what the constraints are going to be, what can we tolerate?” Kshatriya said.
Once officials understand the cause of the heat shield charring, engineers will determine what kind of trajectory Artemis II needs to fly on reentry to minimize risk to the crew. Then, managers will look at building what NASA calls flight rationale. Essentially, this is a process of convincing themselves the spacecraft is safe to fly.
“When we stitch it all together, we’ll either have flight rationale or we won’t,” Kshatriya said.
Assuming NASA approves the flight rationale for Artemis II, there will be additional discussions about how to ensure Orion heat shields are safe to fly on downstream Artemis missions, which will have higher-speed reentry profiles as astronauts return from landings on the Moon.
In the meantime, preparations on the Orion spacecraft for Artemis II continue at NASA’s Kennedy Space Center. The crew and service modules for Artemis II were mated together earlier this year, and the entire Orion spacecraft is now inside a vacuum chamber for environmental testing.
Enlarge/ Nine kerosene-fueled Rutherford engines power Rocket Lab’s Electron launch vehicle off the pad at Wallops Island, Virginia, early Thursday.
Welcome to Edition 6.36 of the Rocket Report! SpaceX wants to launch the next Starship test flight as soon as early May, the company’s president and chief operating officer said this week. The third Starship test flight last week went well enough that the Federal Aviation Administration—yes, the FAA, the target of many SpaceX fans’ frustrations—anticipates a simpler investigation and launch licensing process than SpaceX went through before its previous Starship flights. However, it looks like we’ll have to wait a little longer for Starship to start launching real satellites.
As always, we welcome reader submissions, and if you don’t want to miss an issue, please subscribe using the box below (the form will not appear on AMP-enabled versions of the site). Each report will include information on small-, medium-, and heavy-lift rockets, as well as a quick look ahead at the next three launches on the calendar.
Starship could threaten small launch providers. Officials from several companies operating or developing small satellite launch vehicles are worried that SpaceX’s giant Starship rocket could have a big impact on their marketability, Space News reports. Starship’s ability to haul more than 100 metric tons of payload mass into low-Earth orbit will be attractive not just for customers with heavy satellites but also for those with smaller spacecraft. Aggregating numerous smallsats on Starship will mean lower prices than dedicated small satellite launch companies can offer and could encourage customers to build larger satellites with cheaper parts, further eroding business opportunities for small launch providers.
Well, yeah … SpaceX’s dedicated rideshare missions are already reshaping the small satellite launch market. The price per kilogram of payload on a Falcon 9 rocket launching a Transporter mission is less than the price per unit on a smaller rocket, like Rocket Lab’s Electron, Firefly’s Alpha, or Europe’s Vega. Companies operating only in the smallsat launch market tout the benefits of their services, often pointing to their ability to deliver payloads into bespoke orbits, rather than dropping off bunches of satellites into more standardized orbits. But the introduction of Orbital Transfer Vehicles for last-mile delivery services has made SpaceX’s Transporter missions, and potentially Starship rideshares, more attractive. “With Starship, OTVs can become the best option for smallsats,” said Marino Fragnito, senior vice president and head of the Vega business unit at Arianespace. If Starship is able to achieve the very low per-kilogram launch prices proposed for it, “then it will be difficult for small launch vehicles,” Fragnito said.
Rocket Lab launches again from Virginia. Rocket Lab’s fourth launch from Wallops Island, Virginia, and the company’s first there in nine months, took off early Thursday with a classified payload for the National Reconnaissance Office, the US government’s spy satellite agency, Space News reports. A two-stage Electron rocket placed the NRO’s payload into low-Earth orbit, and officials declared it a successful mission. The NRO did not disclose any details about the payload, but in a post-launch statement, the agency suggested the mission was conducting technology demonstrations of some kind. “The knowledge gained from this research will advance innovation and enable the development of critical new technology,” said Chris Scolose, director of the NRO.
A steady customer for Rocket Lab … The National Reconnaissance Office has become a regular customer of Rocket Lab. The NRO has historically launched larger spacecraft, such as massive bus-sized spy satellites, but like the Space Force, is beginning to launch larger numbers of small satellites. This mission, designated NROL-123 by the NRO, was the fifth and last mission under a Rapid Acquisition of a Small Rocket (RASR) contract between NRO and Rocket Lab, dating back to 2020. It was also Rocket Lab’s second launch in nine days, following an Electron flight last week from its primary base in New Zealand. Overall, it was the 46th launch of a light-class Electron rocket since it debuted in 2017. Rocket Lab is building a launch pad for its next-generation Neutron rocket at Wallops. (submitted by EllPeaTea)
The easiest way to keep up with Eric Berger’s space reporting is to sign up for his newsletter, we’ll collect his stories in your inbox.
Night flight for Astrobotic’s Xodiac. The Xodiac rocket, a small terrestrial vertical takeoff and vertical landing technology testbed, made its first night flight, Astrobotic says in a statement. The liquid-fueled Xodiac is designed for vertical hops and can host prototype sensors and other payloads, particularly instruments in development to assist in precision landings on other worlds. This first tethered night flight of Xodiac in Mojave, California, was in preparation for upcoming flight testing with the NASA TechLeap Prize’s Nighttime Precision Landing Challenge. These flights will begin in April, allowing NASA to test the ability of sensors to map a landing field designed to simulate the Moon’s surface in near-total darkness.
Building on the legacy of Masten … Xodiac has completed more than 160 successful flights, dating back to the vehicle’s original owner, Masten Space Systems. Masten filed for bankruptcy in 2022, and the company was acquired by Astrobotic a couple of months later. Astrobotic’s primary business area is in developing and flying robotic Moon landers, so it has a keen interest in mastering automated landing and navigation technologies like those it is testing with NASA on Xodiac. David Masten, founder of Masten Space Systems, is now chief engineer for Astrobotic’s propulsion and test department. “The teams will demonstrate their systems over the LSPG (Lunar Surface Proving Ground) at night to simulate landing on the Moon during the lunar night or in shadowed craters.” (submitted by Ken the Bin)
Japan’s SLIM spacecraft is seen nose down on the surface of the Moon.
Japan’s first lunar lander made an unsteady touchdown on the Moon last week, moments after one of its two main engines inexplicably lost power and apparently fell off the spacecraft, officials said Thursday.
About the size of a small car, the Small Lander for Investigating Moon (SLIM) landed on Friday, making Japan the fifth country to achieve a soft landing on the lunar surface. Shortly after landing, ground teams in Japan realized the spacecraft was not recharging its battery with its solar panels. The evidence at the time suggested that SLIM likely ended up in an unexpected orientation on the Moon, with its solar cells facing away from the Sun.
With the benefit of six days of data crunching and analysis, officials from the Japan Aerospace Exploration Agency (JAXA) briefed reporters Thursday on what they have learned about SLIM’s landing. Indeed, the spacecraft toppled over after touching down, with its nose planted into the lunar regolith and its rear propulsion section pointed toward space.
It turns out that SLIM overcame a lot to get to that point. In the final minute of Friday’s descent, one of SLIM’s two engines failed, leaving the craft’s sole remaining engine to bring the spacecraft in for an off-balance landing. Still, JAXA officials said the spacecraft achieved nearly all of its primary objectives. The roughly $120 million robotic mission made the most pinpoint landing on the Moon in history, just as it set out to do.
“From the spacecraft, we were able to acquire all the technical data related to navigation guidance leading to landing, which will be necessary for future pinpoint landing technology, as well as navigation camera image data during descent and on the lunar surface,” JAXA said in a statement.
One of two tiny robots released by SLIM just before landing relayed a remarkable image of the lander standing upside down a short distance away. This might be the first close-up view of a crash landing, however gentle, on another world.
One plucky bird
Based on the update JAXA released Thursday, it’s extraordinary that SLIM made it to the surface in one piece.
After launching in September and arriving at the Moon in December, SLIM lined up for a final descent to the lunar surface on Friday. Around 20 minutes before landing, the spacecraft ignited its two hydrazine-fueled rocket engines for a braking maneuver to drop out of lunar orbit.
JAXA officials said everything went according to plan in the initial phases of the descent. The spacecraft pitched over from a horizontal orientation to begin a final vertical descent to the surface. SLIM’s guidance computer was preloaded with a map of the landing zone, and an onboard navigation camera took pictures of the Moon’s surface throughout the landing sequence. The spacecraft’s computer used these images to compare to the map, allowing SLIM to autonomously correct its course along the way.
Enlarge/ The SLIM spacecraft was built by Mitsubishi Electric under contract with JAXA.
JAXA
But at an altitude of around 160 feet (50 meters), something went wrong with the spacecraft’s propulsion system. Less than a minute before touchdown, one of the engines suddenly lost thrust, and moments later, a down-facing navigation camera caught a glimpse of what appeared to be one of the engine nozzles falling away from the spacecraft. JAXA said engineers believe the engine failure was likely caused by “some external factor other than the main engine itself.” Officials are still investigating to determine the root cause.
The spacecraft continued descending on the power of its remaining engine, but it became more difficult to control the lander. The thrust from the single engine imparted a sideways motion to the spacecraft. Normally, SLIM would have used thrusters to tilt itself from the vertical orientation necessary for the final descent and into a position to plop itself on the lunar surface along the spacecraft’s long axis. SLIM had five crushable landing legs to absorb the force of the gentle impact.
While this two-stage landing sequence was the plan, JAXA said Thursday that the spacecraft “touched the ground in an almost straight standing position with lateral velocity.” The vertical speed at touchdown was about 3.1 mph (1.4 meters per second), slightly slower than the expected descent rate.
“Because the ground contact conditions such as lateral speed and attitude exceeded the specification range, a large attitude change occurred after touchdown, and the aircraft settled in a different attitude than expected,” JAXA said.
In other words, the squirrelly landing caused the spacecraft to tip over. SLIM settled in a bottoms-up position on a shallow slope rather than on its side. Its solar panel wasn’t facing up but was instead pointed toward the west, away from the Sun’s position in the eastern morning sky at the landing site.
Enlarge/ A camera on Astrobotic’s Peregrine spacecraft captured this view of a crescent Earth during its mission.
Astrobotic knew its first space mission would be rife with risks. After all, the company’s Peregrine spacecraft would attempt something never done before—landing a commercial spacecraft on the surface of the Moon.
The most hazardous part of the mission, actually landing on the Moon, would happen more than a month after Peregrine’s launch. But the robotic spacecraft never made it that far. During Peregrine’s startup sequence after separation from its United Launch Alliance Vulcan rocket, one of the spacecraft’s propellant tanks ruptured, spewing precious nitrogen tetroxide into space. The incident left Peregrine unable to land on the Moon, and it threatened to kill the spacecraft within hours of liftoff.
“What a wild adventure we were just on, not the outcome we were hoping for,” said John Thornton, CEO of Astrobotic.
Astrobotic’s control team, working out of the company’s headquarters in Pittsburgh, swung into action to save the spacecraft. The propellant leak abated, and engineers wrestled control of the spacecraft to point its solar arrays toward the Sun, allowing its battery to recharge. Over time, Peregrine’s situation stabilized, although it didn’t have enough propellant remaining to attempt a descent to the lunar surface.
Peregrine continued on a trajectory out to 250,000 miles (400,000 kilometers) from Earth, about the same distance as the Moon’s orbit. Astrobotic’s original flight plan would have taken Peregrine on one long elliptical loop around Earth, then the spacecraft would have reached the Moon during its second orbit.
On its way back toward Earth, Peregrine was on a flight path that would bring it back into the atmosphere, where it would burn up on reentry. That meant Astrobotic had a decision to make. With Peregrine stabilized, should they attempt an engine burn to divert the spacecraft away from Earth onto a trajectory that could bring it to the vicinity of the Moon? Or should Astrobotic keep Peregrine in line to reenter Earth’s atmosphere and avoid the risk of sending a crippled spacecraft out to the Moon?
Making lemonade out of lemons
This was the first time Astrobotic had flown a space mission, and its control team had much to learn. The malfunction that caused the propellant leak appears to have been with a valve that did not properly reseat during the propulsion system’s initialization sequence. This valve activated to pressurize the fuel and oxidizer tanks with helium.
When the valve didn’t reseat, it sent a “rush of helium” into the oxidizer system, Thornton said. “I describe it as a rush because it was very, very fast. “Within a little over a minute, the pressure had risen to the point in the oxidizer side that it was well beyond the proof limit of the propulsion tank. We believe at that point the tank ruptured and led to, unfortunately, a catastrophic loss of propellant … for the primary mission.”
Thornton described the glum mood of Astrobotic’s team after the propellant leak.
“We were coming from the highest high of a perfect launch and came down to the lowest low, when we found out that the spacecraft no longer had the helium and no longer had the propulsion needed to attempt the Moon landing,” he said. “What happened next, I think, was pretty remarkable and inspiring.”
In a press briefing Friday, Thornton outlined the obstacles Astrobotic’s controllers overcame to keep Peregrine alive. Without a healthy propulsion system, the spacecraft’s solar panels were not pointed at the Sun. With a few minutes to spare, one of Astrobotic’s engineers, John Shaffer, devised a solution to reorient the spacecraft to start recharging its battery.
As Peregrine’s oxidizer tank lost pressure, the leak rate slowed. At first, it looked like the spacecraft might have only hours of propellant remaining. Then, Astrobotic reported on January 15 that the leak had “practically stopped.” Mission controllers powered up the science payloads aboard the Peregrine lander, proving the instruments worked and demonstrating the spacecraft could have returned data from the lunar surface if it landed.
The small propulsive impulse from the leaking oxidizer drove Peregrine slightly off course, putting it on a course to bring it back into Earth’s atmosphere. This set up Astrobotic for a “very difficult decision,” Thornton said.
Enlarge/ Astrobotic’s first lunar lander, named Peregrine, at the company’s Pittsburgh headquarters.
Nudging Peregrine off its collision course with Earth would have required the spacecraft to fire its main engines, and even if that worked, the lander would have needed to perform more maneuvers to get close to the Moon. A landing was still out of the question, but Thornton said there was a small chance Astrobotic could have guided Peregrine toward a flyby or impact with the Moon.
“The thing we were weighing was, ‘Should we send this back to Earth, or should we take the risk to operate it in cislunar space and see if we can send this out farther?'” Thornton said.
Enlarge/ Artist’s illustration of the SLIM spacecraft on final descent to the Moon.
The Japanese space agency’s first lunar lander arrived on the the Moon’s surface Friday, but a power system problem threatens to cut short its mission.
Japan’s robotic Smart Lander for Investigating Moon (SLIM) mission began a 20-minute final descent using two hydrazine-fueled engines to drop out of orbit. After holding to hover at 500 meters and then 50 meters altitude, SLIM pulsed its engines to fine-tune its vertical descent before touching down at 10: 20 am EST (15: 20 UTC).
The Japan Aerospace Exploration Agency (JAXA), which manages the SLIM mission, streamed the landing live on YouTube. About two hours after the touchdown, JAXA officials held a press conference to confirm the spacecraft made a successful landing, apparently quite close to its target. SLIM aimed to settle onto the lunar surface adjacent to a nearly 900-foot (270-meter) crater named Shioli, located in a region called the Sea of Nectar on the near side of the Moon.
But ground controllers at JAXA’s Sagamihara Campus in the western suburbs of Tokyo soon discovered the lander was in trouble. Its solar array was not generating electricity after landing, and without power, officials expected SLIM to drain its battery within a few hours.
In what could be the mission’s final hours, engineers prioritized downloading data from SLIM, including imagery taken during its descent, and potentially new pictures captured from the lunar surface. Official reported good communications links between SLIM and ground stations on Earth.
“Minimum success”
Even if SLIM falls silent, the mission has achieved its minimum success criteria, JAXA said. The SLIM mission is a technology demonstrator developed to verify the performance of a new vision-based navigation system needed for precision Moon landings.
“First and foremost, landing was made and communication was established,” said Hiroshi Yamakawa, JAXA’s president. “So a minimum success was made in my view.”
One of the core goals of the SLIM mission was to land within 100 meters (about 330 feet) of its bullseye. This accomplishment would be a remarkable improvement in lunar landing precision, which typically is measured in miles or kilometers. It would also be an enabling capability for future Moon missions because it lays the foundation for future spacecraft to land closer to lunar resources, such as water ice.
Hitoshi Kuninaka, director general of JAXA’s Institute of Space and Astronautical Science, said it will take about a month for engineers to fully analyze data from SLIM and determine the precision of the landing.
“But as you saw on the real-time data livestream, SLIM did trace the expected course, so my personal impression is that we probably have been able to more or less achieve a high precision landing within 100-meter accuracy,” Kuninaka said. “So the solar cell state is unlikely to impact the full success criteria.”
Kuninaka said ground teams have seen no evidence of any damage to the solar array on SLIM. It’s possible the lander is sitting in an orientation with its solar cells facing away from the Sun. All other components of SLIM, including its propulsion, thermal, and communication systems, all appear to be functioning well.
SLIM launched September 6 on top of a Japanese H-IIA rocket, riding to orbit alongside an X-ray astronomy telescope. The spacecraft took a long route to get to the Moon, trading time for fuel to preserve propellant for Friday’s landing attempt. SLIM entered orbit around the Moon on December 25, then completed several maneuvers to settle into a low-altitude orbit in preparation for the descent to the surface.
A milestone moment for Japan
The landing of SLIM made Japan the fifth country to soft-land a spacecraft on the Moon, following the Soviet Union, the United States, China, and India. But landing on the Moon is a hazardous thing to do. Three commercial landers similar in scale to SLIM failed to safely reach the lunar surface over the last five years.
One of those was developed by a Japanese company called ispace. Most recently, the US company Astrobotic attempted to send its Peregrine lander to the Moon, but a propellant leak cut short the mission. After looping more than 200,000 miles into space, Peregrine reentered Earth’s atmosphere Wednesday, where it was expected to burn up 10 days after its launch.
A Russian lander crashed into the Moon in August, and India’s first lunar lander failed in 2019. India tried again last year and made history when Chandrayaan 3 safely landed.
Enlarge/ This artist’s illustration shows the SLIM spacecraft descending toward the Moon and ejecting two deployable robots onto the lunar surface.
Japan’s SLIM mission was primarily designed to test out new guidance algorithms and sensors, rather than pursuing scientific objectives. The technologies riding to the Moon on SLIM could be used on future spacecraft bound for the Moon. SLIM cost the Japanese government approximately 18 billion yen ($121 million) to design, develop, and build, according to JAXA.
The spacecraft is modest in size, measuring nearly 8 feet (2.4 meters) tall and nearly 9 feet (2.7 meters) across. Without propellant in its tanks, SLIM has a mass of roughly 660 pounds (200 kilograms).
“The start of the deceleration to the landing on the Moon’s surface is expected to be a breathless, numbing 20 minutes of terror!” said Kushiki Kenji, sub-project manager for the SLIM mission, before the landing.
Enlarge/ The first Vulcan rocket fires off its launch pad in Florida.
United Launch Alliance
CAPE CANAVERAL, Florida—Right out of the gate, United Launch Alliance’s new Vulcan rocket chased perfection.
The Vulcan launcher hit its marks after lifting off from Florida’s Space Coast for the first time early Monday, successfully deploying a commercial robotic lander on a journey to the Moon and keeping ULA’s unblemished success record intact.
“Yeehaw! I am so thrilled, I can’t tell you how much!” exclaimed Tory Bruno, ULA’s president and CEO, shortly after Vulcan’s departure from Cape Canaveral. “I am so proud of this team. Oh my gosh, this has been years of hard work. So far, this has been an absolutely beautiful mission.”
This was a pivotal moment for ULA, a 50-50 joint venture between Boeing and Lockheed Martin. The Vulcan rocket will replace ULA’s mainstay rockets, the Atlas V and Delta IV, with lineages dating back to the dawn of the Space Age. ULA has contracts for more than 70 Vulcan missions in its backlog, primarily for the US military and Amazon’s Project Kuiper broadband network.
The Vulcan rocket lived up to the moment Monday. It took nearly a decade for ULA to develop it, some four years longer than anticipated, but the first flight took off at the opening of the launch window on the first launch attempt.
Standing 202 feet (61.6 meters) tall, the Vulcan rocket ignited its two BE-4 main engines in the final seconds of a smooth countdown. A few moments later, two strap-on solid rocket boosters flashed to life to propel the Vulcan rocket off its launch pad at 2: 18 am EST (07: 18 UTC).
On the money
The BE-4 engines and solid-fueled boosters combined to generate more than 2 million pounds of thrust, vaulting Vulcan off the launch pad and through a thin cloud layer. A little over a minute after launch, Vulcan accelerated faster than the speed of sound, then jettisoned its strap-on boosters to fall into the Atlantic Ocean.
Then it was all BE-4. Each of these engines can produce more than a half-million pounds of thrust, consuming a mixture of liquified natural gas—essentially methane—and liquid oxygen. They are built by Blue Origin, the space company founded by billionaire Jeff Bezos. This was the first time BE-4s have flown on a rocket.
Rob Gagnon, ULA’s telemetry commentator, calmly called out mission milestones. “BE-4s continue to operate nominally… Vehicle is continuing to fly down the center of the range track, everything looking good… Nice and smooth operation of the booster.”
The BE-4s fired for five minutes, then shut down to allow Vulcan’s first stage booster to fall away from the rocket’s hydrogen-fueled Centaur upper stage. Two RL10 engines ignited to continue the push into orbit, then switched off as the upper stage coasted over the Atlantic and Africa. A restart of the Centaur upper stage 43 minutes into the flight gave the rocket enough velocity to send Astrobotic’s Peregrine lunar lander toward the Moon.
The nearly 1.5-ton spacecraft separated from Vulcan’s Centaur upper stage around 50 minutes after liftoff. “We have spacecraft separation, right on time,” Gagnon announced.
With Astrobotic’s lander deployed, a third engine firing on the Centaur upper stage moved the rocket off its Moon-bound trajectory and onto a course into heliocentric orbit. “We have now achieved Earth escape,” Gagnon said.
The spent rocket stage will become a human-made artificial satellite of the Sun. A plate on the side of the Centaur upper stage contains small capsules holding the cremated remains of more than 200 people, a “memorial spaceflight” arranged by a Houston-based private company named Celestis.
