🚀 Why E Hard Well-Well to Land Straight for Moon 🌑
⬇️ Pidgin ⬇️ ⬇️ Black American Slang ⬇️ English
Dis year, two spacecraft don turn gbege for moon surface. E be like say to fall yakata for moon, wey him gravity soft pass ear dey easier than many people fit imagine.
When Odysseus, wey be robotic lander, last month turn di first American-built spacecraft to touch ground for moon after pass 50 years, e just capsize go one kind angle. That limited di amount of science e fit do for moon surface, because him antennas and solar panels no point for di correct direction.
Just one month before, another spacecraft, wey dem call Smart Lander for Investigating Moon, or SLIM, wey Japanese space agency send, self don tip during landing, e come land for head.
Why spacecraft dey do gymnastics roll for moon like Olympic gymnasts dey do for floor routine? E really hard like dat to land straight for there?
For internet and other places, people don dey yarn say na because Odysseus lander tall reach 14 feet from di bottom of di landing feet go reach di solar arrays for top na im make e no land well.
Had Intuitive Machines, di maker of Odysseus, made an obvious error in building di spacecraft that way? 🤔
Di company’s officials provide engineering rationale for di tall, skinny design, but those internet commenters do have a point.
Something tall falls over more easily than an object wey short and squat. And on di moon, where gravity na just one-sixth strong as e dey for Earth, di propensity to tip over na even greater. 🌕
Dis na no be new realization. A half-century ago, Apollo astronauts sef get firsthand experience as dem dey hop around for moon, and sometimes dem go just fall for ground.
For social media site X last week, Philip Metzger, wey be former NASA engineer wey now be planetary scientist for University of Central Florida, don explain di maths and physics behind why e hard to stand straight for moon.
“I don really calculate am, e dey scary,” Dr. Metzger yarn. “Di side motion wey fit make lander of that size tip over na just few meters per second for lunar gravity.” (One meter per second na, for everyday American units, a bit more than two miles per hour.) 📊
There are two parts to dis question of stability.
Di first na static stability. If something dey stand for angle wey too much, e go fall over if di center of gravity dey outside di landing legs.
Here, e turn out say di maximum angle of leaning na di same for Earth as e dey for moon. E go be di same for any world, big or small, because gravity no dey affect di equation.
However, di answer change if di spacecraft still dey move. Odysseus suppose land vertically with zero horizontal velocity, but because of wahala with di navigation system, e still dey move sideways when e hit ground.
“Intuition wey based on Earth na liability now,” Dr. Metzger yarn.
He give example, say if you try push refrigerator for your kitchen. “E heavy so tey small push no go fit push am over,” Dr. Metzger yarn.
But if you change am to piece of Styrofoam wey shape like refrigerator, wey mimic real refrigerator weight for lunar gravity, “then very light push go push am over,” Dr. Metzger yarn.
Assuming di spacecraft remain in one piece, e go rotate for di point of contact where di landing foot touch ground.
Dr. Metzger calculations suggest say for spacecraft like Odysseus, di landing legs need dey splay about two and half times as wide on di moon as on di Earth to counteract di same amount of sideways motion.
If, for example, six feet wide enough for landing on Earth at di maximum horizontal speed, then di legs go need dey 15 feet apart so e no go tip for moon at di same sideways speed.
For simplicity of design, di landing legs of Odysseus no fold up, and di diameter of di SpaceX Falcon 9 rocket wey lift am go space limit how wide di landing legs fit spread out.
“So, for moon, you gats design to keep di sideways velocities very low at touchdown, much lower than you would if landing di vehicle for Earth gravity,” Dr. Metzger write on X. 🌍
I too wonder about di shape of di lander when I visit Intuitive Machines headquarters and factory for Houston for February last year.
“Why e tall so?” I ask.
Steve Altemus, di chief executive of Intuitive Machines, reply say e get to do with di tanks wey hold di spacecraft’s liquid methane and liquid oxygen propellants.
Di oxygen weigh twice as much as di methane, so if di oxygen tank dey placed next to di methane tank, di lander go unbalance. Instead, dem stack di two tanks on top each other.
“That na wetin create di height,” Mr. Altemus say.
Scott Manley, wey dey give commentary about rockets for X and YouTube, note say Mr. Altemus don lead di development of shorter, squatter lander when e dey for NASA a decade ago.
That test lander, named Morpheus, also use methane and oxygen propellants, but di tanks dey configured in pairs to keep di weight balance. E never meant to fly go space.
For interview, Mr. Manley say that design for work for Intuitive Machines lander as well but e for make di spacecraft heavier and more complex.
If di spacecraft need two methane tanks and two oxygen tanks, di spacecraft structure go need to be bigger and heavier. Di tanks go be heavier too.
“You get more surface area, so that’s more surface to insulate,” Mr. Manley say. E add say e go also need “more plumbing and more valves, more things to go wrong.”
For di landing site for south pole region, di height of Odysseus offer another advantage. For bottom of moon, sunlight dey shine for low angles, dey produce long shadows. If Odysseus remain upright, di solar arrays for top of di spacecraft go stay out of shadows longer, generating more power for di mission.
During visit to Intuitive Machines, Tim Crain, di company chief technology officer, say di spacecraft don design to stay upright when e land even for slope of 10 degrees or more. Di navigation software na programmed to look for spot where di slope na five degrees or less.
Because the laser instruments on Odysseus for measure altitude no dey work during descent, di spacecraft land faster than planned on 12-degree slope. That pass e design limits. Odysseus skid for surface, break one of e six legs and tip to e side.
If di laser instruments dey work, “We for nail di landing,” Mr. Altemus say during news conference last week
Di same concern go apply for SpaceX big Starship, wey go carry two NASA astronauts go moon surface as soon as 2026.
Starship, wey tall like 16-story building, gats come down perfectly vertically and avoid big slopes. But those na solvable engineering challenges, Dr. Metzger say.
“It remove some of di margin of error for your dynamic stability, but e no remove all di margin of error,” Dr. Metzger say about tall lander. “Di amount of margin that you have left na manageable as long as your other systems for di spacecraft dey function.”
NOW IN BLACK AMERICAN SLANG
🚀 Why Landing on the Moon Ain’t Easy, Ya Heard? 🌕
This year, we got two spacecrafts out there on the moon, and both of ’em ain’t sitting pretty. Seems like keeping upright on that lunar surface ain’t a walk in the park like we thought.
So, when Odysseus, that robotic lander, made history last month as the first American-built spacecraft to touchdown on the moon in over 50 years, it ain’t stick the landing too well. It leaned over at an angle, messing up its antennas and solar panels and putting a cap on the science it could do up there.
And just a month before that, another one, SLIM, sent by the Japanese space agency, did the same somersault during landing, ending up on its head.
Why we seeing spacecrafts doing flips on the moon like they’re in the Olympics, ya dig? Is it really that tough to land straight up there?
Folks on the internet been pointing fingers at Odysseus’s height — 14 feet tall from its landing feet to its solar arrays — as a big reason why it stumbled.
Did Intuitive Machines, the folks behind Odysseus, mess up by building it so tall?
They got their reasons for that tall, skinny design, but folks online might have a point.
Something tall gonna tip over easier than something short and stocky. And on the moon, where gravity ain’t as strong as back home, tipping over’s a real threat.
This ain’t news to us. Back in the day, Apollo astronauts was bouncin’ around on the moon, sometimes taking a tumble.
Last week on X, Philip Metzger, ex-NASA engineer now doing planetary science at the University of Central Florida, broke it down for us. He said the math and physics behind standing tall on the moon are scarier than you think. The sideways movement that can tip a big lander like that? It’s just a few meters per second in lunar gravity. That’s like walking speed, fam.
Now, there’s two parts to this stability puzzle.
First is static stability. If something’s leaning too far, it’s gonna fall if its center of gravity ain’t over them landing legs.
Turns out, the maximum lean angle is the same on Earth as it is on the moon. Gravity’s a non-factor here.
But, if the spacecraft’s still moving when it lands, that’s where things get tricky. Odysseus was s’posed to come down with zero sideways movement, but it ended up sliding ’cause of a messed-up navigation system.
“Your Earth-based instincts ain’t gonna help you here,” Dr. Metzger said. He compared it to trying to push over a fridge in your kitchen. On Earth, you ain’t budgin’ it. But slap a moon-weight fridge in there, and even a light push will send it crashing.
Assuming the spacecraft stays in one piece, it’s gonna pivot at the spot where the landing leg touches down.
Dr. Metzger’s math says that for a big lander like Odysseus, them landing legs gotta be spread about two and a half times wider on the moon than on Earth to handle the same sideways motion. So, if six feet was enough back home, you’re gonna need 15 feet apart up there.
But Odysseus’s legs ain’t folding up, and the diameter of the SpaceX Falcon 9 rocket that took it up there put limits on how wide those legs could go.
So, you gotta design for low sideways speed at touchdown, way lower than on Earth, Dr. Metzger said.
When I was kickin’ it at Intuitive Machines in Houston last February, I had to ask: “Why’s it gotta be so tall?”
Steve Altemus, the big boss at Intuitive Machines, said it’s ’cause of the tanks holding the spacecraft’s liquid methane and liquid oxygen. Oxygen’s twice as heavy as methane, so if you stack ’em side by side, you’re gonna be lopsided. So they went with the stacked look.
Scott Manley, the rocket guru, pointed out that Mr. Altemus had worked on a shorter lander back in his NASA days. It used the same fuels but kept things balanced. It never flew to space, though.
Mr. Manley said that design could’ve worked for Intuitive Machines too, but it would’ve made things heavier and more complicated. If you need two tanks of each fuel, the spacecraft’s gotta be bigger and heavier. And more stuff means more chances for things to go wrong.
Down at the landing site near the south pole, Odysseus’s height had another perk. Sunlight down there comes in at low angles, making long shadows. If Odysseus had stayed standing, them solar panels would’ve soaked up more juice, powering the mission longer.
During my visit, Tim Crain, the tech chief at Intuitive Machines, said Odysseus was made to stay upright on slopes up to 10 degrees. Their nav software was supposed to find a spot with slopes five degrees or less.
But, with no lasers working during the landing, Odysseus came in too fast on a 12-degree slope. That was more than it could handle. It skidded, busted a leg, and fell over.
If them lasers had been working, “We woulda nailed the landing,” Mr. Altemus said at a press meet last week.
Same worries gonna pop up when SpaceX’s Starship, that behemoth of a rocket, heads to the moon with two NASA astronauts in 2026.
Starship, tall as a 16-story building, gotta come down straight and avoid steep slopes. But that’s just engineering puzzles to solve, Dr. Metzger said. It ain’t perfect, but as long as the rest of the spacecraft’s holding up, we’ll be good to go. 🌌
NOW IN ENGLISH
🚀 Why It’s So Hard to Land Upright on the Moon 🌑
This year, two spacecraft have found themselves in trouble on the lunar surface. It seems that tipping over on the moon, where gravity is softer than a whisper, is easier than many people might think.
When the robotic lander Odysseus touched down on the moon last month, marking the first American-built spacecraft to do so in over 50 years, it keeled over at an angle. This limited the scientific activities it could perform on the lunar surface because its antennas and solar panels were not properly aligned.
Just a month earlier, another spacecraft, the Smart Lander for Investigating Moon (SLIM), sent by the Japanese space agency, also tipped during landing and ended up on its head.
Why are spacecraft suddenly performing acrobatics on the moon like Olympic gymnasts? Is it truly that challenging to land upright there?
On the internet and elsewhere, people pointed to the height of the Odysseus lander — standing 14 feet tall from the bottom of its landing feet to the top of its solar arrays — as a contributing factor to its off-kilter touchdown.
Did Intuitive Machines, the maker of Odysseus, make an obvious error in constructing the spacecraft this way? 🤔
The company’s officials provided an engineering rationale for the tall, slender design, but those internet commenters may have a point.
Something tall is more prone to toppling over than something short and squat. And on the moon, where gravity is only one-sixth as strong as on Earth, the tendency to tip over is even greater. 🌕
This is not a newfound realization. Half a century ago, Apollo astronauts experienced this firsthand as they bounded around on the lunar surface, sometimes tumbling to the ground.
On the social media site X last week, Philip Metzger, a former NASA engineer now working as a planetary scientist at the University of Central Florida, explained the math and physics behind why it’s more difficult to maintain stability on the moon.
“I’ve actually run the calculations, and it’s really alarming,” Dr. Metzger said. “The lateral movement that can tip a lander of that size is only a few meters per second in lunar gravity.” (One meter per second is a bit more than two miles per hour in everyday American units.) 📊
There are two aspects to this question of stability.
The first is static stability. If something is leaning at too great an angle, it will topple over if the center of gravity is outside the landing legs.
Here, it turns out that the maximum leaning angle is the same on Earth as it is on the moon. It would be the same on any celestial body, large or small, because gravity is not a factor in the equation.
However, the answer changes if the spacecraft is still in motion. Odysseus was supposed to land vertically with zero horizontal velocity, but due to issues with the navigation system, it was still moving sideways when it made contact with the ground.
“Intuition based on Earth is now a liability,” Dr. Metzger explained.
He gave the analogy of trying to push over a refrigerator in your kitchen. “It’s so heavy that a slight push won’t topple it,” Dr. Metzger said.
But if you replace it with a Styrofoam replica of the same weight in lunar gravity, “then even a light push will knock it over,” Dr. Metzger added.
Assuming the spacecraft remains intact, it would rotate at the point of contact where the landing foot touches the ground.
Dr. Metzger’s calculations suggested that for a spacecraft like Odysseus, the landing legs would need to be spread about two and a half times as wide on the moon as on Earth to counteract the same amount of sideways motion.
For example, if six feet of width were sufficient for landing on Earth at maximum horizontal speed, then the legs would need to be 15 feet apart to avoid tipping on the moon at the same sideways speed.
For simplicity in design, Odysseus’s landing legs did not fold up, and the diameter of the SpaceX Falcon 9 rocket that launched it into space limited how far apart the legs could spread.
“So, on the moon, you have to design to keep the sideways velocities very low at touchdown, much lower than you would if landing the vehicle in Earth’s gravity,” Dr. Metzger wrote on X. 🌍
I too questioned the shape of the lander when I visited the Intuitive Machines headquarters and factory in Houston last February.
“Why is it so tall?” I asked.
Steve Altemus, the chief executive of Intuitive Machines, explained that it had to do with the tanks holding the spacecraft’s liquid methane and liquid oxygen propellants.
The oxygen tank weighs twice as much as the methane tank, so if the oxygen tank were placed next to the methane tank, the lander would have been unbalanced. Instead, the two tanks were stacked on top of each other.
“That’s what created the height,” Mr. Altemus said.
Scott Manley, who provides commentary on rockets on X and YouTube, noted that Mr. Altemus had led the development of a shorter, stouter lander when he was at NASA a decade ago.
That test lander, named Morpheus, also used methane and oxygen propellants, but the tanks were configured in pairs to maintain balance. It was never intended to fly to space.
In an interview, Mr. Manley said that design would have worked for the Intuitive Machines lander as well but would have made the spacecraft heavier and more complex.
If the spacecraft required two methane tanks and two oxygen tanks, the spacecraft structure would have needed to be larger and heavier. The tanks themselves would have been heavier too.
“You have more surface area, so there’s more surface to insulate,” Mr. Manley said. He added that it would have also required “more plumbing and more valves, more things to go wrong.”
At the landing site in the south pole region, the height of Odysseus offered another advantage. At the bottom of the moon, sunlight shines at low angles, creating long shadows. If Odysseus had remained upright, the solar arrays at the top of the spacecraft would have remained out of shadows longer, generating more power for the mission.
During the visit to Intuitive Machines, Tim Crain, the company’s chief technology officer, said the spacecraft had been designed to remain upright when landing even on a slope of 10 degrees or more. The navigation software was programmed to search for a spot where the slope was five degrees or less.
Because the laser instruments on Odysseus for measuring altitude were not functioning during descent, the spacecraft landed faster than planned on a 12-degree slope. That exceeded its design limits. Odysseus skidded along the surface, broke one of its six legs, and tipped to its side.
If the laser instruments had been operational, “We would have nailed the landing,” Mr. Altemus said during a news conference last week.
The same concerns will apply to SpaceX’s massive Starship, which will transport two NASA astronauts to the moon’s surface as early as 2026.
Starship, as tall as a 16-story building, will have to descend perfectly vertically and avoid significant slopes. But these should be solvable engineering challenges, Dr. Metzger said.
“It reduces some of the margin of error in your dynamic stability, but it doesn’t eliminate all the margin of error,” Dr. Metzger said regarding a tall lander. “The remaining margin is manageable as long as the other systems on the spacecraft are functioning.” 🚀
