NASA rover faces 'seven minutes of terror' before landing on Mars By Steve Gorman
LOS ANGELES (Reuters) - When NASA’s Mars rover Perseverance, a robotic astrobiology lab packed inside a space capsule, hits the final stretch of its seven-month journey from Earth this week, it is set to emit a radio alert as it streaks into the thin Martian atmosphere.
By the time that signal reaches mission managers some 127 million miles (204 million km) away at the Jet Propulsion Laboratory (JPL) near Los Angeles, Perseverance will already have landed on the Red Planet - hopefully in one piece.
The six-wheeled rover is expected to take seven minutes to descend from the top of the Martian atmosphere to the planet’s surface in less time than the 11-minute-plus radio transmission to Earth. Thus, Thursday’s final, self-guided descent of the rover spacecraft is set to occur during a white-knuckled interval that JPL engineers affectionately refer to as the “seven minutes of terror.”
Al Chen, head of the JPL descent and landing team, called it the most critical and most dangerous part of the $2.7 billion mission.
“Success is never assured,” Chen told a recent news briefing. “And that’s especially true when we’re trying to land the biggest, heaviest and most complicated rover we’ve ever built to the most dangerous site we’ve ever attempted to land at.”
Much is riding on the outcome. Building on discoveries of nearly 20 U.S. outings to Mars dating back to Mariner 4’s 1965 flyby, Perseverance may set the stage for scientists to conclusively show whether life has existed beyond Earth, while paving the way for eventual human missions to the fourth planet from the sun. A safe landing, as always, comes first.
Success will hinge on a complex sequence of events unfolding without a hitch - from inflation of a giant, supersonic parachute to deployment of a jet-powered “sky crane” that will descend to a safe landing spot and hover above the surface while lowering the rover to the ground on a tether.
“Perseverance has to do this all on her own,” Chen said. “We can’t help it during this period.”
If all goes as planned, NASA’s team would receive a follow-up radio signal shortly before 1 p.m. Pacific time confirming that Perseverance landed on Martian soil at the edge of an ancient, long-vanished river delta and lake bed.
From there, the nuclear battery-powered rover, roughly the size of a small SUV, will embark on the primary objective of its two-year mission - engaging a complex suite of instruments in the search for signs of microbial life that may have flourished on Mars billions of years ago.
Advanced power tools will drill samples from Martian rock and seal them into cigar-sized tubes for eventual return to Earth for further analysis - the first such specimens ever collected by humankind from the surface of another planet.
Two future missions to retrieve those samples and fly them back to Earth are in the planning stages by NASA, in collaboration with the European Space Agency.
Perseverance, the fifth and by far most sophisticated rover vehicle NASA has sent to Mars since Sojourner in 1997, also incorporates several pioneering features not directly related to astrobiology.
Among them is a small drone helicopter, nicknamed Ingenuity, that will test surface-to-surface powered flight on another world for the first time. If successful, the four-pound (1.8-kg) whirlybird could pave the way for low-altitude aerial surveillance of Mars during later missions.
Another experiment is a device to extract pure oxygen from carbon dioxide in the Martian atmosphere, a tool that could prove invaluable for future human life support on Mars and for producing rocket propellant to fly astronauts home.
The mission’s first hurdle after a 293-million-mile (472-million-km) flight from Earth is delivering the rover intact to the floor of Jerezo Crater, a 28-mile-wide (45-km-wide) expanse that scientists believe may harbor a rich trove of fossilized microorganisms.
“It is a spectacular landing site,” project scientist Ken Farley told reporters on a teleconference.
What makes the crater’s rugged terrain - deeply carved by long-vanished flows of liquid water - so tantalizing as a research site also makes it treacherous as a landing zone.
The descent sequence, an upgrade from NASA’s last rover mission in 2012, begins as Perseverance, encased in a protective shell, pierces the Martian atmosphere at 12,000 miles per hour (19,300 km per hour), nearly 16 times the speed of sound on Earth.
After a parachute deployment to slow its plunge, the descent capsule’s heat shield is set to fall away to release a jet-propelled “sky crane” hovercraft with the rover attached to its belly.
Once the parachute is jettisoned, the sky crane’s jet thrusters are set to immediately fire, slowing its descent to walking speed as it nears the crater floor and self-navigates to a smooth landing site, steering clear of boulders, cliffs and sand dunes.
Hovering over the surface, the sky crane is due to lower Perseverance on nylon tethers, sever the chords when the rover’s wheels reach the surface, then fly off to crash a safe distance away.
Should everything work, deputy project manager Matthew Wallace said, post-landing exuberance would be on full display at JPL despite COVID-19 safety protocols that have kept close contacts within mission control to a minimum.
“I don’t think COVID is going to be able to stop us from jumping up and down and fist-bumping,” Wallace said.
Reporting by Steve Gorman in Los Angeles; Editing by Frank McGurty and Will Dunham
I'm sorry but I'm offended at the thread title concept of "terror"
you don't know terror if you think some unmanned anything on the surface of mars, or some 350 scientitsts careers in the balance even deserves in the same sentence, it's bull
it's not terror that you might fail, boo hoo, terror is a word, don't diminish it with their selfishness of, playing with toys, insignificant job.
2/ The signal from the rover saying it's down should arrive at Earth at 20:55 UTC (3:55 p.m.) after taking 11m 22s to travel the 204 million km from Mars.
But it has a few things on its roster to do in the minutes before that point…
4/ Then a 22-meter parachute designed for supsersonic use will deploy, slowing it much further. Seconds later the heat shield will fall away, and a navigation system will look around to find a safe place to land, matching what it sees against data stored in memory.
6/ I mean, COME ON.
A ROCKET POWERED SKY CRANE.
Wile E. Coyote would be proud. But then, we know this works! It did with Curiosity, which used very nearly the exact same system. Perseverance is heavier, though, so it's more difficult this time.
Has Earth been visited by an alien spaceship? Harvard professor Avi Loeb vs everybody else February 18, 2021 9.50am EST Simon Goodwin, University of Sheffield A highly unusual object was spotted travelling through the solar system in 2017. Given a Hawaiian name,ʻOumuamua, it was small and elongated – a few hundred metres by a few tens of meters, travelling at a speed fast enough to escape the Sun’s gravity and move into interstellar space.
I was at a meeting when the discovery of ʻOumuamua was announced, and a friend immediately said to me, “So how long before somebody claims it’s a spaceship?” It seems that whenever astronomers discover anything unusual, somebody claims it must be aliens.
Nearly all scientists believe that ʻOumuamua probably originates from outside the solar system. It is an asteroid- or comet-like object that has left another star and travelled through interstellar space - we saw it as it zipped by us. But not everyone agrees. Avi Loeb, a Harvard professor of astronomy, suggested in a recent book that it is indeed an alien spaceship. But how feasible is this? And how come most scientists disagree with the claim?
Researchers estimate that the Milky Way should contain around 100 million billion billion comets and asteroids ejected from other planetary systems, and that one of these should pass through our solar system every year or so. So it makes sense that ‘Oumuamua could be one of these. We spotted another last year – “Borisov” – which suggests they are as common as we predict.
Deep knowledge, daily, in The Conversation's newsletter What made ʻOumuamua particularly interesting was that it didn’t follow the orbit you would expect – its trajectory shows it has some extra “non-gravitational force” acting on it. This is not too unusual. The pressure of solar radiation or gas or particles driven out as an object warms up close to the Sun can give extra force, and we see this with comets all the time.
Experts on comets and the solar system have explored various explanations for this. Given this was a small, dark object passing us very quickly before disappearing, the images we were able to get weren’t wonderful, and so it is difficult to be sure.
Loeb, however, believes that ʻOumuamua is an alien spaceship, powered by a “light sail” – a method for propelling a spacecraft using radiation pressure exerted by the Sun on huge mirrors. He argues the non-gravitational acceleration is a sign of “deliberate” manoeuvring. This argument seems largely to be based on the fact that ʻOumuamua lacks a fuzzy envelope (“coma”) and a comet-like tail, which are usual signatures of comets undergoing non-gravitational acceleration (although jets from particular spots cannot be ruled out).
He may or may not be right, and there is no way of proving or disproving this idea. But claims like this, especially from experienced scientists are disliked by the scientific community for many reasons.
If we decide that anything slightly odd that we don’t understand completely in astronomy could be aliens, then we have a lot of potential evidence for aliens – there is an awful lot we don’t understand. To stop ourselves jumping to weird and wonderful conclusions every time we come across something strange, science has several sanity checks.
One is Occam’s razor, which tells us to look for the simplest solutions that raise the fewest new questions. Is this a natural object of the type that we suspect to be extremely common in the Milky Way, or is it aliens? Aliens raise a whole set of supplementary questions (who, why, from where?) which means Occam’s razor tells us to reject it, at least until all simpler explanations are exhausted.
Another sanity check is the general rule that “extraordinary claims require extraordinary evidence”. A not quite completely understood acceleration is not extraordinary evidence, as there are many plausible explanations for it.
Yet another check is the often sluggish but usually reliable peer-review system, in which scientists publish their findings in scientific journals where their claims can be assessed and critiqued by experts in their field.
This doesn’t mean that we shouldn’t look for aliens. A lot of time and money is being devoted to researching them. For astronomers who are interested in the proper science of aliens, there is “astrobiology” – the science of looking for life outside Earth based on signs of biological activity. On February 18, Nasa’s Perseverance rover will land on Mars and look for molecules which may include such signatures, for example. Other interesting targets are the moons of Jupiter and Saturn.
In the next five years, we will also have the technology to search for alien life on planets around other stars (exoplanets). Both the James Webb Space Telescope (due to launch in 2021), and the European Extremely Large Telescope (due for first light in 2025) will analyse exoplanet atmospheres in detail, searching for signs of life. For example, the oxygen in the Earth’s atmosphere is there because life constantly produces it. Meanwhile, the Search for Extraterrestrial Intelligence (Seti) initiative has been scanning the skies with radio telescopes for decades in search of messages from intelligent aliens.
Signs of alien life would be an amazing discovery. But when we do find such evidence, we want to be sure it is good. To be as sure as we can be, we need to present our arguments to other experts in the field to examine and critique, follow the scientific method which, in its slow and plodding way, gets us there in the end.
This would give us much more reliable evidence than claims from somebody with a book to sell. It is quite possible, in the next five to ten years, that somebody will announce that they have found good evidence for alien life. But rest assured this isn’t it.
How Betty and Barney Hill's Alien Abduction Story Defined the Genre LINDA LACINA
Is it chasing us? That thought coursed through Betty and Barney Hill’s minds as they drove down the empty winding country road in New Hampshire’s White Mountains. It was a September night in 1961, they hadn’t seen a car for miles, and a strange light in the sky seemed to follow them.
When they finally got home to Portsmouth at dawn, they were far from relieved. They felt dirty. Their watches stopped working. Barney’s shoes were strangely scuffed and Betty’s dress was ripped. There were two hours of the drive that neither one of them could remember. What had happened?
With the help of a psychiatrist, the quiet couple eventually revealed a startling story: Gray beings with large eyes had walked them into a metallic disc as wide, Betty said, as her house was long. Once inside, the beings examined the couple and erased their memories.
Their experience would kick off an Air Force inquiry, part of the secretive initiative Project Blue Book that investigated UFO sightings across the country. The incident would also become the first-ever widely publicized alien-abduction account and shape how stories like it were told—and understood—from then on. Debate continues as to whether the husband and wife were liars, fantasists, crackpots or simply sleep-deprived people who later recovered seriously scrambled memories.
The Hills’ road trip was spontaneous, a well-earned break Barney decided the couple needed, as explained in The Interrupted Journey, a 1966 book they collaborated on with author John G. Fuller. Barney worked a grueling night shift at the post office, driving 60 miles each way. Betty’s job handling state child-welfare cases was no easier. The little free time this biracial couple had was devoted to their church and activities related to the civil-rights movement. After 16 months of marriage, Betty and Barney saw this trip through Montreal and Niagara Falls as their delayed honeymoon. They left so impulsively they had no time to go to the bank before it closed for the weekend. They got in their car with less than $70 in their pockets.
On the last night of their three-day trip, the tired couple sipped coffee in a Vermont diner to recharge before driving back. Barney figured if they pushed through, they could beat the wind and rains from an approaching hurricane. They left the diner around 10 p.m., estimating they could reach their red-framed house in Portsmouth, New Hampshire between 2 a.m. and 3 a.m. at the latest.
As they drove, strange light in the sky gave another reason to hurry. At first it looked like a falling star, but grew larger and brighter with each mile. Barney, an avid plane watcher and World War II vet, was sure they had nothing to worry about. It’s just a satellite, he assured Betty. It probably went off course.
The light seemed to move with the car as Barney steered down the curving mountain road. The light zigged and zagged, ducking past the moon and behind trees and mountain ridges, only to reappear moments later. Sometimes it seemed to move toward them in a game of cat-and-mouse. It had to be an illusion, they thought. Maybe the car’s movement made it seem like the light, too, was moving.
Curiosity overcame them. The couple pulled over at road stops and picnic turnouts to get a closer look. Through binoculars, Betty saw that the white light was really an object spinning in the air.
“Barney,” she told her husband, “if you think that’s a satellite or a star, you’re being completely ridiculous.”
He knew she was right. Barney had an IQ of 140, noted Fuller in his book. Barney was also a pragmatic man who wouldn’t give flying saucers a second thought, remembered his niece Kathleen Marden in her work, Captured: The Betty and Barney Hill Experience. The night was too quiet for a helicopter, a commercial plane or even military jet with a hotshot pilot. He didn’t want to spook Betty, but he was becoming concerned. What was this light and why was it toying with them?
About 70 miles past the diner, the object hovered just above the treetops, approximately 100 feet above them. Barney abruptly stopped the car, keeping the engine running. He shoved a handgun he’d hidden beneath the seat into his pocket and rushed into a dark field, leaving Betty in the car. What he saw was as big as a jet but as round and flat as a pancake. “My God, what is this thing?” he recalled thinking. “This can’t be real.”
Behind rows of windows, gray uniformed beings seemed to look right at him, Barney recalled. He tried to lift his hand to his pistol but somehow couldn’t. A voice told him not to put down his binoculars.
He had a startling thought: We’re about to be captured. Yelling hysterically, he ran back to the car and barreled down the road as Betty tracked the craft, craning her head outside the car window. Without explanation, loud, rhythmic beeps sounded from the car’s trunk. The couple felt instantly drowsy and lost consciousness.
They came to around two hours later and 35 miles down the road.
Image depicting an alien space ship, at 200 feet and 100 feet above the Earth's surface, drawn by alleged alien abductee Betty Hill and regarded as one of the first examples of the Flying Saucer alien spaceship archetype, September 20, 1961. Image depicting an alien space ship, at 200 feet and 100 feet above the Earth's surface, drawn by alleged alien abductee Betty Hill and regarded as one of the first examples of the Flying Saucer alien spaceship archetype, September 20, 1961.
Back home in Portsmouth, they tried to make sense of the night. Barney felt compelled to examine his body’s lower half. Both seemed aware of a puzzling presence.
In the weeks and months after, Betty, an avid reader, checked out books from the library discovering the civilian UFO group National Investigations Committee on Aerial Phenomena (NICAP). She also reported the sighting to the Air Force, worried about radiation.
In coming years, with Betty suffering from disturbing dreams and Barney developing an ulcer and anxiety, the couple sought mental help. The two met with Benjamin Simon, a psychiatrist and neurologist who specialized in hypnosis, a mainstream technique at the time.
Through months of weekly sessions, Simon helped the couple piece together what they think had happened: A vessel had landed on the Hill’s car, putting them to sleep. Afterward, gray beings walked them up a long ramp and into the spacecraft.
Once inside, the Hills were separated, taking turns in an examination room that had curved walls and a large light hanging from the ceiling. Each was asked to climb up on a metal table. The table was so short, Barney’s legs hung over the side.
During the examinations, the beings removed Betty and Barney’s clothes, plucked strands of their hair, took clippings of their nails and scraped their skin. Each sample was placed on a clear material, not unlike a glass slide. Needles, connected to long wires, probed their heads, arms, legs and spines. One large needle, around 4 to 6 inches long, was inserted into Betty’s belly. This pregnancy test left her twisting in pain. Throughout, a being Barney and Betty called “the leader” watched from the side.
After Betty’s examination ended, the beings rushed back into her room, excited. They discovered that Barney’s teeth could be removed. Betty laughed, explaining that Barney had dentures, a fact of human aging the beings struggled to understand.
Later, alone with the leader, Betty asked where the craft had flown, admitting she knew little of the universe. The being joked with her, saying “if you don’t know where you are, there wouldn’t be any point in telling you where I am.” Later, under hypnosis, she drew a star map shown to her on the ship.
In 1965, the Hills' story was picked up by a Boston newspaper. After that, everything changed. The quiet couple’s story became the subject of a best-selling book and a movie starring James Earl Jones. The upstanding civil servants had become celebrity abductees.
I can't wait to see the footage of the 7 minute of terror. I think they were taping most of that (well, from whenever the heatshield popped off). That would be a cool thing to see in motion.
Also, when they fire up that drone. First ever powered flight on another planet. The details on how they made it are crazy.
“...Iguodala to Curry, back to Iguodala, up for the layup! Oh! Blocked by James! LeBron James with the rejection!”
So. Sure. It defies common freaking sense. How can we believe anything that comes from NASA.
( the concept is called suspend your disbelief, it's for scenes in movies, the same thing that gets you to want to think a person would not get in a running car to escape Jason in Friday the 13th, or that somehow 14 martial artists would wait to attack Bruce Lee one at a time and wait their turn.)
So I'm watching NBC national news, (oh come up, the martian rover.)...
"listen, only a hoaxer, only a magician trying to pull the wool over your eyes, only they would be the ones
to travel 53 million miles with a camera, 100 million miles, I don't know, supposedly land on the surface of mars,
and send back a picture, or the wheel of the robot and some dirt at the wheel.
Are you kidding? How about the view of the Martian sky? How about the Martian horizon? Nope. Those would be complicated. (How can we conclude anything other than this is what someone who was presenting a FAKE would do.)
Does that mean it's fake? No. But it sure doesn't lend itself to authenticicty.
Nasa is probably a waste of money that helps nobody. (Most likely)
Yes the Binary code is legit. It’s a quote from Teddy Roosevelt. They knew it would be televised live, world wide. Many had bets on how long a computer geek would figure out the Easter egg. 6hrs. Winner winner chicken dinner.
A life is not important except in the impact it has on other lives. – Jackie Robinson
"Far better it is to dare mighty things, to win glorious triumphs, even though checkered by failure, than to rank with those poor spirits who neither enjoy nor suffer much, because they live in the gray twilight that knows not victory nor defeat." -Teddy Roosevelt, 1899
SpaceX launches Starship on third test flight, sticks landing in Texas and then blows up Emre Kelly Florida Today
SpaceX's latest Starship prototype launched from its Texas home base on the company's third high-altitude flight Wednesday, successfully completing all objectives and executing its first landing to date.
But minutes after the landing the spacecraft exploded.
Propelled by the thrust of just three Raptor engines, the 165-foot stainless steel vehicle ascended to roughly 10 kilometers, or about 30,000 feet, above Cameron County and then positioned its "belly" toward the ground. As Serial Number 10 plummeted back toward the pad Wednesday afternoon, it used the atmosphere as a brake of sorts to save propellant for its landing.
Just above the pad, it re-fired its Raptor engines and flipped around, successfully touching down not far from where its mission started. All in all, SpaceX said the mission achieved its objectives.
"Third time's the charm, as the saying goes," John Insprucker, an engineer at SpaceX, said during the company's webcast. "The key point of today's test flight was to gather data on controlling the vehicle while re-entering, and we were successful in doing so."
Though everything appeared to go smoothly, trouble was apparently brewing inside Starship – despite the test success and soft landing, the vehicle exploded eight minutes later, sending its futuristic hardware flying through a fireball above the pad. SN10 was lost in the explosion.
SpaceX's Starship SN10 prototype launches from Cameron County, Texas, on Wednesday, March 3, 2021. The prototype was successful in launching, descending toward the ground using atmospheric braking, and flipping around to land. "As if the flight test was not exciting enough, SN10 experienced a rapid unscheduled disassembly shortly after landing," SpaceX said in a statement, using a space industry euphemism for an explosion. What caused the explosion was not immediately clear.
Starship is SpaceX's next-generation vehicle designed primarily for human spaceflight. Elon Musk sees it as the tool that will help humans colonize the moon and Mars, a dream he hopes to fulfill as a way of preserving the species.
Several more Starship prototypes are under construction in Texas, and teams there show no signs of slowing down – just as many test flights are expected through the rest of this year. In the near term, Musk hopes to launch humans to lunar orbit in a Starship no earlier than 2023 as part of a mission purchased by Japanese tech entrepreneur Yusaku Maezawa.
Also on Wednesday, Musk revealed he's working to rename the area around his company's operations to "Starbase, Texas." Currently named Boca Chica Village, SpaceX has already begun the legal process of incorporating it into Starbase, according to the Houston Chronicle.
I'm not a big Grateful Dead fan like many on the board are. And while I don't remember much of the Mercury program I do remember the end of it and everything in space that's happened since. So to use a Dead song lyric, "What a long strange trip it's been".
Intoducing for The Cleveland Browns, Quarterback Deshawn "The Predator" Watson. He will also be the one to choose your next head coach.
As the old saying goes, "I shot a rocket in the air, where it lands I know not where".
Or, uh, umm, maybe it was "I shot an arrow in the air, where it lands, etc, etc. Can't remember.
On a sidenote, anyone have a spare hardhat or 6?
Rather than start a new thread.....
Huge rocket looks set for uncontrolled reentry following Chinese space station launch by Andrew Jones — April 30, 2021
HELSINKI — China launched the first module for its space station into orbit late Wednesday, but the mission launcher also reached orbit and is slowly and unpredictably heading back to Earth.
The Long March 5B, a variant of China’s largest rocket, successfully launched the 22.5-metric-ton Tianhe module from Wenchang Thursday local time. Tianhe separated from the core stage of the launcher after 492 seconds of flight, directly entering its planned initial orbit.
Designed specifically to launch space station modules into low Earth orbit, the Long March 5B uniquely uses a core stage and four side boosters to place its payload directly into low Earth orbit.
However this core stage is now also in orbit and is likely to make an uncontrolled reentry over the next days or week as growing interaction with the atmosphere drags it to Earth. If so, it will be one of the largest instances of uncontrolled reentry of a spacecraft and could potentially land on an inhabited area.
Most expendable rocket first stages do not reach orbital velocity and reenter the atmosphere and land in a pre-defined reentry zone. Some other larger, second stages perform deorbit burns to lower altitude to reduce time in orbit and lower chances of collisions with other spacecraft or to immediately reenter the atmosphere.
There had been speculation that the Long March 5B core would perform an active maneuver to deorbit itself, but that appears not to have happened. At a Wenchang press conference Thursday, [censored] Jue, Commander-in-Chief of Long March 5B launch vehicle, stated (Chinese) that this second Long March 5B had seen improvements over the first launch, but a possible deorbit maneuver was not stated.
Ground based radars used by the U.S. military to track spacecraft and other objects in space have detected an object and catalogued it as the Long March 5B rocket body. Now designated 2021-035B, the roughly 30-meter-long, five-meter-wide Long March 5 core stage is in a 170 by 372-kilometer altitude orbit traveling at more than seven kilometers per second.
A possible amateur ground observation of the rocket core showing regular flashes suggests that it is tumbling and thus not under control.
The first launch of the Long March 5B also saw the first stage reach orbit and make an uncontrolled reentry six days later. Reentry occurred over the Atlantic Ocean according to the U.S. Space Force’s 18th Space Control Squadron.
Had the event taken place 15-30 minutes earlier debris not destroyed by the heat of reentry could have landed on U.S. soil. The incident drew criticism from then NASA Administrator Jim Bridenstine.
Where and when the new Long March 5B stage will land is impossible to predict. The decay of its orbit will increase as atmospheric drag brings it down into more denser. The speed of this process depends on the size and density of the object and variables include atmospheric variations and fluctuations, which are themselves influenced by solar activity and other factors.
The high speed of the rocket body means it orbits the Earth roughly every 90 minutes and so a change of just a few minutes in reentry time results in reentry point thousands of kilometers away.
The Long March 5B core stage’s orbital inclination of 41.5 degrees means the rocket body passes a little farther north than New York, Madrid and Beijing and as far south as southern Chile and Wellington, New Zealand, and could make its reentry at any point within this area.
The most likely event will see any debris surviving the intense heat of reentry falling into the oceans or uninhabited areas, but the risk remains of damage to people or property.
Spaceflight observer Jonathan McDowell told SpaceNews that the previous Long March 5B launch saw the most massive uncontrolled reentry in decades and the fourth biggest ever. “The Long March 5B core stage is seven times more massive than the Falcon 9 second stage that caused a lot of press attention a few weeks ago when it reentered above Seattle and dumped a couple of pressure tanks on Washington state.”
McDowell said he hoped China would have enhanced the core stage to perform a controlled deorbit after separating from Tianhe. “I think by current standards it’s unacceptable to let it reenter uncontrolled,” McDowell said.
“Since 1990 nothing over 10 tons has been deliberately left in orbit to reenter uncontrolled.” The Long March 5B core stage, without its four side boosters, is thought to have a “dry mass”, or when it is empty of propellent, of about 21 metric tons in mass.
Holger Krag, head of the Space Safety Programme Office for the European Space Agency, says from their experience, there is an average amount of mass of about 100 tons re-entering in an uncontrolled way per year. “This relates to about 50-60 individual events per year.”
“It is always difficult to assess the amount of surviving mass and number of fragments without knowing the design of the object, but a reasonable “rule-of-thumb” is about 20-40% of the original dry mass.”
Components made of heat resistant materials, such as tanks and thrusters made stainless steel or titanium, can reach the ground. Surviving objects will fall vertically after deceleration and travel at terminal velocity.
The largest and most famous incident was the 1979 reentry of NASA’s 76-ton Skylab, whose uncontrolled reentry scattered debris across the Indian Ocean and Western Australia.
A night time reentry could make for spectacular viewing, as with a recent reentry of a Falcon 9 second stage, with debris fortunately not causing harm.
China’s 8-ton Tiangong-1 spacelab made a high-profile uncontrolled reentry in 2018, while the successor Tiangong-2 was deorbited in a controlled manner in 2019.
Never-ending detonations could blast hypersonic craft into space By Edd Gent First Published 1 day ago
This conceptual image shows a hypersonic aircraft powered by an Oblique Detonation Wave Engine. (Image credit: Daniel A. Rosato, NASA)
A never-ending detonation could be the key to hypersonic flight and space planes that can seamlessly fly from Earth into orbit. And now, researchers have recreated the explosive phenomenon in the lab that could make it possible.
Detonations are a particularly powerful kind of explosion that move outward faster than the speed of sound. The massive explosion that rocked the port of Beirut in Lebanon last August was a detonation, and the widespread destruction it caused demonstrates the huge amounts of energy they can produce.
Scientists have long dreamed of building aircraft engines that can harness this energy; such craft could theoretically fly from New York to London in under an hour. But detonations are incredibly hard to control and typically last less than a microsecond, so no one has yet been able to make them a reality.
Now, a team from the University of Central Florida has created an experimental setup that lets them sustain a detonation in a fixed position for several seconds, which the researchers say is a major step toward future hypersonic propulsion systems.
"What we're trying to do here is to control that detonation," said Kareem Ahmed, an associate professor of mechanical and aerospace engineering at the University of Central Florida, and lead author of a new paper on the research published Monday (May 10) in the journal Proceedings of the National Academy of Sciences.
"We want to freeze it in space and harness that energy. Rather than it destroying buildings, as you saw in Lebanon, now I want to use it and produce thrust with it," Ahmed told Live Science. "If we can do that, we can travel super fast."
The breakthrough was built on decades of research into a theoretical propulsion system called an oblique detonation wave engine (ODWE). The concept works by funneling a mixture of air and fuel at hypersonic speeds (more than five times the speed of sound) toward a ramp, which creates a shock wave. This shock wave rapidly heats up the fuel-air mixture and causes it to detonate, blasting exhaust gasses out from the back of the engine at high speed. The result? Lots of thrust.
When a mixture of air and fuel detonates in this way, the resulting combustion is extra efficient as close to 100% of the fuel is burned. The detonation also generates a lot of pressure, which means the engine can generate much more thrust than other approaches. In theory, this detonation should be able to propel an aircraft at up to 17 times the speed of sound, say the researchers, which could be fast enough for spacecraft to simply fly out of the atmosphere, rather than needing to hitch a lift on rockets.
The challenge is sustaining the detonation for long enough to power such flight, and previous experimental demonstrations have topped out at just a few milliseconds. The main difficulty, Ahmed said, lies in preventing the detonation from traveling upstream toward the fuel source, where it can cause serious damage, or further downstream, where it will fizzle out.
"There's always been the question of, "Well, if you're holding it for a millisecond or so, did you just hold it temporarily?'" Ahmed said. "You don't know if you've stabilized or not."
To see if they could improve on the previous record, Ahmed and his colleagues built a roughly 2.5-foot-long (0.76 meters) series of chambers that mixes and heats air and hydrogen gas before accelerating it to hypersonic speeds and firing it at a ramp.
By carefully balancing the proportions of the air-fuel mixture, the speed of the gas flow and the angle of the ramp, they were able to generate a detonation that remained fixed in position for around 3 seconds. That's long enough to confirm that the detonation was stabilized in a fixed position and was not travelling up or downstream, Ahmed said, which is a first, major step toward realizing a real-life ODWE.
Frank Lu, a professor of mechanical and aerospace engineering at the University of Texas at Arlington who specializes in detonation-based engines, said demonstrating stable detonation is a significant achievement. To develop a practical engine researchers will now have to work out how to operate over a range of speeds and altitudes and deal with combustion instabilities caused by things like uneven mixing of the fuel and air.
"I think the investigators have done an excellent job and look forward to further results," Lu told Live Science.
The researchers only ran their experiment for a few seconds mainly because the intensity of the detonation rapidly erodes the glass sides of the test chamber, Ahmed explained. They had to use glass in their initial tests so that they could make optical measurements of the detonation, but if they were to replace them with metal sides they should be able to run the detonation for much longer, he said.
And promisingly, Ahmed said the structure of the test apparatus is not that different from the design of a full-scale ODWE. The main challenge for the researchers now is working out how they can alter the three key ingredients of fuel mix, air speed and ramp angle while still maintaining the stability of the detonation.
"Now, we've demonstrated it is feasible, it's more of an engineering problem to explore how to sustain it over a larger operating domain," Ahmed said.
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