If we’re ever to make regular journeys from Earth to Mars and other far-off destinations, we might need new kinds of engines. Engineers are exploring revolutionary new technologies that could help us traverse the Solar System in much less time.
Because of the orbital paths Mars and Earth take around the Sun, the distance between them varies between 54.6 million km and 401 million km.
Missions to Mars are launched when the two planets make a close approach. During one of these approaches, it takes nine months to get to Mars using chemical rockets – the form of propulsion in widespread use.
That’s a long time for anyone to spend travelling. But engineers, including those at the US space agency (Nasa), are working with industrial partners to develop faster methods of getting us there.
So what are some of the most promising technologies?
Solar electric propulsion
Solar electric propulsion could be used to send cargo to Mars ahead of a human mission. That would ensure equipment and supplies were ready and waiting for astronauts when they arrived using chemical rockets, according to Dr Jeff Sheehy, chief engineer in Nasa’s Space Technology Mission Directorate.
With solar electric propulsion, large solar arrays unfurl to capture solar energy, which is then converted to electricity. This powers something called a Hall thruster.
There are pros and cons. On the upside, you need far less fuel, so the spacecraft becomes lighter. But it also takes your vehicle longer to get there.
“In order to carry the payload we’d need to, it would probably take between two to 2.5 years to get us there,” Dr Sheehy tells the BBC.
“For the kinds of outposts we’d need to build on Mars for crews to be able to survive for months, and the vehicles, you’d need a lot of cargo.”
Aerojet Rocketdyne is working on a Hall thruster for the Gateway, a proposed space station in lunar orbit.
“Solar is the best because we know we can scale it up,” Joe Cassidy, executive director of Aerojet Rocketdyne’s space division, explains.
“We’ve already got these flying today on communications satellites. The power level we fly at today is 10-15kW (kilowatts), and what we’re looking to do with the Gateway is to scale it up to something greater than 50kW.”
Mr Cassidy said Aerojet Rocketdyne’s Hall thruster will be much more fuel efficient than a liquid hydrogen and oxygen rocket engine.
But a good way to make access to space cheaper would be to have fewer launches, he explains.
“I think that solar electric propulsion is very good technology, using xenon as the propellant. But the two major drawbacks are the amount of time it takes to get there, and the size of the solar arrays,” says Tim Cichan, a human spaceflight architect at aerospace giant Lockheed Martin.
Dale Thomas, a professor and eminent scholar in systems engineering at the University of Alabama in Huntsville (UAH) concurs.
“Solar electric works well for smaller payloads, but we’re still having trouble getting it to scale,” he tells the BBC.
He thinks it could become an important alternative technology if the technical challenges can be solved. But for now, he says, there are other better options, such as nuclear thermal electric propulsion.
Nuclear thermal electric propulsion
Another idea is to use chemical rockets to lift off from Earth and to land on Mars. But for the middle part of the journey, some engineers propose using something called nuclear thermal electric propulsion.
Astronauts could be sent to the Gateway in Nasa’s Orion capsule. The Orion crew capsule would then dock with a transfer vehicle.
Once Orion has been connected to the transfer vehicle, a nuclear electric rocket would be used to get the crew capsule and the transport module to Mars, where they link up with a Mars orbiter and lander, which are waiting in Mars’ orbit.
In a nuclear thermal electric rocket, a small nuclear reactor heats up liquid hydrogen. The gaseous form of the element expands and shoots out of the thruster.
“If we can cut transit time [to Mars] down by 30-60 days, it will improve the exposure to radiation facing the crew,” says Mr Cassidy. “We’re looking at nuclear thermal as a key technology because it can enable faster transit times.”
Dale Thomas, together with UAH, has a study contract with Nasa to design a space rocket featuring a nuclear thermal engine. He thinks nuclear thermal electric is the closest new engine technology to being ready for use.
“Some of the trajectories we run in my lab, we can get the transit time down to three months, which is still a very long journey, but it’s about a third of the time that chemical propulsion requires to get us there,” he says.
Boeing is not so keen on nuclear thermal propulsion, because it worries about the effects a nuclear reactor might have on astronauts.
Mr Thomas disagrees: “This is a common misperception. The hydrogen propellant is a great radiation shield.
“The crew will be at one end of the vehicle, and the engine at the other end. As such, preliminary estimates show that the crew will get more radiation dosage from cosmic rays than from the nuclear thermal engine.”
However, he admits one downside of the technology is the inability to easily test it on Earth.
But Nasa is designing a ground test apparatus that scrubs the exhaust to remove radioactive particles – making ground tests possible.
Electric ion propulsion
Another idea is electric ion propulsion. These generate thrust by accelerating ions – charged atoms or molecules – using electricity.
Ion propulsion is already being used to power satellites in space. But they produce only a low thrust – more like the power of a hairdryer – and therefore have a low acceleration. But given time, they can reach high speeds.
Ad Astra says it is working on a type of thruster called the Vasimr that uses radio waves to ionise and heat a propellant and then a magnetic field to accelerate the resulting soup of particles – the plasma. The Vasimr is designed to produce much more thrust than a standard ion engine.
The electricity needed can be generated in different ways. But for sending humans to Mars, the team wants to use a nuclear reactor. The Vasimr would use solar electric for smaller payloads.
Ad Astra’s president and chief executive Franklin Chang Diaz, who is a former Nasa astronaut, says crewed missions need to get to Mars in less than nine months, ideally.
Going to the Red Planet is much harder than going to the Moon, he says.
“The solution is to go fast,” Mr Chang Diaz tells the BBC. “For a spacecraft that would weigh 400-600 metric tonnes, with a power level of 200 MW (megawatts), you can get to Mars in 39 days.”
Dale Thomas believes scaling up the Vasimr will be difficult, like going from the power of a lawnmower to a space rocket. But the technology does show promise.
“If, or perhaps I should say, when Ad Astra can solve the technical challenges of Vasimr, it does appear to be the best choice for electric propulsion at the human-ferrying spacecraft scale,” Mr Thomas says.
“The physics says that it should work. However, I must point out that Vasimr is still under development in the laboratory; it’s a long way from being flight-ready at any scale.”
Mr Chang Diaz doesn’t see a problem with scaling up, it’s just that there’s currently no market for a 10MW engine, so Ad Astra is sticking with 200kW.
“We have a market for the 200kW engine, there’s a lot of activity in low-Earth orbit and near the Moon to move cis-Earth satellites,” says Mr Chang Diaz.
Lockheed Martin also thinks the Vasimr is promising technology, but it is focusing on solar electric propulsion.
The case for chemical rockets
Although the new technologies are interesting, veteran space players Lockheed Martin and Boeing both think liquid chemical rockets need to be the bedrock of any human mission to Mars.
Lockheed Martin says we already have the technology we need to get to Mars, and chemical rockets are a proven technology that worked in all the Apollo missions.
“We already have the technology to get us to Mars today,” says Mr Cichan, the former system architect for Orion.
“There are some technical challenges, but it’s really about taking the technology we have, building the systems and gaining experience in flying in deep space that is the work ahead of us, as well as developing technology that will be groundbreaking in the future.”
Hydrogen upper stage launchers have been used since the 1960s, and they have a high success rate, he stresses.
“Nasa’s Space Launch System (SLS) has four liquid hydrogen and oxygen RS-25 rocket engines,” Rob Broeren, a Boeing rocket propulsion specialist tells the BBC.
“These are shuttle heritage engines, and the advantage of the RS-25’s is that they’re well proven, high-reliability engines.
“The nice thing about going with highly proven technologies is that you have full confidence that they definitely work. With new technologies, they sound good on paper, but when it comes to implementing them, you will run into issues that will delay you.”
Given the constraints on Nasa’s budgets, STPI thinks it is much more likely that we will leave for Mars in 2039, though the White House wants the US space agency to explore the Moon first by 2024, under its Artemis programme.
Dr Paul Dimotakis, John K Northrop professor of aeronautics and professor of applied physics at the California Institute of Technology (Caltech) is sceptical of the new technologies, and even chemical propulsion.
“I personally have not seen answers to technical questions of how to have enough chemical propulsion to last the long trip. It’s not known for a hydrogen-oxygen rocket to last longer than six months,” he says.
“We do not have a technical solution that addresses all the issues. Plus, someone has to demonstrate this before we send humans to Mars, and all of these things do not correspond to Nasa’s timetable.”
More than 40 trillion gallons of rain drenched the Southeast United States in the last week from Hurricane Helene and a run-of-the-mill rainstorm that sloshed in ahead of it — an unheard of amount of water that has stunned experts.
That’s enough to fill the Dallas Cowboys’ stadium 51,000 times, or Lake Tahoe just once. If it was concentrated just on the state of North Carolina that much water would be 3.5 feet deep (more than 1 meter). It’s enough to fill more than 60 million Olympic-size swimming pools.
“That’s an astronomical amount of precipitation,” said Ed Clark, head of the National Oceanic and Atmospheric Administration’s National Water Center in Tuscaloosa, Alabama. “I have not seen something in my 25 years of working at the weather service that is this geographically large of an extent and the sheer volume of water that fell from the sky.”
The flood damage from the rain is apocalyptic, meteorologists said. More than 100 people are dead, according to officials.
Private meteorologist Ryan Maue, a former NOAA chief scientist, calculated the amount of rain, using precipitation measurements made in 2.5-mile-by-2.5 mile grids as measured by satellites and ground observations. He came up with 40 trillion gallons through Sunday for the eastern United States, with 20 trillion gallons of that hitting just Georgia, Tennessee, the Carolinas and Florida from Hurricane Helene.
Clark did the calculations independently and said the 40 trillion gallon figure (151 trillion liters) is about right and, if anything, conservative. Maue said maybe 1 to 2 trillion more gallons of rain had fallen, much if it in Virginia, since his calculations.
Clark, who spends much of his work on issues of shrinking western water supplies, said to put the amount of rain in perspective, it’s more than twice the combined amount of water stored by two key Colorado River basin reservoirs: Lake Powell and Lake Mead.
Several meteorologists said this was a combination of two, maybe three storm systems. Before Helene struck, rain had fallen heavily for days because a low pressure system had “cut off” from the jet stream — which moves weather systems along west to east — and stalled over the Southeast. That funneled plenty of warm water from the Gulf of Mexico. And a storm that fell just short of named status parked along North Carolina’s Atlantic coast, dumping as much as 20 inches of rain, said North Carolina state climatologist Kathie Dello.
Then add Helene, one of the largest storms in the last couple decades and one that held plenty of rain because it was young and moved fast before it hit the Appalachians, said University of Albany hurricane expert Kristen Corbosiero.
“It was not just a perfect storm, but it was a combination of multiple storms that that led to the enormous amount of rain,” Maue said. “That collected at high elevation, we’re talking 3,000 to 6000 feet. And when you drop trillions of gallons on a mountain, that has to go down.”
The fact that these storms hit the mountains made everything worse, and not just because of runoff. The interaction between the mountains and the storm systems wrings more moisture out of the air, Clark, Maue and Corbosiero said.
North Carolina weather officials said their top measurement total was 31.33 inches in the tiny town of Busick. Mount Mitchell also got more than 2 feet of rainfall.
Before 2017’s Hurricane Harvey, “I said to our colleagues, you know, I never thought in my career that we would measure rainfall in feet,” Clark said. “And after Harvey, Florence, the more isolated events in eastern Kentucky, portions of South Dakota. We’re seeing events year in and year out where we are measuring rainfall in feet.”
Storms are getting wetter as the climate change s, said Corbosiero and Dello. A basic law of physics says the air holds nearly 4% more moisture for every degree Fahrenheit warmer (7% for every degree Celsius) and the world has warmed more than 2 degrees (1.2 degrees Celsius) since pre-industrial times.
Corbosiero said meteorologists are vigorously debating how much of Helene is due to worsening climate change and how much is random.
For Dello, the “fingerprints of climate change” were clear.
“We’ve seen tropical storm impacts in western North Carolina. But these storms are wetter and these storms are warmer. And there would have been a time when a tropical storm would have been heading toward North Carolina and would have caused some rain and some damage, but not apocalyptic destruction. ”
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It’s a dinosaur that roamed Alberta’s badlands more than 70 million years ago, sporting a big, bumpy, bony head the size of a baby elephant.
On Wednesday, paleontologists near Grande Prairie pulled its 272-kilogram skull from the ground.
They call it “Big Sam.”
The adult Pachyrhinosaurus is the second plant-eating dinosaur to be unearthed from a dense bonebed belonging to a herd that died together on the edge of a valley that now sits 450 kilometres northwest of Edmonton.
It didn’t die alone.
“We have hundreds of juvenile bones in the bonebed, so we know that there are many babies and some adults among all of the big adults,” Emily Bamforth, a paleontologist with the nearby Philip J. Currie Dinosaur Museum, said in an interview on the way to the dig site.
She described the horned Pachyrhinosaurus as “the smaller, older cousin of the triceratops.”
“This species of dinosaur is endemic to the Grand Prairie area, so it’s found here and nowhere else in the world. They are … kind of about the size of an Indian elephant and a rhino,” she added.
The head alone, she said, is about the size of a baby elephant.
The discovery was a long time coming.
The bonebed was first discovered by a high school teacher out for a walk about 50 years ago. It took the teacher a decade to get anyone from southern Alberta to come to take a look.
“At the time, sort of in the ’70s and ’80s, paleontology in northern Alberta was virtually unknown,” said Bamforth.
When paleontogists eventually got to the site, Bamforth said, they learned “it’s actually one of the densest dinosaur bonebeds in North America.”
“It contains about 100 to 300 bones per square metre,” she said.
Paleontologists have been at the site sporadically ever since, combing through bones belonging to turtles, dinosaurs and lizards. Sixteen years ago, they discovered a large skull of an approximately 30-year-old Pachyrhinosaurus, which is now at the museum.
About a year ago, they found the second adult: Big Sam.
Bamforth said both dinosaurs are believed to have been the elders in the herd.
“Their distinguishing feature is that, instead of having a horn on their nose like a triceratops, they had this big, bony bump called a boss. And they have big, bony bumps over their eyes as well,” she said.
“It makes them look a little strange. It’s the one dinosaur that if you find it, it’s the only possible thing it can be.”
The genders of the two adults are unknown.
Bamforth said the extraction was difficult because Big Sam was intertwined in a cluster of about 300 other bones.
The skull was found upside down, “as if the animal was lying on its back,” but was well preserved, she said.
She said the excavation process involved putting plaster on the skull and wooden planks around if for stability. From there, it was lifted out — very carefully — with a crane, and was to be shipped on a trolley to the museum for study.
“I have extracted skulls in the past. This is probably the biggest one I’ve ever done though,” said Bamforth.
“It’s pretty exciting.”
This report by The Canadian Press was first published Sept. 25, 2024.
TEL AVIV, Israel (AP) — A rare Bronze-Era jar accidentally smashed by a 4-year-old visiting a museum was back on display Wednesday after restoration experts were able to carefully piece the artifact back together.
Last month, a family from northern Israel was visiting the museum when their youngest son tipped over the jar, which smashed into pieces.
Alex Geller, the boy’s father, said his son — the youngest of three — is exceptionally curious, and that the moment he heard the crash, “please let that not be my child” was the first thought that raced through his head.
The jar has been on display at the Hecht Museum in Haifa for 35 years. It was one of the only containers of its size and from that period still complete when it was discovered.
The Bronze Age jar is one of many artifacts exhibited out in the open, part of the Hecht Museum’s vision of letting visitors explore history without glass barriers, said Inbal Rivlin, the director of the museum, which is associated with Haifa University in northern Israel.
It was likely used to hold wine or oil, and dates back to between 2200 and 1500 B.C.
Rivlin and the museum decided to turn the moment, which captured international attention, into a teaching moment, inviting the Geller family back for a special visit and hands-on activity to illustrate the restoration process.
Rivlin added that the incident provided a welcome distraction from the ongoing war in Gaza. “Well, he’s just a kid. So I think that somehow it touches the heart of the people in Israel and around the world,“ said Rivlin.
Roee Shafir, a restoration expert at the museum, said the repairs would be fairly simple, as the pieces were from a single, complete jar. Archaeologists often face the more daunting task of sifting through piles of shards from multiple objects and trying to piece them together.
Experts used 3D technology, hi-resolution videos, and special glue to painstakingly reconstruct the large jar.
Less than two weeks after it broke, the jar went back on display at the museum. The gluing process left small hairline cracks, and a few pieces are missing, but the jar’s impressive size remains.
The only noticeable difference in the exhibit was a new sign reading “please don’t touch.”
