Author: peterjang73

COLORADO SPRINGS, Co ?— Sierra Space unveiled a radical new concept for on-demand cargo delivery from Earth orbit. The company aims to land critical supplies anywhere on the planet within 90 minutes of when it was requested.

Sierra Space says the concept could enable soldiers on the battlefield or in remote areas to acquire much-needed supplies on quicker timescales, as they’d be far from traditional infrastructure used to transport goods on the ground. The Ghost orbital delivery platform could also aid first responders in disaster-stricken areas and bolster humanitarian efforts. 

While several commercial launch providers, such as SpaceX and Rocket Lab, in addition to the U.S. military have been discussing using rockets to send cargo rapidly around the Earth, Sierra Space’s Ghost concept could allow payloads to land in areas without dedicated launch or landing facilities. It would be particularly useful for smaller payloads, therefore opening up radical new possibilities for civilian supply chains on top of military demands.

Related: Sierra Space unveils Dream Chaser space plane ahead of 1st flight to ISS (video)

According to a Sierra Space statement announcing the Ghost concept, the system would involve loading pre-determined supplies such as survival kits, an inflatable boat, rations and weaponry onto different "units." There units would then be launched into orbit. 

The Ghost platform could then wait up to five years in orbit before any pre-loaded supplies are called down to Earth. Once materials must be delivered, first, a de-orbit motor would slow the satellite down enough for Earth’s gravity to begin pulling it  towards the planet’s surface. The system’s thermal shield would meanwhile protect the payload from the upcoming intense heat of reentry. 

Once safely within Earth’s atmosphere, the thermal shell would be discarded and the system’s soft-shell, umbrella-like parafoil would open. A steerable rudder on the parafoil can help guide the Ghost’s payload to within 300 feet (100 m) of its targeted landing spot, Sierra Space says.

Sierra Space’s new "Axelerator technology" incubator helped the team develop a prototype of the Ghost system in just 90 days, according to the company’s statement.

Space.com spoke with Sierra Space’s Erik Daehler, Vice President of Orbital Missions & Services, at Space Symposium to learn more about the new Ghost system. Daehler said that while the Ghost system can be scaled to different sizes, between 550 pounds and 1,750 pounds (250 kilograms and 750 kilograms) is the "sweet spot" in terms of cost versus the amount of returnable payload.

Each unit currently costs somewhere in the "tens of millions" of dollars to build, but Daehler said Sierra Space is working to bring that cost down to "single-digit millions."

When asked if the Ghost concept could be scaled up until its large enough to return something as massive as a module of the International Space Station (ISS), Daehler said a similar concept could possibly be used, but it would need to use slightly different design principles.

"As you think about cool things like an ISS segment, you can scale things designed in a similar way," Daehler said. "But you might look at a different structural way to build it nicely. So instead of doing a rigid structure like we did, which is super easy to build, you might do something inflatable."

"We think it’d be really cool to bring back something of our heritage like that," he continued. "We originally started designing this because our cargo modules were designed to burn up for our NASA missions to bring back trash. We’d like to eventually reuse them. So, we’re looking at that scalability; how do we bring back something much larger?"

A test article of the Sierra Space Ghost delivery system was on display here at the 39th annual Space Symposium in Colorado Springs. The bottom of the test article was scuffed from having been test-dropped at Space Florida’s historic Launch and Landing Facility (LLF) in Florida, where NASA’s space shuttles once landed.

During a testing campaign in February 2024, seven different test articles were dropped ?from a Sikorsky S-76 helicopter —? some with the system’s attached parachute, others with only the system’s soft-shell decelerator, and still others involving "terminal" drops of the cargo payload alone ?—? from altitudes between 2,000 feet (610 meters) and 4,000 feet (1,220 meters).

Similar resupply concepts have been discussed for years, except those involving point-to-point rocket launches with reusable systems like SpaceX’s massive Starship vehicle. Just this year, the U.S. Air Force allocated $4 million in research funding to its Rocket Cargo Vanguard, or "Point-to-Point Delivery (P2PD)" program as it is now known. It’s a program that’s "focused on utilizing vehicles that traverse from or through space to transport DoD materiel anywhere around the world within tactically responsive timelines," according to Breaking Defense.

However, such a system would likely not be able to land anywhere it wants, as large rockets currently need dedicated landing infrastructure. A much smaller, more tactical concept like the Sierra Space Ghost system could enable pinpoint deliveries to austere, remote or contested areas without the need for landing pads.

Sierra Space has not yet announced a date by which it hopes to have the system in operation, but the company is moving forward with a testing program to further develop the Ghost concept and determine what infrastructure, communications systems and other architecture will be needed to turn it into a reality.

New research is the latest to suggest that sildenafil—the active ingredient in popular erectile dysfunction drug Viagra—might help fend off Alzheimer’s disease. The study found that people taking sildenafil were noticeably less likely to develop Alzheimer’s than similar patients not taking it. The results do not yet prove that the little blue pill is effective against the neurological disorder, however, and clinical trials will be needed to know for sure, the researchers say.

The study, published in the Journal of Alzheimer’s Disease, was led by scientists from the Cleveland Clinic. In 2021, the same team published a paper finding evidence in the lab and from insurance claims data that sildenafil could prevent or delay the onset of Alzheimer’s in older people—perhaps reducing risk by as much as 69%. Some researchers have questioned whether the study’s design was truly able to show a clear link between reduced Alzheimer’s and sildenafil use, however. The very next year, another study that examined Medicare data failed to find such a connection.

This debate isn’t over, though. This February, a third research team studied healthcare data from the UK and found a significant, if smaller, reduced risk of Alzheimer’s associated with sildenafil. And now the authors of the original study say they’ve uncovered more evidence to support the hypothesis.

This time around, the team analyzed claims data from two large patient databases. They compared patients taking sildenafil with patients taking one of four drugs commonly used to treat pulmonary hypertension, a type of high blood pressure affecting the lungs. While sildenafil is best known as an erectile dysfunction aid, it’s also approved and commonly used for this condition as well.

The team once again found that the patients on sildenafil were less likely to later be diagnosed with Alzheimer’s than the comparison groups, with a reduced risk ranging from 30% to 54%. They also conducted more lab experiments, testing sildenafil on neurons grown from the stem cells of Alzheimer’s patients. They found that the drug seemed to promote the growth of neurites (the projections that neurons use to communicate with each other) and reduced the accumulation of a potentially toxic form of tau protein (one of the two proteins thought responsible for causing Alzheimer’s)—a potential clue as to how sildenafil might actually lower Alzheimer’s risk.

“Our findings provide further weight to re-purposing this existing FDA-approved drug as a novel treatment for Alzheimer’s, which is in great need of new therapies,” said senior author Feixiong Cheng in a statement from the Cleveland Clinic.

The scientists are quick to caution that their research can’t show conclusively that sildenafil can prevent or delay Alzheimer’s. But they and other scientists say there’s been enough encouraging data collected to at least merit a larger-scale and more definitive test of this hypothesis.

“We believe our findings provide the evidence needed for clinical trials to further examine the potential effectiveness of sildenafil in patients with Alzheimer’s disease,” said Cheng.

A team of physicists and engineers at Princeton University built a twisting fusion reactor known as a stellarator that uses permanent magnets, showcasing a potentially cost-effective way of building the powerful machines. Their experiment, called MUSE, relies on 3D-printed and off-the-shelf parts.

Nuclear fusion, the reaction that powers stars like our Sun, produces huge amounts of energy by merging atoms (not to be confused with nuclear fission, which produces less energy by splitting atoms). Nuclear fission is the reaction at the core of modern nuclear reactors that power electric grids; scientists have yet to crack the code on nuclear fusion as an energy source. Even once that long-sought goal is reached, scaling the technology and making it commercially viable is its own beast.

Stellarators are cruller-shaped devices that contain high-temperature plasmas, which can bed tuned to foster the conditions for fusion reactions. They are similar to tokamaks, doughnut-shaped devices that run fusion reactions. Tokamaks rely on solenoids, which are magnets that carry electric current. MUSE is different.

“Using permanent magnets is a completely new way to design stellarators,” said Tony Qian, a physicist at Princeton University and lead author of two papers published in the Journal of Plasma Physics and Nuclear Fusion that describe the design of the MUSE experiment. “This technique allows us to test new plasma confinement ideas quickly and build new devices easily.”

Permanent magnets don’t need electric current to generate their magnet fields and can be purchased off-the-shelf. The MUSE experiment stuck such magnets onto a 3-D printed shell.

“I realized that even if they were situated alongside other magnets, rare-earth permanent magnets could generate and maintain the magnetic fields necessary to confine the plasma so fusion reactions can occur,” Michael Zarnstorff, a research scientist at the university’s Plasma Physics Laboratory and principal investigator of the MUSE project, in a press release. “That’s the property that makes this technique work.”

Last year, scientists at the Department of Energy’s Lawrence Livermore National Laboratory (LLNL) achieved breakeven in a fusion reaction; that is, the reaction produced more energy than it took to power it. However, that accolade neglects to account for the “wall power” necessary to induce the reaction. In other words, there’s still a long, long road ahead.

The LLNL breakthrough was done by shining powerful lasers at a pellet of atoms, a different process than the plasma-based fusion reactions that occur in tokamaks and stellarators. Little tweaks to the devices, like the implementation of permanent magnets in MUSE or an upgraded tungsten diverter in the KSTAR tokamak, make it easier for scientists to replicate the experimental setups and perform experiments at high temperatures for longer.

Taken together, these innovations will allow scientists to do more with the plasmas at their fingertips, and maybe—just maybe—reach the vaunted goal of usable and scalable fusion energy.