October 12, 2020
Enjoy these interesting stories from the scientific community.
*-- First U.S. robotic moon lander since Apollo era planned for mid-2021 --*
A private company handling NASA's long-awaited return to the moon's surface said its robotic Peregrine lander is on track for launch in the spring.
The lander project, which received funding from NASA, would become the first private, commercial mission to the moon, said Sharad Bhaskaran, mission director for Pittsburgh-based Astrobotic Technology.
The Peregrine mission is planned to help prepare for a 2024 crewed landing in NASA's Artemis program. Astrobotic's lead role in the lunar return follows its founding in 2007 by robotics research professor Red Whittaker at Carnegie Mellon University.
"We are trying to become the first to land an American spacecraft on the moon since Apollo," Bhaskaran said Tuesday. "Within a few years, we want to fly Peregrine once every year or 18 months. We believe that is a credible plan."
Astrobotic has a fixed-price contract from NASA of $79.5 million for the first Peregrine mission, which will have 11 experiments or payloads for the space agency.
NASA experiments, for example, will examine the regolith, or dust and rocks on the surface, and test new sensors that guide landing site selection.
The lander also will carry items for 15 other companies and the Mexican Space Agency that range from rovers to ashes of deceased loved ones.
The private payloads are being flown for such entities as Toronto-based Canadensys Aerospace and Carnegie Mellon, which intends to test robotics on a lunar rover.
Astrobotic plans to launch the lander aboard United Launch Alliance's new Vulcan rocket, which is being developed and is on target for service by early 2021, ULA said. The rocket's second stage, called Centaur, would push the lander toward the moon.
The journey to the moon would take between 17 and 45 days, depending on when the mission can launch and the moon's position in its orbit. All systems on the lander would depend on sunlight to operate on the surface, so the mission must land at the start of the lunar day, Bhaskaran said.
The lander's propulsion system would use five engines with hydrazine liquid propellant to enter lunar orbit and land, he said.
At least four rovers on board, and possibly more, would also use the lander's solar-powered systems for the length of the lunar day, which is 14 Earth days, he said.
"We can maneuver each rover within the spacecraft and release them one by one," Bhaskaran said.
NASA has a series of robotic landers and rovers going to the moon after Peregrine's first mission. All of these were awarded based on competitive commercial bidding.
Those probes include another Astrobotic mission, the VIPER rover, which will hunt for water ice near NASA's intended landing site for Artemis in the south pole region in late 2023. Astrobotic has another contract at $199.5 million for that.
"Because we have other customers, these missions are much less expensive for NASA, at least 10 times less than any lunar missions NASA ever planned before," Bhaskaran said.
Having such private customers on a lunar mission is "a real game-changer" for the American space program, said Mark Robinson, professor of earth and space exploration at Arizona State University.
"Space technology has spread out from beyond NASA to many private space companies," Robinson said. "We have much more sophistication in terms of computing power and communications, and our knowledge of the moon is so much better now."
Robinson has helped NASA map out the most ambitious lunar rover mission ever, which is called Intrepid but has no launch date.
The Intrepid rover would roam more than 1,000 miles of the lunar surface over four years as it examines the geology of 100 potential landing sites for U.S. missions.
*-- Graphene-based circuit yields clean, limitless power --*
 Scientists have developed a new graphene-based circuit capable of producing clean, limitless power. Researchers suggest the energy-harvesting circuit -- described Friday in the journal Physical Review E -- could be used to power small, low-voltage devices and sensors.
The circuit's ability confirms the theory -- developed by the study's authors, a group of physicists at the University of Arkansas -- that micron-sized sheets of freestanding graphene naturally move in a way conducive to energy harvesting.
The breakthrough also contradicts the assertion by Richard Feynman that so-called Brownian motion, the thermal motion of atoms, cannot perform work. But lab tests showed the Brownian motion of atoms in freestanding sheets of graphene can generate an alternating current.
Famously, physicist Léon Brillouin proved that a single diode, a one-way electrical gate, added to a circuit was not sufficient to turn Brownian motion into energy. The team of physicists at the University of Arkansas developed their novel circuit using two diodes.
Positioned in opposition, the two diodes allow current to flow in both directions, turning the alternating current into a pulsing direct current. The pulsing direct current, taking separate paths back-and-forth through the circuit, performs work on a load resistor.
"We also found that the on-off, switch-like behavior of the diodes actually amplifies the power delivered, rather than reducing it, as previously thought," lead researcher Paul Thibado, professor of physics at Arkansas, said in a news release. "The rate of change in resistance provided by the diodes adds an extra factor to the power."
According to the researchers, the thermal movement in the graphene and circuit is inherent in the material, not the result of temperature differences between the two components -- no heat flows between the graphene and circuit.
"This means that the second law of thermodynamics is not violated, nor is there any need to argue that 'Maxwell's Demon' is separating hot and cold electrons," Thibado said.
Tests also showed that the graphene's Brownian motion yielded low-frequency currents -- good news for the technology's application, as most electronics are more efficient at lower frequencies.
"People may think that current flowing in a resistor causes it to heat up, but the Brownian current does not. In fact, if no current was flowing, the resistor would cool down," Thibado said. "What we did was reroute the current in the circuit and transform it into something useful."
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