MIT-developed ‘microthrusters’ could propel small satellites

Small-scale satellites show a lot promise, but unless they have equally small-scale thrusters they’re pretty limited in what they can do. Unfortunately conventional thrusters are heavy and take up a lot of valuable space, but a penny-sized rocket engine developed at MIT holds the prospect of not only increasing the capabilities of miniature satellites, but of combating space junk as well.

Cubesats are a class of nanosatellites. Unlike most satellites, which weigh in at several tons and can be as big as a bus, cubesats are, as the name implies, tiny cubes only four inches (10.16 cm) on a side and weighing about three pounds (1.36 kg). They’re attractive to space engineers and scientist because they’re small enough to be launched as hitchhikers with larger payloads and they can be used either singly, flown in formation or docked together like building blocks to form a bigger satellite.

The only problem with cubesats is that space in them is limited and so they tend to economize on things like rocket thrusters for attitude control. Nanosatellite engines do exist, but they are complicated and large in comparison to the tiny satellite, which means that installing them means some severe trade offs in terms of payload and capability.

The MIT team led by associate professor of aeronautics and astronautics Paulo Lozano is tackling this problem with the development of a rocket thruster that’s about the size and shape of a sugar cube. Its upper face is made up of 500 microscopic tips, each a tiny thruster in its own right. The purpose of this thruster is to greatly simplify the design and hence save space and weight. Whether burning fuel or using cold gas, conventional thrusters need valves, tanks, pipes, venturis and other components that take up weight and space. The MIT microthrusters are not only smaller, they’re mechanically very simple, yet technologically very sophisticated.

Each thruster is made of a reservoir of fuel at the bottom of the cube that Lozano describes as a “‘liquid plasma’ of free-floating ions.” Above this reservoir are layers of porous metal. Each pore leads into more numerous, smaller pores on the next level like the spreading branches of a tree. By the time they reach the top layer, there are 500 pores that make up the thruster tips. On the very top is a perforated gold plate, which acts as a cathode. When the plate is electrified, it charges the fuel drops in the thruster tips, turning them into charged ions and expelling them at high speed to generate thrust. In essence, the thruster is a tiny ion drive.

The clever bit about this whole arrangement is that the ions shooting out of the thruster generate a capillary effect in the system of pores. Like sap being drawn up a tree, the capillary pressure draws the fuel to the thruster tips without any mechanical pumps or 

valves.

To test the thrusters, the MIT team had to employ a novel apparatus. They mounted the thrusters on a mockup satellite, suspended it in space using counterbalanced magnets and then placed it in a vacuum chamber. Part of the reason for doing this is that the thrust of the engine isn’t much - only about 50 micronewtons, but for a tiny satellite in freefall, it’s enough for practical attitude control and changing orbits.

The reason why Lozano and his team are developing these thrusters is more than just expanding the capabilities of cubesats. The current technology means that even cubesats with conventional thrusters will have a very limited life. If they’re launched into low-earth orbit, they will end up passively circling the globe until their orbits decay and they burn up in the atmosphere. However, if they’re put into a higher orbit, they are destined to become hazardous space junk.

“These satellites could stay in space forever as trash,” said Lozano.“This trash could collide with other satellites. … You could basically stop the Space Age with just a handful of collisions.”

The hope is that these thrusters could be used to guide the cubesats into the atmosphere at the end of their missions. The team also notes that small increases in electrical voltage produce a disproportionate increase in thrust. This means that in the future cubesats could be sent to rendezvous with dead conventional satellites and herd them into reentry like fleets of miniature space tugs. In addition, Lozano also believes that these thrusters could be formed into large panels that could be used by larger satellites to tack across the heavens.

Source - MIT

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Zero gravity in space may impact astronauts' immunity

Washington: The clue to astronauts' immunity in outer space owing to prolonged travel lies in learning the negative impact of zero gravity on fruit flies.

A team of researchers from the University of California at Davis and the University of Central Florida (UCF) has studied the impact weightlessness has on fruit flies bred in space.

"Our study showed that a biochemical pathway needed to fight fungal infections is seriously compromised in the flies after space flight," said Laurence Von Kalm, a UCF biologist.

"More work would be needed to determine if similar effects occur in humans but this gives us some important clues," he added.

Fruit flies' innate immune system is similar to that of humans and other mammals and is often used as a model in basic studies.

The research team, led by UC Davis biologist Deborah Kimbrell, bred flies in space aboard Space Shuttle Discovery in 2006.

The flies developed into adults while on the 12-day mission.

The flies were retrieved after the mission and researchers found that they were more apt to get fungal infections.

Further analysis revealed that the system the flies use for detecting and defending against fungal infection was deactivated.

In contrast, another system used to defend against bacterial infection was not impaired in the space flies.

The team hopes to carry out research with fruit flies on the International Space Station (ISS).

"Getting a better understanding is particularly important, especially as we look to engage in long-term missions such as interplanetary space flights," added Kalm.

The findings were published in the journal PLOS One. 

Original article on ZEE News

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Now, 'sticky-feet' robots to fix space stations

London: Researchers have developed a climbing robot that has dry but sticky gecko-like feet and can crawl around an orbiting spacecraft to maintain and repair it.

With the invention of the new robot, astronauts won't have to risk their lives in daring spacewalks to fix things like they did last month on the International Space Station to repair a cooling system. Instead, they could just command swarms of crawling automatons to do the job. 

The gecko robot, called Abigaille III, has been developed by Michael Henrey and his colleagues at Simon Fraser University in Burnaby, Canada.

To test Abigaille's space flight credentials, Henrey took it to the European Space Agency's labs in Noordwijk, the Netherlands, where it was put through its paces at the extreme temperatures and zero-pressure conditions of space.

The team developed techniques similar to those used in the microelectronics industry to create "footpad terminators" much like the nanoscopic hairs on a gecko's feet. 

"Technical limitations mean these are around 100 times larger than a gecko's hairs, but they are sufficient to support our robot's weight," Henrey said.

A gecko's feet are sticky due to a bunch of little hairs with ends just 100, 200 nanometres across - around the scale of individual bacteria. 

This is sufficiently tiny that atomic interactions between the ends of the hairs and the surface come into play. 

The robot features six legs, each with four degrees of freedom for optimum agility, allowing the robot to crawl from vertical to horizontal to get around obstacles. 

"Our Abigaille climbing robot is therefore quite dexterous, with six legs each having four degrees of freedom, so it should be able to handle environments that a wheeled robot could not," said ESA's Laurent Pambaguian. 

"For example, it can transition from the vertical to horizontal, which might be useful for going around a satellite or overcoming obstacles on the way," Pambaguian said.

Source – ZEE News

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Moon Rovers Planned for Commercial Lunar Exploration Project

The commercial spaceflight company Golden Spike – which aims fly private missions to the moon by 2020 – has teamed up with the New York-based firm Honeybee Robotics to design robotic rovers for the planned lunar expeditions.

"We're very proud to be working with Honeybee, which has tremendous experience and a record of successful performance in the development of flight systems for NASA," Golden Spike President and CEO Alan Stern said in a statement last month.

 An artist's illustration of a Golden Spike Company moon lander on the lunar surface.
Credit: Golden Spike Company

Golden Spike first announced its goal of launching two-person commercial flights to the moon in December 2012. To boost the scientific output of the expeditions, the company plans to send unmanned rovers to the moon ahead of the crew to collect samples from a wider area than the crew will be able to travel from their landing pad. The rovers will then meet up with the crew's spacecraft once it arrives, according to the mission plan.  [Golden Spike's Private Moon Mission Plan in Pictures]

"Honeybee brings a unique body of knowledge and skills to help us augment the capabilities of human exploration missions with advanced robotics," Clive Neal, a researcher at the University of Notre Dame in Indiana and chair of Golden Spike's lunar science advisory board, said in a statement. "Their participation is a key step forward in helping Golden Spike change the paradigm of human space exploration, through the development of highly capable lunar exploration system architecture for customers around the world."

Honeybee Robotics has been designing planetary sampling devices for clients including NASA and the US Department of Defense for more than 25 years, and has contributed to the last three of NASA's Mars Landers: The company designed the rock abrasion tool for NASA's Mars Exploration Rovers Spirit and Opportunity, as well as the icy soil acquisition device (or "Phoenix Scoop") for the U.S. space agency's Phoenix Mars Lander, and the sample manipulation system and dust removal tool for the Curiosity rover.

Golden Spike officials initially priced the missions at $1.5 billion per person, but has since estimated that the cost could drop down to about $750 million with the help of media coverage and sales of merchandising rights of the missions, Stern told reporters last year at the 29th National Space Symposium in Colorado Spring, Colo. Potential moon flyers include leaders of nations, large corporations, and independently funded individuals. 

The companies plan to complete preliminary tests of their rover design by mid-2014.

Source – Space.com

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Jupiter and Saturn may be studded with diamonds

Washington: Diamonds in the sky! Scientists have found that the atmospheres of Jupiter and Saturn are awash in diamonds. 

Recent work by planetary scientists has indicated that these planets may contain chunks of diamond floating in a liquid hydrogen/helium fluid. 

The new data available has confirmed that at depth, diamonds may be floating around inside of Saturn, some growing so large that they could perhaps be called “diamondbergs.”

 
Planetary scientists Mona Delitsky of California Speciality Engineering in Pasadena, California, and Kevin Baines of the University of Wisconsin-Madison have compiled recent data about the phase diagram of carbon. 

They combined the data with newly published adiabats (pressure-temperature diagrams) for Jupiter and Saturn to calculate that diamond will be stable in the deep interiors. 

Further, at altitudes below the regions where diamond is stable, the pressures and temperatures will be so large as to melt the diamond into liquid, creating diamond rain or liquid diamond. 

Delitsky and Baines reported that elemental carbon such as soot or graphite generated in Saturn’s enormous lightning storms will descend into the planet and will be crushed into diamonds at deep altitudes and then melted into liquid diamond near the cores of the planets. 

While it has been known for 30 years that diamond may be stable in the cores of Uranus and Neptune, Jupiter and Saturn were thought to be too hot or to not have conditions suitable for precipitation of solid diamond, researchers said.

Sourced from – Pune Mirror

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Jupiter-bound NASA probe to grab speed boost from Earth flyby Wednesday

A NASA spacecraft bound for Jupiter will buzz Earth Wednesday (Oct. 9) to snag a gravity speed boost that will slingshot it toward the largest planet in the solar system.

The Juno spacecraft will be within 350 miles (560 kilometers) of Earth when it zooms by our planet at 3:21 p.m. EDT (1921 GMT). It will be passing over South Africa during its closest approach to Earth.

An artists rendering depicts Nasa's Juno spacecraft wit Jupiter in the background. Juno will swing by Earth to gather the momentum it needs to arrive at Jupiter in 2016

Since its 2011 launch on an unmanned Atlas 5 rocket, NASA's Juno mission to Jupiter has followed a circuitous route toward Jupiter. This pass around Earth will give it the boost it needs to make it the rest of the way to the solar system's largest planet, accelerating the spacecraft from its current speed --78,000 mph (126,000 km/h) with respect to the sun -- to a speed of 87,000 mph (140,000 km/h). [See photos of NASA's Juno mission to Jupiter]

"Juno is a large, massive spacecraft," Juno mission principal investigator Scott Bolton with the Southwest Research Institute in San Antonio, Texas, said in a statement. "Even a large rocket couldn't provide enough propulsion to get us all the way to Jupiter, so we are flying by the Earth for a gravity-assist that will provide about 70 percent of the initial boost provided by the Atlas V 551 rocket. The gravity assist essentially provides as much propulsion as a second rocket launch."

SwRI officials released a video of the Juno probe's Earth flyby to describe how the spacecraft will use Earth's gravity to help it reach Jupiter.

Although 97 percent of NASA staff members are furloughed due to the government shutdown, Juno's mission-critical Earth flyby operations have not been affected.

The 8,000-pound (3,267 kilograms) Juno probe is the first solar-powered spacecraft to explore the outer solar system, and has three large solar arrays, each of which is the size of a tractor-trailer. It also holds a titanium vault to protect sensitive electronic equipment from the harsh environment around Jupiter.

"While we are primarily using Earth as a means to get us to Jupiter, the flight team is also going to check and calibrate Juno's science instruments," Bolton said in the statement.

There's a bonus, too. Juno is approaching Earth from the planet's sunlit side, which means it is in a prime position to photograph its home planet from deep space.

"Juno will take never-before-seen images of the Earth-Moon system, giving us a chance to see what we look like from Mars or Jupiter," Bolton said.

The $1.1 billion Juno spacecraft launched in August 2011 and will reach the Jovian system on July 4, 2016. Juno will then orbit around Jupiter for a full Earth year, studying the planet's atmosphere, gravitational field and magnetic field with nine different science instruments, according to the statement.

The mission is named after the goddess Juno, from Greek and Roman mythology. In the myth, the god Jupiter (or Zeus, as the Greeks would have it) used clouds to hide his mischievousness, but his wife Juno was able to peer through the veil to see her husband's antics, according to a NASA description.

Originally Published on Space.com

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A water-rich superearth found 40 lightyears away

Source – PuneMirror

Washington: A research team from Japan has used the Subaru Telescope to observe the water-rich atmosphere of a super-earth, 40 lightyears from our planet.

The astronomers and planetary scientists has used Subaru Telescope’s two optical cameras, Suprime-Cam and the Faint Object Camera and Spectrograph (FOCAS), with a blue transmission filter to observe planetary transits of super-Earth GJ 1214 b (Gliese 1214 b). 

The team investigated whether this planet has an atmosphere rich in water or hydrogen. The Subaru observations show that the sky of this planet does not show a strong Rayleigh scattering feature, which a cloudless hydrogendominated atmosphere would predict. 

When combined with the findings of previous observations in other colors, this new observational result implies that GJ 1214 b is likely to have a water-rich atmosphere. GJ 1214 b is located in the constellation Ophiuchus, northwest of the center of our Milky Way galaxy.

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