Magnetic propulsion system offers new possibilities for space exploration

New electromagnetic propulsion technology being tested by the University of Maryland’s Space Power and Propulsion Laboratory (SPPL) on the International Space Station could revolutionize the capabilities of satellites and future spacecraft by reducing reliance on propellants and extending the lifecycle of satellites through the use of a renewable power source.

Because a finite propellant payload is often the limiting factor on the number of times a satellite can be moved or repositioned in space, a new propulsion method that uses a renewable, onboard electromagnetic power source and does not rely on propellants could exponentially extend a satellite’s useful life span and provide greater scientific return on investment.

Associate Professor of Aerospace Engineering Ray Sedwick and his research team have been developing technology that could enable electromagnetic formation flight (EMFF), which uses locally generated electromagnetic forces to position satellites or spacecraft without relying on propellants. Their research project is titled Resonant Inductive Near-field Generation System, or RINGS.

RINGS was sent to the International Space Station on August 3 as part of a payload launched on Japan’s HTV-4 Cargo Ship from the Tanegashima Space Center. The project is scheduled for four test sessions on the research station. Astronauts will unpack the equipment, integrate it into the test environment and run diagnostics. From there, RINGS will undergo three science research sessions where data will be collected and transmitted back to the ground for analysis.

RINGS is composed of two units, each of which contains a specially fabricated coil of aluminum wire that supports an oscillating current of up to 18 amps and is housed within a protective polycarbonate shell. Microcontrollers ensure that the currents oscillate either in-phase or out-of-phase to produce attracting, repelling and even shearing forces. While aluminum wire was chosen for its low density in this research prototype, eventual systems would employ superconducting wires to significantly increase range and performance.

In the spring of 2013, RINGS was tested for the first time in a microgravity environment on NASA’s reduced gravity aircraft. UMD graduate students Allison Porter and Dustin Alinger were on hand to oversee the testing. RINGS achieved the first and only successful demonstration of EMFF in full six degrees of freedom to date.

“While reduced gravity flights can only provide short, 15-20 second tests at a time, the cumulative test time over the four-day campaign provided extremely valuable data that will allow us to really get the most from the test sessions that we’ll have on the International Space Station,” said Sedwick.

In addition to EMFF, the RINGS project is also being used to test a second technology demonstrating wireless power transfer (WPT). WPT may offer a means to wirelessly transfer power between spacecraft and in turn power a fleet of smaller vessels or satellites. Having the power to support multiple satellites, and using EMFF as a propellant-less means to reposition those same satellites, provides the flexibility to perform formation control maneuvers such as on-orbit assembly or creating synthetic aperture arrays. A synthetic aperture array uses a network of smaller antennas to function collectively as one large antenna. Larger antennas are capable of producing higher resolution images and better quality data.

The RINGS project has been a collaborative effort between UMD SPPL and partners from the Massachusetts Institute of Technology (MIT) and Aurora Flight Sciences (AFS). MIT’s SPHERES (Synchronized Position Hold Engage Re-orient Experimental Satellites) program provided SPPL an existing test bed of miniature satellites and control algorithms that will be used to integrate and test the RINGS technology. AFS has provided hardware development and support for the integration of RINGS onto the SPHERES platform.

Where comets go to die

A team of astronomers from the University of Anitoquia, Medellin, Colombia, have discovered a graveyard of comets. The researchers, led by Anitoquia astronomer Prof. Ignacio Ferrin, describe how some of these objects, inactive for millions of years, have returned to life leading them to name the group the ‘Lazarus comets’. The team publish their results in the Oxford University Press journal Monthly Notices of the Royal Astronomical Society. Comets are amongst the smallest objects in the Solar System, typically a few km across and composed of a mixture of rock and ices. If they come close to the Sun, then some of the ices turn to gas, before being swept back by the light of the Sun and the solar wind to form a characteristic tail of gas and dust. Most observed comets have highly elliptical orbits, meaning that they only rarely approach the Sun.

Some of these so-called long period comets take thousands of years to complete each orbit around our nearest star. There is also a population of about 500 short period comets, created when long period comets pass near Jupiter and are deflected in orbits that last anything between 3 and 200 years. Although uncommon events, comets also collide with the Earth from time to time and may have helped bring water to our planet. The new work looked at a third and distinct region of the Solar System, the main belt of asteroids between the orbits of Mars and Jupiter. This volume of space contains more than 1 million objects ranging in size from 1 m to 800 km. The traditional explanation for asteroids is that they are the building blocks of a planet that never formed, as the movement of the pieces was disrupted by the strong gravitational field of Jupiter. In the last decade 12 active comets have been discovered in the asteroid main belt region. This was something of a surprise and the Medellin team set out to investigate their origin. The team, made up of Prof. Ferrin and his colleagues Profs. Jorge Zuluaga and Pablo Cuartas, now think they have an explanation. “We found a graveyard of comets”, exclaims Professor Ferrín. He adds: “Imagine all these asteroids going around the Sun for aeons, with no hint of activity. We have found that some of these are not dead rocks after all, but are dormant comets that may yet come back to life if the energy that they receive from the Sun increases by a few per cent.” Surprisingly, this can happy fairly easily, as the orbits of many objects in the asteroid belt are nudged by the gravity of Jupiter. The shape of their orbits can then change, leading to a decrease in the minimum distance between the object and the Sun (perihelion) and a slight increase in average temperature. According to this interpretation, millions of years ago the main belt was populated by thousands of active comets. This population aged and the activity subsided. What we see today is the residual activity of that glorious past. Twelve of those rocks are true comets that were rejuvenated after their minimum distance from the Sun was reduced a little. The little extra energy they received from the Sun was then sufficient to revive them from the graveyard. Prof. Ferrin describes the 12 active comets. “These objects are the ‘Lazarus comets’, returning to life after being dormant for thousands or even millions of years. Potentially any one of the many thousands of their quiet neighbours could do the same thing.”

Volcano’s Heat Lights Up Satellite Sensors

Like a maw into the pits of hell, the Paluwej volcano in Indonesia has caught even NASA’s attention.

As the Landsat Data Continuity Mission satellite flew over Indonesia’s Flores Sea April 29, it captured an image of Paluweh volcano spewing ash into the air.
The satellite’s Operational Land Imager detected the white cloud of smoke and ash drifting northwest, over the green forests of the island and the blue waters of the tropical sea. The Thermal Infrared Sensor on LDCM picked up even more.
By imaging the heat emanating from the 5-mile-wide volcanic island, TIRS revealed a hot spot at the top of the volcano where lava has been oozing in recent months.
The two LDCM instruments, working together, illustrate a quote from Aristotle: The whole is greater than the sum of its parts, said Betsy Forsbacka, TIRS instrument manager at NASA’s Goddard Space Flight Center in Greenbelt, Md.

“Each instrument by itself is magnificent,” she said. “When you put them together, with the clues that each give you on what you’re seeing on Earth’s surface, it’s greater than either could do by themselves.”
The image of Paluweh also illuminates TIRS’ abilities to capture the boundaries between the hot volcanic activity and the cooler volcanic ash without the signal from the hot spot bleeding over into pixels imaging the cooler surrounding areas. TIRS engineers tested and refined the instrument pre-launch to ensure each pixel correctly represents the heat source it images on Earth’s surface. Otherwise, Forsbacka said, it would be like shining a flashlight in your eyes — the bright light can leave you seeing spots and halos where it should be dark. The same effect can occur with detectors. But the contrast is sharp on the Paluweh image.
“We can image the white, representing the very hot lava, and right next to it we image the gray and black from the cooler surrounding ash,” Forsbacka said. “It’s exciting that we’re imaging such diverse thermal activity so well.”
The TIRS instrument can also pick up subtle shifts of temperatures, within a 10th of a degree Celsius. And, with two different thermal bands instead of the one band on previous Landsat satellites, LDCM is poised to make it easier for scientists to subtract out the effects of the atmosphere on the signal, obtaining a more accurate temperature of Earth’s surface.
Taking Earth’s temperature from space can be difficult because the atmosphere gets in the way and alters the thermal signals, Forsbacka said. Scientists looking to estimate surface temperatures with the single thermal band on previous Landsat instruments needed measurements or assumptions about atmospheric conditions.
TIRS has two thermal bands, however. The atmosphere affects each band slightly differently, resulting in one thermal image that’s a hair darker than the other. By measuring that difference, and plugging it into algorithms, scientists can better address atmospheric effects and create a more accurate temperature record of the Earth’s surface.
The Landsat program is a joint mission of NASA and the U.S. Geological Survey. Once LDCM completes its onboard calibration and check-out phase in late May, the satellite will be handed over to the USGS and renamed Landsat 8. Data from TIRS and OLI will be processed, archived and distributed from the USGS Earth Resources and Observation Science Center in Sioux Falls, S.D., for free over the Internet.

Russia designs reusable spacecraft good for as many as five missions

A Russian company designing a new spacecraft for the country's space program says the craft will be reusable and able to make as many as five flights.

Energia Rocket and Space Corp. said the spacecraft's technical design has been finalized but is yet to be officially approved, RIA Novosti reported Wednesday.

The new reusable craft is to replace the Soyuz capsule and will have modification to allow it to perform a number of missions, Energia deputy general designer Alexander Chernyavsky said. They include flights to near-Earth and moon orbits, missions to maintain and repair other spacecraft, and for collecting space debris, he said.

A prototype is set to be rolled out in August while flight tests are due to begin in 2017, Energia said.

Planet-Seeking Spacecraft Spies Water Worlds

NASA’s Kepler spacecraft has discovered two planets that are the most similar in size to Earth ever found in a star’s habitable zone — the temperate region where water could exist as a liquid.

The finding, reported online today in Science, demonstrates that Kepler is closing in on its goal of finding a true twin of Earth beyond the Solar System, says theorist Dimitar Sasselov of the Harvard-Smithso

nian Center for Astrophysics in Cambridge, Massachusetts, who is a member of the Kepler discovery team.

Both planets orbit the star Kepler-62, which is about two-thirds the size of the Sun and lies about 1,200 light years (368 parsecs) from the Solar System. The outermost planet from the star, Kepler-62f, has a diameter that is 41% larger than Earth’s and takes 267 days to circle its star. The inner planet, Kepler-62e, has a diameter 61% larger than Earth’s and a shorter orbit of 122 days.

Kepler detected the planets by recording the tiny decrease in starlight that occurs when either of them passes in front of their parent star. Astronomers used those measurements to calculate the planets’ relative size compared to that star.

Worlds apart
In the Science paper, the Kepler team — led by principal investigator William Borucki of NASA — suggests that the planets are solid, but may be rocky or icy. But Sasselov believes that the two orbs are likely to be covered entirely by oceans, based on his own unpublished analysis co-authored with colleagues at Harvard-Smithsonian and the Max Planck Institute for Astronomy in Heidelberg, Germany. They theorize that the two water worlds are either liquid all the way down to their core or have a solid surface just beneath a shallower ocean. The latter model would be more conducive to life as we know it on Earth, where a recycling of material and energy from hydrothermal vents can sustain organisms, Sasselov says.

But some recycling could also occur in a much deeper ocean, owing to...

How the Hubble Space Telescope Works?

Launched from space shuttle Discovery on April 24, 1990, the Hubble Space Telescope orbits at an altitude of about 350 miles (560 kilometers). The telescope is 43.5 feet (13.2 meters) long, weighs 24,500 pounds (11,110 kilograms) and cost $2.5 billion.

Hubble’s six cameras and sensors see visible, infrared and ultraviolet light. At the heart of Hubble is its 8-foot-diameter

(2.4 meters) primary mirror. The Hubble telescope is named after the famed late astronomer Edwin Hubble, who has been lauded as the father of modern cosmology and determined the rate of the expansion of the universe. Incoming light strikes the primary mirror, and is reflected onto the secondary mirror and through a hole in the primary mirror, until it finally reaches a focal point at the science instruments. The complicated path increases the telescope’s focal length. When Hubble was first trained on distant heavenly targets, astronomers were horrified to discover that the images were out of focus. The primary mirror had been ground to the wrong prescription. After astronauts installed corrective optics in 1993, the view was clear. Hubble was designed to be serviced on-orbit by space-shuttle astronauts. Cameras, sensors and even the large solar-panel "wings" have been replaced. Hubble was visited five times: in 1993, 1997, 1999, 2002 and 2009. Since the retirement of the space shuttles in 2011, no more manned Hubble visits are planned.

Scheduled to launch in 2018, Hubble’s successor, the James Webb Space Telescope (JWST) will orbit about 930,000 miles (1.5 million km) away from Earth.

The JWST’s 21-foot-diameter (6.4 m) mirror dwarfs that of Hubble. The James Webb Space Telescope is estimated to cost a total of $8.8 billion.

Astronomers Discover the Birth of the Black Hole ‘Cygnus X-1’

Astronomers have discovered for the first time the complete description of a black hole which allowed them to reconstruct the history of the object from its birth around six million years ago.

The scientists used several telescopes, both ground-based and in orbit, to unravel the mysteries about the object called Cygnus X-1, a famous binary-star system found to be strongly emitting X-rays almost half a century ago. The scientists' efforts yielded the most accurate measurements ever of the black hole's mass and spin rate. "Because no other information can escape from a black hole, knowing its mass, spin, and electrical charge gives a complete description of it," said Mark Reid, of the Harvard-Smithso

nian Center for Astrophysics (CfA). "The charge of this black hole is nearly zero, so measuring its mass and spin make our description complete," he added

Since its discovery, scientists have studied the Cygnus X-1 intensely since its discovery but because of lack of a precise measurement of its distance from Earth previous attempts to measure its mass and spin was not successful.

With the new study, Reid led a team that used the National Science Foundation's Very Long Baseline Array (VLBA), a continent-wide radio-telescope system, to make a direct trigonometric measurement of the distance and their VLBA observations provided a distance of 6070 light-years. Previous estimates had ranged from 5800-7800 light-years. With the new, precise distance measurement, scientists used the Chandra X-Ray Observatory, the Rossi X-Ray Timing Explorer, the Advanced Satellite for Cosmology and Astrophysics, and visible-light observations made over more than two decades, to calculate the black hole in Cygnus X-1. They found out that it is nearly 15 times more massive than our Sun and is spinning more than 800 times per second.

"This new information gives us strong clues about how the black hole was born, what it weighed...