Friday, August 18, 2017

Power Up! System Tests Prepare Orion for Deep Space Exploration

Hurtling beyond the Moon at a speedy 25,000 mph for a three-week mission requires a space processor capable of operating with guaranteed reliability, in a high radiation environment tens of thousands of miles in deep space, at 480,000,000 instructions per second to execute thousands of commands and sequences for controlling the hundreds of spacecraft systems and components to ensure crew safety and mission success.

To ensure everything performs as planned, the Orion spacecraft destined for Exploration Mission-1 was successfully powered up for the first time this week in Orion’s spacecraft factory, the Neil Armstrong Operations and Checkout Facility at NASA’s Kennedy Space Center in Florida.

“The initial power-on procedure verified the health and status of Orion’s core computers and power and data units and marks the beginning of critical spacecraft subsystem tests to get us ready for flight," said Mark Kirasich, NASA Orion program manager. “Our test team, ground support equipment and flight systems all performed remarkably well during the test. This is a major milestone for Orion and for our long range deep space exploration plans.”

During the initial power-on tests, engineers and technicians connected the vehicle management computers to Orion’s power and data units to ensure the systems communicate precisely with one another to accurately route power and functional commands throughout the spacecraft for the duration of a deep-space exploration mission. In spaceflight, Orion will generate power through its four solar array wings which collectively hold about 15,000 solar cells that can harness enough electricity to power eight three-bedroom homes. The power and data units then distribute that power as needed throughout the spacecraft.

“The spacecraft’s power and data units and core computers will continue to undergo additional testing of various components over the next two to three months,” said Rafael Garcia, NASA Orion program test and verification lead at Kennedy.

Orion will launch atop the agency's Space Launch System rocket for an uncrewed mission traveling 40,000 miles beyond the Moon and returning to Earth with a Pacific Ocean splashdown. The mission will demonstrate the integrated system performance of the rocket, Orion spacecraft and ground support teams prior to the first flight with astronauts on board.


Astrophysicists predict Earth-like planet in star system only 16 light years away

Astrophysicists at the University of Texas at Arlington have predicted that an Earth-like planet may be lurking in a star system just 16 light years away.

The team investigated the star system Gliese 832 for additional exoplanets residing between the two currently known alien worlds in this system. Their computations revealed that an additional Earth-like planet with a dynamically stable configuration may be residing at a distance ranging from 0.25 to 2.0 astronomical unit (AU) from the star.

"According to our calculations, this hypothetical alien world would probably have a mass between 1 to 15 Earth's masses," said the lead author Suman Satyal, UTA physics researcher, lecturer and laboratory supervisor. The paper is co-authored by John Griffith, UTA undergraduate student and long-time UTA physics professor Zdzislaw Musielak.

The astrophysicists published their findings this week as "Dynamics of a probable Earth-Like Planet in the GJ 832 System" in The Astrophysical Journal.

UTA Physics Chair Alexander Weiss congratulated the researchers on their work, which underscores the University's commitment to data-driven discovery within its Strategic Plan 2020: Bold Solutions | Global Impact.

"This is an important breakthrough demonstrating the possible existence of a potential new planet orbiting a star close to our own," Weiss said. "The fact that Dr. Satyal was able to demonstrate that the planet could maintain a stable orbit in the habitable zone of a red dwarf for more than 1 billion years is extremely impressive and demonstrates the world class capabilities of our department's astrophysics group."

Gliese 832 is a red dwarf and has just under half the mass and radius of our sun. The star is orbited by a giant Jupiter-like exoplanet designated Gliese 832b and by a super-Earth planet Gliese 832c. The gas giant with 0.64 Jupiter masses is orbiting the star at a distance of 3.53 AU, while the other planet is potentially a rocky world, around five times more massive than the Earth, residing very close its host star—about 0.16 AU.

For this research, the team analyzed the simulated data with an injected Earth-mass planet on this nearby planetary system hoping to find a stable orbital configuration for the planet that may be located in a vast space between the two known planets.

Gliese 832b and Gliese 832c were discovered by the radial velocity technique, which detects variations in the velocity of the central star, due to the changing direction of the gravitational pull from an unseen exoplanet as it orbits the star. By regularly looking at the spectrum of a star - and so, measuring its velocity - one can see if it moves periodically due to the influence of a companion.

"We also used the integrated data from the time evolution of orbital parameters to generate the synthetic radial velocity curves of the known and the Earth-like planets in the system," said Satyal, who earned his Ph.D. in Astrophysics from UTA in 2014. "We obtained several radial velocity curves for varying masses and distances indicating a possible new middle planet," the astrophysicist noted.

For instance, if the new planet is located around 1 AU from the star, it has an upper mass limit of 10 Earth masses and a generated radial velocity signal of 1.4 meters per second. A planet with about the mass of the Earth at the same location would have radial velocity signal of only 0.14 m/s, thus much smaller and hard to detect with the current technology.

"The existence of this possible planet is supported by long-term orbital stability of the system, orbital dynamics and the synthetic radial velocity signal analysis", Satyal said. "At the same time, a significantly large number of radial velocity observations, transit method studies, as well as direct imaging are still needed to confirm the presence of possible new planets in the Gliese 832 system."

In 2014, Noyola, Satyal and Musielak published findings related to radio emissions indicating that an exomoon could be orbiting an exoplanet in The Astrophysical Journal, where they suggested that interactions between Jupiter's magnetic field and its moon Io may be used to detect exomoons at distant exoplanetary systems.


Monday, August 14, 2017

NASA contracts energy firm to refine nuclear thermal propulsion concepts

As the U.S. government continues to pursue plans for a crewed mission to Mars, NASA has contracted with BWXT Nuclear Energy Inc. of Lynchburg, Virginia, to advance concepts in Nuclear Thermal Propulsion (NTP), which could drastically reduce travel times to Mars.

This is part of NASA’s Game Changing Development Program, which takes ideas from academia and industry as well as NASA and other government programs, to advance new approaches to space technologies to accommodate the changing needs of U.S. space efforts.

NTP is not a new concept, but it was abandoned in 1972 when plans for a Mars mission were shelved. NASA conducted ground tests since 1955 to determine the viability of NTP and has occasionally been revisited as a conceptual part of Mars mission feasibility studies.

The advantage of NTP is mainly in that it can provide twice the rocket thrust of the Space Shuttle Main Engines (SSMEs), which are among the most powerful chemical rockets ever developed.

Sonny Mitchell, Nuclear Thermal Propulsion project manager at Marshall, said: “As we push out into the Solar System, nuclear propulsion may offer the only truly viable technology option to extend human reach to the surface of Mars and to worlds beyond. We’re excited to be working on technologies that could open up deep space for human exploration.”

Rex Geveden, BWX Technologies’ president and CEO, said: “We are uniquely qualified to design, develop and manufacture the reactor and fuel for a nuclear-powered spacecraft. This is an opportune time to pivot our capabilities into the space market where we see long-term growth opportunities in nuclear propulsion and nuclear surface power.”

Using conventional rockets, a mission to Mars at opposition would take six months. NTP could cut the travel time to four months. There are several advantages to cutting down travel time. One is that the astronauts would get less exposure to solar radiation – something that is of greater concern, as some recent studies suggest that the Apollo lunar astronauts may have had their health more adversely affected by radiation during their journeys than previously realized.

A shorter travel time will also reduce the vehicle’s mass. It would need to carry less fuel and fewer consumables – and could, therefore, carry more payload.

It works by expanding a propellant, such as hydrogen, by heating it in a nuclear reactor. This differs from chemical rockets, in which the fuel is the heat source. As a result, an NTR rocket can use a propellant with a low molecular weight rather than complex fuels such as kerosene or hydrazine.


Friday, August 11, 2017

NASA's New Plasma Rocket Ready For Testing

Most of today's rockets are chemical rockets, which means they propel themselves through space by combining certain chemicals in a way that makes them explosive. Chemical rockets are heavy and fast-burning, which is great for getting off the surface of Earth, but less great for long voyages to the outer solar system.

For these longer trips, NASA is looking at using a new type of rocket: the plasma rocket.

NASA awarded a contract to the company Ad Astra back in 2015 to build a plasma rocket, and that rocket is rapidly approaching readiness. The company has been running several short tests of the engine and is preparing for a longer, 100-hour test. Once that happens sometime next year, the rocket engine will be closer to real missions.

The plasma rocket, the Variable Specific Impulse Magnetoplasma Rocket (VASIMR), works by heating neon or argon gas to incredibly high temperatures using magnetic fields. That hot plasma is then fired out of the back of the rocket at very high speeds, providing thrust.

The plasma rocket has an advantage over traditional chemical propellants in that it can provide a small amount of thrust over a very long time, such as days, weeks, or months. Longer burn times mean the rocket needs less fuel, and less fuel means the rocket can carry more cargo. Of course, longer burn times also means longer travel times, but when you're just ferrying around supplies a few extra weeks or months isn't too important.

In addition to carrying cargo, plasma rockets could be used to send spacecraft to distant targets more quickly. Plasma rockets could enable us to reach Jupiter, Saturn, or more distant targets in a year or two instead of the better part of a decade, which could mean more missions to the outer solar system.

In a few short years, plasma might be propelling us around the solar system.


Wednesday, August 9, 2017

Four Earth-sized planets detected orbiting the nearest sun-like star

A new study by an international team of astronomers reveals that four Earth-sized planets orbit the nearest sun-like star, tau Ceti, which is about 12 light years away and visible to the naked eye. These planets have masses as low as 1.7 Earth mass, making them among the smallest planets ever detected around nearby sun-like stars. Two of them are super-Earths located in the habitable zone of the star, meaning they could support liquid surface water.

The planets were detected by observing the wobbles in the movement of tau Ceti. This required techniques sensitive enough to detect variations in the movement of the star as small as 30 centimeters per second.

"We are now finally crossing a threshold where, through very sophisticated modeling of large combined data sets from multiple independent observers, we can disentangle the noise due to stellar surface activity from the very tiny signals generated by the gravitational tugs from Earth-sized orbiting planets," said coauthor Steven Vogt, professor of astronomy and astrophysics at UC Santa Cruz.

According to lead author Fabo Feng of the University of Hertfordshire, UK, the researchers are getting tantalizingly close to the 10-centimeter-per-second limit required for detecting Earth analogs. "Our detection of such weak wobbles is a milestone in the search for Earth analogs and the understanding of the Earth's habitability through comparison with these analogs," Feng said. "We have introduced new methods to remove the noise in the data in order to reveal the weak planetary signals."

The outer two planets around tau Ceti are likely to be candidate habitable worlds, although a massive debris disc around the star probably reduces their habitability due to intensive bombardment by asteroids and comets.

The same team also investigated tau Ceti four years ago in 2013, when coauthor Mikko Tuomi of the University of Hertfordshire led an effort in developing data analysis techniques and using the star as a benchmark case. "We came up with an ingenious way of telling the difference between signals caused by planets and those caused by star's activity. We realized that we could see how star's activity differed at different wavelengths and use that information to separate this activity from signals of planets," Tuomi said.

The researchers painstakingly improved the sensitivity of their techniques and were able to rule out two of the signals the team had identified in 2013 as planets. "But no matter how we look at the star, there seem to be at least four rocky planets orbiting it," Tuomi said. "We are slowly learning to tell the difference between wobbles caused by planets and those caused by stellar active surface. This enabled us to essentially verify the existence of the two outer, potentially habitable planets in the system."

Sun-like stars are thought to be the best targets in the search for habitable Earth-like planets due to their similarity to the sun. Unlike more common smaller stars, such as the red dwarf stars Proxima Centauri and Trappist-1, they are not so faint that planets would be tidally locked, showing the same side to the star at all times. Tau Ceti is very similar to the sun in its size and brightness, and both stars host multi-planet systems.

A paper on the new findings was accepted for publication in the Astrophysical Journal and is available online.


Friday, July 28, 2017

SpaceX schedules Falcon Heavy's maiden launch for November

Elon Musk warns that it might not reach orbit, though.

SpaceX chief Elon Musk has revealed that the company is sending its heavy lift rocket to space for the first time in November. The company was originally gunning for a summer launch, but in June, the CEO told a Twitter follower that Falcon Heavy's cores will take two to three months to reach Cape Canaveral. SpaceX will need a bit of time after they arrive to prepare the rocket.

Falcon Heavy is powered by three Falcon 9 cores, which gives it thrice the payload capacity of the smaller launch vehicle. Earlier this year, the private space corporation was thinking of trying to reland and recover its upper stage during its maiden flight. That seems off the table now, though -- in fact, Musk set expectations pretty low for the launch. At a space conference in Washington last week, he said there's a good chance that Falcon Heavy won't even reach orbit the first time it leaves the atmosphere.

The rocket will take off from NASA's historic launch pad 39A at the Kennedy Space Center, but the company hasn't decided on the exact date and time yet. It'll likely announce those details in the next few months, as well as confirm whether it will stream the event online.


After Delays, SpaceX and Boeing Aim to Launch Astronauts Next Year

The race is on between the Dragon 2 and the Starliner.

Back in 2014, SpaceX and Boeing both received contracts under NASA's Commercial Crew Development program to build spacecraft that could carry astronauts to the International Space Station. The program is intended to allow NASA to launch astronauts on American spacecraft again, something that hasn't happened since the last flight of the space shuttle in 2011.

The spacecraft being developed by SpaceX and Boeing—the Dragon 2 and the CST-100 Starliner, respectively—proved to be more difficult than originally anticipated. Both companies pushed back their plans for 2017 flights to 2018. Elon Musk recently said the Crew Dragon, which is what NASA calls the Dragon 2, is "way more difficult" than the cargo version of the spacecraft that is used to take supplies to the ISS. "As soon as people enter the picture, it's really a giant step up in making sure things go right," said Musk at a recent panel on the commercial crew program. "The oversight from NASA is much tougher."

Fortunately, however, the work to achieve flights next year seems to be progressing nicely. NASA along with Boeing and SpaceX have indicated that they are on track to hit target launch dates in 2018. A July 20 report released by NASA shows that SpaceX is still targeting an unmanned test flight in February 2018 and a crewed flight in June 2018, and Boeing is aiming to launch an unmanned test flight in June 2018 and a crewed flight in August 2018. Boeing also plans to conduct pad abort tests in early 2018.

Future delays are certainly possible, and Boeing's director of the Starliner program, Chris Ferguson, called the timeline "a very aggressive test program," as reported by Space News. Still, Ferguson said it's possible that the first real mission to take astronauts to the ISS on the Starliner could launch as soon as December 2018. After that, there will not be another change in personnel aboard the space station until around May 2019.

SpaceX plans to launch its Dragon 2 on an upgraded version of the Falcon 9 rocket known as Block 5, currently in development. The Block 5 iteration of the Falcon 9 should produce more thrust in all engines and have reinforced landing legs. Boeing plans to launch the Starliner on an Atlas V rocket supplied by United Launch Alliance (ULA), a joint venture between Boeing and Lockheed Martin.

While SpaceX tends to keep everything close to the chest, there are a few future announcements from Boeing that could indicate progress in its commercial crew program. First of all, ULA will want a preliminary agreement about a launch about a year in advance, so it's possible we hear something from ULA about the first test flight of the Starliner sooner rather than later.

Also, the crewed test flight of the the Starliner will include a NASA astronaut and a Boeing test pilot. When NASA announces the astronaut for that flight, it will be a strong indication that the the agency is confident the launch is on track. "Once when they feel comfortable that they're about 12 months out from a crewed flight launch, I think you can see an assignment come out," said Ferguson.

SpaceX and Boeing have hit a few snags in their quest to build human-rated spacecraft, but their labors are finally coming together. Come 2018, Americans could fly on American spaceships once again.