NASA HAVOC: Manned mission to Venus Possible

HAVOC. Credit: NASA Langley Research Center

NASA's Systems Analysis and Concepts Directorate has issued a report outlining a possible way for humans to visit Venus, rather than Mars, by hovering in the atmosphere instead of landing on the surface.

The hovering vehicle, which they call a High Altitude Venus Operational Concept (HAVOC), would resemble a blimp with solar panels on top, and would allow people to do research just 50 kilometers above the surface of the planet.

Most everyone knows that NASA wants to send people to Mars, that planet also gets most of the press. Mars is attractive because it looks more like Earth and is relatively close to us.

The surface of Venus on the other hand, though slightly closer, is not so attractive, with temperatures that can melt lead and atmospheric pressure 92 times that of Earth.

There's also that thick carbon dioxide atmosphere with sulphuric acid clouds, lots of earthquakes, volcanoes going off and terrifying lightning bolts.

Perhaps humans could ride through the upper atmosphere of Venus in a solar-powered airship. Dale Arney and Chris Jones, from Nasa's Space Analysis Branch, propose that it may make sense to go to Venus before we ever send humans to Mars.

So, why would anyone rather go to Venus than Mars? Because of far lower radiation and much better solar energy.

No one wants to go the surface of Venus, at least not anytime soon, instead, researchers at NASA are looking into the possibility of sending people to hover in the sky above the planet, conducting research in a far less dangerous place than even on the surface of Mars.

At 50 kilometers up, an HAVOC would experience just one atmosphere of atmospheric pressure and temperatures averaging just 75 degrees Celsius, with radiation levels equivalent to those in Canada.

Astronauts on Mars, on the other hand would experience 40 times the amount of radiation typically faced back here on Earth, which suggests they'd have to live deep underground to survive, a problem that scientists have not yet solved.

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The possible existence of Earth-like Binary Planets

The possible existence of Earth-like binary planets is being described today at the American Astronomical Society's Division for Planetary Sciences meeting in Tucson, AZ. 

Two bodies, each of mass similar to Earth, can form a closely orbiting pair under certain conditions present during the formation of planetary systems.

This theoretical proposal is completely unlike the Earth-Moon system or Pluto-Charon, where the two bodies are very different in mass, and arises in some "kissing" collisions where two similar mass bodies encounter each other and become a bound system because of the energy lost in the strong tides raised on each other in the encounter.

The resulting binary can then persist for billions of years provided it forms well away from the central star, at half an astronomical unit (the distance between the Earth and Sun) or more.

This work was presented by undergraduate Keegan Ryan, graduate student Miki Nakajima, and Dr. David Stevenson of the California Institute of Technology in Pasadena, CA.

The result does not contradict existing data for planets around other stars but suggests that future data may uncover such systems.

This is the first such study to examine the possibility of terrestrial binary planets.

During the formation of terrestrial planets, large rocky bodies orbiting around a star occasionally get close enough to interact with one another.

If two bodies collide head on or obliquely, then this interaction typically results in accretion where the two bodies merge to form a larger one, perhaps leaving behind a disk of debris from which a moon can form.

This is the standard picture for how Earth got its moon and a possible explanation for Pluto's moon, Charon.

If the two bodies collide in a grazing manner but at high velocity, then the two bodies "hit and run" and separate from one another once again, failing to form a bound pair.

The research presented today searched for a middle ground, a scenario in which the interaction results in two large bodes that do not merge but still remain locked in orbit.

This configuration, termed a terrestrial binary planetary system, would necessarily evolve into a state where the two bodies are tidally locked and with the centers of the two planets being separated by only three or so planet radii.

NB: With orbital period being almost the same as day length for both planets.

There is a good reason to believe terrestrial binary planetary systems may be possible.

In a grazing collision the angular momentum is too high to be contained within a single rotating body (it would fission) and if the bodies barely touch then they could retain their identity.

However, it requires an encounter where the bodies are initially approaching each other at low enough velocity.

To test for this possibility, a simulation technique called Smoothed Particle Hydrodynamics (SPH) was utilized.

Smoothed Particle Hydrodynamics represents a body as a collection of tens of thousands of particles, and it has been used to study protoplanetary collisions as well as the giant impact hypothesis of the Moon's formation.

Using SPH, collisions between two rocky Earth-sized bodies were simulated, with impact velocity and impact parameter (a measure of how head-on a collision is) being varied and the output observed.

In the cases where the bodies underwent substantial collision, the scientists replicated previous results in which a binary system did not arise but a moon might form.

However, by including interactions where the bodies are close enough to undergo a large tidal distortion, initial conditions were found that led to a terrestrial binary planetary system.

ICRAR: Hungry black hole consumes material faster than thought possible

A rendering of what Black Hole P13 would look like close up. 

Credit: by Tom Russell (ICRAR) using software created by Rob Hynes (Louisiana State University).

Astronomers have discovered a black hole that is consuming gas from a nearby star 10 times faster than previously thought possible.

The black hole, known as P13, lies on the outskirts of the galaxy NGC7793 about 12 million light years from Earth and is ingesting a weight equivalent to 100 billion billion hot dogs every minute.

The discovery was published today in the journal Nature.

International Centre for Radio Astronomy Research (ICRAR) astronomer Dr Roberto Soria, who is based at ICRAR's Curtin University node, said that as gas falls towards a black hole it gets very hot and bright.

He said scientists first noticed P13 because it was a lot more luminous than other black holes, but it was initially assumed that it was simply bigger.

"It was generally believed the maximum speed at which a black hole could swallow gas and produce light was tightly determined by its size," Dr Soria said.

"So it made sense to assume that P13 was bigger than the ordinary, less bright black holes we see in our own galaxy, the Milky Way."

When Dr Soria and his colleagues from the University of Strasbourg measured the mass of P13 they found it was actually on the small side, despite being at least a million times brighter than the Sun.

It was only then that they realised just how much material it was consuming.

"There's not really a strict limit like we thought, black holes can actually consume more gas and produce more light," Dr Soria said.

Dr Soria said P13 rotates around a supergiant 'donor' star 20 times heavier than our own Sun.

He said the scientists saw that one side of the donor star was always brighter than the other because it was illuminated by X-rays coming from near the black hole, so the star appeared brighter or fainter as it went around P13.

Primary Image: This is a combined optical /X-ray image of NGC 7793. 

Inset image: This is a rendering of what P13 would look like close up. 

Credit: X-ray (NASA /CXC /Univ of Strasbourg /M. Pakull et al); Optical (ESO /VLT /Univ of Strasbourg /M. Pakull et al); H-alpha (NOAO /AURA /NSF /CTIO 1.5m). 

Insert Image: created by Tom Russell (ICRAR) using software created by Rob Hynes (Louisiana State University).

"This allowed us to measure the time it takes for the black hole and the donor star to rotate around each other, which is 64 days, and to model the velocity of the two objects and the shape of the orbit," Dr Soria said.

"From this, we worked out that the black hole must be less than 15 times the mass of our Sun."

Dr Soria said P13 is a member of a select group of black holes known as ultraluminous X-ray sources.

"These are the champions of competitive gas eating in the Universe, capable of swallowing their donor star in less than a million years, which is a very short time on cosmic scales," he said.

More information: 'A mass of less than 15 solar masses for the black hole in an ultraluminous X-ray source' was published in Nature, 9 October 2014. C. Motch, M. W. Pakull, R. Soria, F. Grise, G. Pietrzynski. DOI: 10.1038/nature13730

Nasa Asteroid Capture: Three Possible Candidates Selected

This NASA artist's rendering obtained on May 31, 2013 shows what capturing an asteroid could look like. 

The US space agency has narrowed its hunt for an asteroid to capture to three, NASA said.

The asteroids fit the requirements of being between seven to 10 meters (yards) in size, and further study should be able to narrow the choice even more, scientists said at a conference in San Diego, California.

"We have two to three which we will characterize in the next year and if all goes well... those will be valid candidates that could be certified targets," said Paul Chodas, senior scientist at the NASA Near-Earth Object Program Office.

The plan is to send a robotic spacecraft to capture the asteroid and drag it into orbit around the Moon.

Once there, astronauts could visit the asteroid and take samples of it back to Earth for study.

The spacecraft used for travel there and back would be the Orion multi-purpose vehicle, which is being built but has not yet been used, as well as a new deep space rocket launcher.

The program aims to break new ground by increasing NASA capabilities beyond low Earth orbit, where the International Space Station circles the globe.

Paul Chodas

NASA has touted the planetary defense capabilities the project would build toward protecting the Earth from a potential hazardous asteroid collision, as well as the technology it would boost for future human missions to deep space.

President Barack Obama has proclaimed the project would be a key step on the way to sending humans to Mars by the 2030s.

Bill Gerstenmaier, associate administrator of NASA's Human Exploration and Operations Directorate, described the asteroid mission as "pretty compelling."

"If you think about grabbing an object in space and then manipulating it for our use and putting it into a destination where we could go back and routinely visit and let commercial companies go visit, I think that is a pretty compelling activity."

Obama's 2014 budget for NASA asked for $100 million for the asteroid project, but the overall costs may be as high as $2 billion.

Bill Gerstenmaier

"It's a little different way than just a date and a destination. We are really good at just picking dates and destinations. But that's really hard in this budget environment where things are constrained and we have flat budgets, et cetera et cetera, to pull that off," said Gerstenmaier.

"It is not just a one-time thing. It actually feeds forward into the broader context of what we want to do with humans in space."

The launch could happen as early as 2017 or as late as 2019.

After launch of the robotic mission, the journey to the asteroid would take a year and a half, and the act of towing it toward the moon could take another three and a half years, NASA said.

The project would use a new fuel technology called solar electric propulsion.

"We are talking about engineering the solar system, in a way. We are talking about taking an asteroid which was once here, and then putting it into a useful orbit for our purposes," said Chodas.

"This is a very large idea here that we are talking about and I think it will reinvigorate interest in the space program," he said.