Monday, July 2, 2018

Study: Habitable Zone Exoplanets Kepler-62f and Kepler-186f Have Stable Climate, Regular Seasons

New research from the Georgia Institute of Technology and the Harvard-Smithsonian Center for Astrophysics suggests that exoplanets Kepler-62f and Kepler-186f — both of which reside in the habitable zone around their host stars — have very stable axial tilts, much like the Earth, making it likely that each has regular seasons and a stable climate.

Kepler-62f is the outermost planet among five exoplanets orbiting a single star, Kepler-62, which is approximately 1,200 light-years away toward the constellation Lyra.

The planet orbits its host star every 267 days, is 1.4 times bigger than Earth and is likely a terrestrial or ocean-covered world.

Kepler-62f was the most Earth-like exoplanet until astronomers noticed Kepler-186f in 2014.

Kepler-186f is part of the five-planet system. It is about 1.17 times the radius of Earth, but its mass, composition and density remain a mystery.

It orbits Kepler-186, a M1-type dwarf star located in the constellation Cygnus, about 492 light-years away, once every 130 days.

The brightness of the star at high noon, while standing on Kepler-186f, would appear as bright as the Sun just before sunset here on Earth.

“Our study is among the first to investigate climate stability of exoplanets and adds to the growing understanding of these potentially habitable nearby worlds,” said Dr. Gongjie Li, from the Georgia Institute of Technology and the Harvard-Smithsonian Center for Astrophysics.

Dr. Li and her colleague, Yutong Shan, used simulations to analyze and identify the exoplanets’ spin axis dynamics. Those dynamics determine how much a planet tilts on its axis and how that tilt angle evolves over time. Axial tilt contributes to seasons and climate because it affects how sunlight strikes the planet’s surface.

The researchers suggest that Kepler-186f’s axial tilt is very stable, much like the Earth, making it likely that it has regular seasons and a stable climate. They think the same is true for Kepler-62f.

“How important is axial tilt for climate? Large variability in axial tilt could be a key reason why Mars transformed from a watery landscape billions of years ago to today’s barren desert,” the scientists explained.

“Mars is in the habitable zone in our Solar System, but its axial tilt has been very unstable — varying from zero to 60 degrees,” Dr. Li said.

“That instability probably contributed to the decay of the Martian atmosphere and the evaporation of surface water.”

As a comparison, Earth’s axial tilt oscillates more mildly — between 22.1 and 24.5 degrees, going from one extreme to the other every 10,000 or so years.

“The orientation angle of a planet’s orbit around its host star can be made to oscillate by gravitational interaction with other planets in the same system,” the astronomers said.

“If the orbit were to oscillate at the same speed as the precession of the planet’s spin axis, the spin axis would also wobble back and forth, sometimes dramatically.”

“Mars and Earth interact strongly with each other, as well as with Mercury and Venus. As a result, by themselves, their spin axes would process with the same rate as the orbital oscillation, which may cause large variations in their axial tilt.”

“Fortunately, the Moon keeps Earth’s variations in check. The Moon increases our planet’s spin axis precession rate and makes it differ from the orbital oscillation rate. Mars, on the other hand, doesn’t have a large enough satellite to stabilize its axial tilt.”

“It appears that both exoplanets are very different from Mars and the Earth because they have a weaker connection with their sibling planets,” Dr. Li said.

“We don’t know whether they possess moons, but our calculations show that even without satellites, the spin axes of Kepler-186f and Kepler-62f would have remained constant over tens of millions of years.”

“I don’t think we understand enough about the origin of life to rule out the possibility of their presence on planets with irregular seasons,” Shan said.

“Even on Earth, life is remarkably diverse and has shown incredible resilience in extraordinarily hostile environments, but a climatically stable planet might be a more comfortable place to start.”

The study was published in the May 17, 2018 issue of the Astronomical Journal.


Wednesday, June 20, 2018

NASA unveils bold new plan to protect Earth from asteroids

NASA unveiled its plan to protect Earth and predict the chances for a threat from a near-Earth object (NEO), outlining five goals, including enhanced detection and improved modeling.

The 20-page plan, unveiled on Wednesday, details steps the U.S. should take to be better prepared for objects such as asteroids and comets that come within 30 million miles of the planet.

“The nation already has significant scientific, technical and operation capabilities that are relevant to asteroid impact prevention,” said Lindley Johnson, NASA’s planetary defense officer, at NASA Headquarters, Washington in a statement.

Johnson added: “Implementing the National Near-Earth Object Preparedness Strategy and Action Plan will greatly increase our nation’s readiness and work with international partners to effectively respond should a new potential asteroid impact be detected.”

In addition to enhancing NEO detection, tracking and characterizing capabilities and improving modeling prediction, the plan also aims to develop technologies for deflecting NEOs, increasing international cooperation and establishing new NEO impact emergency procedures and action protocols.

On a conference call with the media, Aaron Miles, White House Office of Science and Technology Policy, Washington, stressed that no threat from an NEO is imminent. "NASA and partners have identified 95 percent of asteroids large enough to cause global catastrophe and none will pose a threat in this century," Miles said.

When asked where the funding for this would come from, Miles said that the plan comes largely from existing resources in the U.S. government, but it's about utilizing those resources and monies in a smarter and more efficient way.

Johnson added that the budget for the entire planetary defense portion of NASA is $150 million per year.

Johnson also said that there are over 18,300 recorded NEOs and just over 8,000 of them are over 100 meters or larger.

In 2016, NASA opened a new office to track asteroids and comets that come too close to Earth, known as the Planetary Defense Coordination Office (PDCO). The PDCO formalizes the agency’s existing program for detecting and tracking NEOs, which NASA has been studying since the 1970s.


Monday, June 18, 2018

Trump orders establishment of 'space force' as 6th branch of military

President Trump vowed on Monday to make space great again.

Speaking at a meeting of the National Space Council, Trump ordered the Pentagon to immediately establish a national “space force” that would become the sixth branch of the armed forces.

“We are going to have a space force,” Trump said in Washington D.C. “An Air Force and a Space Force. Separate, but equal.”

This is not the first time that Trump has floated the idea of establishing a “space force.” The president mentioned the idea in May during a ceremony at the White House honoring the Army Black Knights college football team.

Trump did not go into details about what military role the so-called “space force” would carry out or who would command it, but he framed space as a national security issue, saying he does not want "China and Russia and other countries leading us."

Pentagon spokeswoman Dana White responded: “We understand the President's guidance. Our Policy Board will begin working on this issue, which has implications for intelligence operations for the Air Force, Army, Marines and Navy. Working with Congress, this will be a deliberate process with a great deal of input from multiple stakeholders.”

The president said the United States will “be the leader by far” in space and is looking to revive the nation's flagging space program by returning the United States to the moon and soon reaching Mars.

Trump was joined by Vice President Pence, who heads the National Space Council, as well as NASA Administrator Jim Bridenstine, former astronaut Buzz Aldrin and other members of the council.

Along with the call for the “space force,” Trump also called for a build-up in the long term presence in space, threw his support behind the nascent commercial space travel industry and signed a directive to manage space traffic.

The directive calls for providing a safe and secure environment up in orbit, as satellite traffic increases. It also sets up new guidelines for satellite design and operation, to avoid collisions and spacecraft breakups.

The council's executive secretary, Scott Pace, told reporters before the meeting that space is becoming increasingly congested and current guidelines are inadequate to address the challenge.

Before making his remarks on the space program, President Trump also weighed in on the ongoing immigration crisis – blasting the U.S.’ current immigration laws and saying the crisis is “the Democrats’ fault.”

“The United States will not be a migrant holding facility,” Trump said. “We can't allow that to happen in the U.S. Not on my watch. We want safety and we want security.

Trump added: “If the Democrats would sit down and stop obstructing, we could have something quickly."

The Trump administration’s policy of separating migrant children from their parents has come under increasing scrutiny from both sides if the aisle.

The policy, which has resulted in nearly 2,000 minors being separated from their families over six weeks, has drawn sharp criticism from Democrats and even a number of influential Republicans, including former first lady Laura Bush, who called the policy “cruel” and “immoral” in an opinion piece in the Washington Post.

Friday, June 15, 2018

NASA creates, and fills, high-level position dedicated to exploration

One of NASA‘s principal functions is to provide leadership in space exploration, and now the agency has a position that is the embodiment of that responsibility. Jim Bridenstine, NASA’s new Administrator, recently named Steve Clarke as the agency’s Science Mission Directorate (SMD) Deputy Associate Administrator for Exploration.

In a release issued by the agency on Monday June 11, 2018, Bridenstine provided a broad outline of Clarke’s responsibilities, something for which the new Deputy Associate Administrator may be well-suited.

“He’ll help integrate near-term and long-term lunar exploration with science missions and other destinations, including Mars,” noted the NASA Administrator. Clarke will facilitate interaction between different departments within the agency, as well as with commercial partners and the scientific community.

Clarke returns to NASA after a stint as a senior policy analyst with the Office of Science and Technology Policy (OSTP) in the Executive Office of the President, and assumes his role at a time when the agency has a renewed interest in lunar exploration, with an eye to eventually sending humans to Mars.

Prior to sending astronauts back to the Moon, however, Clarke will oversee NASA’s plans to launch robotic lunar missions as soon as 2019. Those precursor missions will see uncrewed mid-sized landers — built through the cooperation of public/private partnerships — delivered to the lunar surface before eventually evolving into larger, crew-capable vehicles.

Clarke, who earned both a Bachelor of Science degree in engineering — and a Master of Science degree in engineering management — from the University of Central Florida (UCF), has held several positions within the agency since he joined NASA in 2000 as an integration engineer responsible for NASA’s scientific robotic missions. Prior to leaving NASA to work at the OSTP, he served as SMD’s Director of the Heliophysics Division.

As far as Bridenstine is concerned, Clarke’s new position is a natural fit.

“Steve returns to a position ideally suited for him and the agency as we return to the Moon,” stated the  NASA Administrator. Clarke assumes his new role immediately.

His appointment comes at a time when the U.S. space agency is poised to return to objectives that it had been given back in 2004 by then-President George W. Bush. Under the Bush Administration’s Vision for Space Exploration (VSE) the agency had been directed to send astronauts to the “Moon, Mars and Beyond.”

The edicts of this program were scrapped by President Barack Obama, who opted to support the commercial programs instituted under President Bush. The Commercial Resupply Program took its first steps in December of 2008, with the Commercial Crew Program beginning in December of 2009. The Trump Administration announced its “Space Policy Directive 1” in April of this year (2018).

Under the latest change to NASA’s objectives, rather than support the Obama Administration’s directive for the agency to tow either an asteroid or part of an asteroid into lunar orbit – Space Policy Directive 1 has as its mantra to send astronauts to the “Moon, Mars and Worlds Beyond.”


The next space age

Outer space is the last frontier of human exploration. Unfortunately, the glory days of landing men on the moon are now a distant memory. So too are the memories of watching space shuttles rumble to life and roar to space fading away.

That is poised to change and America is ready to lead the way.

Today, the private sector in the United States is on the cusp of unlocking the great economic potential of outer space. Innovators and entrepreneurs are investing in companies to mine asteroids, repair satellites and manufacture goods in outer space.

But regulatory uncertainty and burdensome bureaucracy threatens to push American investment and jobs overseas. It should surprise no one that government rules on testing, launches, reentry, live video, pictures and activities in space are badly outdated.

That’s why Congress and the Trump administration are pursuing aggressive updates to the existing system. As step one, President Donald Trump reconstituted the National Space Council and appointed Vice President Mike Pence to chair the group, which also includes cabinet officials, policy experts and voices from industry and academia.

One of Pence’s first initiatives, approved by the Council, was to “unlock new opportunities, new technologies and new sources of prosperity” by building a robust space economy.

The American Space Commerce Free Enterprise Act, which we introduced along with now-NASA Administrator Jim Bridenstine, accomplishes these goals. The bill empowers the Commerce Department to lead the promotion and regulation of private space activities so American industry can innovate, grow and compete. It creates a competitive regulatory environment so America becomes the country of choice for private sector space activities. All this while also protecting national security and fulfilling our Outer Space Treaty obligations.

Our bill creates a one-stop shop in the Office of the Secretary of Commerce for space activities, something that brings a sigh of relief to anyone who’s had to deal shuffle between federal offices to get multiple approvals for the same proposals.

Plus, the Commerce Department is best equipped — in both its longstanding mission and agency culture — to help entrepreneurs and innovators build companies and succeed in business. A perfect fit for the nascent space economy.

And the bill, along with its various provisions, is progressing. In April, the House unanimously passed the bill and sent it to the Senate. Recently, President Trump included much of the bill’s goals in Space Policy Directive-2. Coinciding with the directive, Commerce Secretary Wilbur Ross announced a major reorganization of his department that adopts our bill’s provisions. To ensure success, Secretary Ross is putting people, money and expertise into a new Space Policy Advancing Commercial Enterprise (SPACE) Administration and a restructured Office of Space Commerce. We applaud the president, the vice president and the secretary for carrying out this reorganization.

Congressional appropriators are also on board. The House Appropriations Committee more than doubled the Office of Space Commerce’s budget in fiscal year 2019 to $5 million.

The momentum is building for the bill, and the last stop before becoming law is the U.S. Senate. We need champions in the Senate to fight for the bill in committee and on the floor. Those individuals will have their names etched in history as the pivotal figures who put on the president’s desk a bipartisan, bicameral bill to invigorate the next space age and maintain America’s leadership in space. Let’s get it done.


Could planets orbiting Alpha Centauri harbor life? NASA findings suggest it's possible

It looks like our next door stellar neighbors might not be so bad for life after all.

NASA’s Chandra space telescope has revealed that any planets circling Alpha Centauri, which is located about 4 light-years from Earth, could be a more friendly place for life than we initially thought.

Scientists have always held Alpha Centauri is one of our best chances for finding life beyond the solar system, but the three-star system was believed to be so inundated with harmful X-ray radiation that hopes for habitability around any yet-to-be-found planets were dim.

However, data gathered by Chandra suggests that this is might not be the case. Rather, two of the stars in the system, called Alpha Centauri “A” and Alpha Centauri “B” (known together as AB), are actually emitting X-ray radiation on par with what we get from our own sun.

“This is very good news for Alpha Cen AB in terms of the ability of possible life on any of their planets to survive radiation bouts from the stars,” astrophysicist Tom Ayres said in a NASA statement. “Chandra shows us that life should have a fighting chance on planets around either of these stars.”

That said, this is all pretty hypothetical at the moment. Scientists have yet to find any planets circling AB, but learning as much as we can about the environment around these stars is still important.

Monitoring X-ray radiation emissions is one of many important aspects in determining whether star systems could support life. So every six months since 2005, Chandra has ventured 25 trillion miles to observe Alpha Centauri’s two main stars.

Since A and B orbit so close to one another, scientists predicted that the radiation from the stars would be so strong that it would degrade the integrity of any planetary atmosphere that could support life.

But because the system's X-ray environment appears to be more mild than expected, that might mean that life would have a chance to thrive.

The third star in Alpha Centauri, known as Alpha Cen C or Proxima, is not nearly as promising when it comes to supporting habitability. Proxima is a red dwarf star known for producing massive amounts of X-ray radiation that would be harmful for life — 50,000 times more radiation than we receive on Earth.

So far NASA has only found one planet, that appears to be about the size of Earth orbiting Proxima, but the search continues. Who knows what yet lurks around Alpha Centauri.


Tuesday, June 12, 2018

How to build a starship — and why we should start thinking about it now

  • With nuclear fusion and nanotechnology advancing at the pace they are, it's possible that we might not be that far away from constructing small, interstellar space probes.
  • If we ever found evidence suggesting life exists on a planet orbiting a nearby star, we'd need to go there for definitive proof — and this would require more sophisticated space travel.
  • The most well thought-out interstellar propulsion concept is the nuclear rocket — but this, along with other concepts, would need to be created in space.
  • To do this, we would first need to prioritize colonizing Mars and the moon.

With a growing number of Earth-like exoplanets discovered in recent years, it is becoming increasingly frustrating that we can't visit them. After all, our knowledge of the planets in our own solar system would be pretty limited if it weren't for the space probes we'd sent to explore them.

The problem is that even the nearest stars are a very long way away, and enormous engineering efforts will be required to reach them on timescales that are relevant to us. But with research in areas such as nuclear fusion and nanotechnology advancing rapidly, we may not be as far away from constructing small, fast interstellar space probes as we think.

Scientific and societal case
There's a lot at stake. If we ever found evidence suggesting that life might exist on a planet orbiting a nearby star, we would most likely need to go there to get definitive proof and learn more about its underlying biochemistry and evolutionary history. This would require transporting sophisticated scientific instruments across interstellar space.

But there are other reasons, too, such as the cultural rewards we would get from the unprecedented expansion of human experience. And should it turn out that life is rare in our galaxy, it would offer opportunities for us humans to colonise other worlds. This would allow us to spread and diversify through the cosmos, greatly increasing the long-term survival chances of Homo sapiens and our evolutionary descendants.

Five spacecraft — Pioneers 10 and 11, Voyagers 1 and 2, and New Horizons— are currently leaving the solar system for interstellar space. However, they will cease to function many millennia before they approach another star, should they ever get to one at all.

Clearly, if starships are to ever become a practical reality, they will need to be based on far more energetic propulsion technologies than the chemical rockets and gravitational sling shots past giant planets that we use currently.

To reach a nearby star on a timescale of decades rather than millennia, a spacecraft would have to travel at a significant fraction — ideally about 10% — of the speed of light (the Voyager probes are travelling at about 0.005%). Such speeds are certainly possible in principle — and we wouldn't have to invent new physics such as "warp drives," a hypothetical propulsion technology to travel faster than light, or "wormholes" in space, as portrayed in the movie Interstellar.

Top rocket-design contenders
Over the years, scientists have worked out a number of propulsion designs that might be able to accelerate space vehicles to these velocities (I outline several in this journal article). While many of these designs would be difficult to construct today, as nanotechnology progresses and scientific payloads can be made ever smaller and lighter, the energies required to accelerate them to the required velocities will decrease.

The most well thought through interstellar propulsion concept is the nuclear rocket, which would use the energy released when fusing together or splitting up atomic nuclei for propulsion.

Spacecraft using "light-sails" pushed by lasers based in the solar system are also a possibility. However, for scientifically useful payloads this would probably require lasers concentrating more power than the current electrical generating capacity of the entire world. We would probably need to construct vast solar arrays in space to gather the necessary energy from the sun to power these lasers.

Another proposed design is an antimatter rocket. Every sub-atomic particle has an antimatter companion that is virtually identical to itself, but with the opposite charge. When a particle and its antiparticle meet, they annihilate each other while releasing a huge amount of energy that could be used for propulsion. However, we currently cannot produce and store enough antimatter for this to work.

Interstellar ramjets, fusion rockets using enormous electromagnetic fields as a ram scoop to collect and compress interstellar hydrogen for a fusion drive are another possibility, but these would probably be yet harder to construct.

The most well developed proposal for rapid interstellar travel is the nuclear-fusion rocket concept described in the Project Daedalus study, conducted by the British Interplanetary Society in the late 1970s. This rocket would be capable of accelerating a 450 tonne payload to about 12% of the speed of light (which would get to the nearest star in about 36 years). The concept is currently being revisited and updated by the ongoing Project Icarus study. Unlike Daedalus, Icarus will be designed to slow down at its destination, permitting scientific instruments to make detailed measurements of the target star and planets.

All current starship concepts are designed to be built in space. They would be too large and potentially dangerous to launch from Earth. What's more, to get enough energy to propel them we would need to learn to collect and manage large amounts of sunlight or mine rare nuclear isotopes for nuclear fusion from other planets. This means that interstellar space travel is only likely to become practical once humanity has become a spacefaring species.

The road to the stars therefore begins here — by gradually building up our capabilities. We need to progressively move on from the International Space Station to building outposts and colonies on the moon and Mars (as already envisaged in the Global Exploration Roadmap). We then need to begin mining asteroids for raw materials. Then, perhaps sometime in the middle of the 22nd century, we may be prepared for the great leap across interstellar space and reap the scientific and cultural rewards that will result.