Saturday, August 17, 2019

How many Earth-like planets are around sun-like stars?

A new study provides the most accurate estimate of the frequency that planets that are similar to Earth in size and in distance from their host star occur around stars similar to our Sun. Knowing the rate that these potentially habitable planets occur will be important for designing future astronomical missions to characterize nearby rocky planets around sun-like stars that could support life. A paper describing the model appears August 14, 2019 in The Astronomical Journal.

Thousands of planets have been discovered by NASA's Kepler space telescope. Kepler, which was launched in 2009 and retired by NASA in 2018 when it exhausted its fuel supply, observed hundreds of thousands of stars and identified planets outside of our solar system—exoplanets—by documenting transit events. Transits events occur when a planet's orbit passes between its star and the telescope, blocking some of the star's light so that it appears to dim. By measuring the amount of dimming and the duration between transits and using information about the star's properties astronomers characterize the size of the planet and the distance between the planet and its host star.

"Kepler discovered planets with a wide variety of sizes, compositions and orbits," said Eric B. Ford, professor of astronomy and astrophysics at Penn State and one of the leaders of the research team. "We want to use those discoveries to improve our understanding of planet formation and to plan future missions to search for planets that might be habitable. However, simply counting exoplanets of a given size or orbital distance is misleading, since it's much harder to find small planets far from their star than to find large planets close to their star."


To overcome that hurdle, the researchers designed a new method to infer the occurrence rate of planets across a wide range of sizes and orbital distances. The new model simulates 'universes' of stars and planets and then 'observes' these simulated universes to determine how many of the planets would have been discovered by Kepler in each `universe.'

"We used the final catalog of planets identified by Kepler and improved star properties from the European Space Agency's Gaia spacecraft to build our simulations," said Danley Hsu, a graduate student at Penn State and the first author of the paper. "By comparing the results to the planets cataloged by Kepler, we characterized the rate of planets per star and how that depends on planet size and orbital distance. Our novel approach allowed the team to account for several effects that have not been included in previous studies."

The results of this study are particularly relevant for planning future space missions to characterize potentially Earth-like planets. While the Kepler mission discovered thousands of small planets, most are so far away that it is difficult for astronomers to learn details about their composition and atmospheres.

"Scientists are particularly interested in searching for biomarkers—molecules indicative of life—in the atmospheres of roughly Earth-size planets that orbit in the 'habitable-zone' of Sun-like stars," said Ford. "The habitable zone is a range of orbital distances at which the planets could support liquid water on their surfaces. Searching for evidence of life on Earth-size planets in the habitable zone of sun-like stars will require a large new space mission."

How large that mission needs to be will depend on the abundance of Earth-size planets. NASA and the National Academies of Science are currently exploring mission concepts that differ substantially in size and their capabilities. If Earth-size planets are rare, then the nearest Earth-like planets are farther away and a large, ambitious mission will be required to search for evidence of life on potentially Earth-like planets. On the other hand, if Earth-size planets are common, then there will be Earth-size exoplanets orbiting stars that are close to the sun and a relatively small observatory may be able to study their atmospheres.

"While most of the stars that Kepler observed are typically thousands of light years away from the Sun, Kepler observed a large enough sample of stars that we can perform a rigorous statistical analysis to estimate of the rate of Earth-size planets in the habitable zone of nearby sun-like stars." said Hsu.

Based on their simulations, the researchers estimate that planets very close to Earth in size, from three-quarters to one-and-a-half times the size of earth, with orbital periods ranging from 237 to 500 days, occur around approximately one in four stars. Importantly, their model quantifies the uncertainty in that estimate. They recommend that future planet-finding missions plan for a true rate that ranges from as low about one planet for every 33 stars to as high as nearly one planet for every two stars.

"Knowing how often we should expect to find planets of a given size and orbital period is extremely helpful for optimize surveys for exoplanets and the design of upcoming space missions to maximize their chance of success," said Ford. "Penn State is a leader in brining state-of-the-art statistical and computational methods to the analysis of astronomical observations to address these sorts of questions. Our Institute for CyberScience (ICS) and Center for Astrostatistics (CASt) provide infrastructure and support that makes these types of projects possible."

The Center for Exoplanets and Habitable Worlds at Penn State includes faculty and students who are involved in the full spectrum of extrasolar planet research. A Penn State team built the Habitable Zone Planet Finder, an instrument to search for low-mass planets around cool stars, which recently began science operations at the Hobby-Eberly Telescope, of which Penn State is a founding partner. A second Penn State-built spectrograph is in being tested before it begins a complementary survey to discover and measure the masses of low-mass planets around sun-like stars. This study makes predictions for what such planet surveys will find and will help provide context for interpreting their results.

In addition to Ford and Hsu, the research team includes Darin Ragozzine and Keir Ashby at Brigham Young University. The research was supported by NASA; the U.S. National Science Foundation (NSF); and the Eberly College of Science, the Department of Astronomy and Astrophysics, the Center for Exoplanets and Habitable Worlds, and the Center for Astrostatistics at Penn State. Advanced computing resources and services were provided by the Penn State Institute for CyberScience, including the NSF funded CyberLAMP cluster.

Source: https://phys.org/news/2019-08-earth-like-planets-sun-like-stars.html

Monday, August 5, 2019

Elon Musk will update the status of Starship development on August 24

"We should have Starship Mk1 with 3 Raptors almost ready to fly by then."


In a series of tweets on Saturday night, SpaceX founder Elon Musk said he planned to provide an update on the development of the company's Starship project on August 24. This new spacecraft will serve as both the upper-stage of a large rocket as well as a vehicle capable of propulsively landing on distant worlds and returning to Earth.

Musk said the update would take place in Boca Chica, an unincorporated area along the southern Texas coast near the border with Mexico. This is where the company recently flew a stubby prototype of Starship and is also building a full-scale version of Starship for suborbital tests called Starship Mk1. A separate team of SpaceX engineers is building a similar prototype, Starship Mk2, in Cocoa, Florida.

Through this internal competition, the teams of engineers are testing systems for structures, propulsion, and avionics that will allow Starship to safely land on, and return from, a variety of surfaces and environments. Potential targets include the dusty, airless surface of the Moon, and Mars with its thin atmosphere and more Earth-like geology.

"Pros and cons"

His presentation, Musk said Saturday night, will include a "detailed review of the first orbital Starship, explaining the pros & cons of each design decision."

In recent years, the development of Starship and its revolutionary new capabilities for spaceflight has consumed much of the time and attention of Musk at SpaceX. Long-time employees have likened his interest and intensity to the first years of the company, when he pushed hard, broke barriers, and rapidly iterated on designs to produce the Falcon 1 rocket in a span of a little more than three years. The aerospace community was skeptical about the company's ability to produce a working rocket then, and Musk seems equally determined to prove the many Starship doubters in the traditional aerospace sector wrong again.

A little more than a week ago, the company took the leash off its Starhopper test vehicle for the first time, demonstrating the controlled flight of the methane-fueled Raptor engine. During the 20-second test, Starhopper showed that Raptor could not only breathe fire, but that the complex engine could be controlled well enough to ascend, hover, move a short distance horizontally, and then safely return Starhopper to the surface.

The company's work on Starship Mk1 was evident when Ars visited the site for the Starhopper test. With employees working at all hours, the vehicle in Texas was broken into two pieces. The top half included its nose cone, and the aft section was composed of barrels making up the fuselage. Although three more barrels had yet to be added, it was already an impressively large vehicle.

In regard to his August 24 presentation, Musk said of this suborbital test vehicle, "We should have Starship Mk1 with 3 Raptors almost ready to fly by then." The orbital version of Starship will ultimately fly on six Raptor engines. The flight of that vehicle into space may come in 2020, or 2021.

NASA Budget


"We should be back on the Moon right now. And we should be going off to Mars immediately... How come we're looking at our shoes instead of at the great nebula in Orion? Where did we mislay the Moon and back off from Mars? The problem is, of course, our politicians, men who have no romance in their hearts or dreams in their heads... If NASA's budgeters could be convinced that there are riches on Mars, we would explode overnight to stand on the rim of the Martian abyss. We need space for reasons we have not as yet discovered, and I don't mean Tupperware... NASA feels it has to justify everything it does in practical terms. And Tupperware was one of the many practical products that came out of space travel. NASA feels it has got to flimflam you to get you to spend money on space. That's B.S. We don't need that. Space travel is life-enhancing, and anything that's life-enhancing is worth doing. It makes you want to live forever." - Ray Bradbury, 'About Ray Bradbury', Playboy, May 1996


Saturday, August 3, 2019

The Space Option is the ultimate environmental solution

"For the environmentalists, The Space Option is the ultimate environmental solution. For the Cornucopians, it is the technological fix that they are relying on. For the hardcore space community, the obvious by-product would be the eventual exploration and settlement of the solar system. For most of humanity, however, the ultimate benefit is having a realistic hope in a future with possibilities...

If our species does not soon embrace this unique opportunity with sufficient commitment, it may miss its one and only chance to do so. Humanity could soon be overwhelmed by one or more of the many challenges it now faces. The window of opportunity is closing as fast as the population is increasing...

Our future will be either a Space Age or a Stone Age."

- Arthur Woods and Marco Bernasconi, Space News, 1995

Wednesday, July 31, 2019

NASA taps SpaceX, Blue Origin and 11 more companies for Moon and Mars space tech

NASA  has selected 13 companies to partner with on 19 new specific technology projects it’s undertaking to help reach the Moon and Mars. These include SpaceX,  Blue Origin  and Lockheed Martin, among others, with projects ranging from improving spacecraft operation in high temperatures to landing rockets vertically on the Moon.

Jeff Bezos-backed Blue Origin  will work with NASA on developing a navigation system for “safe and precise landing at a range of locations on the Moon” in one undertaking, and also on readying a fuel cell-based power system for its Blue Moon lander, revealed earlier this year. The final design spec will provide a power source that can last through the lunar night, or up to two weeks without sunlight in some locations. It’ll also be working on further developing engine nozzles for rockets with liquid propellant that would be well-suited for lunar lander vehicles.

SpaceX will be working on technology that will help move rocket propellant around safely from vehicle to vehicle in orbit, a necessary step to building out its Starship reusable rocket and spacecraft system. The Elon Musk-led private space company will also be working with Kennedy Space Center on refining its vertical landing capabilities to adapt it to work with large rockets on the Moon, where lunar regolith (aka Moon dust) and the low-gravity, zero atmosphere environment can complicate the effects of controlled descents.

“We believe SpaceX’s fleet of advanced rockets and spacecraft, including Falcon Heavy and Starship, are integral to accelerating NASA’s lunar and Mars plans,” SpaceX told TechCrunch regarding these new partnerships in a statement.

Lockheed Martin  will be working on using solid-state processing to create metal powder-based materials that can help spacecraft deal better with operating in high-temperature environments, and on autonomous methods for growing and harvesting plants in space, which could be crucial in the case of future long-term colonization efforts.

Other projects will tap Advanced Space, Vulcan Wireless, Aerogel Technologies, Spirit AeroSystem, Sierra Nevada Corporation,  Anasphere, Bally Ribbon Mills, Aerojet Rocketdyne,  Colorado Power Electronics and Maxar; you can read about each in detail here.

NASA’s goals with these private partnerships are to both develop at speed, and decrease the cost of efforts to operate crewed space exploration, as part of its Artemis program and beyond.

Source: https://techcrunch.com/2019/07/30/nasa-taps-spacex-blue-origin-and-11-more-companies-for-moon-and-mars-space-tech/

Monday, July 22, 2019

NASA’s Artemis capsule is complete, will carry the first woman to the moon

The crew capsule which will carry American astronauts to the moon as part of the Artemis project has been completed. The completion of the Artemis 1 capsule was announced by Vice President Mike Pence during a speech at NASA’s Kennedy Space Center in Florida celebrating the 50 year anniversary of the historic Apollo moon landing mission.

Fifty years after successfully landing a man on the moon, NASA is hoping to recreate this feat. But this time, at least one of the crew members will be a woman. NASA has announced that this capsule will carry the “first woman on the moon.”

“Similar to the 1960s, we too have an opportunity to take a giant leap forward for all of humanity,” NASA Administrator Jim Bridenstine said in a statement. “President Trump and Vice President Pence have given us a bold direction to return to the Moon by 2024 and then go forward to Mars. Their direction is not empty rhetoric. They have backed up their vision with the budget requests need to accomplish this objective. NASA is calling this the Artemis program in honor of Apollo’s twin sister in Greek mythology, the goddess of the Moon. And we are well on our way to getting this done.”

Artemis 1 will be carried aboard a Orion spacecraft and a next-generation Space Launch System (SLS) rocket. The idea is that the mission will start with sending a team to the moon for 2024, and then the moon can be used as a stopover for planned manned missions to Mars.

Fifty years after successfully landing a man on the moon, NASA is hoping to recreate this feat. But this time, at least one of the crew members will be a woman. NASA has announced that this capsule will carry the “first woman on the moon.”

“Similar to the 1960s, we too have an opportunity to take a giant leap forward for all of humanity,” NASA Administrator Jim Bridenstine said in a statement. “President Trump and Vice President Pence have given us a bold direction to return to the Moon by 2024 and then go forward to Mars. Their direction is not empty rhetoric. They have backed up their vision with the budget requests need to accomplish this objective. NASA is calling this the Artemis program in honor of Apollo’s twin sister in Greek mythology, the goddess of the Moon. And we are well on our way to getting this done.”

Artemis 1 will be carried aboard a Orion spacecraft and a next-generation Space Launch System (SLS) rocket. The idea is that the mission will start with sending a team to the moon for 2024, and then the moon can be used as a stopover for planned manned missions to Mars.