Are We Alone In The Universe?
Are we alone in the universe?
There’s never been a better time to ponder this age-old question. We now know of thousands of exoplanets – planets that orbit stars elsewhere in the universe.
So just how many of these planets could support life?
Scientists from a variety of fields — including astrophysics, Earth science, heliophysics and planetary science — are working on this question. Here are a few of the strategies they’re using to learn more about the habitability of exoplanets.
Squinting at Earth
Even our best telescopic images of exoplanets are still only a few pixels in size. Just how much information can we extract from such limited data? That’s what Earth scientists have been trying to figure out.
One group of scientists has been taking high-resolution images of Earth from our Earth Polychromatic Imaging Camera and ‘degrading’ them in order to match the resolution of our pixelated exoplanet images. From there, they set about a grand process of reverse-engineering: They try to extract as much accurate information as they can from what seems — at first glance — to be a fairly uninformative image.
Credits: NOAA/NASA/DSCOVR
So far, by looking at how Earth’s brightness changes when land versus water is in view, scientists have been able to reverse-engineer Earth's albedo (the proportion of solar radiation it reflects), its obliquity (the tilt of its axis relative to its orbital plane), its rate of rotation, and even differences between the seasons. All of these factors could potentially influence a planet’s ability to support life.
Avoiding the “Venus Zone”
In life as in science, even bad examples can be instructive. When it comes to habitability, Venus is a bad example indeed: With an average surface temperature of 850 degrees Fahrenheit, an atmosphere filled with sulfuric acid, and surface pressure 90 times stronger than Earth’s, Venus is far from friendly to life as we know it.
The surface of Venus, imaged by Soviet spacecraft Venera 13 in March 1982
Since Earth and Venus are so close in size and yet so different in habitability, scientists are studying the signatures that distinguish Earth from Venus as a tool for differentiating habitable planets from their unfriendly look-alikes.
Using data from our Kepler Space Telescope, scientists are working to define the “Venus Zone,” an area where planetary insolation – the amount of light a given planet receives from its host star -- plays a key role in atmospheric erosion and greenhouse gas cycles.
Planets that appear similar to Earth, but are in the Venus Zone of their star, are, we think, unlikely to be able to support life.
Modeling Star-Planet Interactions
When you don’t know one variable in an equation, it can help to plug in a reasonable guess and see how things work out. Scientists used this process to study Proxima b, our closest exoplanet neighbor. We don’t yet know whether Proxima b, which orbits the red dwarf star Proxima Centauri four light-years away, has an atmosphere or a magnetic field like Earth’s. However, we can estimate what would happen if it did.
The scientists started by calculating the radiation emitted by Proxima Centauri based on observations from our Chandra X-ray Observatory. Given that amount of radiation, they estimated how much atmosphere Proxima b would be likely to lose due to ionospheric escape — a process in which the constant outpouring of charged stellar material strips away atmospheric gases.
With the extreme conditions likely to exist at Proxima b, the planet could lose the equivalent of Earth’s entire atmosphere in 100 million years — just a fraction of Proxima b’s 4-billion-year lifetime. Even in the best-case scenario, that much atmospheric mass escapes over 2 billion years. In other words, even if Proxima b did at one point have an atmosphere like Earth, it would likely be long gone by now.
Imagining Mars with a Different Star
We think Mars was once habitable, supporting water and an atmosphere like Earth’s. But over time, it gradually lost its atmosphere – in part because Mars, unlike Earth, doesn’t have a protective magnetic field, so Mars is exposed to much harsher radiation from the Sun's solar wind.
But as another rocky planet at the edge of our solar system’s habitable zone, Mars provides a useful model for a potentially habitable planet. Data from our Mars Atmosphere and Volatile Evolution, or MAVEN, mission is helping scientists answer the question: How would Mars have evolved if it were orbiting a different kind of star?
Scientists used computer simulations with data from MAVEN to model a Mars-like planet orbiting a hypothetical M-type red dwarf star. The habitable zone of such a star is much closer than the one around our Sun.
Being in the habitable zone that much closer to a star has repercussions. In this imaginary situation, the planet would receive about 5 to 10 times more ultraviolet radiation than the real Mars does, speeding up atmospheric escape to much higher rates and shortening the habitable period for the planet by a factor of about 5 to 20.
These results make clear just how delicate a balance needs to exist for life to flourish. But each of these methods provides a valuable new tool in the multi-faceted search for exoplanet life. Armed with these tools, and bringing to bear a diversity of scientific perspectives, we are better positioned than ever to ask: are we alone?
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More Posts from Nasa and Others
As Neil Armstrong became the first human to step foot onto another world on July 20, 1969, lunar dust collected on the boots of his spacesuit. He peered through the gold coating of his visor and looked out across the surface of the Moon, an entirely different landscape than he was used to.
Now, just in time for the 50th anniversary of the Moon landing, you can experience the boots that stepped in Moon dust and the visor that saw the moonscape up close. Neil Armstrong’s spacesuit from the historic Apollo 11 Moon landing is on display for the first time in 13 years in its new display case in the Wright Brothers & the Invention of the Aerial Age Gallery of the National Air and Space Museum.
This week, you can also watch us salute our Apollo 50th heroes and look forward to our next giant leap for future missions to the Moon and Mars. Tune in to a special two-hour live NASA Television broadcast at 1 p.m. ET on Friday, July 19. Watch the program at www.nasa.gov/live.
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What aspect of spaceflight always blows your mind, even after all this time?
Getting to Mars: What It’ll Take
Join us as we take a closer look at the next steps in our journey to the Red Planet:
The journey to Mars crosses three thresholds, each with increasing challenges as humans move farther from Earth. We’re managing these challenges by developing and demonstrating capabilities in incremental steps:
Earth Reliant
Earth Reliant exploration is focused on research aboard the International Space Station. From this world-class microgravity laboratory, we are testing technologies and advancing human health and performance research that will enable deep space, long duration missions.
On the space station, we are advancing human health and behavioral research for Mars-class missions. We are pushing the state-of-the-art life support systems, printing 3-D parts and analyzing material handling techniques.
Proving Ground
In the Proving Ground, we will learn to conduct complex operations in a deep space environment that allows crews to return to Earth in a matter of days. Primarily operating in cislunar space (the volume of space around the moon). We will advance and validate the capabilities required for humans to live and work at distances much farther away from our home planet…such as at Mars.
Earth Independent
Earth Independent activities build on what we learn on the space station and in deep space to enable human missions to the Mars vicinity, possibly to low-Mars orbit or one of the Martian moons, and eventually the Martian surface. Future Mars missions will represent a collaborative effort between us and our partners.
Did you know….that through our robotic missions, we have already been on and around Mars for 40 years! Taking nearly every opportunity to send orbiters, landers and rovers with increasingly complex experiments and sensing systems. These orbiters and rovers have returned vital data about the Martian environment, helping us understand what challenges we may face and resources we may encounter.
Through the Asteroid Redirect Mission (ARM), we will demonstrate an advanced solar electric propulsion capability that will be a critical component of our journey to Mars. ARM will also provide an unprecedented opportunity for us to validate new spacewalk and sample handling techniques as astronauts investigate several tons of an asteroid boulder.
Living and working in space require accepting risks – and the journey to Mars is worth the risks. A new and powerful space transportation system is key to the journey, but we will also need to learn new ways of operating in space.
We Need You!
In the future, Mars will need all kinds of explorers, farmers, surveyors, teachers…but most of all YOU! As we overcome the challenges associated with traveling to deep space, we will still need the next generation of explorers to join us on this journey. Come with us on the journey to Mars as we explore with robots and send humans there one day.
Join us as we go behind-the-scenes:
We’re offering a behind-the-scenes look Thursday, Aug. 18 at our journey to Mars. Join us for the following events:
Journey to Mars Televised Event at 9:30 a.m. EDT Join in as we host a conversation about the numerous efforts enabling exploration of the Red Planet. Use #askNASA to ask your questions! Tune in HERE.
Facebook Live at 1:30 p.m. EDT Join in as we showcase the work and exhibits at our Michoud Assembly Facility. Participate HERE.
Hot Fire Test of an RS-25 Engine at 6 p.m. EDT The 7.5-minute test is part of a series of tests designed to put the upgraded former space shuttle engines through the rigorous temperature and pressure conditions they will experience during a launch. Watch HERE.
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NASA’s Satellite Data Help Save Lives
For the first time, measurements from our Earth-observing satellites are being used to help combat a potential outbreak of life-threatening cholera. Humanitarian teams in Yemen are targeting areas identified by a NASA-supported project that precisely forecasts high-risk regions based on environmental conditions observed from space.
Cholera is caused by consuming food or water contaminated with a bacterium called Vibrio cholerae.
The disease affects millions of people every year and can be deadly. It remains a major threat to global health, especially in developing countries, such as Yemen, where access to clean water is limited.
To calculate the likelihood of an outbreak, scientists run a computer model that takes satellite observations of things like rain and temperatures and combines them with information on local sanitation and clean water infrastructure. In 2017, the model achieved 92 percent accuracy in predicting the regions where cholera was most likely to occur and spread in Yemen. An outbreak that year in Yemen was the world's worst, with more than 1.1 million suspected cases and more than 2,300 deaths, according to the World Health Organization.
International humanitarian organizations took notice. In January 2018, Fergus McBean, a humanitarian adviser with the U.K.'s Department for International Development, read about the NASA-funded team's 2017 results and contacted them with an ambitious challenge: to create and implement a cholera forecasting system for Yemen, in only four months.
“It was a race against the start of rainy season,” McBean said.
The U.S. researchers began working with U.K. Aid, the U.K. Met Office, and UNICEF on the innovative approach to use the model to inform cholera risk reduction in Yemen.
In March, one month ahead of the rainy season, the U.K. international development office began using the model’s forecasts. Early results show the science team’s model predictions, coupled with Met Office weather forecasts, are helping UNICEF and other aid groups target their response to where support is needed most.
Photo Credit: UNICEF
“By joining up international expertise with those working on the ground, we have for the very first time used these sophisticated predictions to help save lives and prevent needless suffering,” said Charlotte Watts, chief scientist for United Kingdom’s Department for International Development.
Read more: go.nasa.gov/2MxKyw4
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Jessica Wittner
Jessica Wittner, a lieutenant commander in the U.S. Navy, hails from California. A National Outdoor Leadership School alum, Wittner enjoys riding motorcycles and off-roading. https://go.nasa.gov/49CxwUN
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can you describe how earth looks like from space?
When will we start seeing images from the James Webb telescope??
Sometimes... there’s more than meets the eye. 👀 You’re looking at two very different takes on an iconic image.
Human eyes can see only a small portion of the range of radiation given off by the objects around us. We call this wide array of radiation the electromagnetic spectrum, and the part we can see visible light.
In the first image, researchers revisited one of Hubble Space Telescope’s most popular sights: the Eagle Nebula’s Pillars of Creation. Here, the pillars are seen in infrared light, which pierces through obscuring dust and gas and unveil a more unfamiliar — but just as amazing — view of the pillars. The entire frame is peppered with bright stars and baby stars are revealed being formed within the pillars themselves. The image on the bottom is the pillars in visible light.
Image Credit: NASA, ESA/Hubble and the Hubble Heritage Team
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What is Artemis I?
On November 14, NASA is set to launch the uncrewed Artemis I flight test to the Moon and back. Artemis I is the first integrated flight test of the Space Launch System (SLS) rocket, the Orion spacecraft, and Exploration Ground Systems at NASA’s Kennedy Space Center in Florida. These are the same systems that will bring future Artemis astronauts to the Moon.
Standing 322 feet (98 meters) tall, the SLS rocket comprises of a core stage, an upper stage, two solid boosters, and four RS-25 engines. The SLS rocket is the most powerful rocket in the world, able to carry 59,500 pounds (27 metric tons) of payloads to deep space — more than any other vehicle. With its unprecedented power, SLS is the only rocket that can send the Orion spacecraft, astronauts, and cargo directly to the Moon on a single mission.
Before launch, Artemis I has some big help: the Vehicle Assembly Building (VAB) at KSC is the largest single-story building in the world. The VAB was constructed for the assembly of the Apollo/Saturn V Moon rocket, and this is where the SLS rocket is assembled, maintained, and integrated with the Orion spacecraft.
The mobile launcher is used to assemble, process, and launch the SLS rocket and Orion spacecraft. The massive structure consists of a two-story base and a tower equipped with a number of connection lines to provide the rocket and spacecraft with power, communications, coolant, and fuel prior to launch.
Capable of carrying 18 million pounds (8.2 million kg) and the size of a baseball infield, crawler-transporter 2 will transport SLS and Orion the 4.2 miles (6.8 km) to Launch Pad 39B. This historic launch pad was where the Apollo 10 mission lifted off from on May 18, 1969, to rehearse the first Moon landing.
During the launch, SLS will generate around 8.8 million pounds (~4.0 million kg) of thrust, propelling the Orion spacecraft into Earth’s orbit. Then, Orion will perform a Trans Lunar Injection to begin the path to the Moon. The spacecraft will orbit the Moon, traveling 40,000 miles beyond the far side of the Moon — farther than any human-rated spacecraft has ever flown.
The Orion spacecraft is designed to carry astronauts on deep space missions farther than ever before. Orion contains the habitable volume of about two minivans, enough living space for four people for up to 21 days. Future astronauts will be able to prepare food, exercise, and yes, have a bathroom. Orion also has a launch abort system to keep astronauts safe if an emergency happens during launch, and a European-built service module that fuels and propels the spacecraft.
While the Artemis I flight test is uncrewed, the Orion spacecraft will not be empty: there will be three manikins aboard the vehicle. Commander Moonikin Campos will be sitting in the commander’s seat, collecting data on the vibrations and accelerations future astronauts will experience on the journey to the Moon. He is joined with two phantom torsos, Helga and Zohar, in a partnership with the German Aerospace Center and Israeli Space Agency to test a radiation protection vest.
A host of shoebox-sized satellites called CubeSats help enable science and technology experiments that could enhance our understanding of deep space travel and the Moon while providing critical information for future Artemis missions.
At the end of the four-week mission, the Orion spacecraft will return to Earth. Orion will travel at 25,000 mph (40,000 km per hour) before slowing down to 300 mph (480 km per hour) once it enters the Earth’s atmosphere. After the parachutes deploy, the spacecraft will glide in at approximately 20 mph (32 km per hour) before splashdown about 60 miles (100 km) off the coast of California. NASA’s recovery team and the U.S. Navy will retrieve the Orion spacecraft from the Pacific Ocean.
With the ultimate goal of establishing a long-term presence on the Moon, Artemis I is a critical step as NASA prepares to send humans to Mars and beyond.
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The Nancy Grace Roman Space Telescope’s flight harness is transferred from the mock-up structure to the spacecraft flight structure.
Your Body is Wired Like a NASA Space Telescope. Sort Of.
If our Nancy Grace Roman Space Telescope were alive, its nervous system would be the intricate wiring, or “harness,” that helps different parts of the observatory communicate with one another. Just like the human body sends information through nerves to function, Roman will send commands through this special harness to help achieve its mission: answering longstanding questions about dark energy, dark matter, and exoplanets, among other mind-bending cosmic queries.
Roman’s harness weighs around 1,000 pounds and is made of about 32,000 wires and 900 connectors. If those parts were laid out end-to-end, they would be 45 miles long from start to finish. Coincidentally, the human body’s nerves would span the same distance if lined up. That’s far enough to reach nearly three-fourths of the way to space, twice as far as a marathon, or eight times taller than Mount Everest!
An aerial view of the harness technicians working to secure Roman’s harness to the spacecraft flight structure.
Over a span of two years, 11 technicians spent time at the workbench and perched on ladders, cutting wire to length, carefully cleaning each component, and repeatedly connecting everything together.
Space is usually freezing cold, but spacecraft that are in direct sunlight can get incredibly hot. Roman’s harness went through the Space Environment Simulator – a massive thermal vacuum chamber – to expose the components to the temperatures they’ll experience in space. Technicians “baked” vapors out of the harness to make sure they won’t cause problems later in orbit.
Technicians work to secure Roman’s harness to the interior of the spacecraft flight structure. They are standing in the portion of the spacecraft bus where the propellant tanks will be mounted.
The next step is for engineers to weave the harness through the flight structure in Goddard’s big clean room, a space almost perfectly free of dust and other particles. This process will be ongoing until most of the spacecraft components are assembled. The Roman Space Telescope is set to launch by May 2027.
Learn more about the exciting science this mission will investigate on X and Facebook.
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