Category: Missions (page 2 of 7)

The Gale Winds of Venus Suggest How Locked Exoplanets Could Escape a Fate of Extreme Heat and Brutal Cold

Two images of the nightside of Venus captured by the IR2 camera on the Akatsuki orbiter in September 2016 (JAXA).

 

More than two decades before the first exoplanet was discovered, an experiment was performed using a moving flame and liquid mercury that could hold the key to habitability on tidally locked worlds.

The paper was published in a 1969 edition of the international journal, Science, by researchers Schubert and Whitehead. The pair reported that when a Bunsen flame was rotated beneath a cylindrical container of mercury, the liquid began to flow around the container in the opposite direction at speeds up to four times greater than the rotation of the flame. The scientists speculated that such a phenomenon might explain the rapid winds on Venus.

On the Earth, the warm equator and cool poles set up a pressure difference that creates our global winds. These winds are deflected westward by the rotation of the planet (the so-called Coriolis force) promoting a zonal (east-west) air flow around the globe. But what would happen if our planet’s rotation slowed? Would our winds just cycle north and south between the equator and poles?

The Moon is tidally locked to the Earth, so only one hemisphere is visible from our planet (Smurrayinchester / wikipedia commons).

Such a slow-rotating scenario may be the lot of almost all rocky exoplanets discovered to date. Planets such as the TRAPPIST-1 system and Proxima Centauri-b all orbit much closer to their star than Mercury, making their faint presence easier to detect but likely resulting in tidal lock. Like the moon orbiting the Earth, planets in tidal lock have one side permanently facing the star, creating a day that is equal to the planet’s year.

The dim stars orbited by these planets can mean they receive a similar level of radiation as the Earth, placing them within the so-called “habitable zone.” However, tidal lock comes with the risk of horrific atmospheric collapse. On the planet side perpetually facing away from the star, temperatures can drop low enough to freeze an Earth-like atmosphere. The air from the dayside would then rush around the planet to fill the void, freezing in turn and causing the planet to lose its atmosphere even within the habitable zone.

The only way this could be prevented is if winds circulating around the planet could redistribute the heat sufficiently to prevent freeze-out. But without a strong Coriolis force from the planet’s rotation, can such winds exist?… Read more

Artifacts In Space

Voyager 2 entered interstellar space last month, becoming a space “artifact” of our civilization. (NASA)

 

All of a sudden, we have spacecraft and objects both coming into our solar system and leaving for interstellar space. This is highly unusual, and very intriguing.

The departing spacecraft is Voyager 2, which launched in 1977 and has traveled spaceward some 11 billion miles.  It has now officially left the heliosphere, the protective bubble of particles and magnetic fields created by the sun.  In this it follows Voyager I – which left our solar system in 2012 — and managers of the two craft have reason to think they can travel until they cross the half-century mark.

This is taking place the same time that scientists are puzzling over the nature of a cigar-shaped object that flew into the solar system from interstellar space last year.

Nobody knows what the object – called Oumuamua, Hawaiian for “first messenger,” or “scout” – really is. The more likely possibilities of it being a comet or an solar system asteroid have been found to be inconsistent with some observed properties of the visitor, and this has led some senior scientists to even hypothesize that it just might be an alien probe.

The likelihood may be small, but it was substantial enough for Harvard University Astronomy Department Chairman Avi Loeb to co-author a paper presenting the possibility.  In the Astrophysical Journal Letters, Loeb and postdoc Shmuel Bialy wrote that the object “may be a fully operational probe sent intentionally to Earth vicinity by an alien civilization.”

They also say the object has some characteristics of a “lightsail of artificial origins,” rather like the one that Loeb is working on as chairman of the Breakthrough Starshot advisory committee.  The well-funded private effort is hoping to develop ways to send a fleet of tiny lightsail probes to the star system nearest to us, Alpha Centauri.

 

This artist’s impression of the first detected interstellar visitor: Oumuamua. This object was discovered in October 2017 by the Pan-STARRS 1 telescope in Hawaii. Subsequent observations from ESO’s Very Large Telescope in Chile and other observatories around the world show that it was traveling through space for millions of years before its seemingly chance encounter with our star system.  But some scientists wonder:  might it be instead a probe sent into the cosmos by intelligent creatures?(NASA)

 

Put the two phenomenon together — the coming into our solar system and the going out — and you have a pathway into the world of alien “artifacts,” products of civilizations near and far. … Read more

InSight Lands on Mars For Unique Mission

NASA’s InSight Lander has returned its first picture from Mars via the MarCO CubeSat mission. (NASA)

 

NASA’s InSight lander touched down at 11:54 Pacific Time and followed a seven-month, 300 million-mile (485 million kilometer) journey from Southern California that started back in May.

InSight will spend the next few hours cleaning its camera lens and unfurling its solar arrays.

Once NASA confirms that the solar arrays have been properly deployed, engineers will spend the next three months preparing the lander’s science instruments to begin collecting data.

The touchdown continues NASA’s good fortunes with Mars landings, and is the fifth successful landing in a row.

Only 40% of missions by any agency sent to pass by, orbit or land on Mars have been successful, and NASA has certainly had some failures, too.

This is by way of saying that any successful mission to Mars is a great accomplishment.

The European Space Agency, the Indian Space Research Organisation and the team of ESA and Russia’s Roscosmos currently have satellites orbiting the planet, and Japan, China. Russia and the United Arab Emirates have Mars missions planned for the next decade.  The next NASA mission to the planet is the Mars 2020 rover, a follow-up to the still exploring Curiosity rover which landed in 2012.

 

For those who might have missed it, here is our recent Many Worlds column about the novel science planned for InSight:

 

An artist illustration of the InSight lander on Mars. InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is designed to look for tectonic activity and meteorite impacts, study how much heat is still flowing through the planet, and track Mars’ wobble as it orbits the sun. While InSight is a Mars mission, it will help answer key questions about the formation of the other rocky planets of the solar system and exoplanets beyond. (NASA/JPL-Caltech)

In the known history of our 4.5-billion-year-old solar system,  the insides of but one planet have been explored and studied.  While there’s a lot left to know about the crust, the mantle and the core of the Earth, there is a large and vibrant field dedicated to that learning.

Sometime next month, an extensive survey of the insides of a second solar system planet will begin.  That planet is Mars and, assuming safe arrival, the work will start after the InSight lander touches down on November 26.… Read more

Probing The Insides of Mars to Learn How Rocky Planets Are Formed

An artist illustration of the InSight lander on Mars. InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is designed to look for tectonic activity and meteorite impacts, study how much heat is still flowing through the planet, and track Mars’ wobble as it orbits the sun. While InSight is a Mars mission, it will help answer key questions about the formation of the other rocky planets of the solar system and exoplanets beyond. (NASA/JPL-Caltech)

In the known history of our 4.5-billion-year-old solar system,  the insides of but one planet have been explored and studied.  While there’s a lot left to know about the crust, the mantle and the core of the Earth, there is a large and vibrant field dedicated to that learning.

Sometime next month, an extensive survey of the insides of a second solar system planet will begin.  That planet is Mars and, assuming safe arrival, the work will start after the InSight lander touches down on November 26.

This is not a mission that will produce dazzling images and headlines about the search for life on Mars.  But in terms of the hard science it is designed to perform, InSight has the potential to tell us an enormous amount about the makeup of Mars, how it formed, and possibly why is it but one-third the size of its terrestrial cousins, Earth and Venus.

“We know a lot about the surface of Mars, we know a lot about its atmosphere and even about its ionosphere,” says Bruce Banerdt, the mission’s principal investigator, in a NASA video. “But we don’t know very much about what goes on a mile below the surface, much less 2,000 miles below the surface.”

The goal of InSight is to fill that knowledge gap, helping NASA map out the deep structure of Mars.  And along the way, learn about the inferred formation and interiors of exoplanets, too.

Equitorial Mars and the InSight landing site, with noting of other sites. (NASA)

The lander will touch down at Elysium Planitia, a flat expanse due north of the Curiosity landing site.  The destination was selected because it is about as safe as a Mars landing site could be, and InSight did not need to be a more complex site with a compelling surface to explore.

“While I’m looking forward to those first images from the surface, I am even more eager to see the first data sets revealing what is happening deep below our landing pads.” Barerdt said.… Read more

The Kepler Space Telescope Mission Is Ending But Its Legacy Will Keep Growing.

An illustration of the Kepler Space Telescope, which is on its very last legs.  As of October 2018, the planet-hunting spacecraft has been in space for nearly a decade. (NASA via AP)

 

The Kepler Space Telescope is dead.  Long live the Kepler.

NASA officials announced on Tuesday that the pioneering exoplanet survey telescope — which had led to the identification of almost 2,700 exoplanets — had finally reached its end, having essentially run out of fuel.  This is after nine years of observing, after a malfunctioning steering system required a complex fix and change of plants, and after the hydrazine fuel levels reached empty.

While the sheer number of exoplanets discovered is impressive the telescope did substantially more:  it proved once and for all that the galaxy is filled with planets orbiting distant stars.  Before Kepler this was speculated, but now it is firmly established thanks to the Kepler run.

It also provided data for thousands of papers exploring the logic and characteristics of exoplanets.  And that’s why the Kepler will indeed live long in the world of space science.

“As NASA’s first planet-hunting mission, Kepler has wildly exceeded all our expectations and paved the way for our exploration and search for life in the solar system and beyond,” said Thomas Zurbuchen, associate administrator of NASA’s Science Mission Directorate in Washington.

“Not only did it show us how many planets could be out there, it sparked an entirely new and robust field of research that has taken the science community by storm. Its discoveries have shed a new light on our place in the universe, and illuminated the tantalizing mysteries and possibilities among the stars.”

 

 


The Kepler Space Telescope was focused on hunting for planets in this patch of the Milky Way. After two of its four spinning reaction wheels failed, it could no longer remain steady enough to stare that those distant stars but was reconfigured to look elsewhere and at a different angle for the K2 mission. (Carter Roberts/NASA)

 

Kepler was initially the unlikely brainchild of William Borucki, its founding principal investigator who is now retired from NASA’s Ames Research Center in California’s Silicon Valley.

When he began thinking of designing and proposing a space telescope that could potentially tell us how common distant exoplanets were — and especially smaller terrestrial exoplanets like Earth – the science of extra solar planets was at a very different stage.… Read more

Prepare For Lift-off! BepiColombo Launches For Mercury

Artist illustration of the BepiColombo orbiters, MIO and Bepi, around Mercury (JAXA).

This Friday (October 19) at 10:45pm local time in French Guinea, a spacecraft is set to launch for Mercury. This is the BepiColombo mission which will begin its seven year journey to our solar system’s innermost planet. Surprisingly, the science goals for investigating this boiling hot world are intimately linked to habitability.

Mercury orbits the sun at an average distance of 35 million miles (57 million km); just 39% of the distance between the sun and the Earth. The planet therefore completes a year in just 88 Earth days.

The close proximity to the sun puts Mercury in a 3:2 tidal lock, meaning the planet rotates three times for every two orbits around the sun. (By contrast, our moon is in a 1:1 tidal lock and rotates once for every orbit around the Earth.) With only a tenuous atmosphere to redistribute heat, this orbit results in extreme temperatures between about -290°F and 800°F (-180°C to 427°C). The overall picture is one of the most inhospitable of worlds, so what do we hope to learn from this barren and baked land?

BepiColombo is a joint mission between the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA). It consists of two orbiters, one built by each space agency. The mission is named after Giuseppe “Bepi” Colombo, an Italian mathematician who calculated the orbit of the first mission to Mercury —NASA’s Mariner 10— such that it could make repeated fly-bys of the planet.

When Mariner 10 reached Mercury in the mid-1970s, it made an astonishing discovery:  the planet had a weak magnetic field. The Earth also has a magnetic field that is driven by movement in its molten iron core.

However, with a mass of only 5.5% that of the Earth, the interior of Mercury was expected to have cooled sufficiently since its formation for the core to have solidified and jammed the breaks on magnetic field generation. This is thought to have happened to Mars, which is significantly larger than Mercury with a mass around 10% that of the Earth. So how does Mercury hold onto its field?

The discoveries only got stranger with the arrival of NASA’s MESSENGER mission in 2011. MESSENGER discovery that Mercury’s magnetic field was off-set, with the center shifted northwards by a distance equal to 20% of the planet’s radius.

The mysteries also do not end with Mercury’s wonky magnetic field.… Read more

Human Space Travel, Health and Risk

Astronauts in a mock-up of the Orion space capsule, which NASA plans to use in some form as a deep-space vehicle. (NASA)

 

We all know that human space travel is risky. Always has been and always will be.

Imagine, for a second, that you’re an astronaut about to be sent on a journey to Mars and back, and you’re in a capsule on top of NASA’s second-generation Space Launch System designed for that task.

You will be 384 feet in the air waiting to launch (as tall as a 38-floor building,) the rocket system will weigh 6.5 million pounds (equivalent to almost nine fully-loaded 747 jets) and you will take off with 9.2 million pounds of thrust (34 times the total thrust of one of those 747s.)

Given the thrill and power of such a launch and later descent, everything else seemed to pale in terms of both drama and riskiness.  But as NASA has been learning more and more, the risks continue in space and perhaps even increase.

We’re not talking here about a leak or a malfunction computer system; we’re talking about absolutely inevitable risks from cosmic rays and radiation generally — as well as from micro-gravity — during a long journey in space.

Since no human has been in deep space for more than a short time, the task of understanding those health risks is very tricky and utterly dependent on testing creatures other than humans.

The most recent results are sobering.  A NASA-sponsored team at Georgetown University Medical Center in Washington looked specifically at what could happen to a human digestive system on a long Martian venture, and the results were not reassuring.

Their results, published in the Proceedings of the National Academy of Sciences  (PNAS), suggests that deep space bombardment by galactic cosmic radiation and solar particles could significantly damage gastrointestinal tissue leading to long-term functional changes and problems. The study also raises concern about high risk of tumor development in the stomach and colon.

 

Galactic cosmic rays are a variable shower of charged particles coming from supernova explosions and other events extremely far from our solar system. The sun is the other main source of energetic particles this investigation detects and characterizes. The sun spews electrons, protons and heavier ions in “solar particle events” fed by solar flares and ejections of matter from the sun’s corona. Magnetic fields around Earth protect the planet from most of these heavy particles, but astronauts do not have that protect beyond low-Earth orbit.

Read more

Curiosity Rover Looks Around Full Circle And Sees A Once Habitable World Through The Dust

An annotated 360-degree view from the Curiosity mast camera.  Dust remaining from an enormous recent storm can be seen on the platform and in the sky.  And holes in the tires speak of the rough terrain Curiosity has traveled, but now avoids whenever possible. Make the screen bigger for best results and enjoy the show. (NASA/JPL-Caltech/MSSS)

 

When it comes to the search for life beyond Earth, I think it would be hard to point to a body more captivating, and certainly more studied, than Mars.

The Curiosity rover team concluded fairly early in its six-year mission on the planet that “habitable” conditions existed on early Mars.  That finding came from the indisputable presence of substantial amounts of liquid water three-billion-plus years ago, of oxidizing and reducing molecules that could provide energy for simple life, of organic compounds and of an atmosphere that was thick enough to block some of the most harmful incoming cosmic rays.

Last year, Curiosity scientists estimated that the window for a habitable Mars was some 700 million years, from 3.8 to 3.1 billion years ago.  Is it a coincidence that the earliest confirmed life on Earth appeared about 3.8 billion years ago?

Today’s frigid Mars, which has an atmosphere much thinner than in the planet’s early days, hardly looks inviting, although some scientists do see a possibility that primitive life survives below the surface.

But because it doesn’t look inviting now doesn’t mean the signs of a very different planet aren’t visible and detectable through instruments.  The Curiosity mission has proven this once and for all.

The just released and compelling 360-degree look (above) at the area including Vera Rubin Ridge brings the message home.

Those fractured, flat rocks are mudstone, formed when Gale Crater was home to Gale Lake.  Mudstone and other sedimentary formations have been visible (and sometimes drilled) along a fair amount of the 12.26-mile path that Curiosity has traveled since touchdown.

 

An image of Vera Rubin Ridge in traditional Curiosity color, and the same view below with filters designed to detect hematite, or iron oxide. That compound can only be formed in the presence of water. (NASA/JPL-Caltech)

 

The area the rover is now exploring contains enough hematite — iron oxide — that its signal was detectable from far above the planet, making this area a prized destination since well before the Mars Science Laboratory and Curiosity were launched.

Like Martian clays and sulfates that have been identified and explored, the hematite is of great interest because of its origins in water. … Read more

Large Reservoir of Liquid Water Found Deep Below the Surface of Mars

Artist impression of the Mars Express spacecraft probing the southern hemisphere of Mars, superimposed on a radar cross section of the southern polar layered deposits. The leftmost white line is the radar echo from the Martian surface, while the light blue spots are highlighted radar echoes along the bottom of the ice.  Those highlighted areas measure very high reflectivity, interpreted as being caused by the presence of water. (ESA, INAF. Graphic rendering by Davide Coero Borga )

Far beneath the frigid surface of the South Pole of Mars is probably the last place where you might expect the first large body of Martian liquid water would be found.  It’s -170 F on the surface, there are no known geothermal sources that could warm the subterranean ice to make a meltwater lake, and the liquid water is calculated to be more than a mile below the surface.

Yet signs of that liquid water are what a team of Italian scientists detected — a finding that they say strongly suggests that there are other underground lakes and streams below the surface of Mars.  In a Science journal article released today, the scientists described the subterranean lake they found as being about 20 kilometers in diameter.

The detection adds significantly to the long-studied and long-debated question of how much surface water was once on Mars, a subject that has major implications for the question of whether life ever existed on the planet.

Finding the subterranean lake points to not only a wetter early Mars, said co-author Enrico Flamini of the Italian space agency, but also to a Mars that had a water cycle that collected and delivered the liquid water.  That would mean the presence of clouds, rain, evaporation, rivers, lakes and water to seep through surface cracks and pool underground.

Scientists have found many fossil waterways on Mars, minerals that can only be formed in the presence of water, and what might be the site of an ancient ocean.

But in terms of liquid water now on the planet, the record is thin.  Drops of water collected on the leg of NASA’s Phoenix Lander after it touched down in 2008, and what some have described as briny water appears to be flowing down some steep slopes in summertime.  Called recurrent slope lineae or RSLs, they appear at numerous locations when the temperatures rise and disappear when they drop.

This lake is different, however, and its detection is a major step forward in understanding the history of Mars.… Read more

Back to the Future on the Moon

There have been no humans on the surface of the moon since the Apollo program ended in 1972.  Now, in addition to NASA, space agencies in India, China, Russia, Japan and Europe and developing plans to land humans on the moon. (NASA/Robin Lee)

What does NASA’s drive to return to the moon have to do with worlds of exoplanets and astrobiology that are generally discussed here?  The answer is actually quite a lot.

Not so much about the science, although current NASA plans would certainly make possible some very interesting science regarding humans living in deep space, as well as some ways to study the moon, Earth and our sun.

But it seems especially important now to look at what NASA and others have in mind regarding our moon because the current administration has made a top priority of returning landers and humans to there, prospecting for resources on the moon and ultimately setting up a human colony on the moon.

This has been laid out in executive directives and now is being translated into funding for NASA (and commercial) missions and projects.

There are at least two significant NASA projects specific to the moon initiative now planned, developed and in some cases funded.  They are the placement of a small space station that would orbit the moon, and simultaneously a series of robotic moon landings — to be conducted by commercial ventures but carrying NASA and other instruments from international and other commercial partners.

The goal is to start small and gradually increase the size of the landers until they are large enough to carry astronauts.

And the same growth line holds for the overall moon mission.  The often-stated goal is to establish a colony on the moon that will be a signal expansion of the reach of humanity and possibly a significant step towards sending humans further into space.

A major shift in NASA focus is under way and, most likely in the years ahead, a shift in NASA funding.

Given the potential size and importance of the moon initiative — and its potential consequences for NASA space science — it seems valuable to both learn more about it.

 

Cislunar space is, generally speaking, the area region between the Earth and the moon. Always changing because of the movements of the two objects.

Development work is now under way for what is considered to be the key near-term and moon-specific project. … Read more

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