A Hubble Spectacular

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This image of the Triangulum galaxy is the second-largest image ever taken by Hubble. (NASA, ESA, and M. Durbin, J. Dalcanton, and B. F. Williams, University of Washington)

 

As you may have noticed, there haven’t been Many Worlds columns of late.  The reason, as you can no doubt guess, is that the column is supported to some extent by NASA, and the agency is caught in the government shutdown.  So I have gotten a STOP WORK order and will not be writing much for now. But I do want to continue with my Facebook postings, with some stories or images.

As a starter, this lovely picture is the second largest Hubble image ever taken.  The result of shooting by the space observatory’s iconic Advanced Camera for Surveys, it is made up of 665 million pixels.  It features the Triangulum spiral galaxy, some 3 million light-years from Earth.
The Triangulum is small by cosmic standards, at about half the diameter of the Milky Way and a quarter of the diameter of the Andromeda galaxy. Still, astronomers estimate there are anywhere between 10 and 15 millions stars contained in this image.
Also known as Messier 33, the full galaxy is made up of 40 billion stars, which is faintly visible by naked eye under a dark sky as a small smudge in the constellation Triangulum (the triangle.)
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Weird Planets

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Artist rendering of an “eyeball world,” where one side of a tidally locked planet is always hot on the sun-facing side and the back side is frozen cold.  Definitely a tough environment, but  might some of the the planets be habitable at the edges?  Or might winds carry sufficient heat from the front to the back?  (NASA/JPL-Caltech)

The very first planet detected outside our solar system powerfully made clear that our prior understanding of what planets and solar systems could be like was sorely mistaken.

51 Pegasi was a Jupiter-like massive gas planet, but it was burning hot rather than freezing cold because it orbited close to its host star — circling in 4.23 days.  Given the understandings of the time, its existence was essentially impossible. 

Yet there it was, introducing us to what would become a large and growing menagerie of weird planets.

Hot Jupiters, water worlds, Tatooine planets orbiting binary stars, diamond worlds (later downgraded to carbon worlds), seven-planet solar systems with planets that all orbit closer than Mercury orbits our sun.  And this is really only a brief peak at what’s out there — almost 4,000 exoplanets confirmed but billions upon billions more to find and hopefully characterize.

I thought it might be useful — and fun — to take a look at some of the unusual planets found to learn what they tell us about planet formation, solar systems and the cosmos.

 


Artist’s conception of a hot Jupiter, CoRoT-2a. The first planet discovered beyond our solar system was a hot Jupiter similar to this, and this surprised astronomers and led to the view that many hot Jupiters may exist. That hypothesis has been revised as the Kepler Space Telescope found very few distant hot Jupiters and now astronomers estimate that only about 1 percent of planets are hot Jupiters. (NASA/Ames/JPL-Caltech)

 

Let’s start with the seven Trappist-1 planets.  The first three were detected two decades ago, circling a”ultra-cool” red dwarf star a close-by 40 light years away.  Observations via the Hubble Space Telescope led astronomers conclude that two of the planets did not have hydrogen-helium envelopes around them, which means the probability increased that the planets are rocky (rather than gaseous) and could potentially hold water on their surfaces.

Then in 2016 a Belgian team, using  the Transiting Planets and Planetesimals Small Telescope (TRAPPIST) in Chile, found three more planets, and the solar system got named Trappist-1.  The detection of an additional outer planet was announced the next year, and in total three of the seven planets were deemed to be within the host star’s habitable zone — where liquid water could conceivably be present.

So, we have a most interesting 7-planet solar system quite close to us, and not surprisingly it has become the focus of much observation and analysis.

But consider this:  all seven of those planets orbits Trappist-1 at a distance much smaller than from our sun to the first planet, Mercury. The furthest out planets orbits the star in 19 days, while Mercury orbits in 88 days.

 

 

The Trappist-1 solar system, with the transit data used to detect the presence of seven planets, each one blocking the light curve at different locations. (NASA/JPL-Caltech)

 

Given this proximity, then, why are the Trappist-1 planets so interesting, especially in terms of habitability?  Because Trappist-1 puts out but .05 percent as much energy as our sun, and the furthest out planet (though very close to the star by the standards of our solar system) is nonetheless likely to be frozen.

So Trappist-1 a mini-system, with seven tidally-locked (never-rotating) planets that happen to orbit in resonance to each other.  Just because it is so different from our system doesn’t mean it isn’t fascinating, instructive, and even possibly the home of planets that could potentially support life.

And since red dwarf stars are the most common type of star in the Milky way (by lot), red dwarf solar system research is an especially hot field.

So there are mini planets and systems and massive planets in what used to be considered the impossibly wrong place.  And then there are planets with highly eccentric orbits — very different from the largely circular orbits of planets in our system.

The eccentricity of HD20782b superimposed onto our circular-orbiting inner solar system planets. (Stephen Kane)

The most extreme eccentric orbit found so far is HD 20782, measured at an eccentricity of .96. This means that the planet moves in a nearly flattened ellipse, traveling a long path far from its star and then making a fast and furious slingshot around the star at its closest approach. 

Many exoplanets have eccentricities far greater than what’s found in our solar system planets but nothing like this most unusual traveler, which has a path seemingly more like a comet than a planet.

Researchers have concluded that the eccentricity of a planet tends to relate to the number of planets in the system, with many-planeted systems having far more regularly orbiting planets.  (Ours and the Trappist-1 system are examples.)

Unusual planets come in many other categories, such as the chemical makeup of their atmospheres, surfaces and cores.  Most of the mass of stars, planets and living things consists of hydrogen and helium, with oxygen, carbon, iron and nitrogen trailing far behind.

Solid elements are exceptionally rare in the overall scheme of the solar system. Despite being predominant on Earth, they constitute less than 1 percent of the total elements in the solar system, primarily because the amount of gas in the sun and gas giants is so great.  What is generally considered the most important of these precious solid elements is iron, which is inferred to be in the core of almost all terrestrial planet.

The amount of iron or carbon or sulfur or magnesium on or around a planet generally depends on the amount of these “metals” present in the host star, and then in molecular protoplanetary disc remains of the star’s formation.  And this is where some of the outliers, the apparent oddities, come in.

A super-Earth, planet 55 Cancri e, was reported to be the first known planet to have huge layers of diamond, due in part to the high carbon-to-oxygen ratio of its host star. That conclusion has been disputed,  but the planet is nonetheless unusual.  Above is an artist’s concept of the diamond hypothesis. (Haven Giguere/Yale University)

The planet 55 Cancri e, for instance, was dubbed a “diamond planet” in 2012 because the amount of carbon relative to oxygen in the star appeared to be quite high.  Based on this measurement, a team hypothesized that the surface presence of abundant carbon likely created a graphite surface on the scalding super-Earth, with a layer of diamond beneath it created by the great pressures.

“This is our first glimpse of a rocky world with a fundamentally different chemistry from Earth,” lead researcher Nikku Madhusudhan of Yale University said in a statement at the time. “The surface of this planet is likely covered in graphite and diamond rather than water and granite.”

As tends to happen in this early phase of exoplanet characterization, subsequent measurements cast some doubt on the diamond hypothesis.  And in 2016, researchers came up with a different scenario — 55 Cancri e was likely covered in lava.  But because of heavy cloud and dust cover over the planet, a subsequent group raised doubts about the lava explanation. 

But despite all this back and forth, there is a growing consensus that 55 Cancri e has an atmosphere, which is pretty remarkable given its that its “cold” side has temperatures that average of 2,400 to 2,600 degrees Fahrenheit (1,300 to 1,400 Celsius), and the hot side averages 4,200 degrees Fahrenheit (2,300 Celsius). The difference between the hot and cold sides would need to be more extreme if there were no atmosphere.

 

Could super-Earth HD 219134 b be a sapphire planet? (Thibaut Roger/University of Zurich)

And then there’s another super-earth, HD 219134, that late last year was described as a planet potentially featuring vast collections of different precious stones.

To back up for a second, researchers study the formation of planets using theoretical models and compare their results with data from observations. It is known that during their formation, stars such as the sun were surrounded by a disc of gas and dust in which planets were born. Rocky planets like the Earth were formed out of the solid bodies left over when the protoplanetary gas disc cooled and dispersed.

Unlike the Earth however, HD 219134 most likely does not have a massive core of iron — a conclusion flowing from measurements of its density.  Instead, through modeling of formation scenarios for a scalding super-Earth close to its host star, the researchers conclude the planet is likely to be rich in calcium and aluminum, along with magnesium and silicon.

This chemical composition would allow the existence of large quantities of aluminum oxides. On Earth, crystalline aluminum oxide forms the mineral corundum. If the aluminum oxide contains traces of iron, titanium, cobalt or chromium, it will form the noble varieties of corundum, gemstones like the blue sapphire and the red ruby.

“Perhaps it shimmers red to blue like rubies and sapphires, because these gemstones are aluminum oxides which are common on the exoplanet,” said Caroline Dorn, astrophysicist at the Institute for Computational Science of the University of Zurich.

 

 

A variation on the “eyeball planet” is a water world where the star-facing side is able to maintain a liquid-water ocean, while the rest of the surface is ice. (eburacum45/DeviantArt)

 

Super-Earths, which are defined as having a size between that of Earth and Neptune, are also inferred to be the most likely to be water worlds.

At a Goldschmidt Conference in Boston last year, a study was presented that suggests that some super-Earth exoplanets are likely extremely wet with water – much more so than Earth. Astronomers found more specifically that exoplanets which are between two and four times the size of Earth are likely to have water as a dominant component.  Most are thought to be rocky and to have atmospheres, and now it seems that many have ocean, as well.

The new findings are based on data from the Kepler Space Telescope and the Gaia mission, which show that many of the already known planets of this type (out of more than 4,000 exoplanets confirmed so far) could contain as much as 50 percent water. That upper limit is an enormous amount, compared to 0.02 percent of the water content of Earth.

This potentially wide distribution of water worlds is perhaps not so surprising given conditions in our solar system, where Earth is wet, Venus and Mars were once wet, Neptune and Uranus are ice giants and moons such as Europa and Enceladus as global oceans beneath their crusts of ice.

 

Might this be the strangest planet of all? (NASA)

 

As is apparent with the planetary types described so far, whether a planet is typical or atypical is very much up in the air.  What is atypical this year may be found to be common in the days ahead.

The Kepler mission concluded that small, terrestrial planets are likely more common than gas giants, but our technology doesn’t let us identify and characterize many of those smaller, Earth-sized planets.

Many of the planets discovered so far are quite close to their host stars and thus are scalding hot. Planets orbiting red dwarf stars are an exception, but if you’re looking for habitable planets — and many astronomers are — then red dwarf planets come with other problems in terms of habitability.  They are usually tidally locked and they start their days bathed in very high-energy radiation that could stertilize the surface for all time.

A prime goal of the Kepler mission had been to find a planet close enough in character to Earth to be considered a twin.  While they have some terrestrial candidates that could be habitable, no twin was found.  This may be a function of lacking the necessary technology, or it’s certainly possible (if unlikely) that no Earth twins are out there.  Or at least none with quite our collection of conditions favorable to habitability and life. 

With this in mind, my own current candidate for an especially unusual planet is, well, our own.   Planet-hunting over the past almost quarter-century leads to that conclusion — for now, at least.

And it may be that solar systems like ours are highly unusual, too.  Pretty surprising, given that not long ago it was considered the norm.

 

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

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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.

William Borucki, originally the main champion for the Kepler idea and later the principal investigator of the mission. His work at NASA went back to the Apollo days. (NASA)

“When we started conceiving this mission 35 years ago we didn’t know of a single planet outside our solar system,” Borucki said.  “Now that we know planets are everywhere, Kepler has set us on a new course that’s full of promise for future generations to explore our galaxy.”

The space telescope was launched in 2009.  While Kepler did not find the first exoplanets — that required the work of astronomers using a different technique of observing based on the “wobble” of stars caused by orbiting planets — it did change the exoplanet paradigm substantially.

Not only did it prove that exoplanets are common, it found that planets outnumber stars in our galaxy (which has hundreds of billions of those stars.)

In addition it found that small, terrestrial-size planets are common as well, with some 20 to 50 percent of stars likely to have planets of that size and type.  And what menagerie of planets it found out there.

Astrophysicist Natalie Batalha was the Kepler project and mission scientist for a decade. She left NASA recently for the University of California at Santa Cruz “to carry on the Kepler legacy” by creating an interdisciplinary center for the study of planetary habitability.

Among the greatest surprises:  The Kepler mission provided data showing that the most common sized planets in the galaxy fall somewhere between Earth and Neptune, a type of planet that isn’t present in our solar system.

It found solar systems of all sizes as well, including some with many planets (as many as eight) orbiting close to their host star.

The discovery of these compact systems, generally orbiting a red dwarf star, raised questions about how solar systems form: Are these planets “born” close to their parent star, or do they form farther out and migrate in?

So far, more than 2,500 peer-reviewed papers have been published using Kepler data, with substantial amounts of that data still unmined.

Natalie Batalha was the project and mission scientist for Kepler for much of its run, and I asked her about its legacy.

“When I think of Kepler’s influence across all of astrophysics, I’m amazed at what such a simple experiment accomplished,” she wrote in an email. “You’d be hard-pressed to come up with a more boring mandate — to unblinkingly measure the brightnesses of the same stars for years on end. No beautiful images. No fancy spectra. No landscapes. Just dots in a scatter plot.

“And yet time-domain astronomy exploded. We’d never looked at the Universe quite this way before. We saw lava worlds and water worlds and disintegrating planets and heart-beat stars and supernova shock waves and the spinning cores of stars and planets the age of the galaxy itself… all from those dots.”

 

The Kepler-62 system is put one of many solar systems detected by the space telescope. The planets within the green discs are in the habitable zones of the stars — where water could be liquid at times. (NASA)

 

While Kepler provided remarkable answers to questions about the overall planetary makeup of our galaxy, it did not identify smaller planets that will be directly imaged, the evolving gold standard for characterizing exoplanets.  The 150,000 stars that the telescope was observing were very distant, in the range of a few hundred to a few thousand light-years away. One light year is about 6 trillion (6,000,000,000,000) miles.

Nonetheless, Kepler was able to detect  the presence of a handful of Earth-sized planets in the habitable zones of their stars.  The Kepler-62 system held one of them, and it is 1200 light-years away.  In contrast, the four Earth-sized planets in the habitable zone of the much-studied Trappist-1 system are 39 light-years away.

Kepler made its observations using the the transit technique, which looks for tiny dips in the amount of light coming from a star caused by the presence of a planet passing in front of the star.  While the inference that exoplanets are ubiquitous came from Kepler results, the telescope was actually observing but a small bit of the sky.  It has been estimated that it would require around 400 space telescopes like Kepler to cover the whole sky.

What’s more, only planets whose orbits are seen edge-on from Earth can be detected via the transit method, and that rules out a vast number of exoplanets.

The bulk of the stars that were selected for close Kepler observation were more or less sun-like, but a sampling of other stars occurred as well. One of the most important factors was brightness. Detecting minuscule changes in brightness caused by transiting planet is impossible if the star is too dim.

 

The artist’s concept depicts Kepler-186f, the first validated Earth-size planet to orbit a distant star in the habitable zone. (NASA Ames/SETI Institute/JPL-Caltech)

 

Four years into the mission, after the primary mission objectives had been met, mechanical failures temporarily halted observations. The mission team was able to devise a fix, switching the spacecraft’s field of view roughly every three months. This enabled an extended mission for the spacecraft, dubbed K2, which lasted as long as the first mission and bumped Kepler’s count of surveyed stars up to more than 500,000.

But it was inevitable that the mission would come to an end sooner rather than later because of that dwindling fuel supply, needed to keep the telescope properly pointed.

Kepler cannot be refueled because NASA decided to place the telescope in an orbit around the sun that is well beyond the influence of the Earth and moon — to simplify operations and ensure an extremely quiet, stable environment for scientific observations.  So Kepler was beyond the reach of any refueling vessel.  The Kepler team compensated by flying considerably more fuel than was necessary to meet the mission objectives.

The video below explains what will happen to the Kepler capsule once it is decommissioned.  But a NASA release explains that the final commands “will be to turn off the spacecraft transmitters and disable the onboard fault protection that would turn them back on. While the spacecraft is a long way from Earth and requires enormous antennas to communicate with it, it is good practice to turn off transmitters when they are no longer being used, and not pollute the airwaves with potential interference.”

 

 

And so Kepler will actually continue orbiting for many decades, just as its legacy will continue long after operations cease.

Kepler’s follow-on exoplanet surveyor — the Transiting Exoplanet Survey Satellite or TESS — was launched this year and has begun sending back data.  Its primary mission objective is to survey the brightest stars near the Earth for transiting exoplanets. The TESS satellite uses an array of wide-field cameras to survey some 85% of the sky, and is planned to last for two years.

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15,000 Galaxies in One Image

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Astronomers have just assembled one of the most comprehensive portraits yet of the universe’s evolutionary history, based on a broad spectrum of observations by the Hubble Space Telescope and other space and ground-based telescopes.  Each of the approximately 15,000 specks and spirals are galaxies, widely distributed in time and space. (NASA, ESA, P. Oesch of the University of Geneva, and M. Montes of the University of New South Wales)

Here’s an image to fire your imagination: Fifteen thousand galaxies in one picture — sources of light detectable today that were generated as much as 11 billion years ago.

Of those 15,000 galaxies, some 12,000 are inferred to be in the process of forming stars.  That’s hardly surprising because the period around 11 billions years ago has been determined to be the prime star-forming period in the history of the universe.  That means for the oldest galaxies in the image, we’re seeing light that left its galaxy but three billion years after the Big Bang.

This photo mosaic, put together from images taken by the Hubble Space Telescope and other space and ground-based telescopes, does not capture the earliest galaxies detected. That designation belongs to a galaxy found in 2016 that was 420 million years old at the time it sent out the photons just collected. (Photo below.)

Nor is it quite as visually dramatic as the iconic Ultra Deep Field image produced by NASA in 2014. (Photo below as well.)

But this image is one of the most comprehensive yet of the history of the evolution of the universe, presenting galaxy light coming to us over a timeline up to those 11 billion years.  The image was released last week by NASA and supports an earlier paper in The Astrophysical Journal by Pascal Oesch of Geneva University and a large team of others.

And it shows, yet again, the incomprehensible vastness of the forest in which we are a tiny leaf.

Some people apparently find our physical insignificance in the universe to be unsettling.  I find it mind-opening and thrilling — that we now have the capability to not only speculate about our place in this enormity, but to begin to understand it as well.

The Ultra-Deep field composite, which contains approximately 10,000 galaxies.  The images were collected over a nine-year period.  {NASA, ESA, H. Teplitz and M. Rafelski (IPAC/Caltech), A. Koekemoer (STScI), R. Windhorst (Arizona State University), and Z. Levay (STScI)} 

For those unsettled by the first image, here is the 2014 Ultra Deep Field image, which is 1/14 times the area of the newest image.  More of the shapes in this photo look to our eyes like they could be galaxies, but those in the first image are essentially the same.

In both images, astronomers used the ultraviolet capabilities of the Hubble, which is now in its 28th year of operation.

Because Earth’s atmosphere filters out much ultraviolet light, the space-based Hubble has a huge advantage because it can avoid that diminishing of ultraviolet light and provide the most sensitive ultraviolet observations possible.

That capability, combined with infrared and visible-light data from Hubble and other space and ground-based telescopes, allows astronomers to assemble these ultra deep space images and to gain a better understanding of how nearby galaxies grew from small clumps of hot, young stars long ago.

The light from distant star-forming regions in remote galaxies started out as ultraviolet. However, the expansion of the universe has shifted the light into infrared wavelengths.

These images, then,  straddle the gap between the very distant galaxies, which can only be viewed in infrared light, and closer galaxies which can be seen across a broad spectrum of wavelengths.

The farthest away galaxy discovered so far is called GN-z11 and is seen now as it was 13.4 billion years in the past.  That’s  just 400 million years after the Big Bang.

GN-z11 is surprisingly bright infant galaxy located in the direction of the constellation of Ursa Major. Thus NASA video explains much more:

The farthest away galaxy ever detected — GN-z11. {NASA, ESA, P. Oesch (Yale University, Geneva University), G. Brammer (STScI), P. van Dokkum (Yale University), and G. Illingworth (University of California, Santa Cruz)} 

 

Galaxy formation chronology, showing GN-z11 in context. Hubble spectroscopically confirmed the farthest away galaxy to date. {NASA, ESA, P. Oesch and B. Robertson (University of California, Santa Cruz), and A. Feild (STScI)}

In addition representing cutting-edge science — and enabling much more — these looks into the most distant cosmic past offer a taste of what the James Webb Space Telescope, now scheduled to launch in 2021, is designed to explore.  It will have greatly enhanced capabilities to explore in the infrared, which will advance ultra-deep space observing.

But putting aside the cosmic mysteries that ultra deep space and time astronomy can potentially solve, the images available today from Hubble and other telescopes are already more than enough to fire the imagination about what is out there and what might have been out there some millions or billions of years ago.

A consensus of exoplanet scientists holds that each star in the Milky Way galaxy is likely to have at least one planet circling it, and our galaxy alone has billions and billions of stars.  That makes for a lot of planets that just might orbit at the right distance from its host star to support life and potentially have atmospheric, surface and subsurface conditions that would be supportive as well.

A look these deep space images raises the question of how many of them also house stars with orbiting planets, and the answer is probably many of them.  All the exoplanets identified so far are in the Milky Way, except for one set of four so far.

Their discovery was reported earlier this year by Xinyu Dai, an astronomer at the University of Oklahoma, and his co-author, Eduardo Guerras.  They came across what they report are planets while using NASA’s Chandra X-ray Observatory to study the environment around a supermassive black hole in the center of a galaxy located 3.8 billion light-years away from Earth.

In The Astrophysical Journal Letters , the authors report the galaxy is home to a quasar, an extremely bright source of light thought to be created when a very large black hole accelerates material around it. But the researchers said the results of their study indicated the presence of planets in a galaxy that lies between Earth and the quasar.

Furthermore, the scientists said results suggest that in most galaxies there are hundreds of free-floating planets for every star, in addition to those which might orbit a star.

The takeaway for me, as someone who has long reported on astrobiology and exoplanets, is that it is highly improbable that there are no other planets out there where life occurs, or once occurred.

As these images make clear, the number of planets that exist or have existed in the universe is essentially infinite.  That no others harbor life seems near impossible.

 

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Back to the Future on the Moon

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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.  It used to be called the the Deep Space Gateway as part of the Obama administration proposal for an asteroid retrieval mission, but now it’s the Lunar Orbital Platform-Gateway (LOP-G.)

If built, the four-person space station would serve as a quasi-permanent outpost orbiting the moon that advocates say would enhance exploration and later commercial exploitation of the moon.  It would provide a training area and safe haven for astronauts, could become a center for moon, Earth and solar science, and could continue and expand the international cooperation nurtured on the International Space Station (ISS) project for several decades.

In its Gateway Memorandum, published last month, NASA and the administration also made clear that the station would have, as a central goal, geopolitical importance.

As stated in the memorandum, “the next step in human spaceflight is the establishment of U.S. preeminence in cislunar space through the operations and the deployment of a U.S.-led lunar orbital platform,  “Gateway.”  (“Cislunar space” is the region lying  between the Earth and the moon.)

The administration requested $500 million for planning the LOP-G project in fiscal 2019.  The first component to be built and hopefully launched into cislunar space under the plan is the “power and propulsion element.”

 

An artist version of a completed Gateway spaceport with the Orion capsule approaching. (NASA)

Five companies have put together proposals for the “PPE,” and NASA officials have said they are ready to move ahead with procurement.

During a March meeting of the NASA Advisory Council’s human exploration and operations committee, Michele Gates, director of the Power and Propulsion Element at NASA Headquarters, said the agency will be ready to move ahead with procurement of the module when the five industry proposals are completed.

Some of those companies had been involved in studies for the cancelled Asteroid Redirect Mission and Gates said, “Our strategy is to leverage all of the work that’s been done, including on the Asteroid Redirect Mission.”

Five different companies have contracts to design possible space station habitation modules as well.

So the plan has some momentum.  If all moves ahead as described, NASA will launch the components of the Gateway in the early to mid 2020s.  More than a dozen international agencies have voiced interest in joining the project, including European, Japanese, Canadian and other ISS partners.

As part of that outreach, an informal partnership agreement has already been signed with Roscosmos, the Russian space agency, with the possibility of using a future Russian heavy rocket to help build the station and ferry crew.

 

Astronaut John Young of the Apollo 16 mission on the moon. The primary goal of the NASA moon initiative is to return astronauts to the surface.(NASA)

The other NASA moon initiative involves an effort to send many robotic landers to the moon to look for potential water and fuel (hydrogen) to be collected for a cislunar and ultimately lunar economy.

NASA had worked for some time on what was called a Resource Prospector, a mission to study water ice and other volatiles at the lunar poles.  But this spring NASA Administrator Jim Bridenstine announced the Prospector was being cancelled because it was not suited to the what is called the new Exploration Campaign — NASA’s concept for a series of missions that will initially use small, commercially developed landers, followed by larger landers.

So the Prospector project is now considered “too limited in scope for the agency’s expanded lunar exploration focus,” the agency said in a statement. “NASA’s return to the moon will include many missions to locate, extract and process elements across bigger areas of the lunar surface.”

The agency also says it will rely on private companies to design and build the landers, as well as launching them into space.

So these are the out-of-the gate projects NASA has in mind for the moon. They, however, are hardly where the big money is going.  That is directed to the heavy rocket under development and construction for more than a decade (the Space Launch System, or SLS) and the Orion space capsule.

They are designed to be the main conduits to the Gateway and perhaps beyond some day, and they have been enormously costly to build — at least $22 billion to construct up through 2021, NASA officials told the Government Accounting Office in 2014. And that doesn’t include the more costly second SLS rocket scheduled for 2023 with a crew aboard.

What’s more, it is estimated to cost at least $1.5 billion to launch each SLS/Orion voyage in years ahead.

 

Astronauts go into an Orion capsule mock-up. The un-manned spacecraft is expected to be ready for launch in 2020. (NASA/ Bill Stafford and Roger Markowitz)

 

Another mock-up of the inside of the Orion crew module, which carries four astronauts and is scheduled to launch in 2023. It has 316 cubic feet of habitable space, compared with 210 cubic feet for the Apollo capsules. (NASA)

 

Since this column is primarily about space and origins science, I was drawn to the conference held late Feb. in Denver — billed as the Deep Space Gateway Concept Science Workshop.  The idea, surely, was to share and showcase what science might be achievable on the mini-space station.

As you might imagine, a major scientific focus was on the challenges to humans of living in deep space and techniques that might be used to mitigate problems. Abstracts included studies of the effects of radiation on astronauts, on drugs, on food, on the immune system and more.

NASA and others have studied for years radiation and micro-gravity effects on astronauts aboard the International Space Station, but conditions in a deep space environment would be quite a bit different.  Probably most importantly, astronauts aboard the Gateway would be exposed to much more dangerous radiation than those in the ISS because that low-Earth orbit station is protected by the Van Allen radiation belts.

There was also an intriguing proposal to study the ability of lunar regolith (the rock, dust and gravel on the surface) to shield growing plants on the station from radiation, and others on the role and usefulness of plants and micro-organisms in deep space.

Scientists also proposed many different ways to study the moon, the Earth and the sun.  Harley Thronson of NASA Goddard, one of the moderators of the conference, said that sun scientists seemed especially excited by the opportunities the Gateway could offer.

As far as I could tell, there was but one proposal that involved astrobiology or exoplanets.  It was a plan by scientists from SETI and NASA Ames to study Earth with a spectrometer as a way to understand and measure potential bio-markers on exoplanets.

So there’s undoubtedly good science to be done on a lunar space port regarding human space flight, the moon, the Earth and sun.

What I wonder is this:  Will this new, intense and costly lunar focus on the moon take away from what I like to think of as The Golden Age of Space Science — the unending breakthroughs of recent decades in understanding planets and distant moons in our solar system, detecting and characterizing the billions and billions of exoplanets out there,  as well as revealing the structure and history of the cosmos.

 

The Sombrero Galaxy, as imaged by the Hubble Space Telescope, NASA’s Flagship observatory of the 1990s. The James Webb Space Telescope is delayed but is expected to provide the same remarkable images and science as Hubble once it’s up and working.  WFIRST, the planned flagship observatory of the 2020s was cancelled by the administration earlier this year because of a NASA funding shortfall, but its fate remains undecided. (NASA)

I’m not thinking about today but about when costly NASA flagship space observatories or major planetary missions come up for approval, or non-approval, in the future.  Will the funding, and the deep interest, still be there?

Others more knowledgeable about the mechanics of space travel also criticize the Gateway as a costly detour from what long has been considered the main goal of space exploration — sending humans to Mars — and as redundant when it comes to accessing and studying the moon.

On a more encouraged note, a lunar station and lunar base could become part of a much larger space architecture that will allow for all kinds of advances in the decades ahead.  This is precisely the kind of build-out that Thronson, who is Senior Scientist for Advanced Astrophysics Mission Concepts at NASA Goddard and Chief Technologist for the Cosmic Origins and Physics of the Cosmos Program Offices, has been working towards for years.

Ever mindful of the uses of such a space architecture, he pointed out one potential use of a lunar space station that is seldom heard:  If a powerful new telescope in deep space needs repair or upgrading, he wrote in an email, there’s no way to get humans to it now.  The Hubble Space Telescope could be fixed because it was not in deep space and astronauts could get to it.

Thronson sees a potential parallel use for the Gateway, as he described in an email. “My astronomy colleagues, including myself, have been for many years advocating using a Gateway-type facility to assemble, repair, and upgrade the next generation (and beyond) of major astronomical missions. Nothing beats having a human on site, if there are complicated activities that need to be carried out.”

 

 

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