Recalling Dr. Edgar Mitchell

24 02 2016



We recently lost one of humanity’s pioneers – one of twelve to step on another world and a man who made a distinct impact on me, though in an unexpected way.

Famous for his belief in extraterrestrial life and dabbling in the science of consciousness and extrasensory perception, he is most widely known for planting boot-prints on the Moon’s Fra Mauro Highlands during the Apollo 14 mission: his name was Dr. Edgar Mitchell.

A memorial was held today in his honor in Florida, but I won’t presume here to tread on the numerous articles detailing the many successes and fascinating aspects of his life.  Instead, I’d like to share a story that only I have – the brief tale of how, during a few quiet minutes, he kindly suffered my enthusiastic curiosity and changed my view of planetary exploration forever.

Boots on the Ground

It is a warm, spring afternoon in 2012, and the setting is the U.S. Space Walk of Fame Museum in Titusville, Florida.  Shortly after an interview with Dr. Mitchell held there that I participated in as part of a National Geographic Channel project, I find myself parked in a museum corridor with the affable astronaut while camera equipment is being packed up.

We have a couple of minutes to kill, and after pleasantries (and revealing my own astronaut aspirations, as I’m sure many who meet him do), I decide to make our remaining seconds of polite conversation count.  It’s also at this moment that the Director of Photography for the program is inspired to snap a photo:


Loitering with Apollo 14 astronaut Dr. Edgar Mitchell in the U.S. Space Walk of Fame Museum. (Image credit: Dave West)

Mercifully, I steer clear of the, “What advice would you have for an aspiring astronaut?” spectrum of questions.  (This is an explorer who’d ventured off-world during humanity’s lone period of manned lunar exploration, after all; he has much more valuable insight than opining on what looks good on a resume to a NASA review panel.)

Knowing that most of the details of the Apollo Program’s exploits have been well-captured in books and articles written during nearly a half-century of analysis and reflection, I aim to drill in on a single question I hadn’t yet heard an answer to.  A human question.

I simply ask: “So, what did it feel like to step into the lunar regolith?  I mean, what did it really feel like?  What was the sensation underfoot?”

His answer surprises me, (which, as a lifelong space obsessee, itself surprises me).  I thought I’d envisioned any of his possible answers, and I was wrong.

Dr. Mitchell cocks his head as he takes my meaning.  Then, he grins and thinks for a moment, (almost as if no one had asked him the question before), before replying:

“Honestly, I don’t really know.  The EVA suit was so rigid, we had such a tight timeline, I was so busy focusing on the mission objectives, and you’ve always got somebody chattering in your ear.” 

He shrugs and adds:

“By the time I’d have had time to think about something like that, the EVA was over and I was back in the lunar module.”

For a few moments, I’m flabbergasted.  “I don’t know” was the one answer I wasn’t really prepared for.  My mouth opens involuntarily, and I consider myself fortunate that I will it shut before I can blurt out, “What do you mean you don’t know?”

I mean, if he doesn’t know what it felt like to step on the Moon, who could?


Apollo 14 astronaut Edgar Mitchell checking a map while on the lunar surface. (Credit: NASA)

The Reality of Exploration

Dr. Mitchell’s eyes twinkle slightly, almost as though he suspects the answer would catch me off-guard.  And then, several thoughts hit me in succession:

  • What an injustice that these explorers didn’t even have time to mentally record the sensation of their exploration!
  • But, wait – isn’t tactile information like that important?  Why wasn’t that made a priority?  An objective, even?
  • Doesn’t a sensory awareness of the surface beneath an astronaut relate directly to the ultimate utility an EVA suit on the Moon and the human factors of exploring beyond?
  • Don’t we need to know these things before we consider designing new suits and mission timelines for going back to the Moon and Mars?
  • Wait, did he just let slip a subtle indictment of micromanagement on the Moon?

But, shortly thereafter, the practicality sinks in.  Compared with larger, broader, more fundamental mission objectives, (e.g., survival, navigation, and basic science), smaller details like these were likely to be the first triaged right off of the priority list.  Especially considering that Apollo 14 was an “H-type” mission, which meant only a two-day stay on the Moon and only two EVAs,  they simply didn’t have the luxury of time.

Before I can continue the conversation, we’re swept away with a caravan to another location, and I don’t have another opportunity to pick up the discussion before we part ways for good.

In retrospect, the brief exchange forever changed the way I would view planetary exploration.  I consider it a true dose of lunar reality sans the romance.


Apollo 14 astronaut Edgar Mitchell in the distance with the Lunar Portable Magnetometer experiment during EVA 2.

Lessons for Future Explorers

From this exchange, I was left with an indelible impression that every moment spent by future planetary astronauts on another world will be heavily metered and micromanaged.  Excursions will be rehearsed ad nauseam, and as a result, explorers in the thick of the real deal won’t be afforded much time to think about apparently trivial details like what it actually feels like to step on another world.

By all reckoning, it probably would feel much like another rehearsal.

But these details, even apparently small, do matter.  Things like suit fit, function, and feedback under different environmental conditions can have a huge impact on astronaut fatigue, injury, and mission success.  This is to say nothing of secondary geological information, (e.g., this type of regolith scuffs differently than that type), or the more romantic aspects of the sensation of exploration that are necessary for bringing the experience back home to those on Earth in a relatable way.

So, it should say something to us now that after traveling more than five football fields of distance on foot during the course of only two days, Dr. Mitchell couldn’t tell me what it really felt like to press a boot into lunar dirt.

Ultimately, the most unexpected lesson Dr. Mitchell was kind enough to impart was that unless we work to preserve these apparently smaller details of exploration, (as recalled by the limited number of explorers still with us who ventured onto the Moon), and unless we incorporate their implications into future plans, schedules, and designs, the path walked by future astronauts on other worlds will be more difficult than it should or need be.

Hacking Classrooms via Mars

1 08 2013
Preparing for the Hackathon project showcase at Mozilla headquarters.

Preparing for the Hackathon project showcase at Mozilla headquarters.

A short report today on the inspiring Mars Education Hackathon I recently had the good fortune to be invited to attend in San Francisco.

Hosted by the Mozilla Foundation, digital studio MX, and local PBS affiliate KQED, the two-day blitz included six ad hoc project teams – fresh and interdisciplinary collaborations between planetary scientists, computer scientists, educators, innovators, multimedia producers, and historians.

Attendees represented the gamut of potential stakeholders, from NASA’s Ames Research Center to science and education TV production firm Spine Films.  I was there on behalf of MX studios, with whom I’d had the pleasure of supporting as a space/planetary science consultant.

What was it exactly that brought such a motley crew together near the Bay?

Working as fast as we could, our mission was straightforward:  Leverage recent advances in computing and networking technology in combination with the truly stunning quantity and quality of data available to us from the Red Planet in order to give science education a much-needed kick in the pants.

In my view, it was a rousing success.


View of hacking in progress – two of the Hackathon working groups at KQED headquarters.

The team projects were each ambitious and varied from virtual science learning environments using actual NASA rover models to orbital flight trajectory and planning simulators; from helping students pack for a trip to Mars to using VR headsets to explore the Martian landscape with their own eyes from the comfort of a classroom.

(Yes, I finally got to try an Oculus Rift – it lives up to the hype!)

It was also an excellent opportunity both to meet new faces as well as finally assign faces to names I’ve known (or even been working with from afar) for some time.  (Many thanks to MX and Mozilla for their support!)

In the end, I truly believe the seeds of future models for using computing technology to integrate frontier science into the classroom were sewn here.  Education needs this kind of work to compete with gaming multimedia that, unfortunately, is usually just much more engaging than learning-based systems.  But it doesn’t have to be.

Mars shows us that.

More to follow on the fruits of this little side-adventure…


Could frontier exploration environments like Mars be the key to bridging the divide between new web-based technology and classroom education experiences? (View from outside Mozilla headquarters.)

Pushing Asteroid Mining on the Wow! Signal Podcast

26 06 2013

Just a quick note today on a fun, recent interview I gave with Paul Carr on the Wow! Signal Podcast, where I had the opportunity to discuss the very conceptual genesis of my personal scientific journey as a geologist and space scientist: the lure, importance, and incredible promise of asteroid mining and capitalizing on extraterrestrial resources!


My original 2004 NASA KC135 proposal for an asteroid mineral separation “mining” system. …Still looking for an opportunity to fly this thing…

(Paul is a space systems engineer, skeptical investigator, and a prolific writer who keeps not only the aforementioned podcast but also his own blog and several websites, most of which communicate a fascination with space and life in the cosmos…  Thanks for reaching out, Paul!)

So, for any readers interested in hearing me attempt to talk extemporaneously while simultaneously trying to keep a lid on my enthusiasm for the potential in space resources, now’s your chance. =)

Additionally, I should note that I had the good fortune to share the podcast airspace with engaging planetary system scientist (and dabbler in numerical astrobiology) Dr. Duncan Forgan, as well as Isaac Stott of Stott Space Inc., future asteroid miner and ardent proponent of space resources development.

The only thing that could have made the podcast more of a kick was if the interviews had been temporally-simultaneous and supplied with science-fueling spirits of some kind…  All in good time, I suppose…

Forecasting the End: The Science of Rogue Planets

21 03 2013

ftefbook2I’m pleased to report that I had the opportunity to consult on (and occasionally appear in) an astronomy/geoscience/climate science crossover project for the Weather Channel this past year, entitled, Forecasting the End.

The show, which premiers this evening, uses extremely-low-probability astronomical or geophysical disasters as a hook to explore and present astronomy, geology, meteorology, and physics concepts in a novel (and admittedly fantastic) way.

Of the six-episode series, the first deals with the concept of so-called “rogue” planets, a timely subject of recent research.

What is a Rogue Planet?

Many astrophysicists, astronomers, and exoplanetologists have set their research sights on puzzling out exactly how it is that new star systems go about forming planets, (in this case “exoplanets,” or planets outside our solar system).  Interestingly, the fruits of their labor have in recent years led to the realization that the process is a frequently violent one.  -So violent, in fact, that during the gravity tango performed between a fledgling solar system’s new planets, one of these “dancers” is thrown right off of the dance floor.

In other words, it seems that planets are often ejected from their home star system in the chaos surrounding a newly-formed star.  This actually serves to help the “dance” between the rest of the worlds calm into a more stable, final set of orbits, perhaps turning it into more of a “march.”

Any one of these escaped exoplanets, then, becomes a “rogue” planet – left to wander the cosmos along its lonely escape trajectory for billions of years.

-And to confirm that this knowledge is more than just theoretical, astronomers revealed last November that they captured what looks for all the world to be a rogue planet in the flesh a mere 75 light-years away:

Infrared image of rogue planet CFBDSIR2149. (Credit: CFHT/P. Delorme)

Infrared image of rogue planet CFBDSIR2149. (Credit: CFHT/P. Delorme)

Rogue Planet as Cosmic Bard

Astronomy-savvy readers may recall a splash last year when researchers reported calculating that there may be billions of these dark, lonely worlds wandering the galaxy.  However, as the “giggle-check” champion astronomer Phil Plait of “Bad Astronomy” fame was quick to point out, compared to the amount of free space in the galaxy, the odds of a collision with these seemingly innumerable rogue planets – any collision – are mind-bendingly slim.

Hence, while the Forecasting’s exercise deals with a disaster that is legitimately statistically possible, it is a threat far less likely than, say, being hit by a meteorite.  Or winning the lottery three times in a row.

Instead, the rogue planet has a different, more sublime function.  It can help us tell a story, and in the telling, learn a little bit more about the Earth.

By exploring the “What if?” scenario provided by the idea of a rogue planet breezing through our solar system, we have the opportunity to illuminate a seemingly-unrelated and often misunderstood phenomena at work much closer to home (and – for the “aha” moment – much more relevant to traditional weather):  Seasons.

Wherefore Art Thou Seasons?

The cosmic roots of our annual swing between months spent shoveling snow and sunning on sandy beaches may not be at all intuitive.  However, this reality becomes much easier to grasp in terms of a cosmic disaster.

Allow me to explain.

Many (intuitively) misunderstand why it is that the seasons exist at all, believing logically that summer is when the Earth is closest to the Sun, and winter is when we’re farthest away.  This is actually not the case.

Why not?  Simply, because the Earth’s orbit is almost perfectly circular, there really isn’t that much difference between the heat received by the Earth at closest and farthest approach to and from the Sun.

Instead, the seasons are caused by the fact that the Earth is tilted as it goes around the Sun.  This means that the Earth doesn’t stand “upright” as it goes round, but rather, it leans:

Illustration that weather seasons are related to the Earth's axis tilt; Summer on the hemisphere pointed toward the sun (northern or southern), and winter for the hemisphere pointed away. (Credit: Ben McGee)

Illustration that weather seasons are related to the Earth’s axis tilt; Summer on the hemisphere (northern or southern) pointed toward the sun, and winter for the hemisphere pointed away. (Credit: Ben McGee)

Consequently, summer is when your side of the Earth (northern or southern hemisphere) is pointed toward the Sun, and winter is when your side of the planet is pointed away.

This is also why, at the equator, the temperature is so consistent throughout the year – at the geographic middle of the planet, straddling the line between hemispheres, you’re neither pointed toward or away during any time of year and experience sunny temperatures year-round.  In contrast, if the “near-and-far” season misconception were true, one would expect snowy winters in Barbados, which simply never occurs…

Playing with Weather via Orbital Dynamics

All of this having been said, the reality explained above – the current cause of our seasons – goes completely out the window in the scenario explored in Forecasting’s rogue planet episode.  There, the orbits of Jupiter and the inner planets are enlongated by a rogue planet flyby (ignoring for the sake of brevity orbital resonances that might make such a shift even more catastrophic than advertised), which has a surprising result:

Such an event turns the previously-mentioned misconception (that seasons are caused by distance with respect to the Sun) into fact for life on Earth!

In such a scenario, the shape of Earth’s orbit becomes more oval (ellipse) than circle, and it travels much closer to and farther away from the Sun during its yearly course (aphelion and perihelion) than it does now.  As a result, seasonal changes due to the Earth’s axial tilt are totally overwhelmed by the global swing in temperatures based just on proximity to the Sun.

NOTE: These effects were actually scientifically modeled on Earth by Penn State astronomer Darren Williams and paleoclimatologist David Pollard in an effort to explore the habitability of worlds with more elliptical orbits around other stars and were published in the International Journal of Astrobiology in 2002.  This paper, which formed the conceptual basis for the effects depicted in this episode, can be found here.

So now, on a post-rogue-planet-soon-to-be-apocalyptic Earth, everyone on the planet experiences summer and winter globally, which leads to a rapid sort of climate change completely disruptive to our way of life:

With an elliptical orbit, (where during half the year the Earth is much closer to the Sun than the other), Earth's seasons are global and driven by proximity to the Sun. (Credit: Ben McGee)

With an elliptical orbit, (where during half the year the Earth is much closer to the Sun than the other), Earth’s seasons are global and driven by proximity to the Sun. (Credit: Ben McGee)

Earthly Take-Home in an Exoplanetary Context

Aside from the tantalizing (for space scientists) or terrifying (for everyone else) infinitesimally-remote specter of some sort of  interaction with a rogue planet, this episode provides a a roundabout and extreme way to drive home a simple truth:  Astronomy relates directly to weather.

The knowledge that the study of the universe beyond can help us understand life at home is a powerful one, and the take-home truth (to me) of the rogue planet episode is that orbit shapes and axis tilts work to define the temperature (weather) for any world orbiting a star.

-And today, because our orbit is not elliptical, it is the tilt of our axis that dominates our climate and causes our seasons.

Stay tuned for more, and I’ll try and have one of these out for each episode!

Surviving Radiation in Space

13 02 2013

Apollo 10 image of Earth taken from 100,000 miles.  [Credit: NASA]

Apollo 10 image of Earth taken from 100,000 miles away.
[Credit: NASA]

For those who are interested in the reality of radiation exposure on Earth, in space, on the Moon, and what this exposure means for our prospects of manned exploration of the Solar System, read on!

The Myths and Truths of Death by Space Radiation

There are persistent groves of misinformation taking root about the lethality of radiation doses for astronauts, particularly for those who are bound for the Moon and/or Near-Earth-Objects, (such as asteroids for research or mining).

Unfortunately, these claims have been given the capacity for widespread proliferation in the fertile cyber-soil of the Internet, and worse, they usually sprout symbiotically with claims that the Moon landings were hoaxed, e.g.:

“We could never have landed on the Moon because the astronauts could never have survived the radiation from cosmic sources/the Van Allen Belts/solar wind.  Therefore, at a sound stage in the Nevada desert…”

Well, since most of these authors capitalize on the preexisting, prevalent fear of radiation to sugar-coat their misinformation pill, most people are unprepared to distinguish technically-compelling pseudoscientific fluff from interpretations of actual data.   So, the below is an effort to arm you, fellow readers, with a guide to help navigate these murky radiation/Moon hoax waters.

NOTE: NASA has produced a factsheet on space radiation as well, which covers the basics of radiation and its effects and measurement.

By reviewing some of this information, you’ll ideally emerge with an enhanced ability to see for yourselves if these radiation-lethality claims hold water.

(SPOILER ALERT: They don’t.)

So, to begin, let’s review what we know about radiation exposure right here on planet Earth.

Current Regulation Levels and Common Radiation Doses

After nearly a half-century of dedicated research, it has been found that there is no detectable increase in the incidence of cancer (the primary threat of penetrating gamma-ray radiation exposure) for people who receive an annual radiation dose of 5,000 millirem (5 rem) or less.

Consequently, the U.S. Nuclear Regulatory Commission’s (NRC) federal regulations currently limit nuclear workers to an annual dose of that amount.  Further, the U.S. Department of Energy’s (DOE) federal regulations, to be on the safe side, currently limit radiological workers’ annual doses to one tenth of the NRC’s limit (500 millirem) unless there is some sort of extreme circumstance or emergency.

But what do these numbers mean?  To help visualize this data, please see the below graph, which places these numbers in simple context with radiation doses we receive naturally from things we all can more easily comprehend, like a chest x-ray:

Current radiation exposure limits and common doses.  [Chart credit: Ben W. McGee]

Current radiation exposure limits and common doses. [Chart credit: Ben W. McGee]

As you can see, there is a certain amount of radiation exposure that we all receive just from standing on planet Earth (see the far right-hand side of the graph).  This natural radiation is unavoidable – cosmic rays can penetrate just about any shield that is not located deep within the Earth, which is itself radioactive and contributing gamma rays from below.  In fact, you will note that the DOE administrative limit mentioned above is actually less than the amount of radiation we all already receive from Earth, plants*, rocks, air, and even ourselves* in a given year.  (*Roughly 1-2% of all potassium on earth is the radioactive isotope, K-40.)

The take-home here is that none of the numbers in the above graph indicate any sort of imminent danger.  In fact, all doses depicted above are evidenced to be “safe” levels, in that they are either natural or below any exposure that the data indicates increases the incidence of cancer in a population (see: ICRP, NCRP).

NOTE:  There are actually two separate dangers that get confused during conversations about the health effects of radiation.  The first kind of danger is for lower-level exposures, which is the danger of increasing your risk of developing cancer later in life.  -This is exactly like the common knowledge that more time spent sunning or tanning during youth equates to an increased risk of skin cancer later on in life.  (It won’t harm you now, but it could harm you later.  It’s a roll of the dice based on your own health, habits, luck, and genetics.) 

The second kind of danger is immediate – the damage and destruction of cells due to a brief, intense exposure to radiation.  Following the sun-tanning analogy, this is akin to a sunburn but spread throughout your body – damage directly caused by the radiation due to its intensity.  While this may also increase your risk of cancer, the threat here is direct injury and your body’s ability to cope.

How do these natural and regulated levels of radiation exposure compare to the radiation dose levels we really know to be definitely unsafe?  For that, see the following expanded graph, which has been color-coded to relate it to the previous one:

Dangerous radiation levels in context.  [Chart credit: Ben W. McGee]

Dangerous radiation levels in context. [Chart credit: Ben W. McGee]

So, as you can see, this graph allows you to immediately identify relationships between ordinary and dangerous radiation exposures to help you understand the concept of radiation exposure and recognize how intense radiation has to be in order to be considered truly dangerous.

  • For instance, you have to be exposed to an intensity of radiation ten million times that of Earth’s normal background levels before worrying about developing radiation sickness.  That’s ten thousand times more powerful than a chest x-ray.
  • You would also need to receive 1,000 chest x-ray scans before worrying about definitely having increased your risk of developing cancer later in life by a single percentage point.

Now, with a little context, we can start to evaluate how bad the space radiation environment really is.

Explorer-1, that discovered the Van Allen Radiation Belts in 1958.  [Credit: NASA/MSFC]

Explorer-1, launched in 1958. [Credit: NASA/MSFC]

Debunking Lethal Radiation from the Van Allen Belts

The United States’ first spacecraft, Explorer-1, detected the presence of so-called “belts” of radiation around the Earth.  These were named after the scientist who designed the instrument that discovered them, Dr. James Van Allen of the University of Iowa.  However, we have learned much since then, including measurements from the radiation instrument RADOM aboard the much more recent Chandrayaan-1 spacecraft (launched in 2008).

Results from RADOM showed that the inner Van Allen belt, which extends from roughly 1,000 miles above the Earth to a little more than 6,000 miles up, appears to be composed of highly energetic particles, such as solar protons, (meaning they pack a higher radiation “kick”).  The outer belt, on the other hand, extends from a little more than 9,000 miles up to a full 33,000 miles up, and it appears to be a little gentler – it is composed primarily of electrons (beta particles).

So, just how bad was the radiation measured there?  Well, it wasn’t something to dismiss (and was academically quite interesting), but it also wasn’t something that would strike fear into the hearts of mission planners:

Peak radiation exposure while traveling through the inner, more powerful belt reached 13,000 millirem per hour, (or 13 rem per hour).  So, if an astronaut were to park in worst part of the inner Van Allen belt for an hour with no shielding, he or she would receive a radiation dose nearly three times the annual “safe” dose for DOE workers and may have bumped up their lifetime risk of a fatal cancer by a percentage point.

Fortunately, however, the time the Apollo astronauts spent traveling through the highest radiation zone of the inner Van Allen belt (at a screaming 11,000+ miles per hr) was fractional – their doses averaged 120 millirem per day.

Go ahead and compare this to the above graphs.

So, it is clear that the Apollo astronauts’ radiation doses in this case were much less than a common CT scan and far less than what a modern astronaut on the International Space Station receives during a 6-month tour (~7,000 millirem).

Hence, simply passing through the Van Allen Belts is anything but lethal.

Astronaut exposed to the raw space radiation environment on Apollo 8.  [Credit: NASA]

Astronaut exposed to the raw space radiation environment on Apollo 8. [Credit: NASA]

Debunking Lethal Radiation Doses from the Earth to the Moon

Like our own sun, all of the other stars in the night sky are nuclear reactors.  Consequently, a constant “rain” of high-energy particles and gamma rays comes at us from the rest of the galaxy, which we call Galactic Cosmic Radiation, or GCR.

Many claim that in “deep space,” e.g., the space between the Earth and the Moon or between Earth and Mars, GCR would prove lethal for a human being.  Yet, the data indicates otherwise.  (Actually, GCR is the primary source of radiation an astronaut normally experiences in all cases, whether in Earth orbit or beyond.)

Let’s have a look.

The data we have about radiation doses during travel from the Earth to the Moon, like with the Van Allen Belts, are not limited to the old Apollo mission data.  For example, the same Chandrayaan-1 spacecraft mentioned above also traveled from the Earth to the Moon and showed a dose during the five day trip (a.k.a. during “translunar injection“) of 1.2 millirem per hour.

Granted, while this is a level nearly a hundred times the average gamma-ray background radiation intensity on Earth, it is still low enough to not present an immediate concern.  Why?  See the above graphs for a comparison – An astronaut would have to spent more than 170 days in this radiation field before even reaching the NRC’s limit for nuclear workers, which equates to no statistical increase in developing cancer.

This sort of radiation exposure becomes an issue when planning long-term missions to the Moon or Mars, which involve several months to years of exposure time, but it certainly bore no immediate threat to Apollo astronauts traveling to-and-from the Moon in a matter of days.

View of the Taurus-Littrow Apollo 17 landing site, 7-19 Dec. 1972.  (Credit: NASA)

View of the Taurus-Littrow Apollo 17 landing site. [Credit: NASA]

Debunking Lethal Radiation on the Moon

Like with the trip from the Earth to the moon, radiation doses on the lunar surface did not even approach immediate danger levels, and while they fluctuated strongly with changes in the Sun’s output, the Moon itself was observed to act as a shield from galactic cosmic radiation.

Consequently, doses received by astronauts on the lunar surface were actually less than that received in lunar orbit, and again, averaged 120 millirem per day.

This value is completely consistent with measurements from the RADOM instrument in 2008 that showed radiation dose rates in lunar orbit of approximately 1-2 millirem per hour.

And again, these are far from doses that would pose an imminent threat to an astronaut’s ability to function.  An astronaut would, quite simply, need to stand in a radiation field of an intensity one hundred thousand times greater for a full hour before suffering the effects of radiation sickness.

The final space radiation threat data in context, plotted in green, can be seen in the following chart:

Space radiation doses in context.  [Chart credit: Ben W. McGee]

Space radiation doses in context. [Chart credit: Ben W. McGee]

Looking Ahead to Planetary Exploration

What does this all mean for the future of manned space exploration?  While all of this does show that claims of radiation lethality in space are plainly false, it also indicates that radiation mitigation will have to be a central planning issue in order for future astronauts to remain within the current bounds of acceptable risk.

Prevailing wisdom accepts that spaceflight and planetary exploration is inherently dangerous and limits what is considered to be acceptable risk to a 3% increase in fatal consequences as a result of radiation exposure – regulations for radiation exposure that are more lenient for astronauts than for other radiation workers.  (Surprisingly, however, this level of risk acceptance is actually more conservative than what is currently accepted for workers in other, much more prosaic terrestrial jobs in many industrial and natural resource fields… but that’s another story.)

There is some research to suggest that chronic, lower-intensity radiation exposure to some of the soft tissues of the eye may lead to secondary negative health effects, such as cataracts, but we’ve only just begun to learn what effects the many alien factors of the space environment have on human physiology, including gravity-induced modifications of bone, muscle, and organ function.  -And again, these effects are not imminently prohibitive and are certainly not immediately lethal.

The Take-Home

Radiation exposure is one of space’s primary threats – but it is not the primary threat.

A lack of atmospheric pressure, the presence of boiling and/or freezing temperature extremes, an intrinsic lack of breathable air and water, and the necessity of shielding against (or avoidance of) micrometeoroids are all arguably more pressing threats.

Radiation at any exposure rate measured in cislunar space certainly wouldn’t prevent an astronaut from visiting the moon, and only if trapped in the most unlikely and unfortunate of orbits would an astronaut ever need be concerned about the possibility of developing a radiation-induced depression of the immune system and – at the extreme – acute radiation sickness.

Take alarmists with a grain of salt and look to the data for the truth.  In fact, it can be seriously argued that conquering our fear of the atom may actually be the means by which the rest of the solar system is opened to humanity.

In my view, that’s where the real conversation is.


For more information on space radiation doses to astronauts, link (PDF) to the following landmark document, “Space Radiation Organ Doses for Astronauts on Past and Future Missions” by F.A. Cucinotta.

Escape Trajectory Artifacts at WAC-7

7 01 2013

Artist depiction of Pioneer 10. (Credit: Don Davis for NASA)

Just a quick update today on something I’ve been excited to talk about for some time:

I’ve been working during the past year with Dr. Colleen Beck of the Desert Research Institute on long-term planetary science/space archaeology crossover research, the first fruit of which has just hit the cyberverse.

In short, in an upcoming presentation at the Seventh World Archaeology Congress in Jordan on the 18th entitled, “The Bottle as the Message: Solar System Escape Trajectory Artifacts,” Dr. Beck and I are assessing what our escape trajectory spacecraft are really saying about us…  and how the famed Sagan/Drake engraved plaques and records intended as tools for extraterrestrial intelligence under a distant future recovery scenario may actually be serving as a scientific red herring in our own minds when compared to the extraordinary informational value of the spacecraft itself.

More to follow (and a slew of lingering posts on other topics)!

Pluto’s Pain: The Unsung Story of Ceres

20 07 2012

Pluto is once again in the press, astronomers having recently discovered a fifth moon about the tiny, icy world.  -And, again, Pluto’s official designation as a “dwarf planet” is coming under fire.

However, Pluto’s pain really hearkens back to a much older story – one of an unsung planet that stood proudly in the rightful lineup alongside Earth, Venus, Mars, and the rest of the household-name kin of the Solar System for nearly a half-century, yet today nearly no one knows its name:

This is the oft-overlooked story of the scrappy planet Ceres [planet symbol:], which ultimately becomes the story of Pluto.

A Persistent Pattern

The story begins in the late 1700s, when the maturing discipline of astronomy discovered what was believed to be a pattern in the orbital semi-major axes (read: distances between) the planets.  The Cliff’s Notes version of the orbital mechanics here is that there appeared to be a gap between Mars and Jupiter where another planet should have been.

Thus at the turn of the 19th Century began a concerted effort to find this missing world, bringing to bear a contingent of respected astronomers and an arsenal of the most advanced telescopes the science of the time had to offer.

It wasn’t long before they hit paydirt.

(In an ironic turn, I should note that the subsequent discovery was made despite the fact that the ultimate logic of this proposition – the Titius-Bode Law – turned out to be wrong!)

 A Group Effort

In an unbelievable stroke of serendipity, one of the astronomers selected for the search won the race before he’d even entered.  Before Giuseppe Piazzi at the Academy of Palermo, Sicily had even been approached to join the strike team of planet-hunters, he pegged what would turn out to be Ceres while making separate astronomical observations on New Year’s Day, 1801.

A flurry of activity followed during the next year, with the observations changing hands multiple times before a young mathematician named Carl Friedrich Gauss (of differential geometry and magnetism fame), only 24 at the time, predicted the small world’s position to within a half-degree.

Gauss’s calculations led astronomers to the definitive discovery on December 31, 1801, nearly a year to the day of Piazzi’s initial discovery.

The Rise and Fall of Ceres

The discovery of a new world made waves through the astronomical community, with Piazzi naming the planet after the Roman goddess of agriculture, Ceres.  (The names Hera and Demeter have also been bounced about in different cultures, but the current generally-accepted name is Ceres.)

With a diameter of just over 600 miles, (almost exactly the same size of the peninsula of Korea), the world is something of a planetary runt.  However, this did not stop the planet from being included in astronomy textbooks as a brother amongst the rest of the known planets for more than a half-century.  Unlike the asteroids with which it was eventually found to share its orbit, Ceres is a true differentiated astronomical body that has reached so-called hydrostatic equilibrium, becoming a spherical world.

It was only as telescope technology improved and astronomy advanced that the understanding of what Ceres was began to change.  A sudden flood of asteroid discoveries at roughly the same orbital distance began to cast doubt upon Ceres’s uniqueness in the solar system.  Eventually, it was realized that all of these many new, small bodies would either have to also be called planets in order to remain consistent, or the definition of Ceres would have to be changed.

And so, unceremoniously, Ceres was demoted to the ringleader of the asteroids in the latter half of the 19th Century.  This means that by the time our grandparents came on-scene, one would have been hard-pressed to find a modern book that included more than a passing reference to this once-celebrated world.  It had become merely an asteroid.

The 2006 Upheaval

More than a century passed after the discovery of Ceres, and in the 20th Century a familiar story then began to unfold:  Pluto, which was determined to be a tiny world beyond the orbit of Uranus, was discovered in 1930.  It was added to textbooks as the ninth planet, as many of us grew up with.  However, during the 20th and early 21st Centuries, a flood of discoveries of other small, icy bodies in the outer solar system began to cast doubt upon Pluto’s uniqueness.  All of these objects together made up what became known as the Kuiper Belt, a zone of remnant material left over from our star system’s formation and the reservoir from which comets are occasionally pulled.

So, everyone knows that the reclassification of what makes a “planet” resulted in Pluto’s demotion to a new class of worlds called “dwarf planets.”  What few realized, however, was that Pluto’s loss was another’s vindication!

Ceres – waiting patiently in the wings for nearly 150 years – was promoted as a result of the change.  Instead of being “just” an asteroid, it too became a dwarf planet alongside Pluto.  Each as a result of the change evolved into small but noteworthy masters of their respective belts of material – Ceres the dwarf planet of the asteroid belt, Pluto the dwarf planet of the Kuiper belt.

In a way, the controversy resulted in long-awaited justice for little Ceres.


Perhaps, when engaged in your own debate about whether or not Pluto should be called a planet, you might decide to frame the conversation in a larger context.

It really isn’t just about Pluto.  Remember Ceres.

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