My short bio:

Dr. Barbara Cohen leads the planetary science group at the Marshall Space Flight Center. Dr. Cohen came to NASA MSFC in 2007 specifically to support human exploration planning for the Moon for the Constellation program, including the Lunar Precursor Robotics Program (LPRP) managed at MSFC. During this time, Dr. Cohen worked to bring Constellation engineers what they needed from the Lunar Reconnaissance Orbiter (LRO) and its companion, LCROSS, helped initiate the Lunar Mapping and Modeling Project, and helped write the engineering design specification documents describing the lunar environment. She served as the project scientist for the US nodes of the International Lunar Network, a science mission to provide geophysical information about the Moon’s interior structure and composition. Dr. Cohen helped craft the National Research Council report, “The Scientific Context for Exploration of the Moon,” which set science priorities within lunar exploration plans. Today, Cohen continues to support SMD projects and is a Co-Investigator on several spacecraft and instrument proposal teams.

My Proof:

Comments: 257 • Responses: 58  • Date: 

BoxyCube49 karma

Moon is good, no?

NASAMarshallMoon34 karma


theothermanfromwales32 karma

Do you ever completely space out and forget you're supposed to be working when you're looking through the telescopes? I feel like I'd do that every 10-15 minutes.

NASAMarshallMoon34 karma

I actually looks at rocks in microscopes, but yeah, it's sometimes easy to get lost in the beauty and the exploration and lose track of time and focus :)

theothermanfromwales12 karma

That sounds equally riveting. I like tiny things as well as big things. Thank you.

NASAMarshallMoon18 karma

Thanks. We appreciate your interest and support. We enjoy talking to fans of NASA and space/science exploration. :-)

nae721518 karma

What is the number one question that is currently left unanswered about our moon?

I'm a current senior in high school looking to get into astrophysics and/or astronomy. Do you have any advice, especially for a female, in the field?

Thanks for doing this!

NASAMarshallMoon15 karma

FYI - NASA offers several opportunities for students to get involved. One way is through our intern program. We hire hundreds of interns each semester.

Another education program are as follows: Texas High School Seniors: Community College Students:

NASAMarshallMoon12 karma

We have a whole list of unanswered questions about the Moon, but to me the most understanding will come from knowing the bombardment history of the Moon, which reflects the early history of our solar system. The Earth had as many impacts as the Moon early in its history, so how did that affect us?

Good on you for following your passion. My number one advice is don't let anyone beat that passion out of you. You need to be stubborn and have a thick skin and work through adversity - which is true no matter who you are. Science is a small field and making it is a long road. But it's one well worth trying!

sourdust16 karma

Ask you anything? What did you think of the most recent episode of "Doctor Who"..?


NASAMarshallMoon24 karma

No spoilers! I haven't seen it yet! (but I heard the science was terrible)

reggieHazz13 karma

What's the most bizarre fact you can tell us about the moon?

theothermanfromwales12 karma

Not sure if this is accurate or not, but I was once told it's the only celestial body without a name. That's pretty bizarre.

Edit: I'm stupid.

NASAMarshallMoon30 karma

Well, it does have a name -- it's the Moon, though now that we know of other moons, we typically refer to it as "our moon." Until we discovered other moons, our moon was the only one we knew of. Even though we now know of many others, we still call ours the moon. Think of it like the Earth. Earth is the formal name of our home planet, but also a noun referring to land surface.

calbloom12 karma


NASAMarshallMoon10 karma

I gave this 2 points up in a circle. What can I say, I am interested in the ancient terrain of Mars, and it is naturally exposed by impact craters. However, I have no delusions that I am but a small and humble part of the process.

frozzymm9 karma

What is your favorite flavor of ice cream? Also, what actual significance is there in a lunar eclipse?

NASAMarshallMoon31 karma

It used to be mint but I am currently on a quest to find the best cherry ice cream. The cherry-red color of the Moon during a lunar eclipse will be visible tomorrow morning, due to the refraction of the sun's light through our atmosphere. The significance is that I need more ice cream.

klime027 karma

Is there any chance that with current or near future technology, we can set up a self-sufficient moon base?

NASAMarshallMoon8 karma

Yes, definitely We have much of the technology already, as you can see by the success of the International Space Station. We are working on a few more aspects humans would need: long-duration, closed-loop life support and radiation protection are two that come to mind. But I am still hopeful we will see this happen.

wil6gl7 karma

Would you notice a lunar or solar eclipse if you were on the moon, and have any astronauts been on the moon during a lunar or solar eclipse?

NASAMarshallMoon4 karma

Yes, if you were standing on the moon at high noon (full moon) and the sun were blotted out for a couple of hours, you would definitely notice. However, only orbiting spacecraft have been through lunar eclipses, not humans.

ruthie1476 karma

What is your view of attempts to conserve previous landing sites on the moon? What extra science is needed at locations where Apollo astronauts collected rocks?

NASAMarshallMoon9 karma

I think there is some value in preserving aspects of previous lunar landing sites from unnecessary damage, but there's also value in re-examining old hardware and experiments, and looking at how our disturbances have faded over time. Proper experiments done well would be useful.

fukamundo6 karma

Will I be able to see the eclipse tomorrow from New Jersey, and if so, what tie would it be? Around 5 in the morning?

NASAMarshallMoon10 karma

Thanks for the question! Here is a global viewing map for tonight's Total Lunar Eclipse!

Merney6 karma

Would it be feasible to erect a large telescope on the moon's surface or does this not really provide any actual benefit over simply placing them in orbit?

NASAMarshallMoon8 karma

It depends on what you're trying to observe. In the many years people have thought about this, we've actually gotten really good at free-flying telescopes, like Hubble, Chandra, etc. These exceed the pointing, stability, etc. that you could get from a structure on the Moon, where you also have to deal with gravity, dust. etc. However, there is one thing the Moon is better at: blocking the Earth's noise. There is a "radio shadow" on the lunar far side that would be an ideal location for a long wavelength radio telescope, which has been proposed but not yet funded.

dead_phish5 karma

I see in your bio that you work(ed?) with the Constellation Program. What, if anything, can the average American do to kickstart manned spaceflight beyond low earth orbit?

Kind of related question - do you think we should invest our time and money in manned, or robotic exploration?

Thanks for doing this!

NASAMarshallMoon7 karma

For a start, vote! and make sure your elected officials hear your opinion on things that are important to you. I think both human (come on, it's 2014) and robotic exploration are both important components. However, I am very interested in having them both work together. There are lots of places humans will probably never be able to go - like Uranus, but also like toxic mines and other places on Earth. Robotic presence and virtual reality will help humans explore ALL the places.

sphume5 karma

Hi, does the lunar retro-reflector corner cube mirrors accumulate dust? If so, how does that affects lunar laser Ranging?

NASAMarshallMoon3 karma

Yes, we have definitely seen degradation of the returned laser signals from the corner reflectors. However, we don't know if that is caused by dust settling on the surface, by micrometeorites pocking the surface, or something else. We do know that when the Apollo astronauts landed, there were many rocks with only a thin layer of dust despite being there for several billion years. So there must be a limit or an equilibrium. Still an active area of study.

astland4 karma

Thanks for helping me get less sleep, and enjoying every minute of it.

NASAMarshallMoon1 karma

You are welcome!! :) It's going to be a fun night! Be sure and check out our live Ustream feed tonight at 2am CDT - and thanks for staying up with us.

MichaelJD10214 karma

I have heard there are vast deposits of hydrogen on the lunar surface, also, asteroid mining is quickly becoming a "real thing". These coupled with the fact that there is little atmosphere on the moon make me think that the future of manned spaceflight and the future of inter and outer solar system travel will be on the moon and not on earth. If this is all true (is it?) in your opinion, is the moon a viable launch site for future space travel, and if so, how long/far in the future do you think it will be?

BTW, just saying, id be down to go to mars. even a one way trip!

NASAMarshallMoon4 karma

Yes, native water on the Moon and asteroids could definitely help future human (really, it's 2014!) spacefarers "live off the land. However, like all mining on the earth, there's a lot that needs to be done not just to identify the deposit but then to characterize it and figure out how best to exploit it. Much of that work is still ahead of us.

AdmiralMemo4 karma

Why are there so many maria on the near side of the Moon and very few on the far side?

NASAMarshallMoon9 karma

The short answer is that the crust of the Moon is thinner on the near side than on the far side, so it is easier for lavas to erupt onto the surface of the near side and create the maria (Latin for "seas" because they are wide and smooth). However, the more interesting question is, why is the crust thinner on the near side? That's a question where active research is happening and we still don't have a definitive answer.

Kirkland_Class3 karma

My 4th graders would like to know what made you want to study the moon as opposed to any other body in the solar system? @kirkland_class

NASAMarshallMoon2 karma

I study the Moon, but I also study Mars (I work on the Spirit and Opportunity rovers) and asteroids (I study meteorites in my lab). I am interested in the processes that rocks undergo to tell us about their planets - this is geology, on all the planets!

artisticchipmunk3 karma

Where will you be watching the eclipse tonight? Can I go to the moon and when do I leave?

NASAMarshallMoon1 karma

I will be following along with our Ustream feed - - where we will have telescopes showing the eclipse and also NASA experts giving live commentary on the event. They will also be taking questions.

arkydon2 karma

Apart from uranus + draconid meteors what else should i watch for that will "accompany" this eclipse while I'm looking? :)

NASAMarshallMoon3 karma

For tonight, pretty much what you will see is the total lunar eclipse (which is pretty darn cool :) and also, you may get a glimpse of the draconid meteor shower, even though the peak is tomorrow just before sunrise. We will host a web chat and live Ustream feed during the eclipse, so if you are up, come join us!

MaleCra2 karma

I was always interested in being an Astrogeologists; space rocks - well - rock. But I don't have the necessary mathematical and scientific finesse to do so. Is there any way I can check out space rocks as a hobby for an affordable price?

Jimothy9872 karma

Thanks for doing this AMA. My geology homework involves looking at the geology of the moon - of course I could do the run of the mill Wikipedia and Google data gathering but on top of that, are there any really interesting (that I'm particularly unlikely to find) features in the moon that would be worth writing about?

NASAMarshallMoon1 karma

Thanks for joining us! If I answer this, will you do my math homework for me? :)

_SuperWeenieHutJrs_2 karma

How'd you get your job at NASA? Was the whole process difficult or stressful?

NASAMarshallMoon1 karma

The Sorting Hat :-D

You can always check out for NASA job postings.

Hicrine2 karma

Hi Dr. Barbara! I have two questions: are there any cave systems on the moon and what, in your opinion, is the craziest land formation that we know of on the moon?

NASAMarshallMoon4 karma

There are kinda cave systems. They aren't in limestone like we have here, but there are lava tubes that are buried, and in some places there are skylights ! (

kylewayne2 karma


NASAMarshallMoon7 karma

My fave fact is that when you look at the moon through binoculars, you see tons and tons of craters. Each and every one of those craters had a counterpoint on the Earth in its past - that is, just as many craters formed on the Earth. But it was long in the past, and the Earth recycles its crust, so we don't see them anymore. But we see all that ancient bombardment reflected on the Moon!

hyperhumanimal2 karma

So, how many of these eclipses are supposed to happen in a single year 'normally'? Like, on average, how many total lunar eclipses are there in a single year?

NASAMarshallMoon2 karma

There's actually four total lunar eclipses this year and next. They come in cycles of four, or tetrads, every 18 years or so.

vonsydow12 karma

What effect will this have on tides? Additionally, where would you travel, barring all limitations?

NASAMarshallMoon3 karma

Eclipses are simply the Earth's shadow passing over the Moon's disk - the Moon isn't any closer or further than normal. I would love to travel to Saturn's moon Titan now, or back in time to the formation of the solar system.

Defyingtoitle2 karma

If given the option would you work on a different subject? If so, which one?

NASAMarshallMoon3 karma

Right now, no way. Planetary science is amazing right now - we have data coming in, or soon to come in, from nearly every planet, asteroids, comets, meteorites, and the sun. However, if I ever got kicked out of this field, I have plans to either work in renewable energy, or open a bakery.

GeekOutHuntsville2 karma

Of the local breweries that have sprung up, which one's beer is your favorite, and why is it Straight to Ale's Laika Russian Imperial Stout?

NASAMarshallMoon2 karma

Wrong again, it's Monkeynaut (where's my kickback ;) ?)

Jecktor1 karma

How good will this lunar eclipse be and is it rare?

NASAMarshallMoon1 karma

There's actually four total lunar eclipses this year and next. They come in cycles of four, or tetrads, every 18 years or so. This one is pretty rare, it's a harvest moon eclipse. For viewing, the west coast has the best viewing opportunities. Here's a map - and you can also watch it live on our Ustream feed - Thanks for the question!

Mathema-Chemist1 karma

As of now, how are current prospects of sending a manned mission to the moon in the next few decades?

Also, what do you think would be the most exciting scientific reason to return to the moon?

NASAMarshallMoon1 karma

Currently, NASA is building a new rocket, the Space Launch System - - that will have the capability to take us wherever we want to go in our solar system. Our goal is to eventually get to Mars, and while there are no current human missions to the Moon planned, the great thing about SLS is that it gives us the capability to visit a variety of destinations. I am excited about exploration in our solar system in general, and while I believe there's still a lot we can learn from the moon, I can't wait to see what new destinations we will visit.

reddit_user_6543211 karma

my son's birthday is tomorrow. On the scale of bad fathers, how bad of a father will I be if I accidentally sleep through my alarm and don't wake him up to see his birthday eclipse?

NASAMarshallMoon3 karma

We hope you'll both see it in time, but if you do sleep through the alarm, you can catch the video later at

reddit_user_6543211 karma

neat, thanks!

NASAMarshallMoon2 karma

Thanks for joining the chat! Happy Birthday to your son, in advance!

billysbrew1 karma

Does the moon have any precious metals under the surface?

NASAMarshallMoon2 karma

The Moon is made out of the same material as the Earth and the other planets and it makes the same minerals. The Earth has processes like water and faults that can concentrate metals and create ore deposits. The Moon doesn't have these processes. However, the lunar soil contains billions of years of built-up debris from asteroids, some of which is metal and could be refined. The economic case for mining the Moon doesn't close yet.

jstrydor1 karma

What time is the eclipse? I could google it but that would require some amount of effort. Also, I don't know if where you are matters on the time, so I live in LA county. Thanks for the AMA by the way!

NASAMarshallMoon1 karma

The eclipse will begin about 3 a.m. ET, and best viewing around 5 a.m. You're on the West Coast, which will have excellent views of the entire event.

jumpup1 karma

what point on the planet gives the best viewing point and how long doe it last?

mgdurand1 karma

What is unique about the moon's formation that it does not spin on it's own axis while revolving around the earth? The matter that formed the earth continued to spin as the earth revolves around the sun, but the moon shows only one face to us. And does this suggest anything about how (e.g. asteroid strike vs. proto-earth material) and when the moon was formed?

NASAMarshallMoon2 karma

Thanks for the question. We appreciate it.

The moon does actually rotate on its axis, just very slowly. It used to rotate MUCH quicker -- millions of years ago -- but Earth's gravitational pull eventually slowed it down. Now, the moon is "tidally locked", which means its rotational speed on the axis is the same as its orbital period around Earth.

This slow rotation is why we only see the NEAR side - and not the FAR side, mistakenly called the dark side of the moon. GREAT album, but factually inaccurate :-) ALL sides of the moon get sunlight during the month long orbital period.

It wasn't until the age of space exploration that we could explore the far side. Apollo 8 was the first time humans saw the far side!

hollowdonkey1 karma

There's an eclipse tonight?!?!

I know very little about space stuff but I've always thought it was interesting. This question isn't about the eclipse but you might be able to answer it for me: What causes these super moons we've been having lately?

Also, congrats on working for NASA! I bet it's a dream come true!

NASAMarshallMoon2 karma

Yes, there's a total lunar eclipse tonight (depending on when tonight is in your time zone:

You may have heard about "supermoons" in the news recently, but they aren't new. It happens when the Moon's closest approach to the Earth in its elliptical orbit coincides with its greatest illumination from the sun (full moon). It's a nice phenomenon.

ashitty_redditor1 karma

I live in Denver, CO, whats the best time to try and view the event? Also, thanks for doing this AMA!

NASAMarshallMoon2 karma

Check out this global viewing map for tonight's Total Lunar Eclipse!

ashitty_redditor1 karma

Thanks a bunch! I'll do my best with the interpretation of the info!

NASAMarshallMoon1 karma

Good luck. North America has a great viewing opportunity late tonight. As long as it's not cloudy, like it is here near the Marshall Space Flight Center. We will be up all night, doing live web-chats and showing live feeds on the web. Join us. :-)

JSlamson1 karma

Is it worth staying up until the wee morning hours on a school night to watch or should I wake up at 5 to catch the later stages of the eclipse?

NASAMarshallMoon1 karma

Great question - depends on where you live. The best viewing for those in the U.S. will be on the West Coast. Everyone else will have a partial view. This map can help you figure out your best viewing time:

Nmurig1 karma

Can I see the eclipse tomorrow? I'm from Costa Rica and I like all that stuff

NASAMarshallMoon2 karma

Yes, you ought to be able to see a partial eclipse where you are. It starts at 3 a.m. ET and ends at sunrise.

NASAMarshallMoon2 karma

Here's a link to a time conversion tool:

mgdurand1 karma

What is unique about the moon's formation that it does not spin on it's own axis while revolving around the earth? The matter that formed the earth continued to spin on an axis as the earth revolves around the sun, but the moon shows only one face to us. Does this give any clues to where the matter composing the moon comes from (proto-earth vs. asteroid strike) and when it was created?

NASAMarshallMoon1 karma

Actually, the Moon does rotate on its axis, but the rotational period is the same as its revolution around the earth, which is why you see the same face. This video might help you visualize it:

Our current theory for how the Moon formed is that a Mars-sized body collided with the forming Earth 4.5 billion years ago. Most of the material re-accreted to the Earth but the Moon coalesced out of the debris.

NASAMarshallMoon1 karma

Thanks for the question. We appreciate it. The moon does actually spin on it's axis. Just very slowly. It used to rotate much quicker - millions of years in the past. But, Earth's gravity eventually slowed it down.

You're right that the moon is tidally locked. We always see the NEAR side of the moon. It wasn't until the age of space exploration that we could explore the FAR side, often mistakenly called the dark side of the moon. Apollo 8 was the first time humans ever saw the far side.

victorius211 karma

Can you give some reasons why the US, or any country, should go back to the moon?

NASAMarshallMoon2 karma

The Moon, Mars, and asteroids are all potential destinations, both robotic and human. There are benefits and hazards for each, so no matter where we go we will learn a lot. All of these places also have ways we can "live off the land" and use the minerals and resources. Exploring our solar system, whether its the Moon, Mars, an asteroid, etc, helps us address fundamental questions about our universe, how it was formed, etc. and helps us expand and create new technologies that not only have space applications but can help us here on Earth.

mainvolume1 karma

So it's obvious we're trying to get people on an asteroid and on Mars...but what about back to the moon? Surely it's feasible to put an outpost on the moon to kind of get our feet wet for when we go to Mars(plus it's way easier for a rescue mission if something goes wrong). And aren't there beneficial minerals on the moon that we can mine?

I've always had a thing for the moon :)

NASAMarshallMoon2 karma

Yes, right now, the Moon, Mars, and asteroids are all potential human destinations. There are benefits and hazards for each, so no matter where we go we will learn a lot. All of these places also have ways we can "live off the land" and use the minerals and resources.

mainvolume1 karma

Thanks for the answer! If you guys need slave labor to build structures on the moon, I volunteer as tribute!

NASAMarshallMoon2 karma

And what district are you from? :)

ZmanKietilipooskie1 karma

Do we know anything about the moon's core density?

NASAMarshallMoon3 karma

Yes actually, Dr. Renee Weber here at Marshall studies the lunar core and she found a small (250-km) metal core.

ZmanKietilipooskie2 karma

Wow cool thank you (another question?), is it at the center of the moon or is it "off balanced"?

NASAMarshallMoon2 karma

The center of gravity and the center of mass are indeed slightly different from each other.

NASAMarshallMoon1 karma

Thanks so much for a great AMA! Thanks to our NASA expert Barbara Cohen for her time. Hope you have clear weather tonight to watch the total lunar eclipse. Don't forget that NASA will be hosting a live web chat tonight with astronomer Mitzi Adams and astrophysicist Alphonse Sterling during the eclipse. You can read more here:

We're working on adding some live streaming views of the lunar eclipse to the page above, so please check back later tonight for more about that. You can also find out more about times and viewing here: A good time converter here: Happy viewing tonight!

wykedcomputergirl1 karma

Did you watch the last episode of Doctor Who, called "Kill the moon"? What do you think about their theory that the moon is actually an egg waiting to hatch?

NASAMarshallMoon3 karma

SPOILERS! </riversong>

Pudgy2231 karma

What is the current theory on the formation of the moon (ie, sister, offspring, or captured)?

NASAMarshallMoon2 karma

Our best theory at the moment (a theory is a framework hat explains all our data) is that 4.5 billion years ago, as the planets were forming, a Mars-sized body collided with the Earth. Most of the material accreted to the Earth, but the Moon formed out of the remaining debris in orbit. This theory helps us understand not only the shared characteristics of the Earth and Moon (isotopes, momentum, etc.) but also we know impacts were common - Venus is rotating retrograde and Uranus is knocked on its side. The early solar system was a pretty violent place!

Sick_Wid_It1 karma

What is the best way to get educated about, and involved in our space program (usa) and space exploration in general?

NASAMarshallMoon2 karma - this is NASA's flagship website and has tons of great information about the space program, and also has updates on partnerships with the international space community. For day to day updates, follow NASA's Twitter - @NASA and the center where I work, Marshall Space Flight Center - @NASA_Marshall as those are updated daily with the latest of what's going on. Also if you are an educator - - check out this website for great ways to educate our young people. Thanks for the great question!

CockyChach1 karma

What is your all time favorite picture of the moon?

NASAMarshallMoon2 karma

Actually, this is one of my favorites. It shows the only geologist to have worked in his field site on the Moon taking a sample.

7ente1 karma

Would it be difficult to set up telescopes on the moon?

It seems to me like you could save yourself a lot of earth-related atmospheric visual troubles.

What are the limitations/why isn't it done?

NASAMarshallMoon1 karma

I answered this below (good question).