My short bio: I am Dr. Susan Bailey, an associate professor in the Department of Environmental and Radiological Health Sciences at Colorado State University. My project is one of ten NASA-selected studies focusing on twin astronauts. The project is unique because one study subject will travel to the International Space Station, while the other will remain earthbound. It is the first study of its kind.

Read more about my research here: Ask me anything!

My Proof:

Comments: 111 • Responses: 48  • Date: 

ZombieHitchens201223 karma

Have you considered using Danny DeVito and Arnold Schwarzenegger as participants in your study?

DrSusanBailey8 karma

No.. but great idea!

AndyWarwheels21 karma

What are you expecting to find by using twins? How many people do you plan to run though this study? I can imagine that it is going to be hard to find enough people that you can do this with to make definitive findings.

Also, how many tacos can you eat in one sitting?

DrSusanBailey21 karma

Since the twins are as identical as it gets, we are expecting to find things specific to space flight. We will be able to compare the twins to each other - and to other related astronauts, hopefully at least 10 others to get significant results.

I can eat lots of tacos!

AndyWarwheels22 karma

Thank you for answering my questions, I really appreciate it.

I have logged your taco response in my taco tracker. You are the first scientist that has answered my question and the first female that has not given me an actual number amount of tacos. So that is something you can add to your resume if needed.

DrSusanBailey13 karma

Will do!

Jux_3 karma

A quick follow up, what's your favorite place for tacos in Fort Collins?

DrSusanBailey4 karma

No fav. I love them all :)

portugalthephilosoph10 karma

Hi! I requested this AMA over on /r/IAmARequests, so I'll copy my questions from there:

  1. Will the "Earth Twin" (Mark) be subject to controlled environments to help eliminate some of the extraneous variables?

  2. How far will that extend? Food? Air? Exercise?

  3. What are some of the differences that you already expect to be able to observe once the "Space Twin" (Scott) returns to Earth?

  4. What are some of the differences that would be the most surprising to see?

  5. Can we make "Earth Twin" and "Space Twin" official nicknames?

I understand you probably can't answer all 5, so I am most concerned with how you plan to treat the variables associated with the experiment. Will the "Earth Twin" be living under controlled conditions for the span of the year? What will those conditions be like?

Thanks for doing this AMA with us!

DrSusanBailey12 karma

Mark Kelly is willing to do just so much for the sake of science. For example he will not be eating the same food as Scott does in space. Mark will be giving blood samples taken at about the same times as Scott. For our study, we expect to see accelerated telomere shortening and elevated telomerase activity, both of which may contribute to aging and or disease.

I like those nicknames!

portugalthephilosoph9 karma

Being able to see differences in telomerase activity would be a huge breakthrough. I don't know much about biology or genetics, but even I can see the implications of that research.

Would decelerated telomere shortening make the idea of longer space trips possible? If we don't have to worry so much about astronauts aging, doesn't that make the possibility of longer missions greater?

DrSusanBailey7 karma

You are correct. However, many different types of stress have been shown to shorten telomeres - including life stress, like inadequate nutrition, physical and psychological stress... Hard to imagine a more stressful thing to do than strap yourself on a rocket and then live in space for a year.. Other factors also pose grave risks to the astronauts for longer missions - high on the list is radiation exposure.

aweujasn9 karma

have you taken any precautions against twin shenanigans, such as switching bodies at launch?

DrSusanBailey5 karma

Hmm.. no.. but we'll be on the lookout!

aweujasn2 karma

a more serious question, how have you benchmarked the current differences between the development of the twins' biological features? have you measured differences in changes between the twins for some time on earth?

what sort of practical ramifications could results from this experiment have?

thanks for taking time to answer these questions.

DrSusanBailey5 karma

We will be able to establish some baselines in each of the twins prior to space twin's one year mission. For example, we will getblood samples several times pre-flight for both. The ramifications of the genomics based studies could include not only informing the twins of the effects of space flight, but also influence future astronaunts by helping them to mitigate some of the effects - perhaps as simple as taking antioxidants, or as serious as realizing they are at unusually high risk of developing disease.

0110100100f8 karma

How will the twin who gets to go to the International Space Station be picked? Does it matter?

DrSusanBailey12 karma

Mark, the Earth twin, is retired from NASA so is participating to support his brother. Scott has been training for the mission for over a year.

DrSusanBailey7 karma

Thanks everyone for your interest and your questions! I'll be checking back this afternoon if anyone has anything else.

isamniac5 karma

First off, congratulations on this research opportunity!!! I heard about this study in my Science & Technologies class at UC Davis! My question to you is what is your advice for a student looking for research opportunities in the field of science and society? Any resources you would recommend? Also asada tacos or carnitas tacos?

DrSusanBailey8 karma

Many thanks! It is an exciting project that is getting a lot PR and I'm really looking forward to it. It is a difficult time for research in general with funding so limited, but the opportunities are out there and more will develop with recovery - so most importantly don't give up! The right doors will open. NASA has a number of student training opportunities that you might look into.

rwthompson4 karma

Are you concerned at all that Mark's previous exposure to space flight will bias your results in some way?

DrSusanBailey4 karma

Mark's time in space is much less that Scott's - particularly after the one year mission.. so no, not concerned..

skipseven4 karma

Hey Susan, believe it or not we share the same first and last name and I happen to have twin boys, age 23. One is in the military and the other graduating in a few days in Geoscience. They have always wanted to be astronauts, they would volunteer to be phase 2 testing!

DrSusanBailey4 karma

Terrific! We'll definitely be needing more twins in the astronaut core!

portugalthephilosoph1 karma


DrSusanBailey4 karma

yep. sorry.. it was very early when I responded :)

portugalthephilosoph4 karma

Is telomere shortening and telomerase activity the only thing you will be monitoring in the twins? It seems that there is an excellent opportunity here to study muscle and tissue atrophy, brain activity, and a whole host of things associated with space flight.

DrSusanBailey5 karma

Absolutely! Together, the ten studies will be analyzing a host of things, including DNA and RNA sequencing, the microbiome, and behavior..

portugalthephilosoph1 karma

Are you involved in those projects enough to expand upon them a bit? What specific things are you looking for in DNA and RNA sequencing, for example?

DrSusanBailey6 karma

We will all be collaborating and sharing data between the projects. All will be looking for differences between earth and space twin.

Keep-reefer-illegal3 karma

Why work on twins as opposed to triplets?

DrSusanBailey18 karma

Hard enough to find twin astronauts, much less triplets..

TumorPizza3 karma

I'm not a twin, but I used to use my brother's ID to buy beer. Can we still participate in the experiment?

DrSusanBailey5 karma

Hmm.. sorry but don't think that counts..

Dioxid33 karma

Only 46 comments?? Geesh what's wrong with you all.

Anyway, thanks for doing this AmA!

Is it possible that this would make the Space-twins life ALOT shorter than Earth-twin's? Taking into account all the radiation and the fuss with telomeres and such.

DrSusanBailey5 karma

That is the possibility we are investigating.. Thank you :)

ElfBingley3 karma

Does a sample size this small yield any meaningful results?

DrSusanBailey3 karma

True that there are only two individuals - earth twin and space twin. However, we are also doing the same tests on a group of unrelated astronauts (not spending as long in space), but hopefully that will help us draw meaningful conclusions.

SkeetShoot3 karma

I'm an identical twin, you're more than welcome to send one of us to space! What do you believe the most difficult part in sourcing test subjects is? Is there a preference for males or females?

DrSusanBailey5 karma

NASA has a previously funded study of 15 pairs of female and male identical twins [Dr. Alan Hargens, UC] focused on testing countermeasures against weightlessness and understanding the hereditary contributions to bone mineral density, kidney stones, and cardiovascular function. The current studies are unique in that both twins are astronauts, the duration of the flight (one year), and the focus on genomics.

blueangora3 karma

Were you required to get permission before submitting this AMA? Is there any information that is classified for any reason?

DrSusanBailey6 karma

No. There is a lot of information that NASA is releasing to the press. The confidential part will come with the results of the studies and how the twins want to handle that information.

supermarketsurvivor2 karma

Will this experiment be conducted in other areas of space in the future? Such as the Moon, or maybe even Titan?

DrSusanBailey3 karma

NASA is interested in moving into more genomics based studies, so yes. Whether or not they will have opportunity to do so in twins will is yet to be determined.

supermarketsurvivor2 karma

Thanks for the reply. I find this topic to be extremely interesting :-)

DrSusanBailey2 karma

Thank you.. Be sure to stay tuned!

sean_joseph2 karma


DrSusanBailey3 karma

In many ways this is the dream experiment - which is what's so great about it! Who knows - there may be some surprises, which of course is why the information will be protected.

derphurr3 karma

This isn't really an experiment. Mark isn't eating the same food or restricting alcohol use, heck he isn't even breathing the same pressurized oxygen. This is more of a gimmick for PR than science.

If you wanted to just study radiation in shielded environment, you should find terrestrial twins where one travels a lot on long distance air travel and measure telomeres, in this case you might find twins that have one with thousands of hours of air travel, and no differences in gravity or air.

If you just wanted to study telomeres why not take a sample of the same cells that split rapidly and send half the same to space and measure the other half. Or better yet, twin mice studies where they are given exact same food.

DrSusanBailey3 karma

It all depends on what question you are asking. This is really a remarkable opportunity to study real life situations - much more relevant to our every day lives than that in a controlled laboratory setting, or in a mouse. The identical twins (actual human beings), Mark will be living an everyday existence, typical of many, on earth, while Scott will be living under conditions typical of long duration space travel. The question being what are the effects of space flight? For me, on telomeres and telomerase activity, and for the other studies, a variety of other endpoints.

derphurr1 karma

on telomeres and telomerase activity

Again, if you are scientifically interested in this, put twin mice, or even something with faster cellular splitting, that is even starting from exact same cells.

This twin thing is just a NASA gimmick. You might as well have him hold an atomic clock and take photos of his Earth twin holding a sync'd clock. It won't tell you anything, but will be neato PR.

Twins aren't identical. Sure if your understanding of biology is from the 1920s. Epigenetics plays a large part in any differences you plan to "measure".

DrSusanBailey3 karma

Monozygotic (identical) twins do start from the same fertilized ovum, same sperm. Even so, and as you point out, they are not identical in every way - epigenetics will change patterns of gene expression between the twins, which is why one of the studies will be doing methylomics to analyze differences in methylation patterns between the twins - again, that will be due to space flight. I'm sure you can also imagine the difficulties of doing some of these experiments in space - not only are the human studies more relevant, in many respects they are more doable.

MasFabulsoDelMundo1 karma

I have identical twin daughters, although lifestyle has now completely changed their appearance, interests, activities and values.

Some years ago they were a small cause célèbre as one had a plasia that lodged in her brain leading to epilepsy like symptoms and other, mostly drug induced, behaviours. Brain surgery was the cause for attention, for identical reasons as these ongoing space twin tests. However, research was suspended for two reasons: several medical researchers felt no useful data was being collected and we also felt it was not conducive to healthy recovery. The girls were pre-teens at the time. The information imparted was that most twin-based tests exhibit this phenomena: that which you are looking for is not meaningfully expressed in identical twin based managed studies.

Therefore, I agree with other commenter's, this test sounds fascinating, plausible, exciting even given extraordinary opportunity of identical twin astronauts, yet seems to be a specious academic exercise repeating previous data generation attempts.

However, for sure the opportunity to further space based physical biology knowledge is of inestimable value given the utter alien environment. From my girls' past experience, skepticism is strong, and can't but otherwise say to not be blind to no meaningful results.

DrSusanBailey2 karma

Thank you - and most certainly. These are pilot projects. There may not be anything to follow up on - and then again there may be. These types of genomics based studies have not been done before on the astronauts, and certainly not on twin astronauts.

portugalthephilosoph2 karma

Do you think that we would be able to do more experiments like this if NASA were still a fully-funded governmental organization, capable of launching its own missions?

DrSusanBailey9 karma

Most definitely. These studies are a good example of the potential of the space program to benefit of all mankind. The fact that we have to depend on the Russians to get our astronauts to and from the ISS is somewhat disconcerting.

portugalthephilosoph1 karma

Does privatization offer any hope for the future of US space exploration? SpaceX seems to be doing some great things, especially after yesterday's success.

DrSusanBailey3 karma

Yes it does. SpaceX is a good example, but they've had problems too.. and it only takes supplies - no people.

portugalthephilosoph1 karma

The same could have been said of NASA 60 years ago, though.

DrSusanBailey2 karma


Depletion2 karma

Interesting, this was used as a plot device by influential science fiction author Robert A. Heinlein. The book is called Time for the Stars (wrote in 1956) and has the plot of sending one twin into space and keeping the other here on Earth to be used as a sort of ansible. In the book, the twins have a sense of telepathy between them without the inherent delay that radio waves and other forms of communication had.

I haven't read it in at least 10 years but it was still the first thing I thought of when I saw NASA was doing a twin experiment.

DrSusanBailey3 karma

Interesting indeed. They definitely are both very invested in this.

ChargerEcon1 karma

But what do you expect to learn from this? We already know that perceived time slows down the faster you travel. What theory are you testing here?

DrSusanBailey2 karma

that the stresses of space flight influence important age related pathologies, including reduced immune function, cardiovascular disease and cancer. The ISS is in low earth orbit and does not travel at the speed of light, so the theory of relativity is not so relevant.

blackscorp1 karma

What is the best thing about your job?

DrSusanBailey2 karma

I really enjoy interacting with students and the opportunities I have to interact with colleagues.. This has been a lot of fun too!

DrEzWida1 karma

Does NASA use any of the the data collected by Dr. Mengele during his twin experiments?

DrSusanBailey1 karma

I'm not really sure. I do know that the current twin study is unique in a number of ways. The focus on genomics, the shared data plan, a year in space, and the fact that both are astronauts are first time evers.

stumpysausagefingers1 karma

Hello Dr. Bailey! I hadn't heard of this experiment before, and it sounds fascinating. In your answers thus far, you've stated your hypothesis that the telomere lengths of the two twins could change due to different stress levels. Alongside the genetics-based research, are there any plans for some psychological analysis before, during, or after the Space Twin takes off? While psychology can sometimes be biased, the comparison between reported stress levels and telomere length might be interesting.

DrSusanBailey3 karma

Yes indeed. Results from all of the studies, including some on behavior, will be shared so that we can make relevant comparisons.

capnwinky1 karma

Do these twins in particular share a commonality that other twins seem to have? Such as completing each others sentences and having that distant empathy correlation? Are you exploring any affects in relation to that stuff?

DrSusanBailey2 karma

Not directly. But some of the studies are evaluating behavior.

KidQuestions1 karma


DrSusanBailey2 karma

Sorry.. afraid not..

YoYoDingDongYo1 karma

Have you considered calling your study Project Gemini?

DrSusanBailey4 karma

There is ongoing discussion about a name for the twin studies - Gemini was brought up, but it has already been used by NASA. Another suggestion was Sirius, which is a binary star system (Sirius A and B) perceived as a single star - the brightest in the night sky. To my knowledge, no name has been decided upon.

parallellogic1 karma

It seems like this research could be used to characterize the risks inherent in transporting humans to Mars. Do you foresee any other direct applications of your research findings?

DrSusanBailey2 karma

Yes. That is the idea behind the one year mission - the longest anyone has been in space, and although in low earth orbit, it will still be very informative regarding how humans handle it. The genomics studies should also help to identify risks and possible mitigation strategies for extended space flight.

introvertturtle1 karma

My question brings up some issues with ethics, but I'm curious anyway, so here's my question :

Assuming ethics and whatnot weren't a factor, and assuming this would take place once space stations are more common and people could live and grow up on them (however far in the future that may be), how much do you think we could learn by repeating this experiment in the future with younger twins, who would both grow up individually, as opposed to growing up together and then one going to space? Do you think that it's something that might actually be done in the future?

DrSusanBailey2 karma

So you're getting at the role one's environment as opposed to one's genetics. The classic nature vs. nurture debate. The beauty of the current twins study is that as many of the variables as possible - including environment and genetics - are as similar as possible. Therefore, any differences observed can be attributed to effects of space-flight. We will also have opportunity to compare the results with the twins to unrelated astronauts to address the role of genetics.

GhostCheese1 karma

Weekday specific vectors are you studying between the twins, and what do you hypothesize you'll find?

DrSusanBailey3 karma

We are going to be analyzing changes in telomere length and telomerase activity before, during and after the one year mission. We expect to find shorter telomeres and higher telomerase activity in the space twin compared to the earth twin.

GhostCheese2 karma

Is this because time moves slower away from the source of gravity or because of some other property of living in zero gravity?

DrSusanBailey5 karma

I think it has more to do with stresses associated with space flight.

ueoaeuaoeuaoeu1 karma

Seems without the stress of gravity, the telomeres wouldn't tick as quick. I guess you will find out.

DrSusanBailey3 karma

Since telomeres shorten due to things like replication (cell division), and stress, they may be somewhat independent of gravity - but we shall see :)

ueoaeuaoeuaoeu1 karma

I guess I don't understand the "stress of spaceflight" Seems that there is a 5 minute exposure to ~4gs during the burn then 6 months exposed to ~0gs. You don't need to build bone or mussel mass.

DrSusanBailey3 karma

Astronauts do suffer from muscle wasting and bone loss in microgravity. They have very strict exercise programs while in space to combat such issues. The kinds of stress that I'm referring to are related to things like inadequate nutrition, the physical and psychological stresses associated with long term periods of space flight in relative isolation - very stressful!

Arcterion1 karma

Now I'm curious... Would sending a couple of introverts into space help with the stress of isolation? :P

DrSusanBailey3 karma

Perhaps. That is actually a very real concern/danger of long duration mission - loosing it due to isolation.

Arcterion1 karma

Yeah, that's why I'm thinking that it might be good to send people who are used, or even prefer, to be isolated for long periods of time. :)

DrSusanBailey2 karma

The problem may be in the training for such missions. Takes lots of folks and interaction for that.. Then in space, even if just a few people, they really do need and depend on each other..

Sir-Juju1 karma

Does your experiment require identical or fraternal twins (fraternal twin asking)

DrSusanBailey2 karma

Identical twins are ideal in this situation, as the more similar genetically the twins, the more we can conclude that any differences we observe are due to space flight - not genetics or individual susceptibility.