phlebotomists are (nearly always) highly skilled people who safely and relatively painlessly poke our veins with big needles, take blood samples, then ask us to "press here". The process is called a phlebotomy.

the surgical opening or puncture of a vein in order to withdraw blood, to introduce a fluid, or (historically) when letting blood.

This requires training, practice, a medical background and will often require certification.

It's normally done in a medical setting so if there are any unexpected challenges they can be dealt with.

Phlebotomy has no doubt been common in spaceflight, medical research on the health effects of spaceflight has been central from its beginnings and is highly active today as extended missions are considered.

Question: Are all modern astronauts at least passable phlebotomists?

This would be a real challenge to do on yourself because of both geometry and human nature, every crew member will need at least one other crew member to be able to do this, so in crews of 2 or more there needs to be at least two passable phlebotomists.

Is it something that most or all astronauts are capable of doing, or are there just a few "designated drivers" in each crew?

Do astronauts phlebotomize each other during ground training for practice?

From the NASA.gov feature NASA Researchers Develop a Technique to Predict Radiation Risk on International Space Station Missions:

Japanese Aerospace Exploration Agency astronaut Akihiko Hoshide poses for a photo after undergoing a generic blood draw in the European Laboratory/Columbus Orbital Facility (COF)

Japanese Aerospace Exploration Agency astronaut Akihiko Hoshide poses for a photo after undergoing a generic blood draw in the European Laboratory/Columbus Orbital Facility (COF).

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    $\begingroup$ It's not that difficult. Plenty of IV drug users inject themselves. $\endgroup$
    – PM 2Ring
    Aug 22, 2021 at 11:16
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    $\begingroup$ I'd rather have a bottle in front of me than a fumbled phlebotomy. $\endgroup$ Aug 22, 2021 at 15:54
  • 12
    $\begingroup$ It took me, as a pre-clinical medical student, about 2 minutes to learn how to take venous blood. I rather think it won’t take someone competent enough to be an astronaut any longer than it took me - taking venous blood from fit adults is easy. $\endgroup$
    – rhialto
    Aug 22, 2021 at 17:27
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    $\begingroup$ @alephzero No that's incorrect. IV = intravenous, the needle must puncture a vein under the skin, and for phlebotomy the needle is unusually large in diameter and called a cannula. On the other hand, diabetics need to inject insulin into the layer of fat directly under the skin, known as subcutaneous tissue, with a small needle or a device that looks like a pen Apples and oranges. $\endgroup$
    – uhoh
    Aug 22, 2021 at 22:09
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    $\begingroup$ @ciamej I'd say that a nurse who periodically administers herself an IV and then falls asleep may be self-medicating with something more than vitamin C. $\endgroup$
    – uhoh
    Aug 23, 2021 at 12:14

2 Answers 2


By my count, the OP asks three questions. I'll anecdotally answer two of them ("Is it something that most or all astronauts are capable of doing, or are there just a few "designated drivers" in each crew?" and "Do astronauts phlebotomize each other during ground training for practice?").

I was the "backup" medical officer for STS-109 (the primary medical officer was a veterinarian!).

While training for said mission, I went to the medical clinic at the Johnson Space Center after hours for IV training. NASA had paid an unfortunate volunteer (someone who worked on site) to be my test dummy.

It took me about four pokes to succeed (those little catheters are hard to slide into the vein!). I felt bad for the stickee and did not enjoy the session. There was other medical-related training for me, but that was it as far as starting IV's.

  • 13
    $\begingroup$ @pcman Inserting an IV is harder than drawing blood, and drawing blood is harder than a subcutaneous injection. $\endgroup$ Aug 22, 2021 at 18:14
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    $\begingroup$ Out of curiosity, by "backup medical officer," do you mean that the mission had both a primary and backup medical officer on board when it flew or that only one medical officer was needed for the mission with a backup trained as an alternate in case the primary planned medical officer couldn't fly? $\endgroup$
    – reirab
    Aug 23, 2021 at 6:13
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    $\begingroup$ @PcMan - the vets I know are really good at IVs, particularly the small animal (pets) ones. Try finding a vein on a cat and getting it in without completely pissing off the cat - you get one try... $\endgroup$
    – Jon Custer
    Aug 23, 2021 at 13:13
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    $\begingroup$ @RockPaperLz-MaskitorCasket You didn't ask me, and I'm in infantry not space flight, but I have self-administered an IV while underway in a tracked vehicle bouncing up and down. So it is possible under adverse conditions. But my arm was bruised from armpit to elbow afterwards, as blood seeps from the vein under the skin during the procedure. $\endgroup$
    – dotancohen
    Aug 23, 2021 at 14:04
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    $\begingroup$ @reirab Not certain, but I'm pretty sure that the policy was to have at least two medically-trained crew on board (the thought being, "What if the primary medical officer gets incapacitated?"). Space flight planners are generally in love with redundancy any way they can get it. Organic Marble might know the answer to your question. $\endgroup$
    – Digger
    Aug 23, 2021 at 20:12

Question: Are… astronauts… passable phlebotomists?”

Answer: No reason why they should be. Phlebotomy is passe. There is little potential need for venipuncture during spaceflight.

There are 2 reasons for needle access to veins:

Diagnostic. In hospitals, blood for diagnostics is usually collected by venipuncture using 5ml tubes. However, this volume is not required. Chemistry tests and hematologic tests can be performed on much smaller capillary samples from skin pricks. https://pubmed.ncbi.nlm.nih.gov/18070280 . This is standard practice in neonatal nurseries. Capillary samples are easily collected with no venipuncture skills. They can even be collected by the subject themselves. The ISS is equipped with a Bio-analyzer which requires only pinprick blood samples.https://www.asc-csa.gc.ca/eng/iss/bio-analyzer.asp

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Therapeutics . Fluids and medications can be delivered through a number of non-oral routes:

  1. Transcutanious (across intact skin), and sublingual (under the tongue). This works well for fat soluble medications such as Fentanyl, Lorazepam and Nitroglycerin.

  2. Subcutaneous. A short, fine needle is used to deposit medication in the fat layer just under the surface of the skin. Administration is simple and requires no training. Medicine is slowly absorbed into the capillaries, then carried by the circulatory system. Local anesthetics and Morphine can be administered by this route.

  3. Intramuscular. Medication is injected into a muscle (usually the shoulder) using a longer needle than for subcutaneous. Minimal training is required. Most antibiotics can be administered intramuscularly.

  4. Intravenous (directly into a vein). This is required for medications which require dilution to avoid tissue irritation. An example is Vancomycin. It is also useful for replacing large fluid volumes such as in trauma resuscitation. Volume replacement is particularly urgent in hypovolemic shock (e.g.: massive blood loss) but IV access can be a significant problem due to peripheral vein collapse.

  5. Fluid Replacement via Rectum (FRVR). This is an alternative to intravenous fluid replacement when IV access is not available. It is not routinely used in emergency departments due to availability of intraosseous (needle into bone marrow cavity) and peritoneal (tube into abdominal cavity) methods. Space medicine is a particularly good application for FRVR since it requires virtually no training and astronauts are on a perpetual low residue diet.

So phlebotomy is unlikely to be an essential procedure in space. It would be unreasonable to reject an otherwise qualified astronaut candidate for their poor phlebotomy skills.

  • 1
    $\begingroup$ The ISS has a fairly unusual #3 reason, research. Determining the effects of spaceflight on humans is a major long-term goal of the ISS project, and that involves sampling human bodily fluids at times. $\endgroup$
    – ceejayoz
    Dec 30, 2021 at 16:56
  • $\begingroup$ @ceejayoz What diagnostic test did you have in mind which cannot be performed on a capillary (finger poke) microsample? $\endgroup$
    – Woody
    Dec 31, 2021 at 2:05
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    $\begingroup$ Most of them? There's very little blood labwork that uses finger sticks; blood sugar is the most common. If you want a CBC or a metabolic panel, you're drawing blood from a vein. $\endgroup$
    – ceejayoz
    Dec 31, 2021 at 4:38
  • $\begingroup$ @ceejayoz Yes, routine clinical practice is to use venipuncture to collect blood for adult laboratory studies. But it is not necessary. In neonatal ICU’s, capillary samples are often used to minimize iatrogenic anemia. Automated analyzers can perform hematology and chemistry studies on capillary samples. pubmed.ncbi.nlm.nih.gov/18070280 . Samples can be gathered in anti-coagulated capillary blood collection tubes ramsci.com/capillary-blood-collection-tubes . Astronauts could collect samples from themselves or each other. $\endgroup$
    – Woody
    Dec 31, 2021 at 17:38
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    $\begingroup$ NICUs have the specific problem of their patients sometimes being under a thousand grams. (My kids were 990 and 1000 grams.) Astronauts aren't in that scenario, and the better accuracy you can get from larger samples (which is the problem Theranos had, incidentally; you need enough blood to run the labs) is worthwhile. $\endgroup$
    – ceejayoz
    Jan 1, 2022 at 3:39

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