STS-135 Experiment Design FAQ

This FAQ is specifically for SSEP on STS-135, and is made available as an archive for communities that participated in SSEP on STS-135.
To launch this FAQ, we culled all questions from the STS-134 Flight Experiment FAQ that were also relevant to the STS-135 Flight Experiment Opportunity. This FAQ is now updated as questions are received by the SSEP Team relating to all aspects of flight experiment design for STS-135, e.g., questions on how to think about the experiment opportunity, the science that can be done in microgravity, the operation of the mini-laboratory to be used, constraints on experiment design such as the allowed fluids and solids that can be used in an experiment, and the milestones and due dates associated with the flight experiments. These are topics generally addressed on the Designing the Flight Experiment page, the STS-135 Mini-Laboratory Operation page, and the STS-135 Critical Timeline page.

To submit a question to the SSEP Team, use the Contact Us page, or send an email


Experiments in Microgravity

Q: Is there a list of experiments, with descriptions, that have been flown in the MDA?
Some examples of experiments flown on the MDA, or suitable for the MDA, can be found on the Selected Experiments on STS-134 page. A list of titles of student experiments flown on earlier Shuttle flights can be found here. Some general ideas on the kinds of experiments that could be flown in the MDA are described in the Microgravity Experiment Case Studies document, which is available in the Document Library.

Q: Where can we find information about the impact of re-entry on the samples?
We’re not quite sure we understand the question. As the Shuttle re-enters the atmosphere, the astronauts and everything else aboard Shuttle go from a “weightless” environment to an Earth gravity environment. The samples are fully contained in the MDA wells inside a locker in the crew cabin of the shuttle. They experience the effects of gravity “turning back on” just like the astronauts.

Q: How much shaking will the MDA experience during launch and reentry? Is it similar to bad turbulence aboard an airplane?
Shaking at liftoff can be severe. Describing the effect of liftoff, astronauts have reported that it is very different from “bad” turbulence because unlike in an aircraft in turbulence, you are shaking and pulling a couple of g’s. The term “g” is used to describe the acceleration you can experience due to gravitational forces. If you are standing on the surface of the Earth, you are experiencing the standard 1g; if you are in freefall, you are experiencing 0g, while the typical acceleration aboard the Shuttle during liftoff is 3g. In addition to the acceleration, the acoustic level – the noise in the cabin – is louder than on an airplane. Of the launch environment, astronaut Tom Jones said “Lying on my back when the main engines ignite, I felt the entire stack shudder like a skyscraper in an earthquake. The vibration reached a crescendo six seconds after ignition, when, at T-minus-0, the orbiter computers triggered the two solid-rocket boosters. On each of my four launches, that was the memorable moment — it felt as if a giant hammer had walloped my seat from below, giving me a brutal shove. As the stack leapt off the pad, we were whipsawed left, right, forward and back as the booster nozzles swiveled to balance on a pillar of golden flame. The vibration was more intense than ever, shaking us like a pickup truck bucketing down a dirt road at 50 mph. We were already at 2 g’s, heading for two and a half g’s just before booster burn-out. No, it’s not a ride you forget!”

The reentry environment is far less severe. While some buffeting occurs as the vehicle reenters the thicker atmosphere at high speed, it is more like aboard an aircraft, and the maximum g level is only about 1.7. Touchdown speed is about twice that of a commercial airliner but since the pilots are among the best in the world, any astronaut will tell you that you’d likely never feel the “jolt” of a regular airplane landing.

For experiment design, this means that there is no need to be overly concerned about the effect of liftoff or reentry on your experiment. While the liftoff environment is severe, it will not affect any mixing of samples in the MDA, since the sample wells are not combined until after the Shuttle is in the “quiet” environment of orbit. At the end of the mission, the reentry environment is sufficiently quiet that it is not expected to have an effect on the experiment, either.

Samples (Fluids and Solids) that Can Be Used in the Experiment

Q: We could not find the following on the approved toxicology list [the Master List of Experiment Samples]. Can we use these?
Examples of requested samples from students and teachers across the participating communities:
• Is fluoride permitted in the experiment?
• Will you consider living things not on the materials list already?
• Is rubbing alcohol an approved material?
• Can we use magnets?
• Can we use vitamin K?
• Can we fly blush?
• We’d like to use a carbonated soft drink. Is that OK?

Unfortunately, if it is not on the Master List of Samples, the experiment will not be selected for flight. None of the samples listed above are on the Master List.

Q: Is it viable to expect a mouse cell to survive for the 12 days of flight, plus travel days?
This is a very different kind of question. It really asks details of the potential science to be undertaken, and not the operation of the minilab or the constraints on its operation. It is a question that should be addressed by the student team as part of their research and framing of the experiment. For example, this question could *be* the essential question for an experiment. We suggest you make connections with biologists, and biologists that have worked on microgravity experiments, and invite them to be advisors. Familiarize them with the MDA minilab, and the Master List of Experiment Samples (available in the Document Library, so they can help you noodle around.

Q: We are doing an experiment on vitamin D3 in space and we need to know if there is a way to measure the nutrients in a vitamin in space.
This question is more about the ways one can design the experiment rather than the operation of the minilab or the constraints on its operation. It is a question that should be addressed by the student team as part of their research and framing of the experiment. We suggest you make connections with nutritionists or food scientists in your community (you can start by talking with your school nurse, for example) and discuss different ways to measure the vitamin content of food products available to you in your community. If the nutritionists and food scientists help you come up with a good way to complete your investigation, you may want to ask them to be advisors on your proposal! Also, when designing your experiment, remember that you can make measurements of your sample before launch and after landing, but not while it is in the MDA minilab in space. So in this case you need to figure out how to make the measurements back in your community and need not worry about how to make such measurements in space.

Q: If I was to use the Planaria worm in Artesian well water should I expect to see a difference in regeneration in microgravity considering they will be submerged in water from the start?
This question is more about the ways one can design the experiment rather than the operation of the minilab or the constraints on its operation. In fact, this question could *be* the essential question for an experiment. When thinking about the experiment, remember that even though the Planaria worm is submerged in water in your laboratory, it still feels the gravitational pull of the Earth; when your experiment is in orbit, your worm experiences microgravity for the duration of the flight (in addition to normal surface conditions before and after the flight.) Is there a difference in the rate of regeneration because the worm spent 12 days in microgravity while regenerating? That could be the central question to be answered by the experiment! Note that the Microgravity Science Background and Microgravity Experiment Case Studies documents discuss the kinds of science one could imagine doing with various organisms and samples, including the Planaria worm. These documents can be downloaded from Document Library.

Q: Can we combine items from different material lists to help measure the results of our experiment?
Yes, you are allowed to combine materials listed under different categories of experiments.

Q: Would we be able to boil water before putting it in the well?
Yes, you are allowed to boil water before you provide the sample to be placed in the well.

Q: How could we design a successful experiment using mouse embryonic stem cells?
This question is more about the ways one can design the experiment rather than the operation of the minilab or the constraints on its operation. It is a question that should be addressed by the student team as part of their research and framing of the experiment. We suggest you make connections with stem cell researchers in your community and discuss different ways to conduct a viable experiment in microgravity. The scientists can then act as advisors in your proposal! Familiarize them with the MDA minilab, and the Master List of Experiment Samples (available in the Document Library, so they can help you noodle around.

Q: We need to know a place where we can obtain saltwater fish eggs and sperm of the same species.
Where you can obtain the samples (the fluids and solids) for your experiment is part of your experiment design, and so part of the competition. Therefore, we cannot give you an exact answer as to where you can purchase specific samples. Our advice would be to talk with the teachers in your school and perhaps in other schools in your area, or seek out researchers in your area. For example, biology teachers in a nearby high school may know many places in your community to purchase biological supplies. Also, you may just want to visit a local pet store and have a chat with their fish expert, or search for stores selling saltwater fish eggs online.

Q: May we use some unnamed bacteria?
You may use only the bacteria specifically listed on the Master List of Experiment Samples document, and even other strains of the bacteria listed on the document are not allowed. So, you must name the bacteria you’re using, and it must be one of the strains mentioned in the document.

Q: May we use salt water?
Since water and basic salt (sodium chloride) are both listed in the Master List of Experiment Samples, mixing the two is fine, so you can use salt water, as long as it is just a mixture of salt and water; you are not allowed to just scoop a sample of water from the ocean, for example, and use it as salt water.

Q: The master list has various metal elements such as nickel, aluminum, etc. I have a student who is interested in using calcium. Would this fall under this or any other category?
Since calcium is an alkaline earth metal, it can be flown under the entry:
Various metal filaments (only for Type 1 well) except for mercury and beryllium
listed in the Master List of Experiment Samples. As you can see, the description places some limits on the experiment details. While there is another entry for metals in the Master List:
Small pieces of metal: zinc, iron, nickel, aluminum (with no cadmium or beryllium)
this entry specifies that the pieces of metal have to be zinc, iron, nickel, or aluminum (with no traces of cadmium or beryllium). So, unfortunately other types of metal, including calcium, cannot be flow under this entry. Furthermore, ITA suggests that any pieces of metal a team wants to fly be placed not in a free-flowing fluid solution (so that there is no chance of the pieces of metal jamming the sliding of the blocks of the MDA) but inside or on the surface of solid materials such as silly putty, modeling clay, or cotton.

MDA Operation

Q: Is the MDA to fly on Shuttle sterilized before it is loaded with the experiment samples?
Yes, The MDA is soaked in a bath of 99% pure Isopropyl alcohol to sterilize. The MDA is not heat baked because the MDA blocks are made from a machined polymer material. Heating could cause warping of the block material, which would damage the unit.

Q: What is the temperature of the MDA during the experiment?
The experiments in the MDA will experience the ambient conditions of the Shuttle’s crew cabin, with a temperature of 70-75°F (21-24°C)—a shirtsleeve environment.

Q: Can a heat source be added?
There is no active environmental/thermal control of the minilab. As a result, the experiments in the MDA will experience the ambient conditions of the Shuttle’s crew cabin, with a temperature of 70-75°F (21-24°C).

Q: Are there windows in the experiment containment unit?
The entire minilab is placed inside an aircraft aluminum housing to help ensure that the sample materials are not introduced into the Shuttle crew cabin. Unfortunately this housing does not have windows.

Q: Can part of the analysis include a video recording of the experiment that would occur the duration of the experiment?
The aircraft aluminum housing of the MDA does not include windows, which means that no photographs or video of the experiment can be taken during the flight.

Q: My group’s project uses two wells and we are wondering if we are allowed to put two different substances in one well?
Yes, you can place two different substances in one well.

Q: Is it necessary to mix the substances in space? Or can the substances be mixed on Earth, to ensure that they actually mixed, and compare the Earth results to the space results?
You do not have to mix the substances in space; it is perfectly fine to mix the materials before the experiment is loaded on the Shuttle. In this case, you would just try and see how the results may differ between your experiment that spent 12 days in microgravity and the control you kept on Earth, a perfectly valid approach to designing your experiment. If you plan to mix your samples on Earth, you likely will want to use a Type 1 well for your experiment.

Q: What materials are the wells made of?
The blocks where the experiment wells are housed are made of an inert polymer; examples of these kinds of thermoplastics are Lexan and Lucite.

Q: Will the MDA be shaken or moved somehow to ensure that the samples mix thoroughly.
No, the MDA is not shaken in orbit to mix fluids. The fact is that fluids will not mix readily in microgravity because the effect of gravity is not help with the mixing. If a quick mix is required by an experimenter, there is an option (but NOT available for student experiments because of complexity and cost reasons) where magnetic material can be pulled through the two mixing fluids which forces a quick mix. However, this is not required for a 12-day mission such as STS-135. The wells are completely filled with the samples, which accentuates the mixing process in the MDA wells, and twelve days is normally plenty of time for mixing to take place. When designing your experiment, just remember to take into account the fact that the mixing is not instantaneous and will take a little time. If appropriate, you can add suitable material to speed up moving fluids between the wells. For example, if you want to expose a seed to moisture in orbit, you could place a strip of cotton in the well with the seed to speed up bringing moisture from a water-filled second well once the wells come into contact in orbit.

Q: Are the experiment capsules going to be shut? Does this affect experiments such as growing crystals, which we are proposing?
Yes, the experiments are sealed in their wells. If using Type 1 experiment slot, the well remains sealed throughout the flight, while if using Type 2, Type 2-Prime, or Type 3 slots, the experiment wells come into contact in orbit by having the two sliding blocks of the MDA move so that the wells come to be on top of each other (see the MDA Mini-Laboratory Operation page for more details.) As long as this effect is taken into account in the design of your experiment, there should be no problems with experiments such as growing crystals in the MDA. In fact, these kinds of experiments have been done successfully during earlier Shuttle flights, and many of the experiments listed in the Case Studies document in the Document Library have been conducted with the MDA in the past, including several crystal growth experiments.

Q: Are the samples loaded in the MDA in a sterile environment?
The laboratory where the experiments will be loaded to the MDA for the Shuttle flight is a class 100,000 clean room, but it is not sterile in the medical sense. The Fluid/Samples Compatibility Test will be done in a regular laboratory that is neither a clean room nor a sterile environment. However, the equipment used to place the samples into and extract them from the MDA are sterilized, as described earlier in this section of the FAQ. So, the equipment will be sterile, but the environment not.

More information on the MDA can be found on the MDA Mini-Laboratory Operation page.

MDA Loading and Harvesting of Samples (Fluids and Solids)

Q: How are fluids and solids extracted in terms of not causing damage? e.g. to seedlings or to living tissue or organisms.
ITA personnel that will fill and extract experiments in the MDA are skilled technicians with almost two decades of experience working with the MDA. Fluids are extracted by pipettor. A pipettor is analogous to a sophisticated eye dropper. Solids are very carefully extracted with tweezers. Any solids that cannot be extracted with tweezers because they have grown too large or become wedged or caught between the sliding blocks, are extracted by separating the blocks following fluid extraction.

Q: How is the sample provided to the student team in terms of carrier, e.g.. a vial?
ITA technicians will extract the experiment from the MDA well and place it inside a small inert polymer vial with an air tight threaded cap. The inert polymer vial is approximately 0.25” in dia X .075” long. This small vial is used for both fluid and solid samples. These small vials will be turned over to experimenters either onsite at the lab facilities outside Kennedy Space Center (KSC) following the landing or over-nighted to experimenters via FedEx. We are continuing to work on securing lab space for student groups near KSC.

Q: How are samples to be provided to ITA for loading? Are you looking for samples provided in a vial?
ITA will accept samples sealed in a small plastic test tube or another small, appropriately sealed plastic container.

Q: When do we need to send the supplies (experiment samples) needed for the experiment?
The Crtitical Timeline includes details on the timeline for providing the samples before and collecting the experiments after the Shuttle flight: You will need to provide your experiment samples by Launch minus 7 days if the samples are not time sensitive. If the samples are time sensitive, e.g., they contain living organisms, we will work with you to try and load the samples into the MDA 3 days before launch. It’s also important to recognize that time critical scientific research also flying in the same MDA as the SSEP experiments will be loaded last.

MDA Experiment Design and Ground-truth Block

Q: Other than leasing the MDA Demonstration Unit is there any way we can get our hands on duplicate vials/wells for the ground-truth experiments? Can we contact the supplier for this?
There is no ‘supplier’ in the sense you mean. The MDA is a unique, custom-designed laboratory for use on Shuttle and other orbital and sub-orbital vehicles. The wells are not a ‘standard’ size, and ITA, the company that builds and leases the MDA for research, does not have any vials with the dimensions of the MDA wells. They make available the MDA Demo Unit. But a simple alternative was developed by NCESSE. It is the MDA Experiment Design and Ground-truth Block, which has 16 MDA-sized wells in a clear Lucite block. All communities participating in SSEP on STS-135 have at least one of these blocks. Ask your SSEP Community Program Director to see your Lucite block. It is a great tool for designing your experiment too!

Q: We want to sterilize our Lucite block [the MDA Experiment Design and Ground-truth Block] and perform ground-truth biological experiments in it. Do you know if we can heat to 250 degrees-F without doing damage to the block?
Yes you can; the melting point for acrylic glass (e.g., Lucite, Plexiglas, etc.) is in the 400 to 600 degree-F range, depending on the specific material.

Q: I am wondering how organisms survive in the MDA for such a long period without oxygen.
Since the wells of the MDA are sealed from the outside, there is no good way to provide oxygen from outside the apparatus to replenish the oxygen naturally mixed in the samples (e.g., water.) You may want to look through the list of substances in the allowed materials list to see if there might be a way to introduce additional oxygen into the wells during the experiment. Or, as part of your experiment design, you may also want to take into account the possibility that most, if not all, organisms used in the experiment may perish during flight. In fact, based on similar experiments flown in the past, it is likely that most aerobic organisms will perish, though some could survive. However, even if the organisms were to perish during the flight, your experiment still will provide valuable data, as long as you conduct a control experiment using the same equipment on Earth, following the same timeline for execution of the experiment. Since you’re doing the same experiment in microgravity and on Earth, any differences in for example the appearance or structure of the dead organisms may be due to the lack (or presence) of gravity, rather than the fact that the organisms died at some point.

Q: Can you refrigerate samples (such as cheese or live specimens) before the flight?
Yes, samples can be refrigerated until they are loaded into the MDA before the flight. Just remember to add a special handling request in your proposal asking for refrigeration of the samples.

Q: What are the special handling requirements for different kinds of samples?
There are no special handling requirements from the program’s perspective apart from what is listed in the Master List of Experiment Samples (e.g., soil must be sterilized), except for samples that come from the human body (such as blood), which the student teams must have tested against a few diseases (Hepatitis B, Hepatitis C, HIV-1, HIV-2, HTLV-1, and HTLV-2) before they can be flown. Just make sure that all the samples you are planning to use are listed in the Master List of Experiment Samples. You may make special handling requests for your samples in your proposal form, but whether you’ll want to make these kinds of requests (e.g., request for refrigeration of samples until loading) will depend on your experiment design, of course, and is part of your proposal writing process.

General Questions about Designing SSEP Experiments and Writing the Proposal

Q: Do the student teams that are writing a proposal to conduct an experiment aboard the Shuttle need to test their experiment in advance, or do they just write the proposal, and only the winning group will test and conduct the experiment?
The students are writing an experiment proposal to try and secure the experiment slot aboard the Space Shuttle for their experiment, just like real scientists writing research proposals. Typically, scientists want to try and test their proposed experiment as much as possible before writing the actual proposal to make sure the experiment is viable. In fact, describing the tests in a proposal shows that the experiment is well thought out, and, since the basic operation of the experiment is now well understood, more likely to succeed. For the purposes of the SSEP, tests done by the student teams can answer simple questions such as “Do the samples fit in the wells?”, “Can I obtain the samples I need?”, “Will the seed germinate in 12 days?” that would not be possible to answer just by thinking about them. Also, if a student team is planning to conduct a ground-truth version of the experiment while the Shuttle is in orbit, it would be highly advisable to conduct a test at this time to make sure any easily preventable problems are eliminated before conducting the actual experiment. Therefore, while conducting test experiments before writing a proposal is not required, it is highly recommended.

Q: Will the student teams be given funds to test and conduct their experiments? Will the winning groups be given any money to purchase supplies to conduct their experiment?
The costs of supplies (fluids and solid samples) for testing the experiment design and the supplies for the actual experiment to fly aboard the Shuttle are the responsibility of the participating community. Student teams are encouraged to talk with their teachers and their SSEP community leaders to see if they can obtain funding for their experiment supplies. Given that the volumes of samples to be used in the MDA are quite small, the funds required for supplies to test (and eventually fly) the experiments should be quite reasonable. In fact, if you tell a vendor what the supplies are for – a Space Shuttle experiment – they might even provide the supplies at no cost – particularly if you tell them that SSEP would be happy to list them as a Local Partner organization!

Q: We have a question about page limit specifications. Is the two page limit for the experiment rationale the minimum or maximum? We have the same question for the experiment design-is the three page limit a minimum or maximum?
Both of these are maximum limits; that is, the experiment rationale must not be more than two pages, and the experiment design not more than three pages long.

Q: Are the proposals supposed to be written single- or double-spaced?
The proposal pages should be single-spaced.

See the Flight Experiment Proposal Guide (downloadable from the Document Library) for more details on how to prepare your proposal.

Q: We are using live specimens in our experiment. We were wondering what we would put under “special handling requirements” – does this just include the fact that our specimens would require late loading and early harvesting? Also, we were wondering if we needed to contact the SSEP in advance to let them know we are using live specimens. We were also wondering if there was some agent that could be added to our solution (such as Ethanol) once it is removed from the shuttle in order to kill and preserve our specimens (so that they could be examined later).
You can include in the special handling requirements any details of your experiment that might deviate from the normal experiment handling procedures outlined on the MDA Mini-Laboratory Operation page, which contains more information on how the samples will be loaded into and extracted from the MDA, forming the baseline for experiment handling. We definitely suggest writing in the special handling section of the proposal that you request late loading and early harvesting of the samples because you are using live specimens. As stated, the MDA samples are expected to be harvested within a day of the Shuttle landing, and they will be either turned over to student team representatives at Kennedy or overnighted to your school via FedEx. That means that you might expect to have the samples in hand within a day or two of the landing, and so it may not be necessary to do anything special to preserve the samples. However, if you have any special requests beyond the timing of the loading and harvesting in mind (such as refrigeration of samples before they are loaded into the MDA), be sure to include them in the special handling requirements section, and we’ll work with the experiment teams selected for flight to see how we might be able to accommodate the requests.

Q: Where I can get the username and password for the document library?
Your teacher can give you the username and password to access the Document Library. If your teacher does not have this information handy, she or he can contact your SSEP Community Program Director for the information.


Q: How can I find information about my community’s participation in the SSEP program?
See the SSEP Community Network page for more information on the communities participating in the program. The page includes links to the participating community profiles and blogs.


The SSEP on-orbit research opportunity is enabled through NanoRacks LLC, which is working in partnership with NASA under a Space Act Agreement as part of the utilization of the International Space Station as a National Laboratory.

The Student Spaceflight Experiments Program (SSEP) is a program of the National Center for Earth and Space Science Education (NCESSE) in the U.S., and the Arthur C. Clarke Institute for Space Education internationally. It is enabled through a strategic partnership with DreamUp PBC and NanoRacks LLC, which are working with NASA under a Space Act Agreement as part of the utilization of the International Space Station as a National Laboratory. SSEP is the first pre-college STEM education program that is both a U.S. national initiative and implemented as an on-orbit commercial space venture.