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Students will design and submit devices that carry water and air from a reservoir to a plant's root.

Plant Watering in Microgravity

The Challenge

What is the Challenge?

Teams of grade 9-12 students are challenged to design and build a device that allows air to penetrate towards the bottom on at least one side while liquid climbs along a different side. This can be achieved via geometry (i.e. ice cream cone shape), coatings or a combination of geometries that take advantage or shapes &/or coatings.

What forms do I need to apply?

Why is this Important?

Future long-duration space missions will require crew members to grow their own food, so, understanding how to water plants in microgravity is an important step toward that goal and for understanding how plants behave in such an environment. A key factor in this design challenge is that the plant’s roots need both water and air for the plant to grow well and delivering water and air in the apparent absence of gravity is challenging because they don’t mix well together.

Who Can Apply?

This design challenge is for students in grades 9-12 in the US and its territories, where teams will be favored over individuals in selection. Student proposals will be due in early Nov 2018. Selected teams will have the opportunity to build their experimental hardware and must then send it to NASA by February 15, 2019. Microgravity drop tower testing will take place in February and March 2019. Video results will be provided to the teams for analysis. NASA will then invite the top-performing teams to present their results in a student poster session at the 2019 meeting of the American Society for Gravitational and Space Research (ASGSR).

How Does A Team Participate

There are four phases and ways in which a team can participate in this challenge: 1) prepare your proposal, 2) build your test object(s), 3) analyze & document the results and 4)present at the 2019 ASGSR conference.

Each phase is separated by a submission to NASA – respectively of the proposal, test object(s), and written report. Subsequent phases rely on the earlier ones for continue participation. The proposal is used to determine whether a team will continue to phase 2, and the objects must be submitted for testing to enable phase 3. Finally, the test performance and written report will both be used to determine which teams are invited to present their results in the student poster session at the 2019 ASGSR conference (phase 4).

Prepare Your Proposal

1.1 Understand the challenge

The goal for Plant Watering in Microgravity is to design and build an object that will cause air to penetrate downward into the water on at least one side/surface while the water climbs along a different side/surface in microgravity.

Surfaces can be either hydrophobic or hydrophilic, that is “water fearing” or “water loving.” As an extreme example, the leaves of the Lotus flower have a superhydrophobic surface where researchers are working to mimic the Lotus effect. In free fall, objects with “water fearing” surfaces can be pushed from the water. This was goal of the previous Drop Tower challenge called Microgravity Expulsion from Water where students were asked to use hydrophobic properties to expel the objects from water under microgravity conditions.

When an object is floating on water in normal gravity, an upward force is exerted by water that opposes the weight of the less dense object. However, in microgravity, there is effectively no “weight” and the interaction between the object and the water is governed by the contact angle or wettability of the object by the water. Thus, to submerge the object, it may be necessary to increase the wettability of the object and this was the goal of the DIVER Challenge. For the Plant Watering Challenge, you must use these two basic properties to design and build your object.

Video of hydrophobic object

The expulsion of a floating object in microgravity can be seen in a video at The video is courtesy of researchers at Oregon’s Portland State University (PSU). As can be seen, the ball ‘jumps’ out of the water in microgravity. It must be emphasized that challenge’s test objects must sink in the water in normal gravity, while the object in the video instead floats. Please know that the challenge staff will not share the hydrophobic treatment of the ball in this video, as we are looking for participating teams to research and find their own approaches to the challenge rather than copy what was done in the video.

Video of hydrophilic object

Watch the YouTube video on Ping Pong Ball On Water the response of a floating hydrophilic object to free fall, where it can be seen to dive into the water. IT was from an experiment created by a middle school team for a previous drop tower competition.

Scoring on the challenge

An object’s score is the maximum vertical distance (i.e., delta) between the air’s downward penetration and the water’s rise – in both cases along on the object’s surfaces.

In case of a tie, the following are the tiebreakers:

  • 1st: volumetric amount of gas dive
  • 2nd: delta height of liquid rise.

Design your test object(s)

Design – Based on your research, design your test object(s) using the guidelines below to achieve the highest score as described in the previous section. Note that NASA will provide the rest of the experiment hardware including colored water, the three water containers in which your objects will be tested (with one object per container), the video camera, and lighting.

Number – Each selected team can submit up to three different objects for testing. This allows a team to compare test results, e.g., in the required report and – if invited – at the 2019 ASGSR conference. Of course, at least one test object must be proposed and – assuming selection – built and shipped to NASA for testing.

Materials – The objects must be fabricated from see through or transparent material such as plastic or . Glass and similarly fragile materials are unacceptable. Coatings must also be made of transparent materials. Water-soluble materials and coatings are prohibited, as are materials and coatings which chemically react with water. For safety, corrosive, toxic, and radioactive materials are prohibited. Other hazards such as sharp edges, compressed gases, batteries, and lasers are not allowed. Small creatures (such as insects), are not allowed, whether they are dead or alive. Other biological samples, such as foods, are generally not allowed, but organic materials such as wood, cork, cotton, wool, and leather are allowed exceptions.

Containers – Each object will be tested in its own container of water. The vessel’s interior is a rectangular prism which is 210 mm tall (8.25in) and 63 mm (2.4 in) across, where the cross-section is square. Three independent containers, each with an object in water, will normally be tested during a single drop operation. Each container will be filled with 40 ml (1.6 in) of water and then a team’s object is placed inside. The team must specify if a certain orientation is required, e.g., in a drawing. Three objects, each in a separate container, are typically tested during a single drop operation.

Size – The longest dimension of each object shall be no more than 60 mm (2.36 in) and no less than 5 mm (0.2 in).

Air Penetration (Diving) – The portion of the object that will dive must do so because of their wetting characteristics and must not dive because of other reasons, e.g., mechanical propulsion initiated during free fall, etc. are not allowed.

Liquid Climbing (Water Movement) – In microgravity conditions, the water must rise because of the object’s hydrophilic surface and must not rise because of other reasons, for example, mechanical propulsion initiated during free fall.

Prepare and submit your proposal

Prepare your proposal using the entry form, in Appendix A which will be made available online,. The proposal will include information about your team plus descriptions and depictions of your test object(s). Each proposal shall consist of a single file, in either doc or pdf formats, into which all figures must be ‘pasted.’ The file must be less than 10 MB in size. E-mail the proposal to by no later than Nov. 20, 2018. The proposals will be reviewed and selections will be announced via e-mail to all proposers by mid-December. Teams who’ve been selected for testing will continue to subsequent phases.

Build your test object(s)

mid-December to Feb. 10

Assuming that your team’s proposal is selected, build your test object(s) following the rules in the design section (1.5) of this guide. Also review the Key rules and hints as you design your test object. It is acceptable to change your design(s), e.g., based on research conducted after your proposal submission. But you are strongly encouraged to check with to ensure that the new design(s) are acceptable. Note that you may want to make extra copies of your test objects to keep because the objects sent to NASA won’t be returned, unless at the 2019 ASGSR conference.

It is highly recommended that you conduct your own microgravity trials: Consider putting trial objects with water in a plastic jar and dropping the jar in front of a video camera to get a glimpse of what happens in microgravity. Just a 4-foot fall provides 0.5 seconds of microgravity, which can provide a hint of what will happen in the 79-foot fall in NASA’s 2.2 Second Drop Tower. For inspiration on conducting your own drop research, check out the Fire in Free Fall video by Physics Girl Dianna Cowern.

Once your object(s) are ready, ship your test object(s), with appropriate care in packing, to the following address. The object(s) must arrive at NASA by no later than February 15, 2019.

  • Plant Watering c/o Nancy R. Hall
  • NASA Glenn Research Center
  • 21000 Brookpark Road, MS 77-7
  • Cleveland, OH 44135

Late objects will be disqualified from the competition!

Analyze & document the results

mid-December to May 1

Draft written report

Report writing can and ideally should begin after your team’s proposal has been selected for testing. Even before your object(s) are built and the microgravity test conducted, your team can begin writing an introduction based on what you’ve learned in preparing your proposal and from tests performed by your team. References can also be documented. You can also draft the section describing your experiment (i.e., attempt at the challenge), once the design of your test object(s) has been finalized. But of course, you’ll need to wait until the tests have been conducted to write the results, discussion, and conclusions. Furthermore, the abstract should be the last section of your paper to be written.

There is no required format for the written report, but it is suggested that teams generally follow the guidance found in “A Guide to Writing a Scientific Paper: A Focus on High School Through Graduate Level Student Research” by Renee A. Hesselbach et al.

Analyze results

NASA’s goal is to electronically provide the test data to each team within two weeks of their tests and by at least April 1, with objects tested in the order received at NASA. For each test, the data will consist of a video filmed at 30 frames per second showing the objects’ motion during the drop tests, tentatively supplemented by still images taken from the video.

One option for analyzing the video results is through NASA’s Spotlight software. However, the software is not currently supported and Spotlight-8 is not compatible with current versions of Microsoft Windows. So Spotlight-16 should be used if this option is taken, although many NASA researchers are now instead using ImageJ, which is freely available from the National Institute of Health (NIH). Meanwhile, the free Tracker software is shared by Open Source Physics as a tool for “physics teaching and student activities.” The Tracker software has notably been used by some participants in past drop tower challenges.

Position measurements can also be made with simple graphic software that continually reveals the position of the cursor. Simply load an image, move the cursor to each desired position and write down their values (i.e., by hand). Repeat with successive video frames to track positions as a function of time. Microsoft Paint is an example of such software, where it reveals the position of the cross-hairs in the bottom left of the window (in pixels and relative to the image).

Measurements can also be made manually by taping a transparent overlay to your computer monitor and marking the positions using a permanent marker. You can make measurements for multiple images (i.e., times) using the same transparency, where it may be helpful to mark each position with the image number (or time).

Please understand that these are just suggestions and are not meant to indicate endorsements by NASA or the federal government.

Complete and submit written report

Using the results from the testing, complete your written report (e.g., as described in section 3.1) and e-mail it to by no later than May 1, 2019.

Presentation at ASGSR Conference

present at the 2019 ASGSR conference

mid-May to fall 2019

Based on their scores and written reports, some teams will be invited in mid-May to present their results in a student session at this annual meeting. All participating teams will be contacted by e-mail about the selections.

The meeting dates and location have not yet been announced, but it is expected that the conference will be held in October or November with the student day on a Saturday. Admission will be free on that day for a limited number of students who present their posters at the conference, as well as accompanying advisors and chaperones. The free admission does not include meals or participation in the evening banquet, although tickets could optionally be purchased for the latter.

It is tentatively expected that financial support will be made available to help invited non-local teams travel to the conference for this purpose. That anticipated travel

support is unlikely to cover the full cost of the trip, so teams would need to take action to address the likely shortfall. The travel support would likely be up to $500 per student presenting at the conference. It would be provided as a check at the conference and the funds could be used for any associated costs, including the cost for the adult travel. Receipts would not be necessary as it is not a reimbursement.

Awards will be presented to teams on the student day based on their posters and success with the challenge. The conference will also include opportunities for students to participate tour the exhibit hall, attend research presentations, and interact with microgravity researchers and other students.


For an introduction to the research to enable farming in space, check out these videos:

Meanwhile, educator resources with relevant classroom activities can be found at:

A social-media option for following the ongoing research includes:

What is Microgravity?

For additional inks on how to conduct your own microgravity test, different types of surfaces, analysis software and A Guide to Writing a Scientific Research Paper, download and check out Appendix B of the Plant Watering How to Guide.


Q: How are microgravity conditions created?
A: During its fall in NASA’s 2.2 Second Drop Tower, each object behaves as if there is no gravity, just as if it were in orbit on the International Space Station (ISS). Our sensation of gravity and weight comes from a resistance to its pull, for example because of the floor preventing us from falling. If we are freely falling (e.g. after jumping off a diving board), we feel weightless and free-fall is the basis for many amusement park rides. This occurs because all objects fall at the same acceleration unless acted upon by another force. As one result, the astronauts and the ISS fall together (around Earth) such that the astronauts float within the space station. This happens even though the space station is so close to Earth that the gravity is only about 10% less than that at Earth’s surface.

Q: Can home schools participate?
A: Yes, where teams don’t need to be affiliated with a school at all and can be formed from any group of youth in grades 9-12 including siblings, neighbors, and friends as a few examples. But note that preference in proposal selection will be given to teams over individual participants.

Q: Does the number of objects proposed affect the odds of selection?
A: Preference will be given to plans with two or more objects because their results can be compared. Keep in mind that each team is limited to a maximum of three test objects.

Q: Where do we get the entry form?
A: An entry form can be found in Appendix or on the Plant Watering in Microgravity website

Q: What file formats are acceptable for the proposals?
A: The proposals must be submitted as either doc or pdf files. Teams submitting their proposals in other file formats risk rejection.

Q: Are drawings required for the proposals?
A: Yes; each proposals must include both descriptions and drawing(s) of each test object(s). The drawing(s) must be ‘pasted’ into the proposal, so the proposal will consist of a single file.

Q: What is the maximum file size for the proposals?
A: Each proposal’s file must be less than 10 MB or it will not be deliverable to the challenge staff.

Q: Can we build test object(s) using a 3-D printer?
A: Yes.

Q: Can we simply buy test object(s)?
A: Yes.

Q: Do we get our test object(s) back?
A: No

Q: Is the water used in the drop tests distilled, de-ionized, etc.?
A: It is simply tap water at room temperature that will tentatively be dyed with food coloring to allow us to better see the fluid behavior.

Q: Can a team submit more than one proposal?
A: No, because a student cannot be part of more than one team. However, your organization (e.g.,chool, Scout troop, club, etc.) can submit up to five proposals.

Q: When you say “test objects must sink”, does that mean the object must be totally submerged?
A: No, it needs to be partially submerged


The specifics of this challenge are still being developed, where the details should be available by September 2018. A web page has yet to be created for the challenge, but links to the updated information will be made available through web sites such as: Furthermore, the challenge staff can be e-mailed at

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