Presentation Information
[O12-P77]The behavior of a Mentos geyser in microgravity
*Ao Nakamura1, *Oryza Udagawa1, *Hayato Mizutani1, *Rui Kitayama1 (1. Tokyo Gakugei University Senior High School)
Keywords:
microgravity,free-fall apparatus,drag-shield-type,Mentos Geyser
1.Background and Objective
In recent years, space exploration efforts have intensified worldwide, making the elucidation of physical and chemical phenomena under microgravity an urgent priority. Research on liquids—which are closely tied to our daily lives—is becoming indispensable as we prepare for a future where living in space is commonplace. Therefore, the objective of this study is to use an in-house free-fall test apparatus to verify how a "Mentos Geyser" behaves in space, while also examining the nature of carbonated beverages in a microgravity environment.
2.Data and Analysis Methods
The microgravity environment was generated using the TGu-DS2, a drag-shield-type free-fall apparatus developed in previous studies. The TGu-DS2 was dropped from the third floor to the first floor of a high school building (a height of approximately 10 m), creating a microgravity environment of 10-3~10-2G for approximately 1.0 second. A camera, lighting, and an accelerometer were mounted inside the inner capsule; for this experiment, the Mentos Geyser apparatus was placed inside this capsule and filmed. Comparative experiments were also conducted under normal gravity conditions on the ground. In this study, Coca-Cola Zero and grape-flavored Mentos were used, as previous research indicated they produce a particularly vigorous reaction.
3.Results
The mechanism that drops the Mentos was activated, and the Mentos were inserted into the cola approximately 0.5 seconds before the drop of TGμ-DS2. Upon reviewing the video inside TGu-DS2 during the fall, no significant reaction was observed during the approximately 1.0 second of weightlessness. At that time, the temperature of the cola was 18.1degrees Celsius, with 235.6 g of cola and 11.2 g of Mentos.
4.Consideration
In experiments conducted on the ground, the reaction began within 1.0 second after adding Mentos, so it was considered that 1.0 second is sufficient for the reaction to start. However, under microgravity conditions, no noticeable reaction was observed within 1.0 second. From this, it was concluded that the Mentos geyser phenomenon is highly dependent on gravity. One reason for this is that on the ground, gravity causes the Mentos to quickly sink to the bottom, increasing the total amount of cola that comes into contact with the Mentos. Additionally, the generated bubbles immediately rise due to buoyancy, and as they rise, they push the liquid upward. In contrast, under microgravity, almost no gravitational force acts on the Mentos, so after being dropped into the cola, they drift inside the bottle. Furthermore, since buoyancy does not occur, the generated bubbles are thought to remain in place.
5.Future Prospects
In this study, the experiments were limited to a short duration of approximately 1.0 second, corresponding to the operational time of the drop test apparatus. Furthermore, the total number of experimental trials was limited due to the significant time required for each setup, and a certain amount of time elapsed between opening the beverage and conducting the experiment. In the future, we aim to conduct experiments that replicate ground-level conditions as closely as possible, while specifically isolating the effects of gravity.
6.Acknowledgements
We extend our deepest gratitude to Mr. Rui Nishimura and Mr. Kenji Noshirotani of Tokyo Gakugei University High School for their daily supervision. We also thank the school alumni and contributors for funding the TGu-DS2 apparatus, and our fellow students for their assistance in experimental preparations. Additionally, LLMs (ChatGPT, Gemini) were utilized for researching prior studies and proofreading this document.
In recent years, space exploration efforts have intensified worldwide, making the elucidation of physical and chemical phenomena under microgravity an urgent priority. Research on liquids—which are closely tied to our daily lives—is becoming indispensable as we prepare for a future where living in space is commonplace. Therefore, the objective of this study is to use an in-house free-fall test apparatus to verify how a "Mentos Geyser" behaves in space, while also examining the nature of carbonated beverages in a microgravity environment.
2.Data and Analysis Methods
The microgravity environment was generated using the TGu-DS2, a drag-shield-type free-fall apparatus developed in previous studies. The TGu-DS2 was dropped from the third floor to the first floor of a high school building (a height of approximately 10 m), creating a microgravity environment of 10-3~10-2G for approximately 1.0 second. A camera, lighting, and an accelerometer were mounted inside the inner capsule; for this experiment, the Mentos Geyser apparatus was placed inside this capsule and filmed. Comparative experiments were also conducted under normal gravity conditions on the ground. In this study, Coca-Cola Zero and grape-flavored Mentos were used, as previous research indicated they produce a particularly vigorous reaction.
3.Results
The mechanism that drops the Mentos was activated, and the Mentos were inserted into the cola approximately 0.5 seconds before the drop of TGμ-DS2. Upon reviewing the video inside TGu-DS2 during the fall, no significant reaction was observed during the approximately 1.0 second of weightlessness. At that time, the temperature of the cola was 18.1degrees Celsius, with 235.6 g of cola and 11.2 g of Mentos.
4.Consideration
In experiments conducted on the ground, the reaction began within 1.0 second after adding Mentos, so it was considered that 1.0 second is sufficient for the reaction to start. However, under microgravity conditions, no noticeable reaction was observed within 1.0 second. From this, it was concluded that the Mentos geyser phenomenon is highly dependent on gravity. One reason for this is that on the ground, gravity causes the Mentos to quickly sink to the bottom, increasing the total amount of cola that comes into contact with the Mentos. Additionally, the generated bubbles immediately rise due to buoyancy, and as they rise, they push the liquid upward. In contrast, under microgravity, almost no gravitational force acts on the Mentos, so after being dropped into the cola, they drift inside the bottle. Furthermore, since buoyancy does not occur, the generated bubbles are thought to remain in place.
5.Future Prospects
In this study, the experiments were limited to a short duration of approximately 1.0 second, corresponding to the operational time of the drop test apparatus. Furthermore, the total number of experimental trials was limited due to the significant time required for each setup, and a certain amount of time elapsed between opening the beverage and conducting the experiment. In the future, we aim to conduct experiments that replicate ground-level conditions as closely as possible, while specifically isolating the effects of gravity.
6.Acknowledgements
We extend our deepest gratitude to Mr. Rui Nishimura and Mr. Kenji Noshirotani of Tokyo Gakugei University High School for their daily supervision. We also thank the school alumni and contributors for funding the TGu-DS2 apparatus, and our fellow students for their assistance in experimental preparations. Additionally, LLMs (ChatGPT, Gemini) were utilized for researching prior studies and proofreading this document.