1:45 PM - 3:15 PM
[O11-P102] Study on Capture Angles and Surface Cushioning to Improve the Efficiency of Space Debris Removal Devices
Keywords:Space debris, Capture Device, Model Experiments
1.Background and Motivation
Space debris are artificial objects orbiting the earth which are no longer functional and orbiting the earth at an average speed of 7 to 8 km/sec. Debris are considered as one of the significant problems of the space environment, because it could collide with operational satellites, damaging or destroying them. In fact, there have been accidents that have damaged parts of the International Space Station and caused threats to the safety of the astronauts during their stay. Their number has increased about tenfold in 50 years, and as the number of debris continues to grow, they are expected to hinder human space activities and space utilization in the future.
Although numerous space debris removal devices are currently being proposed, none have yet been fully developed and demonstrated in space. In addition, all the numerous removal ideas involve controlling the device such that it can capture the debris at a fixed relative attitude, for example, at 90°angle, and moving at the same speed. Capturing debris in face-to-face position requires a high level of technical skill. Through this research, I have considered the advantages and disadvantages of the debris removal devices currently being devised and have aimed to pursue a removal method that allows for capture with some degree of angle.
2.Hypothesis
Based on previous research, when considering the following three perspectives, “advanced technical capabilities required for fine-tuning the removal device attitude and position against the debris,” “risk of new debris from the removal device due to destroying debris during capture,” and “cost per removal device: ratio of production cost and number of capture”, I considered the “sticking technique” using adhesives to be the most effective removal method. At the same time, I hypothesized that by adding cushioning to the back of the adhesive in the removal device, the area where the debris collides with the capture surface of the device would deform, making it easier to capture the debris.
In this experiment, I considered the capture of debris with the relative velocity between the debris and the removal device as close to zero as possible.
3.Experimental Methods
To investigate the optimum value of debris catchability on the capture surface of the removal device, I prepared several patterns of cushion (using sponges) thickness and debris impact angles, and conducted experiments in the following order. To determine whether changes in cushioning affect capture, I prepared four types of sponges of different thicknesses (0.0 cm, 1.0 cm, 2.0 cm, and 3.0 cm) under the capture surface. At this time, I used adhesive cloth tape as an adhesive. I rolled a tennis ball (6.7 cm in size, 57.7 g in mass) imitating debris at a speed of 0.76 m/sec, 1/10000 of the speed of debris, from 70 cm from 1, using a slope. I applied the same procedure at 5 different angles (15°, 30°, 45°, 60°, and 90°). Process 3 was applied six times for each of the cushion thickness and angles combination.
4.Experiment Results
I evaluated the degree of ball capture in five levels, averaged the data of six sets per angle, and created a graph with the angle on the horizontal axis and the average value on the vertical axis. The results of the experiment are as follows.
At 15°: Could not catch the ball at all thicknesses
At 60° and 90°: Caught the ball at all thicknesses
At 45°: With a sponge of any thickness, the average value increased about 4 times compared to the case with no sponge
At a sponge thickness of 3 cm, the capture rate was 100% at all angles except 15°
5.Conclusion
Based on the results of the experiment and post-experimental discussion, advantages and disadvantages of the proposed method for debris capture are as follows.
Advantages The closer to 90°, the higher the capture rate. The thicker the sponge is, the more strongly the ball was captured. Even at 1 or 2 cm, the percentage of capture was higher compared to no sponge. Disadvantage The thicker the sponge, the larger the non-adhesive surface, which is thought to cause debris to bounce back more easily. The thicker the sponge, the larger the overall size of the removal device, making it harder to carry to space and more difficult to operate in space. Thicker sponges reduce cost performance. Adding cushioning to the removal device to absorb impact would make debris removal easier, since it would be more likely to capture the debris without needing to align the attitude of the removal device to capture at 90°position, rather than trying to capture it as it is. However, the optimal value for the thickness of the sponge, which is neither too thick nor too thin, should be considered.
Space debris are artificial objects orbiting the earth which are no longer functional and orbiting the earth at an average speed of 7 to 8 km/sec. Debris are considered as one of the significant problems of the space environment, because it could collide with operational satellites, damaging or destroying them. In fact, there have been accidents that have damaged parts of the International Space Station and caused threats to the safety of the astronauts during their stay. Their number has increased about tenfold in 50 years, and as the number of debris continues to grow, they are expected to hinder human space activities and space utilization in the future.
Although numerous space debris removal devices are currently being proposed, none have yet been fully developed and demonstrated in space. In addition, all the numerous removal ideas involve controlling the device such that it can capture the debris at a fixed relative attitude, for example, at 90°angle, and moving at the same speed. Capturing debris in face-to-face position requires a high level of technical skill. Through this research, I have considered the advantages and disadvantages of the debris removal devices currently being devised and have aimed to pursue a removal method that allows for capture with some degree of angle.
2.Hypothesis
Based on previous research, when considering the following three perspectives, “advanced technical capabilities required for fine-tuning the removal device attitude and position against the debris,” “risk of new debris from the removal device due to destroying debris during capture,” and “cost per removal device: ratio of production cost and number of capture”, I considered the “sticking technique” using adhesives to be the most effective removal method. At the same time, I hypothesized that by adding cushioning to the back of the adhesive in the removal device, the area where the debris collides with the capture surface of the device would deform, making it easier to capture the debris.
In this experiment, I considered the capture of debris with the relative velocity between the debris and the removal device as close to zero as possible.
3.Experimental Methods
To investigate the optimum value of debris catchability on the capture surface of the removal device, I prepared several patterns of cushion (using sponges) thickness and debris impact angles, and conducted experiments in the following order. To determine whether changes in cushioning affect capture, I prepared four types of sponges of different thicknesses (0.0 cm, 1.0 cm, 2.0 cm, and 3.0 cm) under the capture surface. At this time, I used adhesive cloth tape as an adhesive. I rolled a tennis ball (6.7 cm in size, 57.7 g in mass) imitating debris at a speed of 0.76 m/sec, 1/10000 of the speed of debris, from 70 cm from 1, using a slope. I applied the same procedure at 5 different angles (15°, 30°, 45°, 60°, and 90°). Process 3 was applied six times for each of the cushion thickness and angles combination.
4.Experiment Results
I evaluated the degree of ball capture in five levels, averaged the data of six sets per angle, and created a graph with the angle on the horizontal axis and the average value on the vertical axis. The results of the experiment are as follows.
At 15°: Could not catch the ball at all thicknesses
At 60° and 90°: Caught the ball at all thicknesses
At 45°: With a sponge of any thickness, the average value increased about 4 times compared to the case with no sponge
At a sponge thickness of 3 cm, the capture rate was 100% at all angles except 15°
5.Conclusion
Based on the results of the experiment and post-experimental discussion, advantages and disadvantages of the proposed method for debris capture are as follows.
Advantages The closer to 90°, the higher the capture rate. The thicker the sponge is, the more strongly the ball was captured. Even at 1 or 2 cm, the percentage of capture was higher compared to no sponge. Disadvantage The thicker the sponge, the larger the non-adhesive surface, which is thought to cause debris to bounce back more easily. The thicker the sponge, the larger the overall size of the removal device, making it harder to carry to space and more difficult to operate in space. Thicker sponges reduce cost performance. Adding cushioning to the removal device to absorb impact would make debris removal easier, since it would be more likely to capture the debris without needing to align the attitude of the removal device to capture at 90°position, rather than trying to capture it as it is. However, the optimal value for the thickness of the sponge, which is neither too thick nor too thin, should be considered.