INTEGEReX 42 Intelligent Gecko Research and

Exploration Boots

By

Aryaman Arora

Common App ID- 20383368

DELHI PUBLIC SCHOOL RK PURAM, NEW DELHI, INDIA

Technical Concept Report

1.Introduction to the Problem

The following are some real experiences of astronauts that highlight problems faced by them

during EVA’s:

1. On an Apollo 16 EVA, Charlie Duke tried to jump but fell backwards and landed on his PLSS.

2. Aldrin commented that the rocks were rather slippery. "The powdery surface fills up the fine

pores on the rocks," he said, "and we tend to slide over them rather easily.”

3.Armstrong said,"Because the terrain varies a good bit relative to your ability to move over it,

on the Moon, you have to keep a good eye out four or five steps ahead.”

4. The most widely used method for locomotion is jumping or kangaroo hopping. Armstrong

showed us it was a dangerous proposition, "I did some fairly high jumps, and found that there

was a tendency to tip over backward on a high jump. One time I came close to falling.”

Jumping too high results in wasting time and also you cannot control where you land.

These incidents show that a solution is required to combat microgravity environments and

help astronauts do more work during EVA’s.

http://cdn2.alphr.com/sites/alphr/files/styles/16x9_480/public/2015/12/astronauts_fallin

g_over.jpg?itok=met2vcq2

Locomotion has been a problem ever since the first moon landing of Apollo 11. Astronauts

have given accounts of how EVA’s were extremely tedious and risky due to the low gravity on

the moon. It had been time consuming and shortened the EVA reducing the amount of

productive work that could be done. The time to perform tasks on the lunar surface was

significantly longer (on the order of 70%) than the time to perform the same tasks in 1g

gravity. Repairs outside the shuttle and the ISS have been tough due to lack of a surface to

stand on. Expeditions to Mars and other planets will increase the need for repairs.

The key problems-

1. Momentum and inertia are functions of mass. An 80 Kg astronaut with 55 Kg of equipment

on Earth would weigh 22.5 Kg on the moon but the astronaut would still have 135 Kg as the

mass.

To move they would have to overcome inertia, and inertia on the moon would be same as

Earth and the momentum too would remain the same. Due to lighter weight the ability to stop

and move is impaired. Grip is dependent on friction and friction depends on the magnitude

with which you're being pulled down towards the surface. Hence low gravity means less

friction and therefore less grip. So running means slipping and sliding, and stopping means

skidding.

2. Falling on the moon can have disastrous consequences like a puncture in the spacesuit,

lunar dust coating and contamination, seal failures, and clogging of mechanisms. The

astronaut could die if a wrong switch or a valve is turned off while falling. After falling it is

extremely difficult to get back up due to the mass of the spacesuit wasting precious energy

and time.

https://cdn.theatlantic.com/assets/media/img/mt/2015/09/fall_collage1/lead_large.jpg?14

42947969

3. While walking, the astronaut may bump their boots on small rocks or small debris

causing cracks in the boot. If the astronaut falls down, high momentum collisions with sharp

objects can pierce the boot leading to rapid depressurization through even small holes also

making them bigger in the process.

4. Bone atrophy is another major problem for astronauts, caused due to the microgravity

environment and the feeling of weightlessness. Each month, astronauts could lose up to 1

percent of their bone density which would be detrimental over a long period of time. By

wearing INTEGEReX42 the astronauts would need to apply some force and allow them

to walk normally.

Materials and Protection:

1. Lunar dust due to its abrasive nature has previously damaged space boots. In

INTEGEReX42, setae at we walk on Earth and this would help in reducing the chance of bone

atrophy.

5. Currently repairs aboard the ISS are made possible by using handrails and footholds and

are inconvenient for the astronauts to use.

Setae which are in contact with the surface would not get damaged since carbon nanotubes

have an extremely high tensile strength and would also be protecting the rest of the boot

from damage by not letting them come in direct contact with the surface.

The pistons used for retraction of setae cannot be jammed because they are protected by the

control unit above and the grid layer below, thus no part of the pistons is directly exposed to

the environment.

2. The boot can been designed with hard materials like Zylon and also has self healing

properties filling punctures instantaneously. The astronaut may step on rough surfaces

during the EVA but Carbon Nanotubes being one of the strongest materials in use will be able

to resist this damage.They can also be repaired after an EVA and due to the density of CNT’s

an emergency will not occur

https://www.le.ac.uk/ph/faulkes/web/images/moonboulders.jpg

.

http://www.lpi.usra.edu/lunar/samples/apollo/tools/images/hammer_lg.gif

Walking Mechanism:

Due to the shear adhesion force being far more than the normal adhesion force the boots get a

strong adhesion force while the lower normal adhesion force allows the boots to be readily

detached in the normal direction when tilted with an angle above 30 degrees. Thus when

the astronauts boot touches the surface it gets stuck to the surface and when the

astronaut tilts the boot, it detaches and the astronaut can lift his foot in the normal

direction and this procedure would be repeated thus simulating the way we walk on Earth.

Currently astronauts undergo extensive training to walk in microgravity environments and

are taught different gaits and hopping techniques that help them perform the EVA. Our boots

would reduce the amount of training required.

Thus the inability of existing space boots to help astronauts perform EVA’s safely and

effectively due to the microgravity environments is why we need INTEGEReX42.

2.Technical Summary INTEGEReX42 are space boots inspired from the concept of gecko adhesion and are designed

to help astronauts perform EVA's safely and efficiently. Setae arranged in the form of grids

provide adhesion to the surface and thus would enable astronauts to navigate the surface

easily and safely. By using Infrared sensors and artificial intelligence, INTEGEReX42 can

detect obstacles and alert the astronauts. The control unit used in INTEGEReX42 will be

outsourced Arduino modules. The upper part is made using materials that can endure rough

surfaces like that of the moon and are also self healing and recyclable. INTEGEReX42 are

modular boots and hence can be customised as per the requirements of different EVA's and

IVA's by adding or removing certain components.

Existing space boots are designed with the sole purpose of protecting astronauts from a

vacuum or low pressure environment and perform no other function as such while

INTEGEReX42 perform a multitude of functions that even spacesuits are not capable of

performing thus making our product unlike anything out there in the industry.

INTEGEReX42 uses technology inspired from gecko lizards. An array of synthetic setae made

of carbon nanotube spatulae will use Van Der Waals force of attraction to help the astronaut

combat weightlessness. Van Der Waals Force is the intermolecular force between atoms or

molecules that are not chemically bonded to each other. This force comes from fluctuations in

charge distributions between neighboring molecules which naturally fall into sync, creating

an attractive force. These fluctuations are minute and thus the molecules cannot be termed as

polar.

The bending of carbon nanotubes will allow side contact thus increasing the surface area in

contact generating 10-20 times more force than a normal hemispherical tip contact . CNT's

being the strongest materials will prevent the setae from getting damaged easily. The

nanotubes will be engineered precisely to prevent the entry of planetary dust inside the boot.

Single-walled nanotubes will be used due to a higher height-radius ratio allowing more

area to come in contact as well as more such spatula to be attached to the sole. Many such

spatula will be clustered together to form a seta.

Image source:https://robotics.eecs.berkeley.edu/~ronf/Gecko/prl-friction.html

[Side contact of Carbon Nanotube Spatulae]

A backing grid layer will be added on the completely detachable and replaceable sole on

which the setae will attach. Space will be provided above this as the setae will be retractable

to control the attractive force between the ground and the boots. Electric pistons will handle

this retraction using signals from a control unit inside the boot. The astronaut will be able to

choose between predefined levels and accordingly the control unit will send signals to

specific pistons to uniformly distribute the setae throughout the sole of the boot.

[Layers: Top to Bottom - Polyurethane Inner Sole; Control Unit; Piston Layer; Backing Layer;

Sole with Setae]

The astronauts require training in

the walking procedure of the boots

but this will be a lot easier than

current regimes.The boots will

prevent tripping over the rough

surface as well as physical fatigue

during surface operations by

making navigation easier. Since

some amount of force will be

required for lifting the feet, it will

lead to regular exercise and will

prevent bone atrophy.

The boots will work on all kinds of

terrains and external conditions

will have minimal effect on the

functioning. The Young-Dupre’s Liquid Droplet Contact Angle equation will not apply here.

Instead, Hiller’s experiments which show that Van Der Waal’s force is not related to the

liquid contact angle when two different kinds of molecules are in contact will be used to

prove that the technology is feasible.

The boot will be strong and self healing due to the mixing of Carbon Nanotube Reinforced

Polyhexahydrotriazine with a chosen polymer. Strong hydrogen bonding between PHT

molecules will allow immediate healing of any crack.

The boot will be worn on top of the cooling and pressure layers of the spacesuit and will have

minimal dependence on the rest of

the suit, even though it will be joint

to the lower torso unit. A

completely independent infrared

obstacle sensor module can be

strapped to the lower-shin part of

the boot. This sensor will send feed

to a computer on the settlement or

shuttle which will process the data

and guide the astronaut via

computer generated voice. Precision

Ultrasonic waves will be used for

maintenance after EVA’s.

Thus, a system of technologies will combine to make EVA operations smoother.

3.Background Technology Different kinds of technologies will be incorporated to produce a single INTEGEReX42

module. Apart from using a self healing material produced by IBM using advanced technology,

embedding the setae will be a painful task taking place on the nano-scale.

Producing the Sole

INTEGEReX42 has a detachable sole made out of silicone rubber. On top of the silicon

rubber, a stencil will be kept during manufacturing, which will contain nanopores in the form

of a grid. Ultraviolet light will be focused on the stencil. This light will penetrate through

the nanopores present in the stencil. The UV light will burn the image of the grid onto the

silicon rubber sole. The sole will then be bathed in an acid, thus carving out the intricate grid

system.

The same process will be used to create a duplicate grid layer of the same which will be a part

of the boot. Since the sole is modular, when the sole is attached to the boot, the extended setae

will attach to the pores of this grid layer.

An electrified tesla coil will be used to assemble and align the carbon nanotubes into

setae. The to and fro oscillation of the tesla coil creates a positive and negative charge on each

carbon nanotube which helps in aligning and assembling the setae. In order to embed the

setae, iron catalyst pads will be taken for chemical vapour deposition growth of carbon

nanotubes which will be patterned on the silicon rubber sole by electron beam

evaporation. Carbon nanotubes will then be grown from the iron pads by chemical vapour

deposition. When the iron pads will be brought near to the pores, each carbon nanotube will

ultimately cross the center of at least one pore. Now, the silicone rubber sole will be

transferred to an Atomic Layer Deposition chamber which will deposit multiple layers of

aluminium oxide onto the surface. This does not affect the growth of aluminium oxide from its

surface but instead grows laterally on the surface of silicone rubber, thus burying the carbon

nanotubes from the surface by shrinking the diameter of the pores. This will leave the carbon

nanotubes buried from the surface and freely suspended from the other end in order to attain

maximum contact with the surface.

Control Unit

The key function of the control unit is to communicate with the spacesuit’s main control unit

and control the retraction mechanism.

An Arduino communication board will be used. This would contain XBee and ZigBee

modules.

ArduinoXbeeShield:

The Xbee shield allows the Arduino communication board to transmit and receive data via

ZigBee. ZigBee is an IEEE 802.15.4 based specification for a suite of high-level communication

protocols used to create personal area networks with small low powered digital radios.

As it has already been used in space, it poses as a tested accessory available to us.

The control board will be manufactured separately and hence, it is detachable. It will be fixed

with the help of small screws, 0.8 mm in diameter and 3 mm in length. This will help maintain

recyclability and allow upgrades to the pre-existing technology by just replacing the control

unit, leaving the other parts unchanged.

A copper foam solid state battery will be used to provide power to the boot. This battery

has been chosen due to its 3-D lattice structure, as opposed to the conventional 2-D ones.

These are cheaper, faster to charge, less hazardous as compared to other commonly used

batteries and smaller, which makes it increasingly fit for the purpose.

The battery will be installed beside the Control Unit module. Due to high power outputs,

reliability and a high number of recharge cycles, the Copper Foam Solid State Battery will

be used to power the infrared sensor module and also electric pistons for retractable setae.

The control unit will extract information from the sensors. This information will then be

communicated to the base. ZigBee would set up channels to communicate with the control

unit of the spacesuit, which in turn would connect it to the base, where the data can be

analyzed.

Infrared Sensor

Spacesuit helmets do not provide a large field of view of the surface and as a result,

astronauts end up tripping over stones or rough terrain that they are not able to see. Some

unfeasible ways to prevent this are:

● Ultrasonic sensors will not be able to solve the purpose since sound cannot travel in

vacuum.

● 3D mapping cameras could have been used to detect obstacles but they require

lighting or heating conditions that are not available on the moon or in space and

cannot be provided artificially due to the infeasibility of the methods to do so.

● 3D mapping cameras also require a high electricity input to function, which would

drain the Copper Foam Solid State Battery.

An Infrared sensor will be attached to the boots for obstacle detection. It will be powered and

controlled by the Control Unit. The module consists of an infrared transmitter, receiver and

an ADC0804 for converting the sensors output from the original analogue form to a

digital form. Once converted, the digital signals will be sent to a computer on the spacecraft

via the boot’s control unit which would analyse that information, and, using AI, a virtual

assistant would convey details, via the microphone in the spacesuit helmet.Thus, along

with obstacle detection, the exact distance can also be calculated. The results would help

to send danger alerts to the astronauts helping them navigate away from the danger.

Table source: http://www.glolab.com/RIR/RIR.html

Reflective IR

A Reflective IR sensor transmits a short wavelength infrared beam and it detects the beam

that is reflected back to it from any biotic or abiotic object within its detection range. It can

continuously detect the presence of both a moving and static object.

Short wavelength infrared used by the Reflective IR will pass through majority of the

materials. It reflects from surfaces of all shades, but it is more prominent from light and

smooth surfaces. Dark and textured surfaces scatter the light which make it seem like a

distant object to the RIR circuit.

Protection of RIR

The RIR sensor will be surrounded by a thin cage made up of carbon nanofibres. The

region from which the sensor emits the waves will have a small opening(∼ 1𝜇𝑚). The sensor

will use this opening to transmit and receive light waves. This will be feasible because the

wavelength of the waves emitted by the RIR is 950 nanometers.. This cage will also protect the

sensor from regolith.

4.Concept Details The following topics will provide a detailed analysis of INTEGEReX42 and the concepts and

calculations proving the practicality of the features.

Material for the Boot:

The materials have been chosen ensuring that they will be able to resist the wear and tear of

outer space operations as described in the need statement above.

The boots will be made of a chosen polymer according to the conditions (for example, for a

particular design of martian boots for rugged terrains, zylon can be chosen being the

strongest polymer). This polymer will be mixed with Carbon Nanotube Reinforced (for

strength) Polyhexahydrotriazine (PHT). PHT is a smart adhesive like material made and

marketed by IBM. When a cut forms between PHT, the hydrogen bonding in the

hemiaminal polymer network helps chemical bonds to be formed within seconds thus

healing the cut. One of the biggest advantages of PHT is that it is recyclable unlike most other

polymers. PHT is inert in neutral and mildly acidic/basic conditions but when pH is less than

2, it hydrolyses into its monomers. These can then be used for polymerisation again.

Thus, when a particular size of the boot is no more needed, the material can be broken down

into monomers and then reused. The inside of the boot will be cushioned with

Thermosetting Polyurethane to prevent the astronaut from hitting the hard covering.

For EVA’s and IVA’s a hard and rigid sole will be used so that the boots are durable enough to

withstand the wear and tear, temperature variations caused by the regolith. Thus a silicone

rubber resin RTV-630 (Room Temperature Vulcanizing) which has a high tensile strength of

850 psi and will be used as a hard sole. Pores will be made and setae will be attached as

mentioned in the background technology.

Dependence of Force on External Conditions

Hiller’s research and experiments in 1969 clearly showed that Van der Waals force is largely

independent of Hydrophobicity of the surface and the temperature for non-identical

surfaces. Thus these can be neglected for force calculations. Gecko adhesion can work on all

types of surfaces and even underwater (though liquid water is not expected to be encountered

in space, this proves the extent of independence from the surface conditions).

Calculations and Results

[Formula and Derivation Source: Wikipedia]

WAB is the potential energy between the molecules (in joules).

CABis the combined interaction parameter between the molecules (in J m6).

ρB is the molecular density of material B (in molecules/m3).

ρA is the molecular density of material A (in molecules/m3). 𝐴𝐻 = 10−20[𝐻𝑎𝑚𝑎𝑘𝑒𝑟𝐶𝑜𝑛𝑠𝑡𝑎𝑛𝑡]

𝐷 = 1.7×10−10[𝑇𝑦𝑝𝑖𝑐𝑎𝑙𝐼𝑛𝑡𝑒𝑟𝑎𝑡𝑜𝑚𝑖𝑐𝐷𝑖𝑠𝑡𝑎𝑛𝑐𝑒]

𝐹𝑆 =−10−20×(2.21×10−7)2

6×(1.7×10−10)3= 1.6623×10−5

𝐹𝑆, 𝐹𝑜𝑟𝑐𝑒𝑝𝑒𝑟𝑠𝑒𝑡𝑎 : 1.6623×10−5

𝜌𝑠, 𝐷𝑒𝑛𝑠𝑖𝑡𝑦𝑜𝑓𝑠𝑒𝑡𝑎𝑒 : 21200×𝑘/𝑚𝑚2[0 < 𝑘 < 1] [Retractability]

𝐴, 𝐴𝑟𝑒𝑎𝑜𝑓𝑏𝑎𝑠𝑒𝑜𝑓𝑏𝑜𝑜𝑡𝑠 : 𝐴𝑚𝑚2 [30000 < 𝐴 < 40000] [Shoe sizes - Total area of base]

The setae made of CNT are thinner and provide a force which is 4 times more than the force

provided by keratin setae of the same size.

The density of setae has been chosen as 21200 because it will provide the maximum amount

of force which may be required. The maximum force will be useful during storms.

This number is feasible, and has been chosen after accounting for the gaps between the setae.

The k-factor or retractability-factor in the density plays an important role by dictating what

percentage of the setae are currently in use, providing the necessary force to the astronaut.

𝐹𝑡𝑜𝑡𝑎𝑙 = 𝐹𝑠×𝜌𝑠×𝐴 = 1.6623×10−5×21200×𝑘×𝐴

= 35.2436×10−2×𝑘×𝐴

Maximum Force that can be provided by the boots, 𝐹𝑚𝑎𝑥 = 35.6623×10−2×𝑘𝑚𝑎𝑥×𝐴 =

35.6623×10−2×1×𝐴

Based on different shoe sizes, Maximum force provided can vary

from10698.7𝑁𝑡𝑜14264.9𝑁. Thus the boot can provide large amount of forces.

The value of k to be used for specific gravity zones can be calculated by comparing the amount

of force required on the Earth.

𝑚×𝑔𝑝 + 35.6623×10−2×𝑘×𝐴 = 𝑚𝑔𝑒

⇒ 𝑘 =𝑚(𝑔𝑒−𝑔𝑝)

35.6623×10−2×𝐴

Where,

𝑔𝑝is the acceleration due to gravity on the surface where the EVA has to be

performed and,

𝑔𝑒is the acceleration due to gravity on the Earth and,

𝑚 is the mass of the astronaut(including the mass of the spacesuit).

The data can be illustrated by for a few specific boot sizes in different gravitational zones:

Base Area

(Single Boot)

Total Base

Area

𝐹𝑚𝑎𝑥

[k=1]

𝑘𝑛𝑜𝑟𝑚𝑎𝑙

Moon𝑔𝑚𝑜𝑜𝑛 = 1.622

Mars 𝑔𝑚𝑎𝑟𝑠

= 3.711

Space Ship 𝑔𝑠ℎ𝑖𝑝 = 0

15000 30000 10689.7 0.1376 0.1024 0.1648

16000 32000 11411.9 0.1289 0.0961 0.1546

17500 35000 12481.8 0.1179 0.0878 0.1413

19000 38000 13551.7 0.1086 0.0809 0.1302

20000 40000 14264.9 0.1032 0.0768 0.1237

𝐹𝑚𝑎𝑥:Maximum force that can be provided by the boots(k=1) 𝑘𝑛𝑜𝑟𝑚𝑎𝑙:Normally required value of k to provide force which is necessary and sufficient during normal EVAs. 𝑘𝑛𝑜𝑟𝑚𝑎𝑙can be calculated using the formula:

𝑘𝑛𝑜𝑟𝑚𝑎𝑙 =𝑚(𝑔𝑒 − 𝑔𝑝)

35.6623×10−2×𝐴

𝑚 = 𝑚𝑎𝑠𝑠𝑜𝑓𝑎𝑠𝑡𝑟𝑜𝑛𝑎𝑢𝑡 + 𝑚𝑎𝑠𝑠𝑜𝑓𝑠𝑝𝑎𝑐𝑒𝑠𝑢𝑖𝑡 = 80𝑘𝑔 + 100𝑘𝑔 = 180𝑘𝑔

[The mass has been chosen arbitrarily, of course, keeping in mind the necessary

allowances]

Radius of seta : 𝑟𝑠 ∼ 2.21×10−7𝑚

Radius of spatula : 𝑟𝑠𝑝 ∼ 0.51×10−9𝑚

𝜂 = 𝑁𝑢𝑚𝑏𝑒𝑟𝑜𝑓𝑠𝑝𝑎𝑡𝑢𝑙𝑎𝑒𝑖𝑛1𝑠𝑒𝑡𝑎 =𝜋𝑟𝑠

2

𝜋𝑟𝑠𝑝2∼ 187777

These calculations show that enough force can be generated to provide enough force to

the astronaut for comfortable movement, and if required, to provide a firm grip for

protection during storms.

Retraction Algorithm

Since it is practically impossible to connect and engineer each nanotube individually,

therefore 187777 nanotubes together form a seta and each column of setae will be

connected to a single electric piston. The force required will be controlled by the astronaut.

The first time a value for the force is set, the control unit will run an algorithm, calculating the

number of columns of setae (M) required to produce the force. Each column will be numbered

from 1 to N(number of columns). The algorithm will calculate K=N/M and starting from the

first piston, every K’th piston will be sent an electric signal making it lower the setae. A

boolean array will store whether a particular piston is active (lowered column) or inactive.

The next time the value of force needed will change, the algorithm will decide whether

additional setae need to be lowered or if some setae need to be retracted. It will again

calculate K=N/M, where N here will be the number of active pistons and M will be the number

of more/less pistons needed. If some active pistons have to made inactive, the algorithm will

send an electric signal to every K’th active piston making it inactive. If more pistons need to

be activated, for every Kth piston, an adjacent piston will be activated as well. This algorithm

will ensure that the force generated by the boots is uniform throughout, and every time

the required force value is changed, all setae do not have to be pulled up and then lowered

again, just modifying the previous setting.

The Algorithm will run in O(N) time and since the maximum value of N possible is the total

number of columns of setae, N will be of the order 104<=N<=105. Thus, the algorithm can

run within a second even on a lower specification microchip.

[Image of the Setae connected to the grid layer above the sole and

pores with the same color will be attached to the same piston]

Modularity

The infrared sensor and the sole are the 2 main detachable/modular parts. Apart from this the

polyurethane layer on top of the control unit can be removed to allow repairs and

changes on the control board and the piston layer below it.

Detachability in Infrared Sensor

Zips cannot be used for attaching and detaching even though they are a part of current

spacesuit. Zips have spaces and these spaces are vulnerable to the corrosive nature of

dust. This will wear them out leading to frequent changes, thus making it cost inefficient.

They require mechanical energy to open and close them. As the astronaut’s space suit

won’t be flexible enough to close the zip, they cannot provide a fully automated assistance to

the astronauts. Moreover, zips, even though tested to be very strong in space can lose

their strength.

Adhesives and Velcro are not safe for the astronauts and sensors because temporary

adhesives will lose their consistency of sticking two objects due to frequent dust abrasion.

Velcro won’t be feasible as the dust will stick to it, reducing its strength considerably.

Attaching The IR Sensors

The IR sensor will have terminals for connection at the bottom. It will be connected to the

corresponding terminal on the spacesuit before the astronaut leaves for the EVA. An

automated system will connect the IR sensor’s terminal into the terminal in the suit. As

soon as the terminals are connected, the circuit will be closed and electricity will start to flow.

This will allow the clamps connected to the IR sensor to lock. The locks have been designed in

such a manner that they will not open unless the flow of electricity is not stopped. When

the astronaut will return from the EVA, a computer will send a signal in return to the IR

sensor. The signal will switch off and stop the electricity flow. This will open the locks of the

clamps.Then the automated system will remove the IR sensor. This system will be used to

connect other sensors as well if need be. Moreover, if the sensor malfunctions and

overheating is detected, it can lead to a blast which can hurt the astronaut despite the

protective layers. In this case, the computer will send the signal for detaching the clamps and

they will fall off thus preventing an injury. The power will also shut and this will cool the

sensor down.

Sole

It will be the bottommost layer of our shoe design and will be embedded with

around8.48×108setae. The sole is replaceable in order to repair and clean the internal grid

system and pistons as well as the setae. Besides, if the sole is ripped off, instead of disposing of

the whole boot, only the defective part will be disposed of, thus, maintaining recyclability.

Soles of the boots will be manufactured in such a way that each seta is equidistant ensuring

that if one seta is inserted in the right micropore, all the other setae are connected.

These connections with the micropore grid will create friction and will help the sole to stay

fixed. Along with this, the boundary of the sole will be extended and stuck to the boots using

the diamine-cured epoxy with the mixture of bismaleimide. This is a strong and

removable adhesive which will provide strength to the soles, and when required, can be

removed by heating it up to 333K.

Thus, parts will be attached in such a way that they can be safely removed, repaired,

updated and replaced.

Rejected Idea - Thrusters

Thrusters could have been used to provide stability to the astronauts during the EVAs to

prevent them from falling. But this idea was not feasible, and was not in agreement with the

laws of physics.

Problems:

● When the astronaut would be falling, he would be rotating about his feet in the

process

● Attaching the thrusters on the boot would mean, applying the force from the boot

present so close to the axis of rotation that they’d provide a very low torque.

● This would mean a huge force would be required, which can be seen from the

following calculations-

Considering the calculations for the Moon:

𝑎𝑐𝑐𝑒𝑙𝑒𝑟𝑎𝑡𝑖𝑜𝑛𝑑𝑢𝑒𝑡𝑜𝑔𝑟𝑎𝑣𝑖𝑡𝑦𝑜𝑛𝑡ℎ𝑒𝑚𝑜𝑜𝑛, 𝑔𝑚𝑜𝑜𝑛 = 1.662𝑚𝑠−2 𝑀𝑎𝑠𝑠𝑜𝑓𝑡ℎ𝑒𝑎𝑠𝑡𝑟𝑜𝑛𝑎𝑢𝑡,𝑚 = 180𝑘𝑔

𝐴𝑛𝑔𝑙𝑒𝑜𝑓𝑑𝑒𝑡𝑒𝑐𝑡𝑖𝑜𝑛𝑜𝑓𝑓𝑎𝑙𝑙𝑓𝑟𝑜𝑚𝑡ℎ𝑒𝑔𝑟𝑜𝑢𝑛𝑑, 𝜃 = 55𝑜 𝐻𝑒𝑖𝑔ℎ𝑡𝑜𝑓𝑡ℎ𝑒𝐶𝑒𝑛𝑡𝑟𝑒𝑂𝑓𝑀𝑎𝑠𝑠𝑜𝑓𝑡ℎ𝑒𝑎𝑠𝑡𝑟𝑜𝑛𝑎𝑢𝑡, ℎ𝑐𝑜𝑚 = 1𝑚

Based on approximations by taking height of astronaut around 1.8m we can approximate the

Moment of Inertia of the astronaut about his feet as, 𝐼𝑓𝑒𝑒𝑡 = 110𝑘𝑔𝑚2

Assuming force required from thrusters to be 𝑓, and the distance of the thrusters from the

axis of rotation of the astronaut as r (r<0.2m)

We can assume that an angular acceleration(𝛼) of 0.15 would work to stabilise the astronaut.

Using,

𝜏 = 𝐼𝛼

Where,

𝜏𝑖𝑠𝑡ℎ𝑒𝑡𝑜𝑟𝑞𝑢𝑒, 𝐼𝑖𝑠𝑡ℎ𝑒𝑚𝑜𝑚𝑒𝑛𝑡𝑜𝑓𝑖𝑛𝑒𝑟𝑡𝑖𝑎𝑎𝑏𝑜𝑢𝑡𝑡ℎ𝑒𝑎𝑥𝑖𝑠𝑜𝑓𝑟𝑜𝑡𝑎𝑡𝑖𝑜𝑛𝑎𝑛𝑑𝛼𝑖𝑠𝑡ℎ𝑒𝑎𝑛𝑔𝑢𝑙𝑎𝑟𝑎𝑐𝑐𝑒𝑙𝑒𝑟𝑎𝑡𝑖𝑜𝑛

Here,

𝜏 = 𝑓𝑟 −𝑚𝑔×𝑐𝑜𝑠𝜃×ℎ𝑐𝑜𝑚 ⇒ 𝑓𝑟 − 𝑚𝑔×𝑐𝑜𝑠𝜃×ℎ𝑐𝑜𝑚 = 𝐼𝑓𝑒𝑒𝑡×𝛼

Substituting the values and solving the equation, we get,

⇒ 𝑓𝑟 = 184 ⇒ 𝑓 ≥ 920𝑁

Which is practically impossible for mini-thrusters to produce.

Thus, using thrusters is not feasible. The Van Der Waals force provides enough adhesion to

control the astronaut from falling.

Conclusion

Careful measures were taken to ensure the practicality and cost-efficiency of each step to

make the product innovative, high-tech but realistic at the same time.

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