Spiderbots - Space Apps Challenge

Awards & Nominations

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Global Nominee

The Challenge | Design by Nature

Design an autonomous free-flyer to inspect a spacecraft for damage from Micro-Meteoroid and Orbital Debris (MMOD).

Araknar

Araknar is a group of autonomous robotic spacecraft designed to inspect a spacecraft as an intelligent group, searching for damage on the spacecraft surface caused by Micro-Meteoroid and Orbital Debris.

Defining the problem and finding the solution

Space is a hostile environment. Aside of the high levels of radiations, severe temperature conditions and all the vacuum's immensity, spacecrafts in orbit are still subject of collisions with Micro-Meteoroid and Orbital Debris (MMOD), which can cause small holes, sealant rupture or even convective mass loss [1].

Each year, the amount of MMODs around the Earth increases significantly. Damage resulted of impacts with MMODs might compromise the life support systems of the spacecraft and result in catastrophic incidents, especially during the reentry [2].

In 2003, a piece of the external structure of the Space Shuttle Columbia was damaged and fell apart during the launch procedure, colliding with the Space Shuttle and ripping off a portion of the thermal protection system (TPS). While re-entering, the damaged TPS lead to the overheating of the spacecraft, destroying it and killing all its crew. That evidentiated the importance of the procedures to identify damage and take preventive/corrective actions.

In that way, to perform frequent survey on the spacecraft's surface, searching for derangement which might compromise the mission success and threaten the lives of the crew, is the uttermost need. By taking notice over the risks, the mission command can take the best decision to solve the problem [3].

We will prevent this type of accident from happening. In order to do that, the Araknar robots are either sent to the main spacecraft by a cargo craft or they are built-in the spacecraft and sent to space together. Once in the space, they copy the motion of arachnids on the surface of the spacecraft, sweeping with its specific-designed embedded sensors, capable of identifying and estimate the damage potential, warning the crew and mission command of the results.

Technical Features

The Araknar is a minor scale (30cmX30cmX25cm) and less expensive solution than the conventionals "free-flyers", because the robots are always attached to the spacecraft surface by their paws using electrostatic adhesion and they employ only electrical motors instead the huge and expensive combustion or ions thrusters.

Because each robot is smaller and less expensive, the Araknar is meant to be used in a group of robots and each one designated to cover different areas on the surface of the spacecraft simultaneously. That way, the inspections on the whole spacecraft are performed faster and can be made more often. The number of robots and the surface area given for each one to cover can be dimensioned based on the needs of the spacecraft, its mission and its crew.

As soon as scheduled or designated, each robot perform its route autonomously, in order to inspect a specific area, mapped upon a 3D model of the spacecraft. They work together, analysing through their sensors and sending the gathered information via radio to the main computer in the main spacecraft.

As soon as they finished their surveillance actions, each Araknar robot returns to its base in a compartment in the craft and goes into "sleep mode" to recharge its batteries and clean and calibrate its sensors.

Each robot embeds four different sorts of sensors: Infrared, LIDAR 3D, ultrasound and a real-time microwave camera, each one with the following functionalities:

The infrared sensor is responsible to analyse temperature and emissivity of the material, looking for discontinuities that may indicate perforations or scratches (Ex.: Visor Solar Sensor);
The LIDAR 3D sensor is responsible to search anomalies by using numerous laser beams in order to create a 3D topology of the spacecraft surface (Ex.: Nasa’s Flash 3D LIDAR);
The ultrasound sensor is responsible for seeking air leak detection through the spacecraft surface (Ex.: Nasa’s Ultrasound Background noise test);
The real-time microwave camera is responsible for detecting failures on the 3D topology on metallic surface and identify metallic debris inside non-metallic surfaces (Ex.: Missouri S&T microwave camera).

Bear in mind that the operation of the Araknar is completely independent of the main spacecraft crew, which are freed to undertake any other activity while the robots are monitoring the spacecraft. Nevertheless, if the crew wants, for any reason, to visualize the surveillance of any Araknar robot, they can do it through the dashboards of the system.

Using the information gathered by all the sensors, the data is processed and the damages found are ranked, taking into account the risks they represent to the craft and crew. With the data available about the risks, the technical team may undertake the alternatives to mitigate/repair the damage. One of the possibilities is to use the STA-54 on the affected spot. This technology has been successfully tested in orbit, showing the effectiveness both in vaccum and on ground [3].

Needless to say that with a high rate of inspections, the data can be used to analyse how the damages evolve over time.

Designed by Nature

The Araknar robots are inspired in several concepts and designs found in Nature. The shape of the arachnid captures the agility and freedom of movements of the animal. Its feature to lock itself to the spacecraft with electrostatic is inspired on the webs of arachnids that lure its victims with electrical properties. Its operations characteristic "divide and conquer" is inspired on the collective behavior of other insects such bees and ants.

References

[1] GARDNER, Job. Orbiter Passive Thermal Protection System. 2015. 59 slides, color. Disponível em: . Acesso em: 20 out. 2018.

[2] UNITED STATES. Judy Corbett. National Aeronautics And Space Administration (Ed.). Micrometeoroids and Orbital Debris (MMOD). 2017. Disponível em: . Acesso em: 20 out. 2018.

[3] ENGINEERING INNOVATIONS, Washington. Thermal Protection Systems. Washington: Nasa Agency Privacy Act Officer. 17 p. Disponível em: . Acesso em: 20 out. 2018.

Space Apps Challenge 2018

Spiderbots | Design by Nature