SensorPod™ Applications

SensorPod Overview - Applications - Dispensing - Emplacement

Ballistically-deployed sensor packages can provide a reliable and cost-effective means for acquiring data in many challenging areas. In planetary exploration applications, a robotic science payload could be landed in safe or convenient area, and this payload could then use a mechanism akin to a mortar to deploy multiple small sensor packages at large distances from the lander. This sensor deployment method can enable a lander to obtain sensor data over a very wide area far more rapidly than could a robotic crawler, and it can deliver sensors into challenging areas such as deep craters or the sides of steep ravines.

In environmental testing and safety markets, this system will provide a low-cost means for rapidly deploying sensors into areas where it is unsafe or impossible for humans to collect measurements manually, such as in a emergency response to chemical spills.

In military markets, it will provide a means for troops in unsecured areas to rapidly deploy sensors to detect chemical or biological weapons and to detect intrusion by hostile forces, as well as a robust communications link for sensors mounted on penetrators. A ballistic sensor deployment system could also enable soldiers to rapidly deploy security perimeters while minimizing their exposure to enemy fire, and could even enable the deployment of cameras and other sensors behind enemy lines.

A prime example of a mission of the type the SensorPod™ technology was developed for, exploration of the lunar poles. A robotic lander could be placed on a constantly sunlit hill or ridge. This craft could then use ballistic deployment to place tethered sensors into the permanently shaded craters to obtain in-situ measurements of soil composition in the crater. Use of tethered sensors would enable the lander to supply power to the distributed sensors, and would eliminate the need for line-of-sight access to communicate with the sensors.

One implementation of this ballistic methodology is the artillery based explorers (ABE) architecture proposed by Garrick-Bethell for planetary geology applications. Garrick-Bethell's analyses evaluated the feasibility and applicability of an ABE architecture for Mars exploration, and found that a system massing under 9 kg could deliver sensor packages up to 5 km from a lander with ≤ 120 m accuracy.

The aforementioned applications cover some of the general categories of missions where SensorPod™ technology is directly applicable. During development of various components of the SensorPod™ system, we worked with individuals interested in using it on specific missions described below.

A. Sensing Mars Dust Devils

Planetary Scientists have expressed a strong interest in the SensorPod™ product because a linear array of pressure sensors can be used to track the formation and movement of dust devils on Mars. Martian Dust Devils are much larger than similar structures on Earth, and not very well understood, but are thought to be an important element of the Martian atmospheric dust cycle. By using the array to estimate the speed and direction of dust devils, it would also be possible to autonomously trigger other high data rate sensors such as a Light Detection and Ranging (LIDAR) or imaging system to gain additional information that has shown to be a challenge otherwise.

B. Atmospheric Diffusion and Dispersion

On Mars and other planetary bodies, better data on atmospheric diffusion and dispersion is important to understanding many atmospheric processes. The SensorPod™ System could enable the collection of such data by deploying a linear array of sensors that could observe the diffusion of a uniquely identifiable gas sample released either from the lander or from the endbody. The time that it takes to be sensed at the other end of the SensorPod™ System directly measures the diffusivity of the atmosphere, a factor that must often be inferred. By releasing samples while the wind is blowing at different speeds, the amount of turbulence in the atmosphere can also be determined, necessary for understanding the thickness of the surface boundary layer.

C. Spectral Analysis of Surface Waves

By providing multiple sensing elements distributed over a large distance, the SensorPod™ can enable information regarding subsurface composition to be extracted by examining the spectral return from a natural or artificial disturbance. This technique has capabilities to map subsurface structures to much greater depths and in much more difficult compositions (such as a soft layer under a very solid layer) than is possible using traditional sounding techniques. If each sensor can also be a source, very detailed mappings can be made. This technique can be performed using a modest “microphone” as a sensor, and a simple off-balance rotating mass, such as is found in pagers, as a source. The exact locations of individual units relative to each other can also be determined by simple triangulation, a technique that may be useful for localization with other SensorPod™ missions. A simple application of this concept as proposed by Dr. Stokoe with the University of Texas, Austin was a simple airdropped system for determining the solidity of a potential landing strip for aircraft. This technique would be very similar to an early SensorPod™ application developed for locating underground bunkers and cave complexes.

D. Biological Detection

Biological detection is difficult to perform in the vicinity of a lander due to the extreme burden that even moderate planetary protection standards place on the lander. A good example of an instrument concept that addresses this concern is JPL's sensor web concept, which uses small, distributed wireless “pods” to measure trace gasses and other potential signs of life (an example of such a sensor is shown below). The SensorPod™ deployment system would provide an ideal method for distributing these sensors over a wide area, and the power and communications capabilities of the tether line can enable the system to achieve a longer lifetime and lower mass than wireless approaches, and can enable freedom from line-of-sight transmission limitations.

Sensor built inline with the tether

E. Unattended Ground Sensors

In general, the concepts categorized as “unattended ground sensors” are intended to provide intelligence and early warning on troop and equipment movement. Extensive sensor fusion of cooperative sensing techniques allows for greatly reduced false alarms and reduces susceptibility to environmental disturbances. Wide spatial separation to cover large sectors is equally important. These features, plus a central processing, uplink, and power source capability make SensorPod™ an excellent choice for many missions. Tethered sensor systems also have inherently fewer subsystems, making the employment of these typically disposable systems affordable, a major factor in their usefulness according to discussion with users. Both fiber optic and shielded twisted pair tethers can also provide greatly increased stealth over wireless system. Unique deployment capabilities such as into or over jungle canopies are also possible.

F. Non-Surface Deployments

A long with the obvious desire for surface measurements, some users expressed interest in subsurface capabilities. For some applications, simple “"lawn-dart"” nose cones were thought to be adequate. For others, such as JPL's Cryobot, a proposed Mars exploration approach under development at NASA's Jet Propulsion Laboratory, integrated sensors along the length of the umbilical tether can provide additional data of the borehole environment. Additionally, some users pointed out that the SensorPod™ system is an ideal approach for investigating vertical surfaces, such as steep cliff or valley walls.

G. Rover Interface

The SensorPod™ may also have use as a relay station, beacon or download/recharge station for planetary rovers. Although the potential for limited endbody mobility has been considered, it is likely that teaming the SensorPod™ technology with a more mobile rover may provide a useful synergy.

H. Underwater Applications

Multiple potential users that were contacted felt that the SensorPod™ has significant promise for deep-sea science. The most obvious application is for seabed sounding, though general “weather” modeling as is normally associated with atmospheric modeling is also an important capability that can be provided by a SensorPod™ system.

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