Project Stratosphere is a joint initiative between TwoNav and GoStem, a non-profit organization whose mission is to motivate students to engage in STEM careers (science, technology, engineering and mathematics).
At TwoNav we like to engage in projects that share and promote our ideals, and investigating new technologies is one of them. The project involved creating a stratospheric probe following the engineering procedures developed by NASA and applying concepts that are closely related to the design of a GPS device: technology, mathematics, physics, design and communication.
We could not miss the opportunity to put our new GPS Trail 2 Plus to the test, while at the same time supporting future engineers, the true protagonists of this challenge.
Challenge 27.000m: The Probe
The challenge was clear: to expose our new GPS Trail 2 Plus to extreme conditions by lifting it up to 27.000m over sea level using a balloon filled with helium.
The GoStem students planned and executed the construction of a stratospheric probe which consisted of the balloon, a capsule with a video camera, our GPS and a parachute, which was needed once the balloon explodes at the desired altitude in the stratosphere.
During the workshop, the students created the general structure of the probe, as well as the capsule – wrapped with thermal insulation paper to protect the camera from the extreme temperatures – and the parachute applying their own calculations and designs and learning how to solve typical problems faced by aerospace engineers.
The structure needed to support the weight of the camera and its additional batteries (which deplete much faster in low temperatures), along with the weight of our GPS (220g). Furthermore, all the weights needed to be evenly distributed to ensure a balanced ascent of the probe.
La estructura debía soportar el peso de una cámara vídeo y sus pilas extra (pues las bajas temperaturas consumen rápidamente las baterías), más el peso de nuestro GPS, 220gr. Además debía elevarse de forma equilibrada, por lo que tuvieron que dividir los pesos.
Once the construction of the structure and the parachute was completed, the moment of truth arrived: it was time to attach it to the balloon filled with helium and launch it to the stratosphere – one of the most exciting moments of the project!
To determine both the best day and best place for the launch, the students had to study the weather forecasts for the region. They needed to identify a day during which the winds, both on the surface and higher up in the atmosphere were not going to be very strong, to reduce the distance between the location of launch and landing.
Using the web http://predict.habhub.org/, the students were able to simulate the route of the flight, which needed to ensure that the predicted point of landing would be far away from a residential area and not covered by high trees, in order to facilitate the search later on.
After entering the expected speeds of ascent and descent, based on the weight of the probe and the volume of the balloon, and taking into account the wind speeds and directions at the time of the launch, the simulator helped us identify the ideal place for the launch: a field close to the town of Bellcaire d’Urgell.
All our GPS devices comply with the standard MIL-STD-810 for resistance to temperature, impact, water and vibration, but never before has a GPS been exposed to conditions as extreme as those given in the stratosphere, with temperatures as low as -56ºC, strong winds above 8.000m and a fall from 27.000m back down to the earth. Without doubt, this was a great challenge for us.
And the result could not have been more pleasing! Our GPS returned to earth in perfect conditions – even the battery lasted through the almost 3 hour long flight, operating in extremely cold temperature (-56ºC). It is known that low temperatures accelerate battery depletion and actually our security alert “battery low” was triggered during the flight, but this has not affected the functionality of the device which continued functioning in spite of the adverse meteorological conditions.
As opposed to the GPS, the video camera which also traveled along, shut itself down due to the very high air temperature at the site of the landing (40ºC). This further proves that our GPS devices are built to resist without any issues both high and low temperatures – in this case ranging from -56ºC to +40ºC.
Furthermore, thanks to our SeeMe service, we were able to follow the flight of the GPS in real time while it was still within the limits of regular mobile phone coverage and we were able to determine its exact location once the device returned into the coverage zone.
We can now proudly say that our GPS had the Freedom to Discover the stratosphere!
Once we had signs that the GPS was starting it´s descent, we needed to adjust the flight plan and determine the location of the landing to pick it back up.
We learned that the speed of descent was even faster than expected due to the lack of air in the higher layers of the stratosphere and the parachute did not slow the descent down until the probe re-entered the atmosphere. Therefore, when we reached the location, the probe had already landed and all we needed to do was to enter the coordinates into our handheld GPS and begin the search for the capsule. Shortly after, we were able to enjoy the impressive images of our Trail 2 Plus flying across the stratosphere.
Max. Altitude reached: 27.000m
Total duration of the flight: 02:55:00
Distance covered: 69.71 km
Average horizontal speed: 23,5 km/h
Min. Temperature: -56ºC
Max. Temperature: 40ºC
Duration of Ascent: 02:24:00
Average vertical ascent rate: 3.1 m/s
Duration of Descent: 00:31:00
Average vertical descent rate: 14.5 m/s
Thank GoStem, who provided assistance in the construction, design and legal part, and all the students who were encouraged to participate in this project without whom our challenge would not have been possible.