The Exist Project

The Examination of Infrasound in the Stratosphere and Troposphere


The Idea

The EXIST project began as an idea by Professor Javier Martin-Torres to perform measurements of infrasound high in the atmosphere, since most measurements are performed on the ground. The few measurements of infrasound made in the stratosphere were mainly recorded in the 1960s in the US during the Cold War, as a way to detect nuclear detonations. In more recent years, a student project lead by Daniel Bowman on the NASA High Altitude Student Platform (HASP) measured infrasound from a stratospheric balloon over New Mexico and Arizona in 2014, 2015 and 2016.

Since these measurements were both performed over the United States, the measurement of Infrasound in the stratosphere in the rest of the world is left unexplored.


Why Infrasound? Why on a balloon?

Infrasound, defined as sound waves propagating with frequencies below the human hearing threshold of 20 Hz, can travel much further than sounds of higher frequencies without suffering from high attenuetion. Therefore it is possible to predict severe weather, earthquakes and even meteors by using infrasonic measurements. A deeper understanding of these kinds of measurements could allow for measurements and predictions on other planets such as Mars and Venus.


The advantages of performing the measurements on a balloon are many. The amount of noise is reduced, as sound propagating close to the ground will suffer interference from man-made and natural obstacles. Also, sensors on the ground can only capture two dimensions of the infrasound, since it is located on the ground, while a free-flying sensor is able to capture the full spectrum of infrasound from all directions.


The balloon that will carry the Exist experiment will be flying from Esrange in Kiruna, which lies above the Arctic Circle. This location has the benefit of lying in an area with a highly developed network of ground stations measuring infrasound.


​One of the greatest noise factors of infrasound recordings are winds. Since the instrument will be placed on a balloon that will follow the winds, the noise will be highly reduced. Making it very advantageous to record low frequency sound in this manner

 

The Team

The EXIST team was created from a larger group of students who wanted to do a REXUS or BEXUS Project. It was decided that the group was too big for a single project, so the group was split into two. One part became the EXIST group, and the other went on to create the IRIS BEXUS project. The groups were created in such a way that both groups had a diverse set of experiences and skills to be able to fill all necessary roles in the projects.


The EXIST group consists of students studying different areas within space engineering, with specializations in Spacecraft and Instrumentation, Spacecraft Design, Aerospace Engineering, and Space and Atmospheric Physics.To learn more about each member of the team, go to the The Team page on this website!

 

The Experiment

The experiment will consist of two sensor boxes fitted to the flight-train of the BEXUS balloon. Within these sensor boxes are instruments that will measure physical parameters, such as temperature, wind speed, and vibrations. The most important  instruments are of course the infrasound microphone arrays. We have been granted the use of
balloon flight ready set up for measuring infrasound through a joint collaboration with Kochi University of Technology via Professor Yamamoto. These arrays have been tested at ISAS/JAXA to withstand the conditions present during a stratospheric balloon flight.

 

After the Flight

The data recieved from the flight will be analysed using software used in the International Monitoring System (IMS), a global network of infrasound measurements, as well as software developed at the Swedish Institute of Space Physics (IRF). The data will be compared with several IMS stations located close to the expected flight path with the help of Professor Johan Kero at IRF. We will also be collaborating with Dr. Daniel Bowman, who lead the HASP project meantioned earlier as well as several flights measuring infrasound since. His experience and knowledge will be a great help in the analysis of our data. This collaboration will also enable us to compare our data with the flights performed by Dr. Bowman.


Our aim is to, through this project, create data that can be used as a basis for future infrasound measurements in the stratosphere, which may lead to a greater understanding of not only our own planet, but other planets in the solar system as well.


The REXUS/BEXUS Programme

The REXUS/BEXUS programme is realised under a bilateral Agency Agreement between the German Aerospace Center (DLR) and the Swedish National Space Board (SNSB). The Swedish share of the payload has been made available to students from other European countries through the collaboration with the European Space Agency (ESA). Experts from DLR, SSC, ZARM and ESA provide technical support to the student teams throughout the project. EuroLaunch, the cooperation between the Esrange Space Center of SSC and the Mobile Rocket Base (MORABA) of DLR, is responsible for the campaign management and operations of the launch vehicles.


Endorsing and supporting senior scientists, organisations and institutions


Professor Lars-Göran Westerberg
Luleå University of Technology
Department of Engineering, Sciences, and Mathematics

​Primary Endorsing Professor


Professor Thomas Kuhn
Luleå University of Technology
Department of Computer Science, Electrical,

and Space Engineering

Associate Professor for the Atmospheric Science Group


Professor Masa-yuki Yamamoto
Kochi University of Technology.
Department of Engineering

Visiting professor, National Institute of Polar Research


Doctor Johan Kero

Swedish Institute of Space Physics

Staff Scientist

Project Leader of Infrasound

Doctor Daniel Bowman
Senior Geosciences Engineer​

High-altitude Infrasound Experiment Adviser


Giovanni Chirulli

European Space Agency ESA-ESTEC

Thermal Engineer


Olle Persson

Luleå University of Technology
Department of Computer Science, Electrical,
and Space Engineering.
Former REXUS/BEXUS Affiliate


Håkan Persson

CEO at Norrköpings Svets & Reparation AB

Purchasing and Handling of Experiment Metals


Michael Steen

Project Chief at Progatec AB
Manufacturing of Experiment Structure

Examination of Infrasound in the Stratosphere and Troposphere (EXIST) is a BEXUS experiment, and will be flown on a stratospheric balloon to a height of more than 25km, where it will record infrasound for the duration of the flight.