The risks of a rocket-borne experiment

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SCRAP is an experiment that involves a semi-hazardous particle powder to be dispersed, either by explosives or by being sprayed mixed in a flammable liquid using highly pressurized gas, from massive containers ejected from a rocket launched 80 km up into the atmosphere. The powder is then to be observed by a radar located 200 km away in a different country north of the Arctic Circle. Now this is not only a very difficult challenge, as mentioned in previous posts, but apparently also a pretty risky business. In fact, there are a great number of things that can go awry, involving not only the safety of our personnel and the success of our experiment, but also that of other people and experiments. During the last few weeks, we have been attempting to identify the main perils, their likelihood and severance as well as how they may be prevented.

This is very unlikely to happen (at least not by our fault)
This is very unlikely to happen (at least not by our fault)

To start with, there are a number of risks involved with our ejection system. This uses a pyrotechnical device to cut wires and a number of strong springs, which could be very dangerous if handled incorrectly and must work in practice. Luckily, the ISAAC team has already done much work on this, which will be a great help in our pursuit of functionality and safety. Several other components could also malfunction during the rocket flight, such as the electronics, batteries or the structure of our entire rocket module. Most of these possible issues are, however, well understood and should be controllable with a few tests in an environment of similarly extreme temperatures, vibrations and vacuum.

Once our ejected units have performed their tasks, parachutes must be deployed, so that the data that has (hopefully) been recorded by the spectrograph and camera on board is not destroyed in the landing. This will require tests involving a car driving at high speed to see that the parachute deploys as expected and fulfills all demands in braking the speed, as well as actual drop tests. When the ejected units have hit the ground, it will of course also be necessary that they can actually be located, for which our localization system will be very important and must be tested for all possible scenarios.

The radar must be operated in a safe way, so that signals are never transmitted directly at the rocket or in any other way interfere with the experiments on board. To learn how this can be done, and hopefully gain much other useful knowledge, we will be sending a team to the radar facilities in Tromsø in the end of March (expect more news about this in the future). In order to actually be able to detect anything of use, we will of course also rely on a suitable distribution of injected particles and sufficiently agreeable plasma conditions.

A powder of particles with a few micrometer radius can be very dangerous if inhaled and can in some cases also be flammable or even explosive. Furthermore, for certain materials and large quantities, such a powder could also have a negative impact on the environment. For copper particles, which is currently our main candidate, these effects are relatively minor for the quantities we will be using. We will, however, still have to analyze how the experiment could affect our surroundings and always treat this powder with utmost care.

Dust explosion (also most improbable)
Dust explosion (also most improbable)

For the spray approach of particle injection we have been considering, there are two main safety risks: the pressurized gas that must be used and the flammable liquids the particles are to be mixed in. For the explosives approach, the major risk is the gunpowder that is to be ignited. Just as with the particle powder, these substances will require strict safety procedures to minimize the risk of accidents. For the flight itself, we will be relying on a solid design and risk analyses to ensure that nothing unforeseen can occur and that we get a sufficient spread of particles.

Last, but not least, there are also some risks in the project management that could be fatal to the experiment. If, for example, we find some critical errors too late in the testing phase to fix before launch, the entire experiment will suffer, but this can hopefully be avoided by managing deadlines appropriately. We must also be prepared for unexpected changes in personnel by always documenting the work that has been done, so that no important knowledge is ever lost.

/The SCRAP team


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