Project Elara Safety Review and Precautions

At Project Elara, we want to develop technologies that people can trust. This page covers a review of the safety of Project Elara’s technologies and discusses what precautions we must take to ensure that our technology is as safe as possible.

We are not perfect. And our technology contains substantial risks - as well as the danger of potential militarization. It is essential that we thoroughly investigate the risks and do everything possible to make our system as safe as possible.

Note: This safety review will not be considered complete until a faculty member (or other expert) experienced enough to give us a proper safety assessment has double-check our planned test setup and audited our safety review.

Preface

When new technologies are introduced, we have seen time and time again that the innovator(s) involved often pursue progress recklessly, at the expense of the safety of the general public. Our technology involves microwave beaming, a potential major safety hazard, as well as many other safety risks such as the possibility of substantial space debris, hazardous materials in rocket launch fuels, pollutants in the manufacturing of the system, etc.

It is important to not dismiss the risks entirely, since space-based solar power is a technology that carries inherent risks. When we think about safety, our first response should not be “the technology is perfectly safe”; rather, it should be “there are risks involved, but we have prepared a substantial set of safety measures to ensure that it is as safe as possible”.

A good example of this strategy in action is with airplanes. Large passenger aircraft pose substantial inherent risks over, say, a car; no matter what, you cannot dismiss the fact that aircraft today can fly close to the speed of sound, often weigh over 100 tons, and can carry over ten times the number of passengers in a typical SUV. These are all characteristics that make them inherently dangerous.

But in general, air travel is much, much safer than car travel. Why? Because aircraft are equipped with advanced safety measures dedicated to ensuring safety, including redundancy of all key aircraft systems, fail-safes, and extensive training for pilots. Remember, dangerous does not mean the same thing as unsafe. Dangers can be mitigated with safety measures and a strong safety-oriented culture, but something that is unsafe is unacceptable.

The safety risks of our technology cannot and must not be dismissed. We will take every effort to consider as many safety risks as possible and investigate each of them as thoroughly as possible. It is also essential that we do declare a conflict of interest in evaluating our own technology’s safety in our papers, and look into the literature carefully. Not all of these measures can immediately be implemented due to the small size of our team at present and our limited resources. However, they are principles we must keep in mind going forwards.

Possible dangers

As Project Elara’s technological development is multi-faceted, we list the different aspects of possible dangers of our technology (and experimental/manufacturing methods) in the following sections.

Hazards of microwave power beaming

First, we will discuss the hazard that is perhaps the default risk people would think of when approaching any microwave-based technology: the microwaves in the power beam itself. We should begin by noting that unlike electron beams in our lasers, microwaves are not ionizing radiation, so they do not have the radiation hazard associated with ionizing light sources (like X-ray and UV lasers). The dangers posed by microwave beams can be divided into two main types:

• Thermal effects, which come from heating caused by microwaves, and are the predominant danger of microwave beams
• Non-thermal effects, which can be further divided between (a) electromagnetic interference with electronics and (b) biological effects of microwaves, both on humans and other organisms

High-energy microwave beams can lead to serious burns due to the dielectric heating they cause. This comes from the interaction of the rapidly-oscillating electric fields of these microwaves with polar molecules, causing the molecules to rapidly rotate back-and-forth (dipole rotation). Among the most well-known polar molecules is, of course, water; hence this mechanism is well-known for heating foods in a microwave oven.

It should be noted that dielectric heating is distinct from Joule heating, which is another mechanism for causing heating due to electromagnetic radiation, although this is more associated with conductive materials. The power density due to Joule heating can be classically described using the differential form of Ohm’s law:

$$\frac{dP}{dV}=\mathbf{J}\cdot \mathbf{E}$$

Assuming a linear homogeneous medium, $\mathbf{J}=\sigma \mathbf{E}$, hence:

$$\frac{dP}{dV}=\sigma |\mathbf{E}{|}^2$$

Lastly, high-energy laser beams also carry energy in the form of thermal radiation. This is not strictly a classical effect as it arises from the internal energy of photons (electromagnetic radiation). The effect of heating due to thermal radiation can be modelled using the Stefan-Boltzmann law:

$$u_{\text{em}}={\epsilon }_m{\sigma }_s{T}^4$$

Where ${\sigma }_s=5.67\times 10^{-8}\mathrm{W}\cdot {\mathrm{m}}^2\cdot {\mathrm{K}}^{-4}$ is the Stefan-Boltzmann constant, $T$ is the temperature, ${\epsilon }_m$ is the emissivity of the material upon which the laser beam is incident (it ranges between 0 and 1), and finally $u_{\text{em}}$ is the electromagnetic power density, given by:

$$u_{\text{em}}=|\mathbf{E}\times \mathbf{H}|\propto |\mathbf{E}{|}^2$$

For laser beams, the electromagnetic power density can be particularly high, not simply because of a laser’s power output (which for industrial lasers can be in the kW range, and for pulsed lasers can be in the MW or even GW/TW range), but also due to the extremely-focused nature of the beam, a feature that is almost universal among laser beams. Since the power density $u_{\text{em}}\propto A^{-2}$ (that is, it is inversely-proportional to the cross-sectional area of the beam), the power densities of a laser can be extremely high. A typical He-Ne laser¹ has a beam power density of about $2.6\mathrm{W}/\mathrm{c}{\mathrm{m}}^2$. While this may not sound like much, a basic calculation using the Stefan-Boltzmann law (assuming a conservative estimate of ${\epsilon }_m=0.1$) tells us that a He-Ne laser can heat its immediate region to a temperature of above $1180°C$. This is (understandably) capable of causing serious damage, hence why you should never look at a laser directly.

Laser safety classes

In our discussions so far, a common feature has been that the capability of a laser to do damage is proportional to the square of the electric field, and thus its power. Hence, lasers are classified into several categories based on their power, as shown below²:

Class	Power density	Risk
Class 1	$<0.39\mathrm{mW}$	Generally safe under all normal conditions
Class 1M	Similar to class 1	Generally safe, except viewed with optical instruments (e.g. telescope)
Class 2	$<1\mathrm{mW}$	Generally safe if viewed briefly, but avoid continuous exposure
Class 2M	Similar to class 2	Generally safe if viewed briefly, but avoid continuous exposure. Dangerous when viewed with optical instruments.
Class 3R	$1-5\mathrm{mW}$	Avoid direct exposure
Class 3B	Between $5\mathrm{mW}$ to $500\mathrm{mW}$	Can cause eye damage if viewed
Class 4	Greater than $500\mathrm{mW}$	Can cause serious eye damage (potentially blindness), skin burns, and are a potential fire risk.

Important information: If the laser is focused (e.g. with focusing optics), the class of laser may change, even if the same laser is used. Also, “viewed briefly” presumes accidental exposure, after which a person immediately and rapidly turns themselves away from the laser. It does not mean intentionally looking into a laser for a subjectively-short period of time. In any case, a safe rule is to generally not look at a laser at all!

It is important to note that laser safety classes specifically describe visible-light continuous-wave lasers. Hence they do not apply for pulsed lasers or for infrared/microwave lasers. The biological effects of microwave lasers are thus more complicated, compounded by the fact that they are more rare and primarily used for specialist applications. High-powered microwave and infrared lasers are also particularly dangerous to test because their beams are invisible, and hence it is easy to accidentally expose oneself to the beam if not careful.

Hazards of electron guns

See https://sciencedemonstrations.fas.harvard.edu/presentations/%CE%B1-%CE%B2-%CE%B3-penetration-and-shielding

Most substantial dangers:

• The 2 kV power source is powerful enough to cause severe organ damage and even death if not operated properly. Authorization is required to operate it. It should never be turned on without clearly and loudly notifying everyone in the vicinity of the power source that it is being powered on.
• The UV-C light source is ionizing radiation and is carcinogenic. Again, it should never be turned on without prior notice, and when it is turned on, it should never be facing anyone (directly or indirectly).

Others:

• Vacuum chamber/pump - a pressurization failure could lead to an explosive implosion with devastating consequences
• For more advanced/powerful designs of the electron gun that use photon-enhanced thermionic emission, the incredibly hot thermocathode can cause a fire if not in vacuum by heating up the surrounding air to hundreds of degrees up to the autoignition temperatures of materials in the laser/room
• If the electron beam is not carefully controlled and/or poorly-collimated, its ionizing radiation can easily go off-course and strike the surrounding chamber, leading to radiation damage and potentially a fire

A particularly important aspect is that the device’s electronics must be carefully shielded to prevent radiation damage. In addition, the device must have a manual shutdown in case the software fails due to radiation exposure to the electronics.

Hazards of undulators

Strong magnetic fields that could in theory affect sensitive devices (e.g. pacemakers); also if the electron beam goes off-focus and hits the walls, it could punch a hole through the undulator and this becomes a major health risk. Beam dump needs to be positioned correctly as a countermeasure.

Hazards of spacecraft/rockets

The solar mirror on the spacecraft uses highly-concentrated and possibly blinding sunlight. During terrestrial testing, it must be operated carefully, as otherwise it could cause skin burns, severe eye damage, and potentially a fire.

Also discuss hazards rocket launches pose (e.g. possible booster drop over a residential area). There are also possibly-toxic materials in spacecraft/launch vehicle (e.g. hydrazine).

Safety mechanisms

To ensure safety, a variety of safety mechanisms must be put in place, preventing a single point of failure or single issue from causing a catastrophic result³.

Safety-by-design

The most fundamental method of guaranteeing safety is to have it built-in, with strong redundancy, numerous failsafes, and rigorous safety checks/inspections. That is to say, a design should be built to be safe even if it fails, and should be carefully vetted before it is actually run. In practice, this means several things:

1. All Elara safety-critical software must follow the power of ten rules, be checked with a static analyzer, and be compiled with the strictest compiler settings possible to show all warnings and errors
2. All hardware should have hardware kill switches that can fully shut down the entire system, as well as automatic shutdown capability, where an automatic shutdown is initiated if the system detects it is operating outside safe operational limits
3. Rigorous simulations and calculations should be conducted to identify problems before we activate any potentially hazardous components⁴
4. Prior to space launch, tests must be conducted in real-world conditions, not just in a controlled lab setting

The third point is particularly essential because knowing the math and physics removes uncertainty and allows us to show our design is safe rather than needing to just trust (or worse, hope) that it’s safe.

Elara safety training course

Since we are working with dangerous technology it is essential that we do things in a safe manner where everyone is aware of what they’re doing. There are, however, no courses to our knowledge that sufficiently teach safety information about building and running our specific type of laser (a free-electron laser in the RF regime); these are such niche machines that they are generally operate only by experienced professionals. Hence, we use our own training curriculum:

1. A general safety presentation should be given to everyone on the build, embedded, engineering, and research teams, informing them of the risks of the equipment, how to use the equipment safely, and what to do if something goes wrong
   1. A basic safety test should be administered to the entire team at the end of the presentation
   2. Members of the build/embedded teams should write one build log that summarizes what they learned from the presentation, and commit it to the relevant repository/repositories they are working on
2. Three (or more) contrasting safety case studies should be presented to the team, in order to cement the importance of proper safety procedures.
   • While the precise case studies chosen may change over time, the current ones chosen are as follows, with each emphasizing a different aspect of safety:
     1. The first case study is on the OceanGate Titan submersible disaster, a classical example of poor engineering and a reckless disregard for safety. Emphasis should be on (a) the design flaws of the submersible itself, (b) the lack of tests to verify the safety of the submersible, and (c) the negligence of the company involved, which ultimately led to a disastrous outcome.
     2. The next case study is on Qantas Flight 72, which suffered an extensive systems failure during flight, but was able to make a safe emergency landing. The flight showed: (a) the consequences of software failure, (b) the importance of redundancy and checks (in this case, checking to identify invalid and/or faulty data), and (c) the importance of skill and experience in operating equipment (in this case, the airmanship demonstrated by the pilots flying the aircraft)
     3. The third case study is on Air Florida Flight 90, which crashed into the Potomac river shortly after takeoff from Washington DC, leading to the deaths of almost everyone on board. The tragedy showed: (a) the dangers of deviating from safe procedures and taking shortcuts, (b) the importance of proper training, and (c) the contrast between the inexperienced crew vs. the experienced crew of the Qantas flight in an emergency situation
   • Each watching member should then personally write one build log for each case study, summarizing the incident involved and providing their reflection on the safety lessons from each. They should then commit it to the relevant repository/repositories they are working on
   • It is planned to offer all case studies in documentary format, to be watched by the entire team together. The aim of watching these documentaries is to actively engage the team in systems and operational safety; videos have the advantage of increasing focus and attention compared to just listening to presentations, particularly when shown in a public environment.
3. Everyone should additionally take the laser safety training course, radiation safety course, and electrical safety course from Skillsoft Percipio and present their certifications for all of the above courses

Procedural safeguards

These are the SOPs (standard operating procedures) that must be followed:

• No one should be operating equipment that they are not previously trained to use
• No one should be working alone. Every piece of equipment that is a safety hazard must be operated by two or more people: one person operating the equipment, and one person monitoring.
• The hardware should have kill switches to shut it down even in the case of a software bug, and should be fail-safe.
• At least one professor/expert should be informed prior to any risky experiments, and give the go-ahead to proceed. That professor/expert should be present during testing as much as is possible.

What to do if something happens:

• Shut down all equipment and cut off power (hard shutdown)
• Evacuate the room (and if needed, the surrounding rooms)
• If a person collapses or shows acute distress, call 911 immediately

Power beaming control

It is necessary to recognize that not all locations need to receive the same amount of power. Recall that the power density (intensity) is given by $I=P/A$, where $P$ is the power transmitted and $A$ is the cross-sectional area upon which the beam is incident. If we want to beam to smaller dishes, for the power density to still be safe, we will need to reduce the power. For this, we may simply dial down the power in the appropriate beams.

Footnotes

1. See this commercial He-Ne laser, which has a beam diameter of $0.7\mathrm{mm}$ and a power output of $10\mathrm{mW}$. This translates to a power density of an astounding $26\mathrm{kW}/{\mathrm{m}}^2$! However, since the beam diameter is so small, without some form of rapid-scanning mechanism a He-Ne laser is unlikely to stay continuously-incident on anything with a diameter close to a meter, so it is more practical to use units of $\mathrm{W}/\mathrm{c}{\mathrm{m}}^2$, in which case the power density is around $2.6\mathrm{W}/\mathrm{c}{\mathrm{m}}^2$. ↩

2. Compiled from a combination of sources, including Laserax, the ANSI standards blog, Wikipedia, UC Berkeley’s EHS, the Laser Institute, FDA guidelines, Weill Cornell Medical Center, and the Board of Laser Safety. ↩

3. This is well-known as the Swiss Cheese Model professionally. ↩

4. It is acceptable to start building hardware prior to completing simulations/calculations, but hardware that carries safety risks should not be live-tested or powered on until simulations/calculations are completed. ↩