RF monitoring for spaceports: protecting payloads and ensuring safe landings

SpaceX might have started the space race, but it is not the only company competing for market share. Estimated to grow to $1 trillion by 2030, the space industry has taken off. Companies such as Rocket Lab, Blue Origin, Virgin Galactic, Astra, and Relativity Space are all competing in the commercial space launch industry.  

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Hunting interference from friendly communications 
Safeguarding against hostile actors 
Monitoring ambient signals 
Ensuring safe landings for reusable rockets 
Conclusion 

However, increased space activity involves higher levels of risk in the electromagnetic spectrum. More space activity means greater chances of signal interference, navigation disruptions, nefarious activity, and potential harm to sensitive electronic equipment due to the crowded electromagnetic environment. As such, for safe spaceport operations, careful management and monitoring of the radio frequency (RF) environment is essential. 

Hunting interference from friendly communications 

The most likely risk to highly sensitive payloads on rockets comes from friendly communications.  

The density of wireless communications at spaceports operating on different frequencies means a high risk of unintentional interference can inflict catastrophic damage on scientific equipment.  

If exposed to interference, an instrument could enter into a feedback loop, causing it to fail. Instruments can also absorb RF energy, which converts to heat and consequently affects performance by causing physical damage to sensitive components. Additionally, strong interference can affect payloads with sensors designed to detect specific phenomena (such as cosmic radiation and magnetic fields) by saturating the sensors, rendering them unable to function.  

Of course, spaceports have rigorous control and testing procedures designed to shield sensitive components from electromagnetic interference; however, a forgotten Bluetooth device operating on a higher-than-intended power level still has the potential to cause irreparable damage.   

Unintentional, friendly RF interference can be prevented and mitigated by thorough, proactive spectrum monitoring before the sensitive payload enters the launch site. Ensuring clean spectrum by identifying any interference in real-time will help ensure the integrity of sensitive payloads.  

Techniques such as hybrid validation (which uses Time Difference on Arrival (TDoA) to geolocate a source of interference and then corroborates this measurement by taking intersecting lines of bearing) can help to swiftly identify the precise transmission location and who is responsible for the transmission. Any interference can then be mitigated before it causes more significant problems.   

Spaceports hunting interference can also benefit from automated spectrum monitoring software, which runs constantly and sends immediate alerts if interference is detected.  

Safeguarding against hostile actors 

Although friendly interference is the most likely risk for payloads, spaceports are always concerned with protecting sensitive equipment against nefarious activity from criminal elements or hostile state actors.  

Damaging equipment or compromising a mission is a high prize, and hostile actors can take advantage of a congested and complex electromagnetic environment to achieve these goals. There are several ways adversaries could do this.  

Jamming, or overwhelming friendly signals by transmitting rogue signals on the same frequency band as a payload’s operational system, can cause a payload to malfunction or suffer data corruption. By preventing the payload from receiving legitimate signals, adversaries could also induce a denial of service. 

Moreover, by carefully designing an interfering signal, an attacker could invoke a fault in the payload’s hardware or software, leading it to behave erratically or causing physical damage. Physical damage can also be caused by high-power radio frequency emissions that harm electronic components due to increased temperature.  

A more subtle approach could be to use interference to corrupt data sent to a payload, causing false readings and affecting engineers to make erroneous decisions. A nefarious actor might also want to indirectly interfere with the payload—gathering intelligence by intercepting signals transmitted from a payload.  

To safeguard against hostile actors, any robust security system should comprise a multi-layered approach. In addition to measures such as frequency hopping and anti-jamming techniques, spaceport operators benefit from implementing strict control over their electromagnetic environment, constantly monitoring the spectrum for unusual signal activity.  

Spectrum monitoring teams can protect their RF environment by rapidly identifying suspicious signals through real-time monitoring. They can then use techniques such as creating a detector to hunt for a specific signal and then forensically analyze its I/Q data to ascertain signal structure, modulation type, and temporal characteristics.  

Monitoring ambient signals 

Monitoring ambient signals at spaceports involves systematically scanning and analyzing the spectrum for electromagnetic signals within the spaceport and surrounding areas. Understanding what the spaceport spectrum looks like by establishing a baseline and then monitoring it intermittently is crucial as, in the field of RF, what you don’t know can certainly hurt you.  

Scanning a wide range of frequencies to find the highest power level signals and detecting, identifying, and recording various signals is crucial for several applications.  

First, ensuring wireless communication is uninterrupted by interference helps ensure that authorized or unauthorized transmissions do not threaten the safety of the spaceport and its operations.  

Second, by identifying the strongest signals, the spaceport can effectively manage its frequency spectrum—vital to avoid several signals being broadcast on the same frequencies and to allocate frequencies efficiently among multiple users.  

Third, understanding the signal environment allows for an efficient, long-term spectrum management plan by optimizing signal use and power levels. Such a system will help spectrum managers troubleshoot and maintain the integrity of all wireless communications in their spaceport.  

Some spaceports chose to manage spectrum by outsourcing the task to local spectrum managers who establish a baseline and advise on spectrum use for space operations. While outsourcing offers flexibility and cost-efficiency during the scaling phase of spaceport operations, there will eventually come a time when diminished control, heightened security considerations, and the risk of divergent priorities begin to present significant challenges.  

At this point, spaceport operators may decide to build their own RF receiver and direction-finding network—potentially with fixed and mobile assets that can be used for multiple missions by multiple users to ensure a return on investment. Additionally, automated RF monitoring software can ensure 24/7/365 monitoring, immediately alerting an RF expert only when an anomaly is detected.  

Ensuring safe landings for reusable rockets 

While more rockets are going up, the cost of space launches is going down. SpaceX has propelled both the surge in launches and the drop in costs. The Falcon 9’s first-stage booster saves millions of dollars as it can be reused up to fifteen times. The company’s latest Starship is a fully reusable transportation system that carries up to 150 metric tons to space. 

Reusable components have challenged engineers to design new technologies and methodologies for space landings, a process continuously being refined and enhanced. One central question is where is the best place to land: land or sea? 

SpaceX’s inaugural landing on a barge in the Atlantic in 2016 presents a strong case for maritime landings. However, regardless of where the booster lands, it relies on an extensive wireless communication system to safely navigate the capsule down to Earth.   

Although interference at sea is less likely than in a busy area such as the East Coast of the United States, interference from passing ships could still affect navigation systems. But perhaps the most significant concern is from nefarious actors deliberately attempting to interfere with the landing through GNSS jamming.  

Robust spectrum monitoring can help ensure vital communication channels are clear of interference and suspicious signals. By deploying direction-finding Arrays on the launch site—ideally directly on the barge and on multiple autonomous support vessels—the spectrum monitoring team can establish an RF baseline before the rocket is launched. This will help detect any future interference, which can be mitigated by geolocating the source with multiple intersecting lines of bearing.   

Arrays house spiral directional antennas optimized for different frequency bands; they are also sensitive to most incoming signal polarizations. Timing and synchronization features enable engineers to combine direction-finding techniques, permitting all signal types to be mapped, irrespective of signal power, bandwidth, or frequency. However, despite their sophisticated technology, Arrays are functional and straightforward to use. This enables aerospace engineers to concentrate on their specialized field without having to master complex direction-finding RF systems.  

Conclusion 

At a time when spaceport operators are focusing on reducing the cost of launching things into orbit, investing in advanced spectrum monitoring hardware and software might seem counterintuitive.  

However, spaceports’ reliance on wireless communication, threats from nefarious actors, highly sensitive payloads being sent to space, and the need to navigate back to Earth demand that spaceport operators understand their spectrum. Houston needs no more problems; it requires the ability to geolocate and mitigate interference immediately.