Earth Imaging Journal has long been known for showcasing beautiful and/or intriguing remotely sensed images. But often the real story isn't the images, but the intelligence that can be gleaned that move the mission forward. We know our readers are often on the cutting edge of imaginative techniques that are used to address difficult and sometimes intractable problems. These pages will profile a tough problem where sensing specialists, scientists and engineers have had some success tackling a tough problem with unique solutions, but with the ultimate goal left unanswered.
In this issue, Earth Imaging Journal spoke with Lance S. Filler, Airfield Damage Repair Team Lead at the Air Force Civil Engineer Center, and Major Robert Liu, Government Program Lead, U.S. Air Force. They discussed the Rapid Airfield Damage Assessment System (RADAS), an ongoing project to provide Airfield Damage Repair (ADR) to open, expand, maintain and recover airfields after a military attack, as quickly and safely as possible.
If an airfield gets attacked, there's the expectation for unexploded ordnance and damage that needs to be assessed before mitigating the threat and repairing the airfield, notes Major Liu. As ordnance may go off during inspection and the fight may be ongoing as aircraft need to land or takeoff, this is an extremely hazardous situation.
The goal is to automate and get the man out of the middle of the fight, adds Liu. The idea is to do the damage assessment via remote sensing so it can be quicker and safer.
The military is working to shrink the entire ADR process to about eight hours, and most of that is in the actual repair. The goal is to assess the damage via remote sensors in only 30 minutes, and the Airfield Damage Repair Team is looking at a variety of platforms and sensors.
We need a 24/7 capability that can be used in all weather and in a variety of conditions worldwide, says Filler. And it needs to be safe from enemy attack. It's a unique deployment requirement.
In terms of sensing platforms, the ADR team is looking at a combination of fixed-installation sensors housed on towers, ground mobile systems and UAS technology. Airborne UASs have advantages in security, because they can be launched and flown off station and then brought in for assessment. On the downside, it will be difficult to assess UAS data automatically, which will add delays.
We can have some automated damage detection (with UASs), but that requires developing very complicated algorithms, says Filler. Tower-based monitoring could handle change detection, but it's on the ground and at risk. There's a lot of tradeoffs between what's technically possible, the environment for deployment, and how to process the data.
In terms of imaging sensors, Air Force engineers have looked at the following:
- Infrared (LW, MWIR, NIR, SWIR)
- RADAR (MMW, Ku, X-Band, SAR)
- Seismic and Acoustic
So far, the team has found that electro-optical sensors work well in a daytime environment and in all weather conditions, but not at night. Infrared works well at night, but small amounts of weather create large problems. Radar is another platform that performs well in most environments, but does very poor during rain or bad weather.
The problem is that with weather, something the size of a golf ball can suddenly look like a garbage pail, adds Filler.
An important consideration when choosing sensors for ADR is being able to recognized the different types of airfield damage, which includes the following:
- Craters: Left when an object punctures the bottom surface of the pavement and aggregate is exposed. They can be as small as three feet and as large as 50 feet.
- Spall: Similar to a crater, but it doesn't puncture the bottom surface of the pavement.
- Camouflet: Munition penetrates the pavement and explodes under the surface to create a cavity. These are difficult to find and a dangerous hazard as aircraft weight can collapse these unseen holes.
- Unexploded ordnance (UXO): The main challenge is to determine the classification (e.g., bomb, missile, rocket, etc.), but sensors need to be able to determine the fuse type to assess the threat as well as the mitigation strategy.
All of [this detail] needs to be located within three feet, says Filler. We want to measure plus or minus 20 percent to understand how much material is involved. And all that needs to be processed almost in real time.
Another unique challenge of battlefield sensing is something the military calls brass flake, which is all the munitions metal in the atmosphere. Brass flake can affect radar, so short-wave infrared (SWIR) is useful in this situation because it can see through particulates in the air.
In the civilian space, if you have bad weather, you just wait an hour before you fly, notes Filler. But we have to perform the mission. Our operational space isn't negotiable.
The combination of sensors and platforms the military will choose for ADR are expected to evolve through time. Engineers are working on short-term solutions as well as looking 10-20 years into the future. And accomplishing all the necessary remote sensing and analysis in 30 minutes is an audacious goal, but one the military believes it can and will accomplish.
It's a giant leap from where we are now, but we feel it's necessary to meet our mission, says Major Liu. The goal is always going to be now. The threat is always there.
If this problem has sparked an idea on a possible solution, you can reach out to the ADR team via e-mail: [email protected].
Call for Challenges:
We recognize and appreciate that our readers are problem solvers, and we would like to make the Sensing Challenge a regular feature in this magazine. Let us know if you have a remote sensing challenge. We're happy to help you profile it in these pages, and perhaps you'll receive a solution from those that have encountered similar problems. Please reach out to us via e-mail at [email protected].