In our last article on the Government Satellite Report, we featured part one of a two-part conversation about on-orbit servicing with Dr. Gordon Roesler, a Program Manager in DARPA’s Tactical Technology Office who has been at the forefront of many of DARPA’s on-orbit servicing initiatives and programs.
During the first part of our conversation with Dr. Roesler, we talked about the current state of on-orbit servicing, differentiated Gen One from Gen Two servicing, and spoke about what future generations of this technology will enable and why on-orbit servicing is in such high demand.
In the second part of our discussion, Dr. Roesler provided some additional details about the exciting and innovative capabilities that robotics can enable in space in the future, and how Gen One and Gen Two servicing may be just opening the door for some truly revolutionary services in space.
Here is what Gordon had to say:
Government Satellite Report (GSR): We’ve covered Gen One and Gen Two on-orbit servicing, but what does the future after those two generations look like?
Dr. Roesler: With the introduction of Gen Two capabilities, we’ll have access to dexterous robotics that can make something like changing out a reflector to address a new service area something that’s relatively easy to do. For example, the Dragonfly Project, a NASA-funded program, is intending to take reflectors and put them in place with a robotic arm on a commercial communication satellite.
So if you can put that in place with a robotic arm, you can also take it off again and put a different reflector on. That will give operators the ability to change the property of the satellite payload on-orbit. To better enable that, there are some easy things we could start doing to our new satellites that would allow us to take more advantage of robotic capabilities.
For example, NASA Goddard has developed a refueling quick disconnect. Today there are still many steps required to refuel a satellite, but this quick disconnect greatly cuts down that number of steps. That quick disconnect would have to be integrated into the satellite design before launch, but it’s not a painful installation and it could greatly facilitate the ability to transfer fuel.
Another new addition we should be considering adding to satellites during design and construction is the equivalent of a USB port on your laptop. It’s something DARPA has developed for the servicer, but it can also be installed on satellites before launch. With a USB port, you can plug in to a thumb drive or hard drive and it recognizes what the component is and it provides new services. DARPA’s port will be used to hold the robotic tools on the servicer, but it also has power and data feeds just like a USB port. So you could bring up a new payload, plug it in, and take advantage of the power and communications of the host satellite.
That’s when you’re starting to get into Generation Three, which we haven’t discussed yet – modular satellites.
There is a tremendous amount of research and development that still needs to be done to create a truly modular satellite. But that research and development is extremely valuable because, if you have a modular satellite, you can take advantage of lower cost, more prolific launch systems that are being developed. Modular satellites would be assembled on orbit from components sent up on low-cost launches, or modules could be replaced in the future on a satellite that you already built and launched. That said, there would be a lot of testing that would need to be done on the ground and a lot of progress needs to be made.
The other revolutionary Gen Three capability is the assembly of large structures, such as antennas and telescopes, in orbit. NASA is working on in-orbit assembly for future astrophysics missions, on the premise that something large, like a 20-meter telescope, must be assembled in-orbit, due to the massive size of the hardware. In those instances, there is no way you could fold it into a single launch fairing – so [the hardware] would need to be assembled robotically in space.
In the same way, being able to assemble the largest reflector or antenna possible would give communication service providers significantly more flexibility.
GSR: Looking back at Gen Two capabilities and the addition of payloads to existing satellites, what types of payloads and capabilities could be added to a satellite in space with this technology? Why is this an attractive option for the military? For commercial operators?
Dr. Roesler: There would be many different possibilities. For example, one simple thing operators could do is to add cameras that provide the satellite the ability to see around it. In geosynchronous orbit, these satellites are 22,000 miles away and it’s difficult to see small objects. So if these cameras could see small objects close to the satellite, it would give operators the ability to react appropriately.
One other capability that could be added is space weather sensors. I mentioned earlier the consequences of not knowing what caused an outage. If you built a space weather sensor and attached it on-orbit, you’d have an indication of whether or not an outage was related to a solar event. There are also other ways of detecting nearby satellites that could be integrated into a small payload and attached.
The advantage of an attachable payload is that you don’t have to integrate it with a propulsion system and attitude control system. The cost is lower, it’s available for use faster, and the opportunities to get it on-orbit are more numerous.
For example, DARPA has developed a capability called PODS – which stands for Payload Orbiting Delivery Systems – that could carry a wide variety of separable mass elements to orbit – including attachable payloads – aboard commercial communications satellites. With 15 commercial launches to GEO a year, we can take advantage of such methods to get small payloads up there without having to buy entire launch vehicles.
In terms of commercial offerings for attachable payloads, many have told me that they are excited about the opportunity to host some of these payloads. It will produce a revenue stream for them for sure, but it also allows them to start thinking about other approaches for fleet flexibility. It’s also an entrepreneurial opportunity. There are people out there who want sensors for applications like agricultural use or environmental data collection, and some of these things can be done from GEO.
GSR: We often hear that concerns over timing – not having payloads built in time for launch – are a main reason why some agencies shy away from hosting payloads on commercial spacecraft. Could you see a reality where we put military or government payloads on commercial spacecraft on-orbit? Could this help alleviate some of those concerns and drive up adoption of hosted payloads?
Dr. Roesler: You really hit the nail on the head. Sometimes, secondary payloads, hosted payloads – or even the payloads for the primary mission – aren’t ready in time. The ability to add them after launch should be extremely freeing for the whole space enterprise and adds a tremendous amount of flexibility.
GSR: During the panel discussion, the panelists touched on the possibility of constructing satellites in space. Why would it be attractive to literally build or construct a satellite in space? What would that enable us to do that we can’t do with our current system of building satellites on Earth and launching them already constructed?
Dr. Roesler: One of the huge advantages is the reduction in testing and design requirements. If I’m going to launch something in pieces, I don’t have to worry about whether the entire assembly survives during launch – I only have to worry about whether the individual pieces survive. By testing at a lower level of integration, I’m saving costs and I’m saving time when I put them together on-orbit.
Another thing that approach lets you do is change your mind. Say you’re building numerous satellites and you have a choice of payloads and maybe you have a choice of power systems. If you have a modular architecture, you can change your mind about what a particular satellite is going to be in real-time. That’s basically unheard of now.
And, as I mentioned earlier, there’s this idea of taking advantage of smaller launch vehicles. There’s a group of investors today that are developing launch vehicles of much lower capacity than available medium-lift ones. Similarly, DARPA is working on a launch system called XSP, which stands for Experimental Spaceplane, which is going to put 3,000-5,000 pounds into low Earth orbit. That mass range fills a gap between the very small launch vehicles and the larger ones. So by taking advantage of that emerging launch infrastructure that has a lot more variety to it, we get another reason to consider building satellites in orbit.
GSR: When it comes to all of these technologies and capabilities – on-orbit refueling, on-orbit servicing, adding payloads to existing satellites, building satellites in space – who is taking the lead in the development of these solutions?
Dr. Roesler: In the case of Gen One –life extension– it’s primarily industry. In the case of Gen Two– on-orbit refueling and on-orbit servicing– it’s definitely DARPA.
RSGS is a very large program dedicated to building a GEO robotic servicing vehicles and getting it on-orbit quickly. When I say that, I should also mention our commercial partner, SSL, who is building the bus and the ground segment and will eventually operate the satellite. And I should also mention the Naval Research Laboratory, which is responsible for all the advanced robotic work that’s leading to this capability. The technology is government-initiated, but we know that commercial players are eager to participate.
Then looking at Gen Three, I would say it’s a combination of DARPA, NASA, and industry. DARPA has some small projects centered around on-orbit assembly and also the idea of putting a persistent platform into GEO. One where payloads can come and go.
The analogy I like to use for such a platform is the antenna tower that you see along the highways. When you look at one of those towers, you’ll see a number of devices – cellphone antennas, point-to-point microwave, public safety radio antennas – all hanging on it. That’s because it’s cheaper to pay rent to the tower owner than it is to buy land and build a tower.
Obviously that makes sense in GEO as well. If you can just send up a payload to a persistent platform, you don’t have to worry about propulsion and attitude control. You have all that provided by the platform and you pay a fee to the platform operator for hosting your payload.
That’s really a win-win.
It could also provide flexibility, being able to swap the payloads more frequently and not have to worry about what the market is going to be like a few years from now.