Issue 126

I hope you enjoyed XSS-11 Part 1. XSS-10 was a success, it was a one-day mission that opened many eyes to the utility of a small satellite being able to maneuver in proximity to another satellite, take and downlink images. Might be good to have this capability someday. Well, several space technology experts at the AFRL Space Vehicles Directorate were busy on the task of creating a one-year space experiment mission to demonstrate how a small satellite could do the job. The XSS-11 program development was running in parallel to XSS-10. In this article I will introduce the team that stepped up to the XSS-11 mission. I will also review a little about the mighty XSS-11 spacecraft that was built and flown in what would be an 18-month space mission that captured the interest of the AF Space Command leaders…and perhaps our adversaries. I will also share a story of team determination in the face a snowy travel and end with a rather funny tie XSS-11’s Lockheed-Martin folks had with the 1984 British movie “Spinal Tap.” Really!

I served twice in the AFRL space arena as an AF officer. As a Major, I was involved with the TAOS space experiment program and as a Colonel I was the Chief of the Space Experiments Division. I worked alongside some great space technology experts and many who were not afraid to “daring greatly.” During the ideation and formulation of the XSS-11 mission, the TAOS space mission was underway. Launched in 1994 on the first Orbital Science Corporation’s Taurus rocket, TAOS was slated for a 2-year mission, but the mission kept going for 6+ years. It was an array of technologies put through their paces in space and these technologies were gadgets developed in the

ran the Aerospace Engineering Facility (AEF) and another facility where spacecraft can be built and complete testing. The AFRL team reached out to their Air Force colleagues of the then Space and Missile Systems Center on Kirtland AFB. Specifically, the Space Test Program (STP) and the SMC’s RDT&E Support Complex satellite control center that used the AF Satellite Control Network stations around the world to transmit to and receive data from orbiting spacecraft. The Rocket Systems Launch Program (RSLP) small launch vehicle team was a key player in the XSS-11 effort to get to space working the Minotaur 1 ride to space. Several experts from The Aerospace Corporation were embedded with these government teams. Aerospace’s Clark Keith would emerge and be respected as the Flight Director helping many Air Force and government civilians learn tons about the art and science of RPO (he was a fabulous teacher and motivator). In Cheyenne Mountain AF Station in Colorado Springs was a group of astrodynamics experts who would serve as the trackers and orbit determination experts as the XSS-11 and Minotaur RPO “dance” would occur with these two craft getting close and at times appearing to be on a collision course. (Spoiler Alert: they never collided!). While it was a challenge to track and separate out the two spacecraft, these were the best in the business to keep an independent eye on things as the XSS-11 team in Albuquerque executed RPO experiments. Now for the industry partners. AFRL selected Lockheed-Martin Space Systems Company in Denver as their primary space industry partner. Their challenge was designing and building a small spacecraft (the size of a dishwasher with two solar panels sticking out looking like wings), the LM team had never made something so small.

They were indeed up to the challenge and created a very capable small spaceship to execute RPOs many, many times during the mission. In Part 3, I will outline all the different RPO techniques they stepped up to do. With LM was a company called Octant Technology, out of San Jose CA. These were the RPO astro dynamos who helped XSS-10 be so successful. From the math, to the tools to the processing of spacecraft sensor measurements and orbit data from Space Command, Octant was a great team to have and they were joined by another space dynamics group at Draper Lab in Boston. They developed capability both on the ground and on the spacecraft to plan RPOs. An important partner was MacDonald Dettwiler/OpTech of Canada who provided the primary range and bearing scanning LIDAR. There were other organizations comprising the team and I’ll give them a shout out in the spacecraft review below. I have included a photo of the team shirt that shows all the partners of the XSS-11 team.

Let’s now learn about the XSS-11 space vehicle. Earlier in this Part 2 essay I said XSS-11 was the size of a dishwasher, with two nifty solar panels (1.6 meters squared) sticking out the side (see photo of XSS-11 in Thermal Vacuum Chamber). XSS-11 was 32 inches tall, 20 inches wide, and 24 inches deep. I measured our dishwasher here in our home and it is 33 x 24 x 24 inches. How do you like that? XSS-11 is a “dishwasher-sat.” It was a mighty and amazing spaceship that was put through its paces for 1.5 years showcasing all sorts of RPO and orbital maneuvering techniques and advanced space technologies needed to be an agile RPO system. XSS-11 was 107 Kg “dry” (235 lbs.). To get the “wet” weight, we need to know about the propulsion system. XSS-11 carried 40 Kg (88 lbs.) of Mono-Methel Hydrazine. So, the XSS-11 spaceship tips the scales at 323 lbs. This amount of propellant equals nearly 700 m/s of Delta V capability! There were 10 small thrusters that were each capable of about 0.2 lbs. of thrust. Two were designed to be used to do in-track thrusting and the other 8 were for attitude control, no momentum wheels were in the design, that’s OK. These “wee little thrusters” had a big brother along that was 5 lb. thruster, for the big burns. For command-and-control support, the Naval Research Lab provided a transceiver that enables communications with the AFSCN and to provide range and range rate for ground-based orbit determination. The spacecraft included an inertial measurement unit and sun sensor to support 3-axis control and pointing the solar arrays at the Sun. XSS-11 was a composite structure and had Gallium Arsenide solar arrays and 30 Ahr Lithium Hydride battery by Yardley. XSS-11 had a LIDAR which was the range finder sensor and SAIC’s dual visible/star camera system for getting the angles for use in RPO calculations. General Dynamics provided a high-rate streaming video transmitter. Guess what, XSS-11 also had a halogen illuminator…a head light! On board was an avionics package and RAD 750 processor that held a lot of RPO related software provided by Broad Reach Engineering. There was code to manage the sensor data, provide collision avoidance insight, and process the visible images and even plan RPOs. Here’s a fun-fact related to what did not fly as part of XSS-11. The original design had a sphere that was going to be ejected by XSS-11 for initial RPO testing but was later deleted in favor of simply hanging out with the Minotaur upper stage rocket body and RPO-ing with it.

On the ground in the control center, there was all sorts of nifty software and smart people to use it to execute RPOs…more on that in Part 3. This ground capability was there to plan and execute RPO. Bottomline, XSS-11 was a small and capable spaceship jampacked with capability to give it a shot at doing all sorts of RPO activities. It was built with limited budget, and it was built in Denver, shipped to Kirtland for final preparations before being transported to Vandenberg AFB in early 2005 to be integrated onto the Minotaur upper stage. The Minotaur rocket used Minuteman rocket stages and was a very capable launch vehicle built by Orbital Sciences Corporation (now part of Northrop Grumman).

Now for a story of dedication and winter driving skills. When a satellite is launched, it is important to have all your experts in the mission control room to aid if there is a challenge. The plan for the Lockheed-Martin folks in Denver was to get to Albuquerque the Sunday before the Monday Minotaur launch from Vandenberg. Well, that Sunday featured BIG snowstorm on the Colorado front range. The airport and I-25 were closed for a while. The Lockheed team selected 8 spacecraft experts to pile into two 4-wheel drive vehicles and head for Albuquerque. They took Colorado Highway 285 into the mountains where the road was passable and then continued down the central valley of northern NM to ABQ. Launch went off as planned on Monday 11 April 2005. Hooray and now it was time for the team to bring XSS-11 to life on-orbit with everybody in their seats ready to contribute.

One more story and this is a funny one. Have you seen the movie This Is Spinal Tap? It is a British 1984 movie comedy about a rock-n-roll band called Spinal Tap. There is a scene where Nigel explains an Amplifier “that goes to 11.” Here’s a 50-second YouTube video of the scene. The “We go to 11” line Nigel states resonated with the LM team, so, they made team T-shirts and I include a photo of it.

Next time we will fly the XSS-11 space experiment mission. One point to end on. Four days after the XSS-11 was launched there was the launch of the NASA Demonstration of Autonomous Rendezvous Technology (DART) mission. It would attempt a RPO of the DART spacecraft with the main satellite launched on a PegasusXL rocket. The demo would occur right after getting on orbit. DART used its autonomy capability to attempt an RPO with the satellite just launched. Well, things did not go as planned. There was a “slight” collision between DART and the satellite. Don’t worry, it did not create any debris. All eyes were now on XSS-11 as it was completing its initial orbit checkout and get to the business of RPO-ing. With the DART mishap in the books, the XSS-11 team received some sage advice – Do not collide!