Spotlight | Aerospace Corp. Microsatellite Systems Department
The Aerospace Corp. did not set out to establish an organization focused on designing and building miniature satellites. During the late 1990s and early 2000s, engineers who began building spacecraft weighing a few kilograms or even less worked in multiple departments. That changed in 2007 when the company established its Mechanics Research Department.
“At the time, the Mechanics Research Department seemed like a good home for microsatellite activity,” said Richard Welle, who led the department and now serves as Microsatellite Systems Department director. “Then the microsatellite activity just outpaced everything else in that department.”
The Microsatellite Systems Department, established in May 2014, has only 12 full-time employees and a few summer interns. However, Aerospace is a matrix organization, which means project leaders form teams by bringing in experts from the company’s Engineering and Technology Group.
“For cubesats, we can bring in subject matter experts for all the subsystems, including attitude control, communications, thermal, power, software, navigation, propulsion,” Welle said. “That organizational structure is particularly valuable for the microsatellite program where the budgets are simply too small to support the breadth of expertise that’s essential to a successful program.”
Aerospace has been designing and building miniature satellites for nearly two decades. Customer interest began to surge in 2012, however, as people recognized that microelectronics could enable extremely small satellites to take over many of the tasks performed by larger spacecraft.
“Aerospace was in on that from the beginning, pushing that development,” Welle said. “As a result, we’ve learned a lot of lessons, built a lot of capabilities and our business in that area has grown substantially.”
Aerospace’s first microsatellites, two tethered spacecraft weighing only 250 grams each and developed with funding from the U.S. Defense Advanced Research Projects Agency, were launched in 2000 from the Stanford University Space Systems Development Laboratory’s 23-kilogram Orbiting Picosatellite Automated Launcher. Since then, Aerospace has built and launched more than two dozen spacecraft weighing between 250 grams and 6.4 kilograms, including a series of increasingly capable cubesats known as AeroCubes.
Although the first AeroCube was destroyed when its Dnepr rocket failed in 2006 and the second AeroCube operated for less than 24 hours in orbit before losing power, Aerospace has continued to develop, launch and operate cubesats.
“We like to take risks and push the limits so we expect to have some failures,” Welle said. “At the same time, we learn from our mistakes and work hard to build in mission assurance in the form of redundancy.”
That redundancy is apparent in a NASA project, the Optical Communications Satellite Demonstration, which includes three satellites each weighing 2.5 kilograms designed to showcase the potential of laser communications. Each of those spacecraft is equipped with Earth horizon sensors, Earth nadir sensors, sun sensors, Earth magnetometers and star trackers.
Currently, six Aerospace cubesats are in orbit: two AeroCube 4s, two AeroCube 5s and two AeroCube 6s. The satellites, which weigh between 0.5 and 1.5 kilograms, were built for one of the nonprofit organization’s primary customers, the U.S. Air Force Space and Missile Systems Center. AeroCube 4s feature three-axis attitude control with three-degree pointing capability, solar panels that also are designed to provide variable drag and custom-built transceivers. AeroCube 5s are equipped with more advanced pointing and tracking subsystems than their predecessors, and AeroCube 6s carry dosimeters to measure radiation.
“We like to see these things evolve from one generation to another,” Welle said. “Since the cubesat lifecycle is so short, we can fly things, test them, learn lessons and fly them again.”
The Optical Communications Satellite Demonstration was Aerospace’s first NASA project. It was designed initially to demonstrate that cubesats could transmit data at a rate of five megabits per second to a ground station with a 30-centimeter diameter antenna. Now, the Aerospace team expects the satellites to transmit 200 megabits of data per second. “It’s not a whole lot more difficult to hit 200 megabits per second than it is to hit five,” Welle said. “So that’s what we are aiming for.”
Aerospace delivered the first Optical Communications Satellite Demonstration spacecraft to NASA in March. That satellite is scheduled to launch in August as a secondary payload on a United Launch Alliance Atlas 5 rocket carrying a National Reconnaissance Organization payload. Engineers have nearly finished assembling the other two satellites in the series but are waiting to monitor the performance of the first satellite before completing construction. The final two satellites are scheduled to launch in December on a SpaceX Falcon 9 rocket.
Another Aerospace cubesat scheduled to launch on the same Falcon 9 is the Integrated Solar Array and Reflectarray Antenna. NASA’s Jet Propulsion Laboratory is building the satellite payload, a high-bandwidth Ka-band communications system including a high gain antenna for three-unit cubesats. Aerospace plans to build the satellite bus, integrate the payload and perform flight operations jointly with JPL.
Aerospace’s Microsatellite Systems Department also is responsible for the company’s Reentry Breakup Recorder (REBR), a 4-kilogram device similar to an aircraft’s black box that is designed to hitch a ride into Earth’s atmosphere with a spacecraft. REBRs feature GPS receivers, temperature sensors, accelerometers, rate gyroscopes and pressure sensors to monitor and report on the destruction of the vehicle during the re-entry process.
When Aerospace’s first REBR was destroyed on an Antares rocket launch failure in October, the company quickly built NASA a replacement, which is now on the International Space Station waiting for a ride.
“The design of REBR can be applied to future crewed spacecraft and even aircraft,” said Dan Rasky, director of the Space Portal at the NASA Research Park and a REBR co-investigator. “Such a capability would provide assured communications in the event of a vehicle disaster and breakup. Even if the vehicle breaks up and disappears, you still can recover data very quickly after the event on the vehicles final moments before break-up.”