History and Sponsors

As spaceflight pioneers with over 50 years of experience, APL has designed, built, and operated 69 spacecraft and more than 150 instruments. From the first days of spaceflight to autonomous interplanetary spacecraft, APL's history of space exploration and experience is diverse, including small, mid-sized, and interplanetary spacecraft and instruments developed for a variety of sponsors.

APL's long history of developing instruments for both in situ and remote sensing observation has benefited our various government sponsors. The Civil Space Mission Area designs and develops advanced instruments and novel methods and software to conduct innovative research. Unique APL instruments range from the first hyperspectral imager in space to sample-return methods and technologies.

Capabilities, Facilities, and Methodology

APL is recognized as a leader in mission design and navigation; instrument development; mechanical engineering; mechanical design, thermal, and instrument accommodation; communications hardware; electrical subsystems and power; precision timekeeping devices, and mission operations. Our facilities are essential to support our spaceflight build process.

APL operates with an AS9100C certified quality management system. That certification is specific to the Laboratory's spaceflight program management, systems engineering, design, development, production, integration, test, and operation processes. APL maintains an impressive record of delivering high quality space systems on time and on budget.

A few defining innovations and expertise we incorporate are described below.

Systems Engineering

APL's robust systems engineering philosophy guides the development of systems. A systems engineering approach defines system needs and functionalities early in the development cycle, documents those requirements, and then monitors the requirements throughout the design, build, and system validation. Trades studies, system performance, and system optimization are considered at the beginning of each mission and weighted against the operational requirements. A life-cycle view ensures that requirements affecting other aspects of development, production, and operation are considered and evaluated before implementation. APL's systems engineering approach requires interdisciplinary skills as well as teamwork.

Spacecraft Autonomy Work and Research at APL

Autonomy is the ability of a spacecraft to act independently from ground control. APL has developed and steadily, over three generations, increased the capability of a flexible and expressive autonomy system spanning seven spacecraft programs. Today, APL is embarking on the development of a new set of autonomy systems that will meet the critical challenges of our national security space and NASA customers into the future.

New Horizons Autonomy System

The New Horizons mission to Pluto and to the Kuiper Belt offers several unique autonomy challenges based on the great distance this spacecraft has to travel.

Autonomous First Aid

Even though New Horizons left Earth in 2006 at the fastest launch speed ever recorded for a man-made object, it took 12 years to reach Pluto. During cruise, the spacecraft spends up to a year without ground commands, so any problems it encounters during the mission must be fixed autonomously.

Last-Minute Self-Reliance

As the New Horizons spacecraft makes its final approach to Pluto, signals traveling from the spacecraft take 4 hours to reach Earth, which means that ground operators who might need to respond to anything happening onboard during the final approach would be unable to reach the spacecraft in time. So New Horizons has to operate autonomously for the final approach to Pluto. The pressure is on. After a 12-year voyage, the spacecraft could not make any mistakes, or it could miss a 1 in 230 year opportunity. Luckily, APL autonomy is on the job ensuring that New Horizons keeps going.

MESSENGER Autonomy System

The MESSENGER autonomy system was the first in the third generation of APL autonomy systems, and it is followed by other third-generation systems in the NASA STEREO and New Horizons missions. The MESSENGER autonomy system offered amounts of flexibility and expressiveness, allowing large amounts of telemetry to be manipulated and combined in order to identify and detect multiple onboard faults. The harsh environment around Mercury required a robust autonomy system. The MESSENGER spacecraft was tucked behind a heat shield to stay cool, but mere minutes outside the shield overheats the spacecraft. The MESSENGER autonomy system's job is to make sure that didn't happen...ever.

Spacecraft Autonomy Visualization

Spacecraft are intensely complicated devices producing huge amounts of data. At approximately 5,000 unique data values per second (18 million per hour), the ability to quickly review the data in order to quickly understand the current state of the system is daunting. This is important for autonomy systems during testing in order to ensure that autonomy judgments and responses are correct. This is also important during flight, when operators have to understand what the spacecraft has done autonomously in between scheduled contact times. Engineers at APL have developed Spacecraft Autonomy Visualization (SAV), a visualization technique that combines a matrix-like data display with TiVo-like time controls. The result is a single view of all 5,000 data points with the ability to examine onboard autonomy response over time and across the entire data set. SAV is used on the NASA STEREO mission and was used on the NASA MESSENGER mission.


ExecSpec, short for Executable Specification, is the fourth generation in APL autonomy systems. It defines autonomous operation through diagrams. In ExecSpec, a user, without any programming capability, can draw diagrams describing how he or she wants the spacecraft to act. The diagrams are then loaded directly into the spacecraft, which interprets the diagrams in order to control the spacecraft. This capability involves more engineers in the design process and makes the system easier to review and understand. ExecSpec will make its first appearance on the Solar Probe Plus.

Onboard autonomy systems usually function in a reactive (condition leads to response) or time-based (at this time do this) mode. Hierarchical Activity Planning (HAP) is a development and execution system for time-based sequences. Similar to ExecSpec, HAP focuses on diagrams to explain how the system should behave. However, the main feature of HAP is the ability to change sequences on the fly without endangering the spacecraft or current ongoing sequence. National security space customers may desire the ability to add observations to an on-orbit spacecraft and accomplish that observation in minutes to hours. The current ability to add observations takes days to weeks and may result in a specific target eluding detection.


Rad-hard ASICs

APL has a long history of digital, analog, and mixed-signal application-specific integrated circuit (ASIC) development. At APL, ASICs have ranged from 32-bit language directed real-time processors, radar chirp generators, signal processing and communications ASICs, as well as numerous gate arrays and mass memory input controllers. Within APL's Space Department, the development of ASICs has been focused on mixed-signal design targeted at both spacecraft bus and instrument applications. ASICs provide many advantages to spacecraft design; they also come with unique challenges. One of the most significant challenges is the radiation environment in which these devices must operate.

Radiation environments can have negative effects on electronic devices, resulting in sudden changes to internal signals that can cause an electronic component to malfunction or to be damaged. Additionally, prolonged exposure to radiation can change the electrical properties of ASIC transistors. Long-term radiation exposure has been successfully dealt with at APL by using a specialized radiation-hardened manufacturing processes.

Mission Design

Proximity Operations

Space situational awareness (SSA) and spacecraft rendezvous are two important and related technologies. APL is building a proximity-operations (ProxOps) simulator to develop and test rendezvous, proximity operation, reconnaissance, surveillance, and SSA algorithms and concepts for near operations on planetary surfaces.

APL's ProxOps simulator benefits mission concept development through added realism and engineering insight. A full-scale simulator and laboratory with realistic motion stages, cameras, sensors, stimulators, and lighting, however, is often prohibitively expensive. Nevertheless, significant progress can be achieved with a system consisting of processors and algorithms, along with provisions to link in specialized hardware such as single-board computers or optical sensors and motion stages in order to emulate realistic motion.

Surface Mobility and Robotics

As NASA and the international space community seek to unlock the scientific secrets of our solar system, the capability to operate on the surfaces of planets, moons, and small bodies (such as asteroids and comets) becomes critical to achieving mission goals. Robotic spacecraft are essential tools for solar system exploration, and APL has a rich history and world-class track record of developing and operating robotic missions for NASA. Building on our capability to produce cost-effective robotic spacecraft for flyby and orbiter missions, APL is focused on meeting the technological challenges of producing robotic systems for surface operations. Our developments will support NASA goals of human and robotic exploration on the surfaces of solar system bodies.

NASA requires further development of technologies ranging from robotic mechanisms for locomotion and dexterous manipulation and associated sensing and autonomy software to integrated systems that provide manipulation and mobility capabilities critical to the success of surface science and exploration missions. Technological advances will enable robotic operations on inhospitable surfaces in space environments that pose tough challenges to current robotic and avionics hardware.

To meet NASA's critical challenges of planetary surface mobility and robotics, APL is addressing surface operations issues associated with mobility in difficult terrain, mechanisms for material and sample manipulation, and component technology for supervised robotic autonomy. Tasks under study include application and development of robotic hardware, software and simulation tools leveraging APL spacecraft expertise and systems engineering strengths, and unmanned vehicle autonomy developments for terrestrial applications. With an aim to conceive, develop, and demonstrate practical solutions, APL technology will advance the capability of mobile robotic platforms to perform critical science and utility functions supporting future NASA surface missions.

One JHUAPL developed example of surface operations is the POGO development project.