The Exploration and Space Communications (ESC) projects division provides full-coverage communications and navigation services, as well as cross-cutting technical expertise to move NASA into the future. These services are critical to returning ground-breaking scientific data to Earth where it can be used for the benefit of humanity.
Relationship with SCaN
ESC works on behalf of the Space Communications and Navigation (SCaN) program office at NASA Headquarters to effectively implement their vision. SCaN is a division of the Space Operations Mission Directorate and provides programmatic oversight of NASA’s networks, advanced communications technologies, and other space communications and navigation requirements. These capabilities support missions by providing critical connectivity from spacecraft to ground. At Goddard, ESC provides the leadership and expertise to make mission success a reality.
NASA’s Near Space Network fulfills the essential needs of missions, empowering them with mission-critical communications and navigation services and enabling the transmission of science and exploration data from space to Earth.
As a single, end-to-end network, the Near Space Network orchestrates communications services through government or commercial providers for missions in the near-space region. The network serves missions throughout their entire lifecycle, from planning to on-orbit services.
As a result, the network ensures its users have robust and reliable services that fully support their mission objectives.
For more information, check out the Near Space Network project page.
The Exploration and Space Communications (ESC) division elevates technology. As sought-out experts, the ESC team takes a two-pronged approach to assisting with NASA’s missions: contributing innovative ideas to the NASA community, and updating existing technology to meet evolving requirements. Additionally, we seek to ensure that ESC’s work can be transitioned to industry so that all may benefit from the groundbreaking technologies we produce. To nurture creative thinking and problem-solving, the division focuses on fresh perspectives each employee brings -from organization leaders to interns.
Radio frequency communications
NASA has been using radio frequency communications since the early days of spaceflight. Using radio waves, NASA can communicate with spacecraft, sending commands and receiving data. This is the basis of all space communications.
Over the course of 60 years, NASA’s Goddard Space Flight Center has remained at the forefront of development and sustainment of communications capabilities for NASA. Today, Goddard is the home to NASA’s Near Space Network which brings down terabytes of mission data every day.
What is Radio Frequency?
Radio waves are a form of electromagnetic radiation on the spectrum. The electromagnetic spectrum is a range of types of energy that travel through the universe. Missions encode their scientific data onto the electromagnetic signals to send back to Earth. Radio waves are invisible; however, visible light is another part of the electromagnetic spectrum.
Communicating with Spacecraft
There are two types of radio frequency communications services available through the Near Space Network: space-based relay communications and direct-to-Earth communications.
Direct to Earth
To communicate with the direct-to-Earth portion of the network, spacecraft must have an unobstructed view of a ground station on Earth with antennas capable of receiving the satellite’s signal. The Near Space Network has ground stations all over the world to receive data periodically throughout a spacecraft’s orbit. This method of communication is well suited to science missions that do not need to be in constant contact with Earth. For direct-to-Earth communications, the Near Space Network leverages both commercial providers and government-owned, contractor-operated systems.
The Near Space Network also supports missions that need continuous communications coverage throughout an entire orbit, such as human spaceflight missions. For missions needing these services, the network directs them to the Advanced Communications Capabilities for Exploration and Science Systems (ACCESS) project.
ACCESS operates NASA’s fleet of Tracking and Data Relay Satellites (TDRS), which are located in geosynchronous orbit over three key areas on Earth, about 120 degrees apart. Geosynchronous orbit is such that, as the TDRS travels around Earth, they always stay above the same relative point on the ground as the planet rotates. There are ground stations located within line of sight of where these TDRS are orbiting, so that the satellite can always transmit data down to the antennas at any time.
As spacecraft like the International Space Station and the Hubble Space Telescope orbit Earth at a different rate and altitude, they send their data to a TDRS spacecraft, which then relays the data back down to the “stationary” ground stations below it.
Goddard is recognized as the NASA center of excellence for optical communications by NASA Headquarters. Early exploration of optical was done at Goddard through the Lunar Laser Communications Demonstration (LLCD), which launched in 2013 and proved that optical communications is possible from the lunar region.
Since then, Goddard and ESC are infusing optical communications into a series of demonstration missions to prove its capabilities in a variety of applications.
In 2021, NASA launched the Laser Communications Relay Demonstration (LCRD) as a hosted payload aboard the Department of Defense’s Space Test Program Satellite-6 (STPSat-6) by a United Launch Alliance Atlas V rocket. LCRD is NASA’s first two-way optical communications relay system. Using optical, LCRD will send data to Earth from geosynchronous orbit at 1.2 gigabits-per-second (Gbps). At this speed and distance, you could download a movie in under a minute.
In 2022, NASA launched the TeraByte Infrared Delivery (TBIRD). TBIRD is a hosted payload on the Pathfinder Technology Demonstrator (PTD) 3 mission, which was launched via the SpaceX Transporter-5 rideshare. The system will demonstrate a direct-to-Earth optical communications downlink at 200 Gbps, NASA’s fastest laser link from space.
Today, ESC is working on several cutting-edge optical communications missions. Check out these pages for more information:
Integrated LCRD Low-Earth Orbit User Modem and Amplifier Terminal (ILLUMA-T), launching in 2023
Orion Artemis II Optical Communications System (O2O), launching in 2023
Optical communications, also known as laser communications, represents a major step forward in space communications. Optical communications use lasers in the infrared portion of the electromagnetic spectrum, allowing more data to be encoded into each transmission.
Currently, NASA primarily uses radio frequency communications to communicate. Both infrared and radio are part of the electromagnetic spectrum, a range of types of energy that travel through the universe. Optical communications can send more information per second to Earth than any other communications system so far. This means scientists can get larger volumes of data in less time.
Optical communications systems also have reduced size, weight, and power requirements. Spacecraft have very limited room and power on board, and optical uses less of these resources than traditional radio systems.
Additionally, only a few missions currently utilize the infrared spectrum for space communications. While radio provides reliable technology tested by time, laser opens new avenues for communications, avoiding crowded areas of the electromagnetic spectrum.
How It Works
As the capacity for science and research continues to grow, NASA is implementing laser communications technology to enable greater return of science data from space. But laser communications capabilities also present unique challenges, including the need for extreme pointing accuracy when beaming spacecraft data to ground stations. NASA engineers are solving these challenges by testing and implementing cutting-edge laser-pointing technology.
Lasers not only enable the capacity for greater space data delivery, but they also offer greater security. When pointed at Earth, laser beams expand at a much lower rate than the radio frequency waves and therefore cover less surface area. For this reason, laser communications technology is more secure, minimizing the potential for outside interference to space signals.
But the narrower widths of laser beams require that lasers are very accurately pointed toward optical telescopes on the ground. Using traditional radio waves, spacecraft can dump down data as they pass over antennas without using special pointing mechanisms, but with lasers, the spacecraft must maintain contact with the ground antenna.
So how does this process occur? First, the ground station is notified in advance when a spacecraft will be making a pass. As the spacecraft nears the ground station, the ground station emits a signal that scans the general area of the spacecraft; because the pass was pre-scheduled, the spacecraft already knows to look for this signal. Sensors on both the spacecraft and the ground station drive the pointing mechanisms, enabling both to maintain contact, also known as “lock.” This is typically achieved within seconds.
Then, the spacecraft’s modulator transfers science or other data onto the laser beam, and the signal travels through the spacecraft’s optical terminal by bouncing on a series of strategically-positioned mirrors inside the system. When the laser beam reaches the spacecraft telescope, it is pointed at the ground station with the help of the controller unit, which maintains lock with the ground terminal.
The challenge of acquiring and maintaining lock is even greater in deep-space environments, such as from Mars. From such a great distance, data takes significantly longer to reach the ground station, so the rotation and orbit of Earth must be considered. From Mars, for example, spacecraft telescopes must be pointed ahead of Earth to account for where in its orbit around the Sun, Earth will be by the time the data reaches the planet.
New communications technologies
ESC is constantly evolving technologies to keep up with mission needs. This includes advancing networking capabilities for both radio and optical communications, enhancing navigation techniques, and using industry skills and components to embrace commercialization. Some examples of on-going enhancements include:
NASA’s communications networks have a long legacy, dating back to even before the agency began in 1958. NASA’s Goddard Space Flight Center provides the communications connection that enables NASA to explore our universe.
These networks can trace their lineage back to the 1950s. Before NASA, the Naval Research Laboratory built Minitrack, a network of 10 antenna sites intended to help track the first satellites. NASA assumed responsibility for the network shortly after the agency was formed in 1958, and Goddard has managed most NASA’s communications capabilities ever since. In the 1960s, Goddard evolved the Minitrack system to become the Satellite Tracking and Data Acquisition Network, supporting spacecraft requiring enhanced communications.
In 1983, NASA launched the first Tracking and Data Relay Satellite (TDRS), a relay to enable missions without direct-to-Earth, line-of-sight to communicate data home. In the 1990s, as TDRS enabled coverage of mid-latitude missions, the Ground Network shifted to support a number of Earth-observing missions in polar orbit. The Ground Network was, and still is, comprised of commercial and government ground antennas. In the late 90s, the network was renamed the “Near Earth Network (NEN)” and the TDRS fleet was deemed the “Space Network.”
The two networks worked side by side, each with its own strengths. Both were upgraded over the decades. The NEN integrated both government and commercial ground stations worldwide into the network to provide high-quality services most efficiently. Since the launch of the first TDRS satellite, Goddard has launched two additional generations of TDRS spacecraft, evolving capabilities to add Ka-band frequencies and expand demand-access service. The final satellite of the third generation, TDRS-M, launched in 2017.
In October 2020, the ESC reorganized its network operations and management portfolio to execute the bold commercialization plan set forth by NASA’s Space Communications and Navigation (SCaN) program. This plan cements the U.S. government’s commitment to engage with private industry to build a commercial space economy.
In 2020, ESC established the Near Space Network, which connects missions to essential communications and navigation services from planning to launch pad to orbit. As a single point of service for missions in the near-space region — out to two million kilometers away — the network connects users with either government or commercial service providers.
The network connects missions to the provider that best suits the mission’s objectives and requirements. For missions needing NASA’s TDRS or direct-to-Earth systems, the network connects them to the Advanced Communications Capabilities for Exploration and Science Systems (ACCESS) project. ACCESS operates, maintains, and sustains government-owned, contractor-operated ground and flight-based systems. The ACCESS project combined the government portions of NASA’s historic Space Network and Near Earth Network.
With commercialization being a major thrust for the agency, ESC established the Commercialization, Innovation, and Synergies (CIS) office to foster partnerships with innovators in the space communications and navigation marketplace and grow the commercial provider base for the Near Space Network.