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Connecting the Cosmos: How NASA’s SCaN Program Powers Space Communication…
Connecting the Cosmos: How NASA’s SCaN Program Powers Space Communication and Navigation
SCaN's Focus Areas
Space Communications Technology
Delay/Disruption Tolerant Networking (DTN)
The capability enables data delivery in situations that involve:
Delays (e.g., Deep Space missions)
Data rate mismatches (e.g., high data rate Science downlinks but lower rate terrestrial connections)
A DTN architecture is a store-and-forward communications architecture in which source nodes send DTN bundles through a network to destination nodes.
Disconnections (e.g., end-to-end link unavailability)
DTN Benefits
Increases science data return through interoperability and more efficient link utilization
Enables communications between and through constellations and swarms of smallsats
Facilitates science across distributed platforms
Reduces of operational complexity
Enables responsive mission operations
Increases scalability
Enables reuse
Increases interoperability
Facilitates streamlined operations and more efficient use of personnel
overview
DTN provides assured delivery of data using automatic store-and-forward mechanisms.
The DTN protocol suite can operate in tandem with the terrestrial IP suite or it can operate independently.
DTN is a foundational capability for creating the Solar System Internet and will be bring internet-like functionality to space communications.
DTN is a suite of standard protocols that use information within the data stream to accomplish end-to-end data delivery through network nodes.
DTN Capabilities
Security
DTN Bundle Protocol includes integrity checking, authentication, and encryption—even on links that previously lacked such protections.
Efficiency, Utilization & Robustness
Provides more reliable and efficient data transmission, increasing usable bandwidth.
Enhances link robustness by supporting multiple potential network paths for communication.
Interoperability & Reuse
Standardized DTN protocols allow spacecraft and ground systems from different agencies or commercial providers to work together.
Enables NASA to reuse the same communication protocols for missions in low Earth orbit, near-Earth space, and deep space.
Developmental Scans Technology
Deep Space Atomic Clock
What is an atomic clock?
Atomic clocks are the most accurate timekeepers in the world.
Ground-based atomic clocks have long been the cornerstone for space navigation to the Moon, Mars and beyond.
Atomic clocks use the rhythmic characteristics of atoms the same way a grandfather clock uses a pendulum.
How does DSAC impact NASA?
Moon to Mars
Currently, Earth antennas can send navigation signals to only one spacecraft at a time, but DSAC-equipped spacecraft can generate and receive their own precise timing signals.
At NASA’s upcoming Gateway station in lunar orbit, the Deep Space Atomic Clock (DSAC) can be tested alongside autonomous onboard navigation systems to demonstrate its accuracy and reliability for future deep-space missions.
Radio-Based Science
The Deep Space Atomic Clock (DSAC) provides highly precise timekeeping that improves the accuracy of spacecraft radio-based scientific measurements.
Enhanced timing leads to better analysis of planetary gravity fields, atmospheric properties, and other remote-sensing data.
This capability could help determine whether Jupiter’s icy moons contain subsurface oceans and reveal details about the composition of planetary atmospheres.
Ground Antenna Arrays
Building more large antennas is costly and risky; instead, NASA is shifting toward arrays of many smaller antennas, which offer:
Higher reliability — failure of a single small dish has minimal impact compared to losing one large antenna.
Scalability — capacity can be matched to diverse mission requirements by adding or allocating antennas as needed.
Enhanced efficiency — arrays can downlink multiple spacecraft on the same frequency band simultaneously, provided they’re separated into different synthesized beams.
Operational advantages of antenna arrays include:
Radio-frequency interference nulling, improving signal quality.
Adjustable beam patterns — beams can be widened to capture data from multiple spacecraft or focused to isolate a single spacecraft.
Optical Communications
Optical communication uses light to transmit information over long distances and is highly beneficial for space missions.
These systems require less volume, weight, and power than traditional radio systems, freeing spacecraft resources for additional science instruments and reducing power demands.
NASA’s SCaN program supports several optical communications demonstrations, including:
TBIRD (TeraByte InfraRed Delivery)
LCRD (Laser Communications Relay Demonstration)
O2O (Orion Artemis II Optical Communications System)
Some of the benefits
Faster: Higher data rates can enable increased data volume for missions that have been able to generate far more data than they could downlink, or enable new “high definition” instruments that collect larger volumes of data.
Secure: Optical communications terminals use narrower beam widths than radio frequency (RF) systems.
Lighter: Optical communications flight terminals reduce user Size, Weight, and Power (SWAP) because they are smaller, lighter and require less power than traditional RF communications equipment.
Flexible: Optical communications open the possibility of building low-cost ground segments (for low Earth missions) that can be located at mission sites or data centers
Systems Engineering
Systems Engineering is applied across the entire lifecycle of SCaN technologies.
Systems engineers look at the big picture—integrating hardware, software, people, facilities, policies, and documentation into a complete system.
They guide technology from early Technology Readiness Levels (TRLs) to ensure it aligns with SCaN goals and can be supported by NASA’s communication networks:
Deep Space Network (DSN)
Near Earth Network (NEN)
Space Network (SN)
Technology Readiness Levels
TRL 1: Basic principles observed and reported
TRL 2: Technology concept and application formulated
TRL 3: Analytical and experimental critical function and characteristic proof-of-concept
TRL 4: Component and breadboard validation in laboratory environment
TRL 5: Component and breadboard validation in laboratory environment
TRL 6: System/subsystem model or prototype demonstration in a relevant environment (ground or space)
TRL 7: System prototype demonstration in a space environment
TRL 8: Actual system completed and "flight qualified" through test and demonstration (ground or space)
TRL 9: Actual system "flight proven" through successful mission operations
Optical Communications
overview
NASA has transitioned to higher-bandwidth radio spectrum usage. However, there is no way for NASA to use radio frequency communications to carry higher data rates without increasing the size of its antennas or power of its radio transmitters.
NASA is developing optical communications to address limitations of radio frequency (RF) communications, including: bandwidth, spectrum and overall size of frequency packages and power used.
Optical spectrum uses light as a means of transmitting information via lasers.
Optical communications benefits include being faster, more secure, lighter and more flexible.
Optical communications challenges include a need for precise laser beam accuracy and Earth’s atmosphere interference, such as clouds.
Optical communications timelines are outlined in both a technology and demonstration timeline through 2023, as well as an operational timeline through 2026.
Optical Spectrum
Optical communications use light as a means of transmitting information over long distances.
NASA, optical communications technology sends data across space using lasers instead of radio frequencies.
benefits
Faster: Higher data rates can enable increased data volume for missions that have been able to generate far more data than they could downlink, or enable new “high definition” instruments that collect larger volumes of data.
Secure: Optical communications terminals use narrower beam widths than radio frequency (RF) systems.
Lighter: Optical communications flight terminals reduce user Size, Weight, and Power (SWAP) because they are smaller, lighter and require less power than traditional RF communications equipment
Flexible: Optical communications open the possibility of building low-cost ground segments (for low Earth missions) that can be located at mission sites or data centers
GPS
What is GPS?
The Global Positioning System (GPS) is a space-based radio-navigation system, owned by the U.S. Government and operated by the United States Air Force (USAF).
GPS is comprised of three different parts:
Space Segment: A constellation of at least 24 US government satellites distributed in six orbital planes inclined 55° from the equator in a Medium Earth Orbit (MEO) at about 20,200 kilometers (12,550 miles) and circling the Earth every 12 hours.
Control Segment: Stations on Earth monitoring and maintaining the GPS satellites.
User Segment: Receivers that process the navigation signals from the GPS satellites and calculate position and time.
NASA's Use of GPS
Space Communications & Positioning
NASA spacecraft can determine position and time using the Deep Space Network (DSN), Near Space Network (NSN), or by receiving GNSS signals (e.g., GPS).
DSN/NSN tracking is primary, many missions now use GPS as a supplement or backup, even out to Geosynchronous Orbit (36,000 km).
Orbit and Trajectory Determination
NASA determines spacecraft orbits using two-way communication tracking between spacecraft and ground stations.
Missions using on-board GPS processing gain:
Higher spacecraft autonomy
Reduced demand on NASA tracking networks
New operational flexibility in spaceflight
Science and Earth Monitoring Applications
GPS supports major scientific fields, including:
Atmospheric and ionospheric research
Monitoring sea levels, ice melt, and Earth’s gravity field
Global geodesy and geodynamics
Benefits
Significantly improves real-time navigation performance from km-class to meter-class
Supports quick trajectory maneuver recovery from 5-10 hours to minutes
Timing capabilities reduce a spacecraft’s need for expensive on-board clocks
Supports increased satellite autonomy, lowering mission operations costs
Enables new and enhanced capabilities and better performance for users in high-Earth orbit and Cislunar space
near space network
overview
Supports continuous data downlink through space relays and global direct-to-Earth (DTE) antennas.
Provides communications and navigation services up to 1.25 million miles (2 million km) from Earth.
The NSN provides telemetry, commanding, ground-based tracking, data and communications services to a wide The network’s services include telemetry, commanding, ground-based tracking, data, and communications to a wide range of customers with satellites in:
Low Earth orbit
Geosynchronous orbit
Highly elliptical orbit
Lunar orbit
Sun – Earth LaGrange 1 & 2
Tracking and Data Relay Satellites (TDRS)
The Three Segments of Operation
The Space Segment: A constellation of several TDRS satellites in high geosynchronous orbit (about 22,300 miles above Earth). In this orbit, the satellites remain over the same relative point on the Earth's surface, giving them a wide, constant view of lower-orbiting spacecraft.
The Ground Segment (Ground Stations): Primary ground terminals are located at the White Sands Complex in New Mexico and the Guam Remote Ground Terminal.
The User Segment (Client Spacecraft): This includes a variety of missions in low-Earth orbit (LEO), such as the International Space Station (ISS) and the Hubble Space Telescope.
How the Relay Process Works
Uplink (Ground to TDRS): Voice commands, operational instructions, and tracking signals are transmitted from the ground stations to one of the TDRS satellites in geosynchronous orbit.
Crosslink (TDRS to User Spacecraft): The TDRS satellite receives the signal and re-transmits it to the specific user spacecraft
Downlink (User Spacecraft to Earth): The user spacecraft collects data (science data, health/safety information, etc.) and transmits it back to the TDRS satellite.
Key Functions
Near-Continuous Coverage: Before TDRS, NASA relied on a worldwide network of ground stations, which resulted in communication blackouts whenever a spacecraft was out of view of a station. The TDRS constellation ensures near-constant, 24/7 communication coverage.
Two-Way Communication: The system provides essential two-way communication, allowing for both the commanding of spacecraft and the retrieval of valuable data.
Data and Tracking: TDRS handles not just data and voice communications, but also tracking services, using time delay and frequency shifts to determine a user spacecraft's precise range and Doppler measurements (location and speed).
High Data Rates: The system is designed to handle high data rates, enabling the rapid transfer of large volumes of digital information.
Near Space Network Services Contract
Category 1: Direct-to-Earth (DTE) Providers
These companies supply ground-based antenna services that allow spacecraft to communicate directly with Earth:
Intuitive Machines, LLC – Houston, Texas
Kongsberg Satellite Services (KSAT) – Norway
Swedish Space Corporation (SSC) Space U.S. Inc. – Horsham, Pennsylvania
Viasat, Inc. – Duluth, Georgia
Category 2: Near Space Relay Provider
Intuitive Machines – Houston, Texas
Awarded the contract to develop lunar relay satellites, enabling communication without direct line-of-sight to Earth.
These relay systems will be crucial for Artemis lunar missions, supporting continuous communications and navigation around the Moon.
Deep Space Network
overview
The Deep Space Network (DSN) is the world’s largest and most sensitive scientific telecommunications system, used for long-distance communication with interplanetary spacecraft.
Operated by NASA’s Jet Propulsion Laboratory (JPL), it supports most of NASA’s interplanetary robotic missions and some Earth-orbiting spacecraft.
The DSN is composed of three global antenna complexes, spaced 120° apart in longitude to enable continuous communication as Earth rotates:
Madrid, Spain
Canberra, Australia
Goldstone, California, USA
DSN antennas perform:
Spacecraft communication (commands, telemetry, and data return)
Radio astronomy
Radar observations to study planets, asteroids, and the broader universe
The DSN serves as the essential communication link between Earth and spacecraft exploring deep space, delivering images and science data that expand our understanding of the solar system and our place in it.
what does DSN do?
Sending Control Commands: Sending commands and instructions from Earth to robotic spacecraft to control their operations.
Receiving Data: Collecting scientific data (e.g., images, measurements, etc.) and technical data (about the condition of the spacecraft) that spacecraft send back to Earth.
Tracking and Positioning: Using precise measurements of radio signals (Doppler effect) to determine the position and velocity of spacecraft with high accuracy, helping engineers navigate them.
Scientific Research: DSN antennas are also used as tools for scientific research, including radio astronomy and radar mapping of asteroids, comets, and nearby planets.