Deep Space Network

The Deep Space Network (DSN) is NASA’s international array of large antennas that supports interplanetary spacecraft missions, radio and radar astronomy observations, and communications with spacecraft traveling beyond Earth orbit. It is one of the most important infrastructures for deep-space exploration. Here’s a detailed breakdown:

1. Purpose of the DSN

  • Spacecraft Communication: Provides tracking, telemetry, and command services for spacecraft traveling to the Moon, Mars, and beyond.
  • Scientific Observations: Conducts radio astronomy, radar observations of planets, and planetary science experiments.
  • Navigation: Helps determine spacecraft trajectories and positions in space using precise Doppler and ranging measurements.

2. DSN Facilities

The DSN consists of three main complexes around the world, spaced roughly 120° apart in longitude to maintain constant contact with spacecraft:

  1. Goldstone, California, USA
  2. Madrid, Spain
  3. Canberra, Australia

Each site contains multiple large antennas, typically 34m and 70m dishes, capable of receiving extremely weak signals from millions or even billions of kilometers away.

3. How the DSN Works

  • High-Gain Antennas: Focused parabolic dishes allow reception of faint radio signals from distant spacecraft.
  • Radio Communication Bands: Uses S-band (~2 GHz), X-band (~8 GHz), and Ka-band (~32 GHz) for communication.
  • Signal Processing: Advanced electronics amplify weak signals, decode telemetry, and measure Doppler shifts for navigation.
  • Network Coordination: Because of the 24-hour coverage, at least one DSN station is always in view of a spacecraft anywhere in the solar system.

4. Key Achievements

  • Supported Voyager, Mars rovers, Cassini, New Horizons, and James Webb Space Telescope.
  • Enabled communication with spacecraft at billion-kilometer distances, like Voyager 1 in interstellar space.
  • Provided precise measurements for planetary radar, helping map asteroids and planets.

5. Fun Fact

The DSN antennas must track spacecraft with incredible precision—sometimes moving at fractions of a degree per hour, yet receiving signals as weak as a few trillionths of a watt.

Doppler Shift for Velocity

The Doppler effect is the change in frequency of a signal due to the relative motion between the source and the observer. DSN uses this principle to measure how fast a spacecraft is moving toward or away from Earth.

How it works:

  1. DSN sends a radio signal at a known frequency (e.g., X-band ~8 GHz) to the spacecraft.
  2. The spacecraft transponds (repeats) the signal back to Earth, often at a slightly different frequency.
  3. If the spacecraft is moving toward Earth, the received frequency is slightly higher.
    If moving away, it’s slightly lower.
  4. By precisely measuring the frequency shift (Δf\Delta fΔf), the DSN calculates the spacecraft’s radial velocity:

v=cΔff0v = c \frac{\Delta f}{f_0}v=cf0​Δf​

Where:

  • vvv = velocity toward/away from Earth
  • ccc = speed of light (~3×10⁸ m/s)
  • f0f_0f0​ = transmitted frequency
  • Δf\Delta fΔf = measured frequency shift

Precision: DSN can measure velocities to millimeters per second even at distances of billions of kilometers.

Ranging for Distance

To determine the spacecraft’s distance from Earth, DSN uses ranging signals:

  1. The DSN sends a coded radio signal to the spacecraft.
  2. The spacecraft immediately returns the signal.
  3. DSN measures the time delay (ttt) between sending and receiving the signal.
  4. Distance ddd is calculated as:

d=c⋅t2d = \frac{c \cdot t}{2}d=2c⋅t​

  • The factor of 2 accounts for the round-trip of the signal.
  • Modern ranging can achieve meter-level precision over billions of kilometers.

Combining Doppler + Ranging

By using both techniques together, DSN can:

  • Determine radial velocity (Doppler)
  • Determine distance (ranging)
  • Track trajectories and orbits precisely in 3D space

This is how NASA navigators can predict where a spacecraft will be years in advance, like for the New Horizons flyby of Pluto.

Extra Tricks

  • Very Long Baseline Interferometry (VLBI): DSN can use multiple antennas to triangulate spacecraft positions with sub-kilometer accuracy.
  • Gravity assists: Precise measurements allow spacecraft to use planets’ gravity efficiently.
  • Error correction: The DSN must correct for delays caused by Earth’s atmosphere, solar plasma, and relativistic effects.

DSES’s plan to Implement a Receive Capability for DSN Satellites

DSES member Alex Nersesian K6VHF has prepared a design for hardware and software in 2025 that we plan to implement soon The design documents will be available here soon.

Above is the latest design by Alex K6VHF. The RF system includes a septum feed (LH & RH) to the polarity switching relay (RLY) that feeds the low loss band pass filter (BPF) followed by an optional low noise amplifier (LNA) and finally a downconverter and the AirSpy R2 software defined radio (SDR).

The main component is a DEMI downconverter which has built-in LNA (20dB) and LO operating at 7968MHz. With input RF 8.4GHz-8.5GHz our IF is 432M-532MHz. The AirSpy R2 SDR receives that frequency range, and never goes higher than 532MHz. Both downconverter and SDR are using external 10MHz from an OCXO, so they are locked.  The 60ft dish at 8.4GHz may have a very high gain (over 55dB) so the use of an external LNA is not necessarily required.

On May 26, 2025 Alex K6VHF presented information about the NASA Deep Space Network. The detailed discission included missions, receiving equipment and software. Note that the recording starts a few minutes late but includes all the important information. Click here to go to the YouTube presentation.

Alex K6VHF has uploaded the “Deep Space Network Probe Detection Simulation (PDS)” software on the DSES groups.io repository. PDS is a desktop app (Tkinter + Matplotlib) for exploring detectability of deep-space downlink carriers at X-band. It provides a detailed link budget, multi-mission signal estimates, static/realtime spectrum & waterfall views, and a simple PLL tone tracker with drift. Optional Skyfield support shows live AZ/EL pointing for mapped mission bodies.