What are Space Modulation Techniques?

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Oct 8, 2024

Modulation techniques are fundamental to the operation of communication systems, serving as the key enabler for the transmission of information across vast distances. This is particularly critical in the context of space missions, where spacecraft and ground stations must exchange data for which maintaining robust and efficient communication is essential for the success of various operations, including spacecraft navigation, telemetry (data related to the health and status of the spacecraft), scientific observations, and even voice communication in manned missions. The challenges associated with space communication are immense, given the unique environment that spacecraft must operate in. Signals degrade significantly as they travel, leading to what is known as signal attenuation, where the strength of the signal diminishes over time. Additionally, the inherent background noise of space, which can be caused by cosmic rays and other electromagnetic radiation, introduces further difficulties in maintaining a clear, error-free transmission. Therefore, space modulation techniques are crucial because they help overcome these challenges by ensuring that data is accurately transmitted and received, even in the presence of such disturbances.

Modulation refers to the process of altering the characteristics of a carrier signal based on the information that needs to be transmitted. The carrier signal is essentially a high-frequency waveform that can travel over long distances and through the vacuum of space. By modulating this carrier signal, whether through changing its amplitude, frequency, or phase communication systems can encode the desired information onto the signal. In space communications, the information being transmitted can vary widely. For instance, telemetry data, which refers to the real-time transmission of a spacecraft's health and status, includes critical information like fuel levels, temperature, and battery status. Similarly, scientific data collected by onboard instruments such as images of distant planets, sensor readings, and spectroscopic analyses must be sent back to Earth for analysis. These data transmissions require modulation techniques that can handle the large data volumes often associated with space missions, especially when high-resolution images or video feeds are involved.

Types of Space Grade Modulation

There are three foundational modulation schemes used in space communications, each with distinct characteristics that make them suitable for different communication needs. These include Amplitude Modulation (AM), Frequency Modulation (FM), and Phase Modulation (PM). While these techniques have been widely adopted in early space missions, modern advancements in space communications have led to the development of more advanced methods like Quadrature Amplitude Modulation (QAM) and Spread Spectrum Techniques, which enhance data throughput and improve the reliability of communication links in the face of interference and noise. Each modulation scheme has its own strengths and limitations, which influence its suitability for specific space missions, ranging from simple telemetry to complex deep-space data transmissions. Modulation techniques not only serve to encode information onto the carrier signal but also help to optimize bandwidth usage, power consumption, and data integrity. For instance, in deep space missions, where the available power on spacecraft is often limited, efficient modulation techniques are needed to ensure that signals can be transmitted with minimal energy consumption while maintaining high data accuracy. As spacecraft ventures farther from Earth, the time delays in communication increase significantly, which can make real-time transmission challenging. Modulation schemes must therefore be optimized for such long-distance transmissions to prevent signal loss or degradation.

1. Amplitude Modulation (AM)

Amplitude Modulation (AM) is one of the simplest and earliest modulation techniques used in communication systems. In AM, the amplitude of the carrier wave is varied in direct proportion to the amplitude of the input signal, which could represent any type of information, such as telemetry data or voice signals. As the amplitude of the input signal changes, the carrier signal’s amplitude changes correspondingly, encoding the information. Although AM played an important role in the early stages of space communication, it is no longer the preferred choice for modern space missions. With the increasing complexity of space missions, the demand for higher data rates, greater efficiency, and more reliable communication links has led to the adoption of more advanced modulation techniques. AM’s simple design and ease of implementation have been overshadowed by its vulnerabilities in challenging environments like space, where signal degradation and power limitations are persistent challenges.

Advantages of Amplitude Modulation

  • Simplicity of Implementation: AM is relatively straightforward to implement, making it a practical choice in early communication systems. The process of modulating the amplitude of a carrier wave is easy to execute and decode, requiring less complex hardware compared to other modulation schemes.
  • Useful for Basic Signals: AM is effective for transmitting simple telemetry data and voice signals. In early space missions, where communication needs were relatively modest and data rates were low, AM was an adequate solution.

Disadvantages of Amplitude Modulation

  • High Susceptibility to Noise: One of the most significant disadvantages of AM is its vulnerability to noise. Since the information is encoded in the amplitude of the carrier wave, any noise or interference affecting the signal’s amplitude can distort the transmitted data. This makes AM unsuitable for environments where signal degradation is common, such as the space environment with its high levels of electromagnetic interference and cosmic radiation.
  • Inefficiency in Bandwidth and Power Usage: AM is also inefficient in terms of bandwidth usage. It requires a relatively wide frequency band for transmission yet provides lower data throughput compared to more advanced modulation schemes. Additionally, AM systems tend to waste a considerable amount of power, which is a critical limitation in space communications where power availability is constrained by the spacecraft’s onboard energy resources.

Applications of Amplitude Modulation

  • Historical Usage in Early Space Missions: AM was used in the early days of space exploration, particularly in missions where the primary communication needs involved transmitting basic telemetry and voice signals. Examples of such early missions include the initial satellite programs and early manned spaceflights where communication requirements were less data-intensive.
  • Replaced by More Advanced Techniques: Due to its limitations, particularly its susceptibility to noise and inefficient use of bandwidth and power. AM has largely been replaced by more robust modulation techniques, such as frequency modulation (FM) and phase modulation (PM), which offer greater resistance to noise and better efficiency.

2. Frequency Modulation (FM)

Frequency Modulation (FM) is a widely used modulation technique in space communication. In FM, the frequency of the carrier signal is varied in accordance with the information being transmitted, while the amplitude of the signal remains constant. This makes FM more resistant to noise compared to Amplitude Modulation (AM), as the information is encoded in the frequency variations, which are less susceptible to interference than amplitude changes. This technique is especially useful for analog signals, making it a popular choice for transmitting telemetry data and voice communications in space missions.

Advantages of Frequency Modulation

  • Better Noise Resistance than AM: Since FM encodes information in the frequency variations rather than the amplitude, it is more resilient against noise and interference. This is particularly valuable in the noisy environment of space, where signals are prone to distortion from cosmic radiation and other electromagnetic sources.
  • Maintains Signal Quality Over Longer Distances: FM signals are better at maintaining their integrity over long distances, making them suitable for deep-space communication where the signal needs to travel over millions of kilometers without significant degradation.

Disadvantages of Frequency Modulation

  • Requires More Bandwidth than AM: Although FM provides better noise resistance, it typically requires a broader bandwidth for transmission. This increased bandwidth demand can be a limitation, especially when spectrum efficiency is a priority in space communication systems.
  • Less Efficient for High Data Rate Applications: FM is less efficient when it comes to transmitting high data rates, as it is primarily designed for analog signals. In modern space missions, where digital data transmission is often required, FM may not be the most efficient option.

Applications of Frequency Modulation

  • Telemetry Systems: FM is commonly used in telemetry systems, where data from spacecraft sensors (e.g., temperature, pressure, and system status) is transmitted to ground stations. The stability and noise resistance of FM make it ideal for ensuring reliable telemetry transmission, even in the harsh conditions of space.
  • Voice Communications in Manned Space Missions: FM has historically been used for voice communication between astronauts and ground control during manned space missions. Its ability to maintain signal clarity over long distances is critical for maintaining communication links during such missions.

3. Phase Modulation (PM)

Phase Modulation (PM) is another key technique in space communication. Unlike FM, which varies the frequency of the carrier signal, PM alters the phase of the carrier signal to encode information. Phase modulation is more bandwidth-efficient than both AM and FM, making it a suitable choice for transmitting digital data. Its robustness against signal degradation, combined with its efficiency in bandwidth usage, has made PM a dominant modulation scheme in modern space communication systems.

Advantages of Phase Modulation

  • Robust Against Signal Degradation: PM is highly resistant to signal degradation, which is essential for ensuring the integrity of communication links in space. Since the information is encoded in the phase of the signal, it remains relatively unaffected by amplitude-related noise and interference, improving the overall reliability of the communication system.
  • Efficient in Bandwidth Usage: PM is more bandwidth-efficient than both AM and FM, making it ideal for applications where bandwidth is limited, and high efficiency is required. This efficiency is particularly beneficial in space communication, where the spectrum is a valuable resource.
  • Suitable for Digital Data Transmission: PM is well-suited for transmitting digital data, which is increasingly prevalent in modern space missions. It can be combined with advanced digital modulation techniques, making it a versatile option for high-data-rate applications.

Disadvantages of Phase Modulation

  • Complex to Implement: Phase modulation is more complex to implement compared to AM and FM. The systems used to encode and decode phase-modulated signals require more sophisticated technology, which can increase the cost and complexity of space communication systems.
  • Phase Ambiguity: One potential challenge with PM is phase ambiguity, where the receiver may have difficulty distinguishing between different phase states. To overcome this, additional error-correction techniques are often employed, adding to the system’s complexity.

Applications of Phase Modulation

  • Digital Satellite Communication: PM is widely used in digital satellite communication systems, where its efficiency and robustness make it an ideal choice for transmitting large volumes of data. Many modern communication satellites employ PM to ensure reliable, high-data-rate communication with ground stations.
  • Telemetry Systems for Spacecraft-to-Ground Communication: PM is also used in telemetry systems, particularly for spacecraft-to-ground communication in digital data formats. Its ability to handle high data rates and resist signal degradation is crucial for maintaining stable communication links in modern space missions.

4. Digital Modulation Techniques

As space communication has evolved, digital modulation techniques have become the standard due to their superior performance in terms of data rate, power efficiency, and noise resistance. These techniques are designed to maximize the amount of information transmitted while minimizing power consumption and maintaining signal integrity in the challenging conditions of space. Some of the most common digital modulation techniques used in space communication include Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK), and Quadrature Amplitude Modulation (QAM).

a. Binary Phase Shift Keying (BPSK)

BPSK is a simple and widely used digital modulation technique that involves shifting the phase of the carrier signal to one of two distinct states, representing binary data (0 and 1) BPSK is favored for its simplicity and robustness, especially in power-limited scenarios like deep space communication.

Pros of BPSK:

  • Highly Noise-Resistant: BPSK is highly resistant to noise, making it an ideal choice for communication in environments with significant interference, such as deep space.
  • Efficient in Power-Limited Scenarios: BPSK is particularly useful in missions where power is a critical constraint, as it offers reliable performance even with limited transmission power.

Cons of BPSK:

  • Limited Data Rate Capacity: BPSK’s simplicity comes at the cost of a relatively low data rate. It can only transmit one bit per symbol, which limits its efficiency in high-data-rate applications.
  • Requires More Bandwidth than Advanced Techniques: While robust, BPSK requires more bandwidth than more advanced modulation techniques, which can be a limitation in bandwidth-constrained environments.

Application of BPSK:

  • Deep Space Probes: BPSK is commonly used in low-data-rate communications with deep space probes, such as the Voyager and Mars Odyssey missions. Its noise resistance and power efficiency make it ideal for maintaining communication over vast distances.

b. Quadrature Phase Shift Keying (QPSK)

QPSK is an extension of BPSK that increases data transmission efficiency by using four distinct phase shifts to represent two bits per symbol. This effectively doubles the data rate for the same bandwidth compared to BPSK, making QPSK a popular choice for satellite communication systems.

Pros of QPSK:

  • Improved Data Rate: QPSK offers a significant improvement in data rate compared to BPSK, making it suitable for higher data rate applications.
  • More Bandwidth-Efficient: QPSK is more efficient in its use of bandwidth, enabling it to transmit more data without requiring additional spectrum.

Cons of QPSK:

  • More Complex Implementation: The increased complexity of QPSK requires more sophisticated demodulation hardware and software, which can add to system costs.
  • Slightly More Susceptible to Noise than BPSK: While still robust, QPSK is slightly more susceptible to noise compared to BPSK due to the increased number of phase states that need to be distinguished by the receiver.

Application of QPSK:

  • Satellite Communication: QPSK is widely used in satellite communication systems to transmit video, data, and telemetry. Its balance between bandwidth efficiency and data rate makes it an ideal choice for Earth observation satellites and interplanetary missions.

c. Quadrature Amplitude Modulation (QAM)

QAM is a hybrid modulation technique that combines both amplitude and phase modulation. By varying both the amplitude and phase of the carrier signal, QAM can transmit multiple bits per symbol, making it highly efficient in terms of both bandwidth and data rate.

Pros of QAM:

  • Highly Bandwidth-Efficient: QAM is one of the most bandwidth-efficient modulation techniques, capable of transmitting large amounts of data without requiring excessive bandwidth.
  • High Data Rates: QAM can achieve high data rates, making it suitable for applications that require the transmission of large volumes of data, such as satellite internet services.

Cons of QAM:

  • More Susceptible to Noise: QAM’s reliance on both amplitude and phase modulation makes it more susceptible to noise and interference compared to phase-only modulation schemes like BPSK and QPSK.
  • Requires Complex Demodulation Algorithms: QAM systems require more sophisticated and complex demodulation algorithms, which can increase the cost and complexity of the communication system.

Application of QAM:

  • High-Data-Rate Satellite Communications: QAM is widely used in high-data-rate satellite communication systems, including satellite TV broadcasts and satellite-based internet services. Its ability to transmit large amounts of data efficiently makes it an ideal choice for such applications.

Space communication has transitioned from basic analog techniques like AM to more sophisticated digital techniques like BPSK, QPSK, and QAM, allowing for more efficient, reliable, and high-data-rate communication across vast distances. As space missions continue to grow in complexity, the adoption of advanced modulation techniques will be critical for ensuring the success of future missions.

5. Spread Spectrum Techniques

Spread Spectrum Techniques play a crucial role in enhancing the reliability, security, and robustness of space communication systems. Unlike traditional modulation schemes that confine signals to narrow frequency bands, spread spectrum techniques distribute the signal over a wider bandwidth. This helps mitigate interference, reduces the likelihood of eavesdropping, and improves the resilience of signals against jamming and noise, making them ideal for space environments. The two primary spread spectrum techniques used in space communications are Direct Sequence Spread Spectrum (DSSS) and Frequency Hopping Spread Spectrum (FHSS).

a. Direct Sequence Spread Spectrum (DSSS): In Direct Sequence Spread Spectrum (DSSS), the data signal is spread over a wide frequency band by multiplying it with a high-rate pseudo-random noise (PN) code. This spreading makes the transmitted signal appear as noise to unintended receivers, rendering it less susceptible to interference and jamming. The receiver, which knows the PN code, can despread the signal, recovering the original data. DSSS significantly enhances signal robustness, especially in noisy environments like space, where electromagnetic interference and cosmic radiation are prevalent.

Application of DSSS:

  • GPS Systems: DSSS is widely used in Global Positioning System (GPS) technology, where accurate and secure signal transmission is essential for navigation and positioning, especially in space-based systems.
  • Military Space Assets: DSSS is also employed in secure communication links for military space assets, ensuring that vital data can be transmitted without fear of interception or jamming by adversaries. This makes it an important component in defense-oriented satellite communications.

b. Frequency Hopping Spread Spectrum (FHSS): In Frequency Hopping Spread Spectrum (FHSS), the carrier frequency of the signal is rapidly changed (hopped) over a sequence of frequencies according to a predetermined pattern. The receiver, which follows the same hopping sequence, can correctly decode the signal. By constantly shifting frequencies, FHSS makes the communication link much harder to intercept, jam, or disrupt. This technique is particularly valuable in secure or military communication systems where maintaining signal integrity is paramount.

Application of FHSS:

  • Military Space Communication Systems: FHSS is extensively used in military space communication systems, where security is a top priority. The technique ensures that signals can evade attempts at interception and jamming, providing a reliable and secure communication channel.
  • Secure Satellite Links: FHSS is also applied in secure satellite links for both military and civilian use, where maintaining the confidentiality of transmitted data is critical.

6.  Adaptive Modulation and Coding (AMC)

 As space missions increasingly demand higher data rates and more efficient communication systems, adaptive modulation techniques have become increasingly relevant. Adaptive Modulation and Coding (AMC) adjusts the modulation scheme and error-correction coding dynamically based on the current signal-to-noise ratio (SNR) and other channel conditions. AMC enables communication systems to adapt their modulation scheme and error-correction coding in real-time based on the current channel conditions, such as signal-to-noise ratio (SNR), link distance, and atmospheric interference. In favourable conditions, higher-order modulation schemes like 16-QAM or 64-QAM can be used, increasing data rates. Under poor conditions, the system may revert to more robust schemes like BPSK. However, when channel conditions deteriorate, such as during periods of high interference or low SNR, the system dynamically switches to more robust schemes like BPSK or QPSK, which sacrifice data rate for reliability. This flexibility allows space communication systems to maintain optimal performance in varying conditions, making AMC highly suited for complex space missions.

Application of AMC:

  • Modern Deep-Space Missions: AMC is widely employed in deep-space missions, where communication distances can vary significantly, and signal degradation due to cosmic noise, solar radiation, and the Doppler effect can occur. By adjusting the modulation scheme in response to real-time conditions, AMC ensures that communication links remain robust and efficient throughout the mission.
  • Earth Observation Satellites: AMC is also used in Earth observation satellites, which often face varying atmospheric and signal conditions as they orbit the planet. With AMC, these satellites can maintain high data rates when conditions are optimal, such as when transmitting images or data to ground stations and reduce the risk of signal loss during challenging conditions.

Spread spectrum techniques like DSSS and FHSS provide essential enhancements to the robustness and security of space communication, making them vital for secure and interference-resistant links. Advanced techniques like AMC ensure that space communication systems remain flexible and adaptive, optimizing performance under varying signal conditions, thereby ensuring the success of modern space missions.

Error Correction and Redundancy in Space Modulation


In space communications, ensuring the accurate transmission of data over vast distances is critical. Signals often has degradation due to various challenges, such as cosmic radiation, atmospheric interference, and signal attenuation over long distances. To combat these challenges, modulation techniques are often paired with error correction and redundancy mechanisms. These methods help in maintaining data integrity and minimize the chances of data loss or corruption. Two of the most widely used error correction techniques in space communication are Forward Error Correction (FEC) and Automatic Repeat reQuest (ARQ). These methods are designed to detect and correct errors that may occur during transmission, ensuring that data arrives in its intended form even under adverse conditions.

Forward Error Correction (FEC)

Forward Error Correction (FEC) is a powerful technique in which additional redundant data is added to the transmitted signal to allow the receiver to detect and correct errors on its own, without the need for retransmission. This is especially important in space communications, where retransmissions might not be practical or possible due to significant time delays between the spacecraft and ground stations. With distances spanning millions of kilometers in deep-space missions, retransmitting data could introduce long delays, which FEC aims to mitigate by correcting errors during the initial transmission. In FEC, the transmitter applies a specific algorithm, such as a Reed-Solomon code, Turbo code, or Low-Density Parity-Check (LDPC) code, to encode the data with redundancy before sending it over the communication channel. The receiver can then use the redundant information to reconstruct the original data, even if some parts of the transmitted signal are lost or corrupted.

Benefits of FEC:

  • No need for retransmission: Since FEC can detect and correct errors without asking for a retransmission, it is especially advantageous for space missions where retransmissions would cause significant delays or might be impossible due to power constraints.
  • Reliable performance in noisy environments: FEC is highly effective in combating the noise, interference, and signal degradation that frequently occur in space due to cosmic radiation, solar storms, and other environmental factors.
  • Increased data integrity: By adding redundancy, FEC improves the chances that the original data will be received intact, ensuring the mission's success even when the communication link is weak or noisy.

Application of FEC:

  • Low Earth Orbit (LEO) Satellites: FEC is employed in communications between Earth and satellites in low Earth orbit to ensure reliable data transmission despite the potential for signal interruptions caused by atmospheric conditions and other orbital debris.
  • Interplanetary Missions: In deep-space missions, such as communications between Earth and spacecraft exploring planets like Mars or Jupiter, FEC is essential for ensuring the integrity of telemetry, scientific data, and control signals, where transmission times can range from minutes to hours.
  • Space Probes and Rovers: Spacecraft like the Voyager probes, Curiosity Rover, and upcoming missions to outer planets use FEC to safeguard data transmission over interstellar distances.

Automatic Repeat reQuest (ARQ)

Automatic Repeat reQuest (ARQ) is another error control technique where the receiver detects errors in the received data and requests a retransmission from the sender if needed. Unlike FEC, which corrects errors on its own, ARQ depends on feedback from the receiver to ensure that the transmitted data is received correctly. This process is often implemented with a stop-and-wait protocol or a sliding window protocol, where the receiver sends an acknowledgment (ACK) for correctly received data or a negative acknowledgment (NACK) if errors are detected. ARQ is more suitable for near-Earth missions where the time delay is shorter, while deep-space missions rely more heavily on FEC.

Benefits of ARQ:

  • Guaranteed accuracy: ARQ ensures that only accurate data is accepted by requesting retransmission if errors are detected.
  • Useful for low-latency communications: For short-range space communications, where the time delay is minimal, ARQ can effectively enhance data integrity by asking for retransmissions.

Limitations of ARQ:

  • Not suitable for deep-space missions: In deep-space scenarios, the time delays make ARQ less efficient. Waiting for acknowledgment and re-transmission would add excessive latency to the communication process.
  • Increased bandwidth usage: Re-transmissions can consume additional bandwidth, which may be a constraint in missions where power and data rates are limited.

Application of ARQ:

  • Low Earth Orbit (LEO) Satellites: ARQ is sometimes used in near-Earth communication, such as with telecommunication satellites or Earth observation satellites, where the time delay is relatively small, and retransmissions are feasible.
  • Space Station Communications: Communication links between Earth and the International Space Station (ISS), where the delay is minimal, can leverage ARQ to ensure reliable data transmission for scientific experiments, crew communications, and telemetry data.

Combining FEC and ARQ for Enhanced Performance

In some cases, space communication systems may combine both FEC and ARQ to take advantage of the strengths of each. This hybrid approach, called Hybrid ARQ (HARQ), allows for error correction through FEC, with ARQ serving as a backup mechanism when errors cannot be corrected. HARQ provides an extra layer of reliability in space missions, ensuring that even if FEC fails to recover the data, ARQ can still request a retransmission when time delays allow.

Space modulation techniques are crucial for the successful execution of space missions, forming the foundation of reliable communication between spacecraft and ground stations. These techniques enable the transmission of vital data ranging from telemetry, scientific measurements, images, and video across vast distances in challenging environments where traditional communication methods struggle to maintain accuracy and clarity. Various modulation techniques have been employed to meet the distinct challenges posed by space communication. Basic analog methods such as Amplitude Modulation (AM) and Frequency Modulation (FM) were among the earliest techniques used in space missions. While effective in certain conditions, these analog methods have largely been surpassed by digital modulation techniques due to their superior noise resistance, bandwidth efficiency, and overall reliability. Most widely used digital techniques are Phase Modulation (PM), Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK), and Quadrature Amplitude Modulation (QAM). Advanced techniques like Spread Spectrum methods, including Direct Sequence Spread Spectrum (DSSS) and Frequency Hopping Spread Spectrum (FHSS), provide enhanced security, robustness, and interference mitigation. These approaches are particularly valuable in military and deep-space missions, where ensuring signal integrity against jamming or interference is critical. With new challenges like deep-space exploration, manned missions to Mars, and large-scale satellite constellations, the development of more sophisticated error correction, modulation, and transmission technologies will remain a top priority.

Space Missions - A list of all Space Missions

esa

Name Date
Altius 01 May, 2025
Hera 01 Oct, 2024
Arctic Weather Satellite 01 Jun, 2024
EarthCARE 29 May, 2024
Arctic Weather Satellite (AWS) 01 Mar, 2024
MTG Series 13 Dec, 2022
Eutelsat Quantum 30 Jul, 2021
Sentinel 6 21 Nov, 2020
OPS-SAT 18 Dec, 2019
Cheops 18 Dec, 2019

isro

Name Date
INSAT-3DS 17 Feb, 2024
XPoSat 01 Jan, 2024
Aditya-L1 02 Sep, 2023
DS-SAR 30 Jul, 2023
Chandrayaan-3 14 Jul, 2023
NVS-01 29 May, 2023
TeLEOS-2 22 Apr, 2023
OneWeb India-2 26 Mar, 2023
EOS-07 10 Feb, 2023
EOS-06 26 Nov, 2022

jaxa

Name Date
VEP-4 17 Feb, 2024
TIRSAT 17 Feb, 2024
CE-SAT 1E 17 Feb, 2024
XRISM 07 Sep, 2023
SLIM 07 Sep, 2023
ALOS-3 07 Mar, 2023
ISTD-3 07 Oct, 2022
JDRS 1 29 Nov, 2020
HTV9 21 May, 2020
IGS-Optical 7 09 Feb, 2020

nasa

Name Date
NEO Surveyor 01 Jun, 2028
Libera 01 Dec, 2027
Artemis III 30 Sep, 2026
Artemis II 30 Sep, 2025
Europa Clipper 10 Oct, 2024
SpaceX CRS-29 09 Nov, 2023
Psyche 13 Oct, 2023
DSOC 13 Oct, 2023
Psyche Asteroid 05 Oct, 2023
Expedition 70 27 Sep, 2023