The First Image from the “Tolou-3 (Paya)” Satellite Has Been Received
Hassan Salarieh, Head of the Iranian Space Agency, commented on the latest status of three Iranian satellites recently launched into space, stating:
“Last week, on the 7th of Dey, at exactly 16:48, three Iranian satellites were launched by the Soyuz launch vehicle and were successfully placed into orbit.”
He added:
“According to prior predictions, the injection process of all three satellites was fully completed between 19:00 and 21:30 on the same day. Based on earlier planning, we successfully established communication with the satellites one by one between 21:30 and 22:00.”
Referring to the reception of initial signals, Salarieh said:
“The initial communications established on the night of the 7th of Dey with all three satellites, and the signals received, indicated the correct injection and proper functioning of the satellites during their first orbital passes.”
Resolving the Rotational Speed Challenge of the ‘Paya’ Satellite
Salarieh went on to mention a challenge encountered with one of the satellites, noting:
“As previously announced on the Ministry of Communications’ website, during the injection process of the Paya satellite, we faced a minor challenge, as the satellite’s rotational speed after launch was somewhat high.”
He emphasized:
“Fortunately, through the process carried out over the past week, the stabilization operation of the Paya satellite was successfully completed, and the issue was resolved. Currently, as also stated by the Minister of Communications, all three satellites are in very good condition.”
Start of Orbital Testing Phase and Subsystem Evaluation
The Deputy Minister of Communications explained post-launch technical measures, stating:
“According to operational planning, the orbital testing phase usually begins within the first one to two months after launch. Although satellites undergo numerous tests on the ground, the performance of all subsystems must be carefully reassessed in space.”
He added:
“These subsystems include communications (telemetry and telecommand), power generation and distribution, stabilization, thermal control, and various payloads installed for imaging or communications.”
Noting that no major challenges existed other than the angular speed issue of the Paya satellite, Salarieh said:
“In line with the plan, subsystem testing has begun. Over the past week, power generation and distribution subsystems were examined, which are extremely critical, as any defect could render the satellite completely inoperable.”
Critical Importance of Communications at a 500-kilometer Orbit
Emphasizing the importance of space-based data collection, Salarieh stated:
“Communications, telemetry, and command transmission from Earth to space are crucial. The satellite operates at an altitude of 500 kilometers, and sensors collect data and transmit it to Earth via the communications subsystem. Proper functioning of this system is vital; otherwise, contact with the satellite would be lost.”
He continued:
“Sending commands from Earth is essential. Based on received data, specific commands are issued. These processes, including thermal control, rotational stabilization, and others, are carried out step by step with precision and under strict procedures approved by space industry experts. Fortunately, nearly all subsystem tests of the Paya satellite have been completed and confirmed.”
Activation of the Main Payload and Reception of the First Image
The head of the Iranian Space Agency announced the activation of the satellite’s main payload, stating:
“The significant development for the Paya satellite is that its cameras, which constitute the main imaging payload, were activated yesterday, and we are now in the process of testing the imaging payload.”
He added:
“In fact, the Paya satellite is ahead of the predicted orbital testing schedule. All stages of its multiple subsystem tests have been approved, and we are now in the imaging payload testing phase, which represents the satellite’s primary mission. The first image was received yesterday, as confirmed and announced by the Minister of Communications.”
Commencement of the Sensitive Camera Calibration Process
Salarieh noted that expectations for the three satellites have been met, explaining:
“In the coming days and weeks, we will enter the very important process of camera calibration. The received images require various corrections, including geometric, spectral (color), and positional corrections.”
He explained:
“Geometric correction ensures that objects and shapes appear in images exactly as they are on Earth, preserving proportions and angles. Spectral calibration ensures that recorded colors and light spectra accurately match real conditions on the ground.”
Salarieh attributed the need for these corrections to harsh space conditions, stating:
“Launch shocks, various accelerations, and extreme temperature differences cause orbital conditions to differ significantly from laboratory environments. Even minute changes, on the order of micrometers, in camera geometry can affect image quality; therefore, performing these corrections from Earth is essential.”
Ideal Status of the “Kosar” Satellite and Start of Pointing Operations
The Deputy Minister of Communications explained the status of the other satellites, stating:
“With regard to the other two satellites, conditions are very good and progressing according to plan. Based on the latest communications with the Kosar satellite, its rotational stabilization process has been completed, and we have reliable data and command transmission. Thermal control and power distribution are also in an ideal state.”
He announced the start of the complex “pointing” or attitude control operation for the Kosar satellite, saying:
“We have now begun the process of controlling and pointing the Kosar satellite toward Earth. For optimal imaging, the side of the satellite carrying the camera must be perfectly perpendicular to the Earth’s surface—this is what we refer to as pointing.”
Salarieh added:
“The control algorithms for this pointing operation are currently being tested. The attitude control subsystem is one of the most complex parts of a satellite, relying on highly advanced technology. At an altitude of 500 kilometers, the satellite must autonomously determine its position and orientation based on commands, eliminate excess rotations, and stabilize itself precisely toward Earth.”
He expressed hope that once these stages are completed, the Kosar satellite will soon be fully operational.
He emphasized that this system must absorb unwanted rotations and maintain full stability toward Earth, requiring precise sensors, mechanical actuators, and advanced algorithms—demonstrating the high technological level of these satellites.
Status of Other Satellites and Imaging Capabilities
The head of the Iranian Space Agency stated that orbital stabilization and testing usually take several weeks, noting that the Paya satellite completed this phase rapidly and received approval. Work on the Kosar satellite is ongoing due to the need for fine adjustments.
Regarding the Zafar satellite, he said its de-spinning process has been fully completed, communication stability is satisfactory, battery charging and power subsystems are functioning well, and pointing operations will soon begin.
Addressing the type of data received, Salarieh said:
“All three satellites are capable of imaging. Paya offers 10-meter resolution in color and 5-meter resolution in black-and-white, with potential for further enhancement through processing. Zafar provides approximately 15-meter resolution, while Kosar achieves better than 5 meters, around 4 meters.”
He noted that Paya’s imaging payload uses mirror-based optics, which significantly improves image quality.
Applications and Future Outlook
Satellite imagery, he explained, is essential for agriculture, water resource management, environmental monitoring, crisis management, and updating national maps. He also highlighted the IoT capabilities of Zafar and Kosar satellites.
Salarieh outlined future priorities, including increasing satellite numbers, improving resolution to sub-meter levels, advancing projects such as Pars-2 and Pars-3, and developing communications satellites like Nahid-2 and Nahid-3.
He also emphasized the strategic importance of the “Martyr Soleimani” satellite constellation, comprising 24 satellites to provide narrowband IoT services nationwide, especially for crisis management.
In closing, he stressed the importance of combining domestic development with international cooperation, noting that sustained satellite performance strengthens confidence in national capabilities, attracts elite talent, and accelerates the growth of Iran’s space industry.
/ Tasnim
