Hurdle for NISAR: Thermal Analysis Triggers Launch Postponement

Changes to a major expandable antenna on a joint radar satellite project between the U.S. and India will postpone its launch.

Changes to a major expandable antenna on a joint radar satellite project between the U.S. and India will postpone its launch, now anticipated to occur in the later part of the year.

NASA, in a statement dated March 22, mentioned that the scheduling of a new launch date for the NASA-ISRO Synthetic Aperture Radar (NISAR) mission would occur at April’s end. This rescheduling is necessary to undertake modifications safeguarding the spacecraft’s 12-meter-wide antenna reflector against temperature impacts in its folded configuration.

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NASA stated that testing and analysis revealed the reflector might encounter temperatures higher than initially expected while in its compacted state or folded configuration during flight.In the statement, NASA mentioned that to mitigate these elevated temperatures, a “special coating” will be applied to the antenna to enhance its sunlight reflection capabilities.

NASA explained that this task involves transporting the antenna, which is presently assembled with the NISAR spacecraft in India, to a Californian facility equipped to apply the coating. NASA did not specify the duration required to apply the coating, including the time needed to ship the antenna to California and subsequently return it to India.

Before, NASA had hoped to launch NISAR this spring. At a meeting in December, the people running the project said they were aiming to get it off the ground by the end of March.

In a conversation with the Times of India, ISRO’s chairman, S. Somanath, mentioned that NISAR’s launch would be postponed beyond the initial quarter of the year. He provided limited information on the cause, indicating that it wasn’t related to the Geosynchronous Satellite Launch Vehicle (GSLV) Mark 2 rocket slated for the launch.

NISAR marks the inaugural joint venture in Earth science satellite projects between NASA and ISRO, symbolizing one of the most significant collaborations between the two agencies. NASA has invested over $1 billion solely in the planning and development phases of the mission.

NASA is contributing an L-band radar and engineering payload, whereas ISRO is responsible for supplying the S-band payload, the spacecraft bus (1-3K bus), and the launch vehicle.

As of February 2023, the amount spent by ISRO on developing the NISAR satellite totals Rs 469.40 crore, not including the costs associated with its launch.

L-Band and S-Band radars are types of synthetic aperture radars used in Earth observation satellites. The L-Band radar operates at lower frequencies (1-2 GHz), offering deeper ground penetration and is less affected by atmospheric conditions, ideal for vegetation and soil moisture studies. S-Band radar, with higher frequencies (2-4 GHz) , excels in finer resolution imaging, useful for detailed surface feature analysis.

The radar systems aboard NISAR are equipped with the capability for sophisticated radar imaging. These systems cater to various Earth science requirements, such as assessing glacier flow rates and monitoring volcanic activity. The satellite itself is designed to monitor shifts caused by earthquakes, landslides, and volcanic eruptions. Additionally, it can track evolving conditions in forests, wetlands, and agricultural areas.

NISAR is specifically engineered to orbit the Earth in a sun-synchronous orbit. This orbit has an altitude of 747 kilometers and an inclination of 98.4 degrees. With this orbit, the satellite completes a survey of the entire Earth every 12 days, ensuring comprehensive coverage and monitoring capabilities.

The initiative that evolved into NISAR was initiated in response to a significant Earth science report in 2007. Now, it plays a vital role in NASA’s execution of strategies based on the latest 2018 Earth science report. This means NASA is acting on the insights and proposals from the 2018 study, a comprehensive analysis focusing on Earth sciences. Known as a decadal survey, this report sets forth critical priorities and recommends major missions for the next ten years in Earth science, steering NASA’s projects like NISAR to tackle these key areas.

The study advised undertaking five specific “designated observables” through different missions, among them a mission focused on surface deformation and change, or SDC, which would incorporate a radar imaging component.

NASA was exploring ideas for the SDC mission as a segment of its broader Earth System Observatory project, which aims to carry out the study’s recommended observables. However, the agency intended to postpone the development of the SDC mission. This delay was planned so that NASA could apply insights and knowledge gained from the NISAR project to enhance the SDC mission’s execution.

In a change announced with the fiscal year 2025 budget request on March 11, NASA has revised its plans for the Earth System Observatory. As part of this restructuring, the agency has decided not to proceed with the development of a specific SDC mission. Instead, NASA will rely on data collected by NISAR to meet the objectives associated with the surface deformation and change observable. This adjustment signifies a shift in strategy, leveraging NISAR’s capabilities to achieve the goals initially set for the SDC mission.

Karen St. Germain, the head of NASA’s Earth science division, explained during a presentation on March 20 at a meeting organized by the National Academies’ Committee on Earth Science and Applications in Space, that if the SDC mission were to start, it would likely commence towards the end of the ten-year period outlined by the decadal survey. This statement clarifies that any initiation of the SDC mission was anticipated to happen later in the timeline set by the decade-long strategic plan for Earth science.

Karen St. Germain mentioned that because NISAR is scheduled for launch later this year and there’s a desire to apply insights gained from it, the study for the SDC mission was discontinued. She added that the decision was made with the thought that, in the next ten-year planning period, there would be a reassessment to decide whether to initiate a similar project. This approach allows NASA to leverage the lessons from NISAR before moving forward with any related future endeavors as informed by SpaceNews

With an estimated total cost of US$ 1.5 billion, NISAR is poised to become the most costly Earth-imaging satellite ever built.

(The author Girish Linganna of this article is a Defence, Aerospace & Political Analyst based in Bengaluru. He is also Director of ADD Engineering Components, India, Pvt. Ltd, a subsidiary of ADD Engineering GmbH, Germany. You can reach out to him at: [email protected])

(Views expressed in the article are of author’s own and do not reflect the editorial stance of Business Upturn)