Antenna for joint NASA-ISRO radar satellite needs fix, delaying launch
The large deployable antenna for a joint NASA-ISRO radar satellite, dubbed NISAR, that was targeting a spring launch will require an extra coat of reflective material, thus delaying the satellite’s launch until the second half of this year.
In a March 22 statement, NASA said a new launch date for the NASA-ISRO Synthetic Aperture Radar (NISAR) mission will be set at the end of April because of work to protect the spacecraft’s reflector, an antenna that is 12 meters across when fully deployed, from temperatures when in its stowed configuration. “Testing and analysis identified a potential for the reflector to experience higher-than-previously-anticipated temperatures in its stowed configuration in flight,” NASA said in the statement. To prevent those increased temperatures, a “special coating” will be applied to the antenna so that it reflects more sunlight.
That work, NASA said, requires shipping the antenna, currently with the rest of the NISAR spacecraft in India, to a facility in California that can apply the coating. NASA did not state how long the process of applying the coating, as well as shipping the antenna to California and then back to India, will take.
It appears that the need for this additional coat was discovered during environmental testing by ISRO engineers in India as part of its preparation for launch on India’s GSLV rocket. Based on the JPL website for this mission, it appears this antenna system was built by JPL.
NASA is providing the mission’s L-band synthetic aperture radar, a high-rate communication subsystem for science data, GPS receivers, a solid-state recorder and payload data subsystem. ISRO is providing the spacecraft bus, the S-band radar, the launch vehicle and associated launch services.
Though the purpose of the final environmental testing prior to launch is specifically to find such issues and correct them, the question remains why this issue occurred. One can’t help wondering if the many management problems detailed at JPL in several reports (here, herej, here) might have contributed, including the organization’s total commitment since 2022 to Diversity, Equity, and Inclusion quotas, making skin color and sex the primary qualifications for hiring, rather than skill, education, or talent.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The print edition can be purchased at Amazon or from any other book seller. If you want an autographed copy the price is $60 for the hardback and $45 for the paperback, plus $8 shipping for each. Go here for purchasing details. The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
The large deployable antenna for a joint NASA-ISRO radar satellite, dubbed NISAR, that was targeting a spring launch will require an extra coat of reflective material, thus delaying the satellite’s launch until the second half of this year.
In a March 22 statement, NASA said a new launch date for the NASA-ISRO Synthetic Aperture Radar (NISAR) mission will be set at the end of April because of work to protect the spacecraft’s reflector, an antenna that is 12 meters across when fully deployed, from temperatures when in its stowed configuration. “Testing and analysis identified a potential for the reflector to experience higher-than-previously-anticipated temperatures in its stowed configuration in flight,” NASA said in the statement. To prevent those increased temperatures, a “special coating” will be applied to the antenna so that it reflects more sunlight.
That work, NASA said, requires shipping the antenna, currently with the rest of the NISAR spacecraft in India, to a facility in California that can apply the coating. NASA did not state how long the process of applying the coating, as well as shipping the antenna to California and then back to India, will take.
It appears that the need for this additional coat was discovered during environmental testing by ISRO engineers in India as part of its preparation for launch on India’s GSLV rocket. Based on the JPL website for this mission, it appears this antenna system was built by JPL.
NASA is providing the mission’s L-band synthetic aperture radar, a high-rate communication subsystem for science data, GPS receivers, a solid-state recorder and payload data subsystem. ISRO is providing the spacecraft bus, the S-band radar, the launch vehicle and associated launch services.
Though the purpose of the final environmental testing prior to launch is specifically to find such issues and correct them, the question remains why this issue occurred. One can’t help wondering if the many management problems detailed at JPL in several reports (here, herej, here) might have contributed, including the organization’s total commitment since 2022 to Diversity, Equity, and Inclusion quotas, making skin color and sex the primary qualifications for hiring, rather than skill, education, or talent.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The print edition can be purchased at Amazon or from any other book seller. If you want an autographed copy the price is $60 for the hardback and $45 for the paperback, plus $8 shipping for each. Go here for purchasing details. The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
Robert commented: “Though the purpose of the final environmental testing prior to launch is specifically to find such issues and correct them, the question remains why this issue occurred.”
I decided early in my career that I was glad I didn’t become a thermal engineer. In theory we know how to control temperatures well, but in practice the hardware and the thermal surfaces act in ways that were not predicted.
One instrument I designed (with an experienced thermal engineer doing the radiator parts and the thermal conduction to the radiators) had to go through thermal vacuum testing three times, with modifications to the thermal control system between each one. He never did get the sensors as cold as specified, but he got them cold enough to give good data.
Even in college, the thermal dynamics textbook had tables of thermal characteristics for various materials, but they didn’t always agree with each other. My favorite example was bulk copper having a coefficient for convection that was an order of magnitude different than the coefficient for a copper teakettle. You read that right, and I wrote it right. An order of magnitude! The professor kindly put a copper-clad steel boiler on the final exam. Which coefficient to use? I chose the teakettle on the ir-rationalization that thickness of the material made for some unjustifiable difference in convection properties. With an order of magnitude difference in the possible answer, I decided right then and there to never become a thermal engineer, and my observations since have reinforced that choice.
The Merlin vacuum engine operates with a combustion chamber at extremely high pressure and extremely high temperature, but the launch videos show on the outside, just a couple of inches away, a string of oxygen ice bouncing around on the engine. It took rocket scientists a while to figure out how to do that kind of thermal control. Goddard started finding that problem a century ago.
Why would this thermal issue occur on NISAR? Because the darnedest things happen when you’re building and operating spacecraft. You might think your car is fussy and has an obstinate personality, but cars are mature compared with the constant hissy fits that spacecraft throw. You would think that they were three-year-olds or Democrats.