Artists impression of. Sentinel-1 satellite. Image Courtesy of ESA/ATG medialab
News of problems for Copernicus Sentinel-1B, and a glimpse of the Earth Observation (EO) priorities for NASA, this week.
Starting in Europe, the concerning news is that Copernicus 1B suffered an anomaly on the 23rd December, as reported on the Copernicus Hub on Christmas Day, which meant that its SAR instrument had been turned off and no data was collected.
An update issued on the 10th January described that the issue was caused by part of the satellite’s power system. Steps had been taken to try and reactivate the satellite and prevent the issue reoccurring, but they were unsuccessful. The power supply on the satellite was not sufficient for the radar operations to be resumed.
A third update was issued on the 17th January, which reiterated that further steps taken to resolve this issue have so far being unsuccessful. The team are able to manage the satellite’s systems such as thermal and orbit control, are working as normal. However, they have been unable to get the power unit functioning correctly to enable the SAR instrument to be reactivated. Further updates are expected as further actions are taken.
Sentinel-1B is one-half of the twin Sentinel-1 mission and was launched on the 25th April 2016, with Sentinel-1A being launched two years earlier on the 3rd April 2014. The pair of satellites are identical, and orbit 180 degrees apart at an altitude of approximately 700 km. They both carry a 12 m long C-band Synthetic Aperture Radar (SAR) instrument and together cover the entire planet every six days; whereas, now it will only be covered every 12 days with just Sentinel-1A.
Over land, Sentinel-1 captures data in a number of modes with the most common being the Interferometric Wide swath mode, meaning it takes three scans and combines them into a single image. Each scan has a width of 250km and a spatial resolution of 5m x 20m. Its data has a variety of applications including monitoring sea ice, maritime surveillance, disaster humanitarian aid, mapping for forest, water and soil management. Sentinel 1C and 1D missions are already planned, with ID due to launch later this year and 1D in 2023.
To compound things for SAR data users, was that Sentinel-1A had a software anomaly for around sixteen hours over Christmas Eve and Christmas Day, meaning that no SAR data was collected by either Sentinel-1 satellites from around 19.30pm on Christmas Eve to midday on Christmas Day.
Obviously disappointing to have an unplanned problem with one of the Sentinel-1 satellites, and even more to have a data hole over Christmas, it does once again highlight the challenge for companies, particularly SMEs, to build services based on free-to-access satellites. Without any direct control over the satellite, their services can only be provided if data is collected. This is not to suggest that SMEs should not use free-to-access data, which of course they should, it is to highlight that they must ensure that their contracts and service level agreements protect them from this issue. Or to have contingency plans in place to switch data providers to another SAR free-to-access data source, alternatively another option is to bring onboard one of the every growing commercial SAR constellations.
Over at NASA, on Tuesday 11th January, they held a teleconference to introduce Dr Katherine Calvin who has taken over the joint role of NASA’s Chief Scientists and Senior Climate Advisor. An article on the session was written by Elizabeth Howell on Space.com, which highlighted interesting EO news.
It started with the acknowledgement that planning is required to resolve the key steps in replacing NASA’s aging EO fleet, as a lot of the current satellites are at, or beyond, a 20 year mission lifetime. The first step is the implementation of the Earth System Observatory, which will be a set of EO missions complementing each other with the aim to develop a three-dimensional holistic view of the planet. The Earth System Observatory will help determine what capabilities are aging and need replacing, or even missing.
Coincidentally, given the news from Copernicus, the first Earth System Observatory mission will be NISAR (NASA-ISRO synthetic aperture radar). This joint NASA and Indian Space Research Organisation mission will combine L-Band (NASA) and S-band (ISRO) radars on the same satellite and measure changes of less than one centimetre in the Earth’s surface, supporting the study of ice-sheet collapse and natural hazards such as earthquakes, volcanoes and landslides. It’s currently planned for a January 2023 launch.
It will be interesting to see how both of these news stories develop in the coming weeks and months!
