The European Space Operations Center (ESOC) within the European Space Agency has chosen SUSE Linux Enterprise Server as its operating system in its deep space ground stations and spacecraft operational control center.

Overview With 390 instances of SUSE Linux Enter­prise Server already deployed, and a further 50 to be deployed in 2013, ESOC is enjoying faster installation, better control over system configuration, excellent performance and reliability, strong technical support from SUSE, and the confidence that it has an operating system that it can maintain for the long term. Further deploy­ment of SUSE Linux Enterprise Server is under consideration for the remaining antennas in the network (15m diameter class, used mainly for near-­Earth missions) and for mission control for new spacecraft missions currently under preparation. The European Space Agency (ESA) is Eu­rope’s gateway to space. An intergovern­mental organization created in 1975, ESA aims to shape the development of Europe’s space capability and ensure that investment in space delivers benefits to the citizens of Europe and the world. By coordinating the financial and intellectual resources of its members, ESA can undertake programs and activities far beyond the scope of any single European country.

The Challenge The European Space Operations Center (ESOC) in Darmstadt, Germany, is respon­sible for monitoring and controlling space­craft throughout their operational life. ESOC also sets up, operates and maintains spacecraft-­support infrastructure on the ground, including the network of ground stations in Argentina, Australia, Belgium, French Guiana, Portugal, Spain and Swe­den (ESTRACK). The network must provide cost-­effective, accurate and timely communications with manned and robotic missions that may be billions of kilo­meters from the Earth. It uses cutting-­edge technology including high-­precision point­ing antennas, multi-­frequency radio recep­tion and transmission, cryogenically cooled low-­noise amplifiers and high-­power uplink amplifiers. ESOC must also ensure consistent and re­liable operations throughout the full dura­tion of ESA missions that can span decades. This presents significant challenges in a number of areas, not least the technology platforms that support communication with and control of satellites and other spacecraft. The organization undertakes continuous research to determine which technologies will offer the best long-­term maintainability. Ernesto Doelling, head of the ICT Evolution section at ESOC, said: “Performance is important, but it’s the reliability and the maintainability that are key for the ESOC Missions Operations Infrastructure when it comes to operating systems. From an engineering perspective, we need a product that is easy to understand and that isn’t overcomplicated. And it’s vital to choose a system that will be backed by long-­term professional support.” Depending on each mission’s individual requirements, ESOC had previously deployed a variety of different operating systems, including Microsoft Windows NT, OpenVMS, Sun Solaris and other variants of UNIX.

“There are always unforeseen things in any new software deployment, but the consistency and control that SUSE Linux Enterprise Server gives us means we can rule many things out very quickly.”

SUSE Solution Aiming to rationalize its IT landscape as far as possible, and considering factors such as usability, long-­term maintainabil­ity, and the availability of professional external support, ESOC decided to adopt SUSE Linux Enterprise Server 11 as the operating system for its network of ground stations. “Our internal IT function recommended Linux—and specifically SUSE Linux Enter­prise Server—as the most reliable option,” said Euan Hogg, Senior IT engineer at the European Space Operations Center. ESA has deployed around 100 instances of SUSE Linux Enterprise Server within the last 12 months, including both new sys­tems and migrated environments. How­ever, some applications have remained on their legacy platforms. “Most commonly, we migrate—but we eval­uate on a case-­by-­case basis,” said Marco Lanucara, Head of the Systems and Project Support Section in the ground stations division. “For example, we determined that for a certain application running on QNX, the link between the OS and the hardware made it better not to migrate.” The deployment of SUSE Linux Enterprise Server in the ground stations aligns them to the ESA baseline operating systems. Indeed, SUSE Linux Enterprise Server is the baseline for other ESA major applications, including the Mission Control Systems and the Simulator. In the future, although the hardware platform may vary from domain to domain, there will be a single version of Linux for all ESA applications using that operating system. Any new release or service pack will be validated at ESA, then uniformly used and deployed in all domains, including the ground stations. This was not the case in the past, when different approaches were used in different domains. SIMPLE PORTING

ESA generally uses specialized applications custom-­developed by external software companies. The porting to Linux is also handled by external companies—though not necessarily the same ones that wrote the original software. To increase maintainability and reduce risk, ESA has a policy of obtaining sufficient intellectual property rights for each piece of software to enable it to outsource future development to third parties. “It reduces our risk in the long term if we know that two or three companies have done some work on the software, and if we have the source code,” said Marco Lanucara. While ESOC has encountered no major issues with deploying or using SUSE Linux Enterprise Server, there were some minor challenges to overcome during the migra­tion of the telemetry/telecommand appli­cation from Solaris to SUSE Linux Enterprise Server. “The telemetry and telecommand processor is perhaps the most critical application we have in the ground stations,” said Euan Hogg. “Telemetry is the data received from the satellite, while telecommand is the data we send to the satellite to operate it. Our colleagues in the software engineering division ported the application from Solaris to SUSE Linux Enterprise Server to keep it maintainable from an operating system point of view.” The key challenge ESOC faced was getting the telemetry/telecommand application to work with the legacy network infra­structure. “The system previously used six Ethernet ports, and there was all sorts of routing magic happening in the Solaris ker­nel to get the IP packets to go in the right direction and with the right quality of service,” said Euan Hogg. “When we first migrated the application to SUSE Linux Enterprise Server, it worked perfectly, but we then decided to reduce the six Ethernet ports to two. The Solaris kernel behaves in a different way from the Linux kernel in routing packets, and it took some time and effort to fix. But that’s really the only issue we encountered related to the porting—and we solved it!”