OrbitalHub

Credits: NASA/Goddard Space Flight Center Scientific Visualization Studio

Predictions of space weather are important as the effects of magnetic storms can be very significant: disruptions in radio communications, radiation hazards to astronauts in LEO, and power lines surges, just to name a few. The goal of NASA’s Living With a Star (LWS) Program is to understand the changing Sun and its effects on the Solar System. The Solar Dynamics Observatory (SDO) is one of NASA’s LWS missions.

SDO will take measurements of the solar activity. There are seven science questions SDO will try to answer. Among them, what is the mechanism that drives the cycles of solar activity? How do the EUV variations relate to the magnetic activity of the Sun? Is it possible to make predictions regarding the space weather and climate? The last question, if answered, will make choosing the launch windows for future interplanetary manned missions an easier task.

The spacecraft is 2.2 x 2.2 x 4.5 m and 3-axis stabilized. At launch, it has a mass of 3200 kg (270 kg the payload and 1400 kg the fuel). The solar panels are 6.5 m across, cover 6.6 m², and produce up to 1540 W of power.

Credits: NASA

SDO carries three instruments: the Atmospheric Imaging Assembly (AIA), EUV Variability Experiment (EVE), and the Helioseismic and Magnetic Imager (HMI). The instruments will take measurements that will reveal at a very high rate the variations of the Sun.

The HMI was developed at Stanford University and it will extend the SOHO/MDI instrument. The HMI will help to study the origin of variability and the various components of the magnetic activity of the Sun. The measurements aim at understanding the origin and evolution of sunspots, sources and drivers of solar activity and disturbances, connections between the internal processes and the dynamics of the corona and the heliosphere.

You can find more information about the instrument on the HMI page on Stanford University’s web site.

The AIA will capture images of the solar atmosphere in ten wavelengths every ten seconds. The data collected by the instrument will improve the understanding of the activity in the solar atmosphere. The instrument was developed by Lockheed Martin.

EVE was developed at University of Colorado at Boulder. EVE will measure the solar extreme ultraviolet irradiance.

The SDO will launch aboard an Atlas V launch vehicle from SLC 41 at Cape Canaveral. SDO will operate on a geosynchronous orbit, which will allow continuous observations of the Sun. The orbit will also allow a continuous contact with a single dedicated ground station. The high data acquisition rate required such a mission profile, as a large on-board storage system would add to the overall complexity of the system.

You can find more information about SDO on NASA’s website.

Credits: ESA – P.Carril

The European Union’s Global Monitoring for Environment and Security (GMES) initiative was born as the result of a growing need for accurate and accessible information about the environment, the effects of climate change, and civil security. GMES uses as its main information feed the data collected by satellites developed by ESA. Data is also collected by instruments carried by aircraft, floating in the ocean, or located on the ground.

GMES provides services that can be grouped into five main categories: land management, marine environment, atmosphere, aid emergency response, and security.

There are five Sentinel missions designed as components of the GMES initiative. These missions will complement the national initiatives of the EU members involved. The missions will collect data for land and ocean monitoring, and atmospheric composition monitoring, making use of all-weather radar and optical imaging. Each of the Sentinel missions is based on a constellation of two satellites.

Sentinel-1 is an all-weather radar-imaging mission. The satellites will have polar orbits and collect data for the GMES land and ocean services. The first satellite is scheduled for launch in 2012. Sentinel-1 will ensure the continuity of Synthetic Aperture Radar (SAR) applications, taking over from systems carried by ERS-1, ERS-2, Envisat, and Radarsat. Sentinel-1 satellites will be carried to orbit by Soyuz launch vehicles lifting off from Kourou.

Sentinel-2 will provide high-resolution multi-spectral imagery of vegetation, soil, and water, and will cover inland waterways and coastal areas. Sentinel-2 is designed for the data continuity of missions like Landsat or SPOT (Satellite Pour l’Observation de la Terre). Each satellite will carry a Multi-Spectral Imager (MSI) that can ‘see’ in thirteen spectral bands spanning from the visible and near infrared (VNIR) to the shortwave infrared (SWIR). The first Sentinel-2 is planned to launch in 2013. Vega will provide launch services for Sentinel-2 missions.

Credits: ESA – P.Carril

Sentinel-3 will determine parameters such as sea-surface topography and sea and land surface temperature. It will also determine ocean and land colour with high accuracy. The first Sentinel-3 satellite is expected to reach orbit in 2013. The spacecraft bus has a three-meter accuracy real-time orbit determination capability based on GPS and Kalman filtering.

Sentinel-4 is devoted to atmospheric monitoring and it will consist of payloads carried by Meteosat Third Generation (MTG) satellites that are planned to launch in 2017 and 2024. Sentinel-5 will be used for atmospheric monitoring as well. The payload will be carried by a post-EUMETSAT Polar System (EPS) spacecraft, planned to launch in 2020. A Sentinel-5 precursor will ensure that no data gap will exist between the Envisat missions and Sentinel-5.

You can find out more about the GMES initiative and the Sentinel missions on a dedicated page on ESA’s website.

Credits: The British Interplanetary Society

Daedalus was a British Interplanetary Society (BIS) project conducted in the 1970’s. The project aimed to design an interstellar probe capable of flying to the Barnard’s star. The Daedalus design was a 54,000 ton two-stage vehicle powered by a D/He3 fusion engine, which could reach a speed of 10,000 km/s. It seems that the motivation behind the Daedalus project was the Fermi paradox.

Among the stated guidelines of the Daedalus project were the use of current or near-future technology and that the spacecraft must reach its destination within a human lifetime. There were interesting aspects to be considered during the design phase, such as infrastructure, propulsion, supporting technologies, and choice of targets.

Icarus, a new theoretical study of a mission to another star, builds on the solid base of the Daedalus project. Icarus aims to crystallize the design for an interstellar probe. Declared goals of the project include generating greater interest for interstellar precursor missions, and motivating a new generation of scientists to design interstellar space missions.

You can find more information about Project Icarus and the team behind the design efforts on the Project Icarus website.

Credits: ESA – P. Carril, 2009

PROBA-2 is part of an ESA program called In-Orbit Technology Demonstration Program, which is dedicated to the demonstration of innovative technologies.

The PROBA-2 payload consists of scientific instruments that will make observations of the Sun in the ultraviolet portion of the spectrum and will measure certain properties of the plasma surrounding the spacecraft.

Among the new equipment and technologies demonstrated by PROBA-2 are new models of star trackers, GPS receivers, and reaction wheels, a new type of lithium-ion battery, an advanced data and power management system, composite carbon-fibre and aluminum structural panels, and magnetometers. PROBA-2 also hosts a digital Sun-sensor, an experimental solar panel, and a xenon gas propulsion system.

PROBA-2 will be launched onboard the same launch vehicle as SMOS. While the SMOS Mission will provide global maps of moisture over the Earth’s landmasses and salinity over the oceans, PROBA-2 is a small technology demonstrator. Launched as a secondary payload, PROBA-2 will orbit in the same plane as SMOS, but at a lower altitude. The planned mission duration is two years.

The spacecraft is a 600 mm x 700 mm x 850 mm box-shaped structure, with a mass of 130 kg. Aluminum honeycomb panels make the primary mechanical structure of the spacecraft. The two deployable solar panels and the one outer solar panel provide a maximum of 110 Watts of electrical power. A lithium-ion battery provides power during eclipse periods. A single 20 mN thruster is used for orbit adjustments.

Credits: ESA – P. Carril, 2009

PROBA-2 is three-axis stabilized. Attitude changes are performed using four reaction wheels that can be unloaded by magnetorquers, while the attitude determination is provided by star trackers, GPS sensors, and a three-axis magnetometer.

The spacecraft was built by Verhaert Design & Development NV, Belgium.

The scientific payload comprises of four experiments: two for solar observations (LYRA and SWAP) and two for space weather measurements (DSLP and TPMU).

LYRA is a Lyman-Alpha radiometer that will monitor four bands in a very wide ultraviolet spectrum. SWAP (the Sun Watcher using Active Pixel-sensor) will make measurements of the Sun’s corona. DSLP (Dual Segmented Langmuir Probes) will make measurements of the electron density and temperature in the background plasma. TPMU, which is the Thermal Plasma Measurement Unit, will measure ion densities and composition.

Launch services for the PROBA-2 mission are provided by EUROCKOT Launch Services GmbH. PROBA-2 will achieve its lower orbit by an orbit change maneuver of the Breeze-KM upper stage of the Rockot launch vehicle.

Credits: ESA – P. Carril, 2009

Rockot is a three-stage liquid propellant launch vehicle based on the Russian SS-19 Intercontinental Ballistic Missile (ICMB).

Rockot’s first and second stages (provided by SS-19) are completed by a third re-ignitable stage, the Breeze-KM upper stage. Rockot can deliver 1950 kg payloads to Low Earth Orbits (LEOs).

The length of the launch vehicle is 29 m. The external diameter of the stages is 2.5 m, while the payload fairing has an external diameter of 2.6 m and a height of 6.7 m. The mass of the vehicle at launch is 107 metric tons.

PROBA-2 will be carried into orbit from Plesetsk Cosmodrome, Russia. The operational orbit is a 700 km sun-synchronous orbit, with a 98 degree inclination.

You can read more about PROBA-2 on ESA’s dedicated web site. ESA’s web site also provides information about PROBA-1, which is already flying, and future PROBA missions, like PROBA-3 and PROBA-V.

Credits: NASA

Software is a key component of present-day aerospace systems. Increased reliability is required from operating systems that host critical software applications.

Wind River’s VxWorks is a real-time operating system that is widely used in the aerospace industry. Missions using VxWorks include the Mars Reconnaissance Orbiter, the Phoenix Mars Lander, the Deep Impact space probe, Spirit and Opportunity Mars Exploration Rovers, and Stardust.

Mike Deliman, Senior Engineering Specialist at Wind River Systems, answered a few questions related to the new VxWorks MILS Platform 2.0.

DJ: What is VxWorks MILS Platform 2.0?
Mike Deliman: VxWorks MILS Platform 2.0 is a platform for creating systems that are evaluatable to high levels of the Common Criteria / Evaluated Assurance Level scale. VxWorks MILS 2.0 separation kernel is currently under evaluation by NIAP labs to an EAL 6+ level. The VxWorks MILS 2.0 Platform contains a separation kernel and technology to allow you to create multi-partitioned software systems where each partition can be evaluated to handle multiple independent levels of security (MILS) or to handle multiple levels of security (MLS). The long-and-short of it is similar to a VxWorks 653 flight OS, you can use a VxWorks MILS 2 platform to design a single platform that is capable of replacing multiple legacy systems. In other words, like a VxWorks 653 flight system, you can create a single modern system to replace multiple legacy systems, reducing Space, Weight and Power (SWaP) requirements.

DJ: What is a separation kernel and how did the concept make its way into software development for the aerospace industry?
M.D.: Separation Kernels allow you to take a single modern high-powered CPU and use it to replace several legacy systems. There are many examples of separation kernels and paradigms for their use. ARINC 653 defines a time and memory-space partitioning paradigm, services, and an API that must be provided (the Application Executive, or APEX). We have a platform – VxWorks 653 – that implements the ARINC 653 APEX separation and API. Separation Technologies are becoming quite popular, many are called “Hypervisors”. There are many Hypervisors out in cyberspace, the “Type 1” Hypervisors can all be thought of as forms of separation kernels. The Aerospace industry is a prime target for separation technologies because of the need to reduce the “SWaP” factors.

DJ: How does the VxWorks MILS separation kernel improve the reliability of aerospace applications?
M.D.: The VxWorks MILS separation kernel could be used to allow a single satellite to fulfill multiple missions. For instance, there may be a number of sensors and experiments on board, some for civilian / educational interests, some for NASA, some for research entities, perhaps some for the USAF. A MILS kernel could be used to collect, encode, and steer data safely, providing assurance that the data will not be mixed until it is in a state deemed “safe” for mixing. A satellite running a MILS separation kernel to handle such data wrangling could combine and satisfy multiple mission masters. If I were to be asked to design such a system, I would most likely recommend a flight computer separate from the science computer. Even if the science and flight SW were to share a single CPU, the separation technology would help ensure that no problems on any science application could affect any of the other science applications or any flight applications. In this way the flight system would be protected from anomalous events in the science packages, and the overall system would benefit from improved reliability.

DJ: John Rushby introduced the concept of separation kernel in order to provide multilevel secure operation on general-purpose multi-user systems. Do software applications developed for the aerospace industry (and I have in mind software running on micro-controllers) have the level of complexity that would require a separation kernel?
M.D.: Concentrating on the micro-controller aspect, no, most single (federated) systems running one micro-controller (or even several) do not even need a 32-bit processor dedicated to their operation. However, with a proper separation kernel and time-sliced architecture, you could use one modern high-speed 32-bit CPU to control and monitor a large number of smaller systems, and ensure any faults occurring on those control-and-monitor loops are contained. And as noted above, in a system used to satisfy requirements of multiple masters (agencies), MILS-style data separation may be the only way to keep satellite weight within limits and provide the information assurance the agencies require.

DJ: What features make the VxWorks operating system reliable and secure?
M.D.: Focusing on the VxWorks family of operating systems and the VxWorks OS API, VxWorks has been used in millions of devices over more than two decades of service, in applications as simple as MP3 players and as complex as autonomous space exploring robots, and as life-critical as telerobotic surgeons. There is no way a software company could anticipate the wide range of use that our customers have dreamed up and implemented. The VxWorks family of OSes share a common ancestry of code and all can benefit from bugs discovered and fixed in any of the family line.
 
Focusing on the VxWorks MILS platform, the separation kernel was designed expressly in compliance with the SKPP (the Protection Profile for separation kernels), with a focus on controlling embedded applications that require some degree of real-time control.

DJ: What are the features that make VxWorks a real-time operating system?
M.D.: Determinism is king in the real-time world. The ability to react to events in the real world with a high degree of determinism is what gives VxWorks its hard real-time responsiveness. This hard-determinism is carried over into all of the VxWorks family line, including our separation kernels and VxWorks SMP.

DJ: What toolchain is shipped with VxWorks? What programming languages are supported by the toolchain?
M.D.: Depending on the VxWorks package, one or more toolchains may be supplied and supported. For the most part, various versions of the Wind River Complier (formerly “Diab”), and various versions of the Gnu tools are supplied / supported with VxWorks. For the VxWorks MILS 2 platform we use a couple of versions of the GNU tool chains, specially modified for the parts they are used to build.

DJ: What hardware is targeted by the platform? Is an actual board necessary for development of applications or is an emulated target environment available for software engineers?
M.D.: Specifically, chips we are targeting include the following:
– Freescale 8641D (CW VPX6-165)
– Freescale 8548 (Wind River SBC8548)
– Intel Core 2 Duo (Supermicro C2SBC-Q)
– Freescale P2020, P1011, P4080 (future)
– Intel Atom, Nehalem (future)
We currently support Simics as the only simulation environment available for the VxWorks MILS platform.

Wind River Systems was founded in Berkeley, California in 1981. Intel bought Wind River Systems for a reported $884 million in July 2009. VxWorks real-time operating system is one of the Wind River flagship products.

Credits: NASA

The Gravity Recovery And Interior Laboratory (GRAIL) is a mission that will measure the lunar gravity field in unprecedented detail. The twin spacecraft will orbit the Moon in tandem and collect scientific data for several months.

The GRAIL mission will cost $375 million and launch in 2011 as part of NASA’s Discovery Program. The window for the launch is 26 days long and opens on September 8, 2011.

After a dual launch aboard a Delta II 2920-10, the spacecraft will spend three to four months cruising on a low-energy trans-lunar trajectory. The two spacecraft will orbit the moon on 50 km, near-circular polar orbits, with a spacecraft separation of 175 – 225 km. The science phase of the mission will take 90 days, and it will be followed by a 12-month science data analysis.

The technique used by GRAIL for collecting scientific data was also used for the Gravity Recovery And Climate Experiment (GRACE) mission, launched in 2002. Small changes in the distance that separates the two spacecraft are translated in variations of the lunar gravity field.

The GRAIL spacecraft are based on the Lockheed Martin XSS-11 bus. The XSS-11 (Experimental Small Satellite 11) is the result of research done at Lockheed Martin Space Systems in the field of agile and affordable micro-satellites. Interesting to mention here is that there were speculations that XSS-11 could also be used as the base for the development of a kinetic anti-satellite weapon (ASAT).

The spacecraft is a rectangular composite structure. Two non-articulated solar arrays and lithium ion battery provides power. The attitude control system, the power management system, and the telecommunications system are also inherited from the XSS-11 bus.

The payload consists of a Ka-band Lunar Gravity Ranging System (LGRS), which is derived from the instrument carried by the GRACE spacecraft.

The spacecraft flight operations will be conducted from Lockheed Martin’s Denver facility. Science Level 0 and 1 data processing will be done at Jet Propulsion Laboratory (JPL), Level 2 data processing at JPL, the Goddard Space Flight Center (GSFC) and the Massachusetts Institute of Technology (MIT). The final scientific data will be delivered by MIT.

While missions like the Lunar Reconnaissance Orbiter (LRO) will find safe landing sites, locate potential resources, and take measurements of the radiation environment of the lunar surface, GRAIL will explore the moon from crust to core, and determine the moon’s internal structure and evolution.

More information about GRAIL is available on the GRAIL mission page on MIT’s web site.