OrbitalHub

Credits: ESA

Formation flying has been a field of study since the beginning of the manned space flight. The final lunar spacecraft of the Apollo program had to be assembled in orbit. Also, docking maneuvers were required during the Skylab missions from 1973 to 1979.

The current focus of spacecraft formation flying is on maintaining a formation of various spacecraft. Maintaining the relative position of a cluster of satellites in orbit is much more challenging than having two or more spacecraft docking, as the first is more sensitive to modeling errors.

ESA’s Proba-3 will be the demonstrator for the technologies required for formation flying of multiple spacecraft.

The two independent, three-axis stabilized spacecraft comprising the Proba-3 mission will form an external coronagraph. An external coronagraph is a much more effective instrument than a terrestrial coronagraph, as the complete absence of atmosphere eliminates the glare that affects the observations from the ground.

By maintaining an accurate relative position, one of the spacecraft will block the direct light from the Sun so that the solar corona can be observed by the instruments mounted on the other. It is expected that the two spacecraft will be capable of positioning relative to each other with a sub-millimeter accuracy over a separation range of 25 to 250 meters. This positioning will be made possible by using S-band radio metrology and optical laser techniques.

You can find out more about the Proba-3 mission on ESA’s website.

Data from the Chandra X-ray Observatory revealed hundreds of young stars in the central cluster and the fainter clusters on either side of the Rosette star formation region, located about 5,000 light years from Earth. In the cluster on the right side of the region, named NGC 2237, about 160 new young stars have been discovered using the data collected by Chandra.

Read more about the Chandra X-ray Observatory…

On September 2, 2010, a Proton-M heavy launch vehicle lifted off from the Baikonur cosmodrome with three Glonass-M satellites. The satellites were placed into the designated orbits by the DM-2 upper stage.

Read more about GLONASS…

Credits: NASA

In a nutshell, it is really tough! The higher you go, more bad things can happen to you… the increasingly rarefied air, freezing temperatures, ionized atoms, radiation, and space debris make life challenging. So, besides thinking of how to place spacecraft in orbit, engineers must consider all of the factors mentioned above (and much more) when designing a spacecraft.

The space environment (the vacuum, the radiation, the space debris, etc.) definitely poses big challenges to spacecraft design engineers. From 1971 to 1989, more than 2,700 spacecraft anomalies related to interactions with the space environment were recorded. These interactions with the space environment are called space environment effects and the changes in the space environment define what is called the space weather. Believe it or not, there are dedicated programs aimed at developing the ability to predict these changes in the same way the weather forecasting does for terrestrial weather. The Space Weather program was formed in the mid-1990s by the National Science Foundation (NSF). The Europeans developed a similar program under the umbrella of the European Space Agency (ESA).

The space environment effects can be grouped into several categories. Such categories include: vacuum, neutral, plasma, radiation, and micrometeorid/orbital debris. So, basically, we can discuss the effects of the vacuum environment, the neutral environment, etc. Each one of these environments interact with the subsystems that comprise a spacecraft: the propulsion system that provides the means of maintaining a certain orbit or attitude, the electrical power system that provides power to the rest of the subsystems onboard, the thermal control system, the attitude and orbital determination and control system, etc.

The vacuum environment imposes challenges when it comes to designing the structure, choosing the materials, and defining a strategy for thermal control. The pressure differential between the inside and the outside of a manned spacecraft is tremendous (around 350 km above the surface of the Earth, the pressure is ten orders of magnitude less). The lack of atmosphere translates into the fact that the spacecraft will have to deal with solar ultraviolet (UV) radiation (the UV radiation is energetic enough to degrade material properties). Also, the spacecraft can only cool itself by conduction or radiation.

Credits: NASA

Even if very rarefied, the neutral atmosphere in low Earth orbit is dense enough to cause a significant atmospheric drag force. The atoms can physically sputter material from surfaces and even cause erosion. All these mechanical and chemical interactions depend on the atmospheric density.

In low Earth orbit, the solar UV radiation ionizes the oxygen and nitrogen atoms. This environment, known as the plasma environment, can give rise to very interesting effects, like spacecraft charging and arcing between regions of differing potentials.

By far, the most dangerous environment in Earth orbit is the radiation environment. In the regions of charged particles, known as trapped radiation belts, particles with energy levels in the order of MeV pass through the surface layer and interact with the materials inside the spacecraft. Present shielding technology cannot protect living organisms inside a spacecraft in these regions.

Micrometeoroids and orbital debris are a cause of great concern to spacecraft design engineers and spacecraft operators as the kinetic energies associated with impacts at orbital velocities are very high. The main effect on spacecraft in this case is the physical damage upon impact. Other effects include surface erosion, ejecta resulted from impacts, changes in thermal control properties, and generation of electro-magnetic impulses (EMIs).

As most of the characteristics of the space environment were determined by remote observations or during short duration missions, one long duration mission was necessary to verify and validate these measurements.

In April 1984, the Space Shuttle Challenger placed into low Earth orbit (LEO) a spacecraft carrying a number of experiments for the purpose of characterizing the low Earth orbit environment. The spacecraft (known as the Long Duration Exposure Facility, or LDEF for short) was a twelve-sided cylindrical structure three-axis stabilized in order to ensure an accurate environmental exposure. The spacecraft was supposed to spend one year in orbit, but just before the planned retrieval, the Space Shuttle fleet was grounded as a result of the Challenger accident on January 28, 1986.

The spacecraft was returned to Earth by the Space Shuttle Columbia in January 1990. After almost six years in low Earth orbit, the results of the experiments onboard the facility contributed a great deal to the understanding of interactions between artificial objects and the environment in low Earth orbit.

You can find all the above in much more detail in Alan Tribble’s book The Space Environment – Implications for Spacecraft Design. Alan Tribble presents an excellent account of the effects the space environment can have on operational spacecraft. The book offers a unique perspective, as it combines the study of the space environment with spacecraft design engineering. .

Alan Tribble spent over ten years designing spacecraft. He is a technical project manager in the International Software Defined Radios group for Rockwell Collins.

Credits: NASA/CSA

Canadian astronaut Chris Hadfield will take command of the station during the second half of his third space mission. Hadfield will launch aboard a Soyuz rocket in December 2012, and spend six months on the station as part of the crew of Expedition 34/35. He will return to Earth in a Soyuz capsule in June 2013.

Hadfield is the only Canadian to board the Russian Mir space station, in 1995, during his first space flight, while he served as Mission Specialist 1 on STS-74. He is also the first Canadian mission specialist and the first Canadian to operate the Canadarm in orbit.

His second space flight was onboard STS-100, where he served as Mission Specialist 1. STS-100 was the International Space Station assembly flight 6A, which delivered and installed the Canadarm-2 on the station. During this mission, Hadfield performed two spacewalks.

Chris Hadfield also served as Director of Operations for NASA at the Yuri Gagarin Cosmonaut Training Centre in Star City, Russia; as Chief of Robotics for the NASA Astronaut Office at the Johnson Space Center in Houston, Texas; as Chief of International Space Station Operations; and as the Commander of NEEMO 14, a NASA undersea mission to test exploration concepts living in an underwater facility off the Florida coast.

The official announcement was made by the Canadian Space Agency. Chris Hadfield’s biography is also available here.

NASA and ATK successfully tested a five-segment solid rocket motor. The motor, dubbed DM-2, is the largest and the most powerful solid rocket motor designed for flight. It is designed to generate up to 3.6 million pounds of thrust at launch.

Read more about the DM-2 test…