OrbitalHub

ESA dixit:

“A safe and secure space environment is a requirement for all current and future space activities. Analyses performed by ESA and NASA indicate that the only means of sustaining the orbital environment at a safe level for space operations in future will be by carrying out both active debris removal and end-of-life de-orbiting or re-orbiting of future space assets. ESA, through its Clean Space (CS) initiative, is devoting an increasing amount of attention to the environmental impact of its activities.

To contribute to space sustainability, some agencies and governments have established or adopted policies to mitigate space debris creation. For instance, the ESA Policy on Space Debris states that satellites must remove themselves from the protected regions, less than 25 years for LEO and less than two months for GEO after operations are complete.

Nevertheless, even if spacecraft are designed to achieve an End-of-Life (EOL) compliance with these Space Debris Mitigation (SDM) requirements, a failure of the spacecraft, or other unforeseen events, may lead to the satellite becoming non-operational in the protected regions (this is even reflected in the SDM requirement, which calls for a reliability of 90%). Therefore, such a failed satellite may require active debris removal (ADR).”

Video Credit: ESA

Wikipedia dixit:

“With the 1979 beginning of the NASA Orbital Debris Program the term space debris also includes the debris from the mass of defunct, artificially created objects in space, most notably in Earth orbit, such as old satellites and spent rocket stages. It includes the fragments from their disintegration, erosion and collisions. As of December 2016, five satellite collisions have resulted in generating space waste. Space debris is also known as orbital debris, space junk, space waste, space trash, space litter or space garbage.

As of 5 July 2016, the United States Strategic Command tracked a total of 17,852 artificial objects in orbit above the Earth, including 1,419 operational satellites. However, these are just objects large enough to be tracked. As of July 2013, more than 170 million debris smaller than 1 cm (0.4 in), about 670,000 debris 1–10 cm, and around 29,000 larger debris were estimated to be in orbit. Collisions with debris have become a hazard to spacecraft; they cause damage akin to sandblasting, especially to solar panels and optics like telescopes or star trackers that cannot be covered with a ballistic Whipple shield (unless it is transparent).

Below 2,000 km (1,200 mi) Earth-altitude, debris are denser than meteoroids; most are dust from solid rocket motors, surface erosion debris like paint flakes, and frozen coolant from RORSAT nuclear-powered satellites. For comparison, the International Space Station orbits in the 300–400 kilometres (190–250 mi) range, and the 2009 satellite collision and 2007 antisat test occurred at 800 to 900 kilometres (500 to 560 mi) altitude. The ISS has Whipple shielding; however, known debris with a collision chance over 1/10,000 are avoided by maneuvering the station.

The Kessler syndrome, a runaway chain reaction of collisions exponentially increasing the amount of debris, has been hypothesized to ensue beyond a critical density. This could affect useful polar-orbiting bands, increases the cost of protection for spacecraft missions and could destroy live satellites. Whether Kessler syndrome is already underway has been debated. The measurement, mitigation, and potential removal of debris are conducted by some participants in the space industry.”

Video Credit: ESA

ESA dixit:

“Rosetta launched in 2004 and travelled for ten years to its destination before deploying the lander Philae to the comet’s surface. Following the comet along its orbit around the Sun, Rosetta studied the comet’s surface changes, its dusty, gassy environment and its interaction with the solar wind. Even though scientific operations concluded in September 2016 with Rosetta’s own descent to the comet’s surface, analysis of the mission’s data will continue for decades.”

Video Credit: ESA

Blue Origin dixit:

“The BE-4 is our fourth-generation liquid rocket engine, made to take us into orbit and beyond.

The BE-4 uses oxygen-rich staged combustion of liquid oxygen and liquefied natural gas to produce 550,000 lbs. of thrust. Liquefied natural gas is commercially available, affordable, and highly efficient for spaceflight. Unlike other rocket fuels, such as kerosene, liquefied natural gas can be used to pressurize a rocket’s propellant tanks. This is called autogenous pressurization and eliminates the need for costly and complex pressurization systems, like helium. Liquefied natural gas also leaves no soot byproducts as kerosene does, simplifying engine reuse.

United Launch Alliance has selected Blue Origin’s BE-4 as the engine that will power the Vulcan rocket’s first stage. The announcement ends the need for the Russian made RD-180 on their next-generation vehicle Vulcan with the American-made BE-4.”

From the ULA press release: “Following completion of a competitive procurement, ULA has selected Blue Origin’s BE-4 engine for Vulcan Centaur’s booster stage. The liquefied natural gas (LNG) fueled booster will be powered by a pair of BE-4 engines, each producing 550,000 pounds of sea level thrust. As previously announced, ULA has selected Aerojet Rocketdyne’s RL10 engine for the Centaur upper stage, Northrop Grumman solid rocket boosters, L‑3 Avionics Systems avionics, and RUAG’s payload fairings and composite structures for the new Vulcan Centaur rocket system.”

Video Credit: Blue Origin