وان آلن پروبز
وان آلن پروبز (به انگلیسی: Van Allen Probes) شامل دو فضاپیمای روباتیک بود که برای مطالعهٔ کمربند تابشی وان آلن که زمین را احاطه کردهاند، مورد استفاده قرار گرفت. این پروژه توسط ناسا انجامگرفت. این دو فضاپیمای روباتیک در تاریخ ۳۰ اوت ۲۰۱۲ به فضا پرتابشدند.
The Van Allen Probes, formerly known as the Radiation Belt Storm Probes, are two robotic spacecraft being used to study the Van Allen radiation belts that surround Earth. NASA is conducting the Van Allen Probes mission as part of the Living With a Star program. Understanding the radiation belt environment and its variability has important practical applications in the areas of spacecraft operations, spacecraft system design, mission planning and astronaut safety. The probes were launched on 30 August 2012.
NASA's Goddard Space Flight Center manages the overall Living With a Star program of which RBSP is a project, along with Solar Dynamics Observatory (SDO). The Applied Physics Laboratory is responsible for the overall implementation and instrument management for RBSP. The primary mission is scheduled to last 2 years, with expendables expected to last for 4 years. The spacecraft will also work in close collaboration with the Balloon Array for RBSP Relativistic Electron Losses (BARREL), which can measure particles that break out of the belts and make it all the way to Earth's atmosphere.
The Johns Hopkins University Applied Physics Laboratory (APL) manages the mission and is building and will operate the Van Allen Probes for NASA.
On 16 March 2009 United Launch Alliance (ULA) announced that NASA had awarded ULA a contract to launch RSBP using an Atlas V 401 rocket. NASA delayed the launch as it counted down to the four-minute mark early morning on 23 August. After bad weather prevented a launch on 24 August, and a further precautionary delay to protect the rocket and satellites from Hurricane Isaac, liftoff occurred on 30 August 2012 at 4:05 AM EDT.
End of mission
On 12 February 2019, mission controllers began the process of ending the Van Allen Probes mission by lowering the spacecrafts' perigees, which will increase their atmospheric drag and result in their eventual destructive reentry into the atmosphere. This is to ensure that the probes reenter in a reasonable timespan, in order to pose as little threat as possible with regards to the problem of orbital debris. The probes are projected to cease operations in early 2020, when they run out of the fuel necessary to keep their solar panels pointed at the sun. Reentry into the atmosphere is predicted to occur in 2034.
The Van Allen radiation belts swell and shrink over time as part of a much larger space weather system driven by energy and material that erupt off the Sun's surface and fill the entire Solar System. Space weather is the source of aurora that shimmer in the night sky, but it also can disrupt satellites, cause power grid failures and disrupt GPS communications. The Van Allen Probes will help scientists to understand this region and to better design spacecraft that can survive the rigors of outer space. The mission is to gain scientific understanding of how populations of relativistic electrons and ions in space form or change in response to changes in solar activity and the solar wind.
The mission's general scientific objectives are to:
In May 2016, the research team published their initial findings, stating that the ring current that encircles Earth behaves in a much different way than previously understood. The ring current lies at approximately 10,000 to 60,000 kilometres (6,200 to 37,000 mi) from Earth. Electric current variations represent the dynamics of only the low-energy protons. The data indicates that there is a substantial, persistent ring current around the Earth even during non-storm times, which is carried by high-energy protons. During geomagnetic storms, the enhancement of the ring current is due to new, low-energy protons entering the near-Earth region.
In February 2013, a third temporary Van Allen Radiation Belt was discovered by using data gathered by Van Allen Probes. The said third belt lasted a few weeks.
The Van Allen Probes consists of two spin-stabilized spacecraft that were launched with a single Atlas V rocket. The two probes must operate in the harsh conditions they are studying; while other satellites have the luxury of turning off or protecting themselves in the middle of intense space weather, the Van Allen Probes must continue to collect data. The probes have, therefore, been built to withstand the constant bombardment of particles and radiation they will experience in this intense area of space.
Because it is vital that the two craft make identical measurements to observe changes in the radiation belts through both space and time, each probe carries the following instruments: