Күн жүйесі мен жұлдызаралық кеңістікті зерттеуші IBEX спутнигі

NASA satellite of the Explorer program

Interstellar Boundary Explorer (IBEX or Explorer 91 or SMEX 10) is a NASA satellite in Earth orbit that uses energetic neutral atoms (ENAs) to image the interaction region between the Solar System and interstellar space. The mission is part of NASA's Small Explorer program and was launched with a Pegasus XL launch vehicle on 19 October 2008. The mission is led by Dr. David J. McComas (IBEX principal investigator), formerly of the Southwest Research Institute (SwRI) and now with Princeton University. The Los Alamos National Laboratory and the Lockheed Martin Advanced Technology Center built the IBEX Hi and IBEX Lo sensors respectively. The Orbital Sciences Corporation manufactured the satellite bus and was the location for spacecraft environmental testing. The nominal mission baseline duration was two years after commissioning, and the prime ended in early 2011. The spacecraft and sensors are still healthy and the mission is continuing in its extended mission. IBEX is in a Sun oriented spin stabilized orbit around the Earth. In June 2011, IBEX was shifted to a new, more efficient, much more stable orbit.

The Interstellar Boundary Explorer (IBEX) mission science goal is to discover the nature of the interactions between the solar wind and the interstellar medium at the edge of the Solar System. IBEX has achieved this goal by generating full sky maps of the intensity (integrated over the line of sight) of ENAs in a range of energies every six months. Most of these ENAs are generated in the heliosheath, which is the region of interaction.

The IBEX satellite was mated to its Pegasus XL launch vehicle at Vandenberg Air Force Base, California, and the combined vehicle was then suspended below the Lockheed L 1011 Stargazer mother airplane and flown to Kwajalein Atoll in the central Pacific Ocean. Stargazer arrived at Kwajalein Atoll on 12 October 2008.

The IBEX satellite initially launched into a highly elliptical transfer orbit with a low perigee and used a solid fuel rocket motor as its final boost stage at apogee in order to raise its perigee greatly and to achieve its desired high altitude elliptical orbit. IBEX is in a highly eccentric elliptical terrestrial orbit, which ranges from a perigee of about to an apogee of about Its original orbit was about

In June 2011, IBEX shifted to a new orbit that raised its perigee to more than The new orbit has a period of one third of a lunar month, which, with the correct phasing, avoids taking the spacecraft too close to the Moon, whose gravity can negatively affect IBEX's orbit. The now spacecraft uses less fuel to maintain a stable orbit, increasing its useful lifespan to more than 40 years.

The heliospheric boundary of the Solar System is being imaged by measuring the location and magnitude of charge exchange collisions occurring in all directions. The satellite's payload consists of two energetic neutral atom (ENA) imagers, IBEX Hi and IBEX Lo. Each consists of a collimator that limits their fields of view (FoV) a conversion surface to convert neutral hydrogen and oxygen into ions, an electrostatic analyzer (ESA) to suppress ultraviolet light and to select ions of a specific energy range, and a detector to count particles and identify the type of each ion. Both of these sensors are a single pixel camera with a field of view of roughly 7° x 7°. The IBEX Hi instrument is recording particle counts in a higher energy band (300 eV to 6 keV) than the IBEX Lo energy band (10 eV to 2 keV). The scientific payload also includes a Combined Electronics Unit (CEU) that controls the voltages on the collimator and the ESA, and it reads and records data from the particle detectors of each sensor.

Compared to other space observatories, IBEX has a low data transfer rate due to the limited requirements of the mission. blockquote| IBEX data transfer rates are slow compared with other telescopes due to the nature of the data it collects. IBEX does not need a "high speed" connection, since it only has the opportunity to collect up to a few particles per minute. Communication from the satellite to the ground is 20 times slower than a typical home cable modem (320,000 bits per second) [is the satellite's transfer speed], and from the ground to the satellite only 2,000 bits per second, which is 250 times slower! Once the signal is collected by the receivers on Earth, it is carried over the internet to Mission control center in Dulles, Virginia, and to the IBEX Science Operation Center in San Antonio, Texas".|NASA's IBEX Q and A

On the average IBEX Hi detects about 500 particles per day, and IBEX Lo, less than 100. By 2012, over 100 scientific papers related to IBEX were published, described by the principal investigator as "an incredible scientific harvest". Initial interpretations suggest that "the interstellar environment has far more influence on structuring the heliosphere than anyone previously believed". The Sun is currently traveling through the Local Interstellar Cloud, and the heliosphere's size and shape are key factors in determining its shielding power from cosmic rays. Should IBEX detect changes in the shape of the ribbon, that could show how the heliosphere is interacting with the Local Fluff. It has also observed ENAs from the Earth's magnetosphere. It went on to detect neutral atoms from outside the Solar System, which were found to differ in composition from the Sun. Surprisingly, IBEX discovered that the heliosphere has no bow shock, and it measured its speed relative to the local interstellar medium (LISM) as , improving on the previous measurement of by Ulysses. Those speeds equate to 25% less pressure on the Sun's heliosphere than previously thought.