The infrared imaging satellite “AKARI” completed its operations on Nov. 24, 2011, but we are still analyzing its vast volume of observation data. We recently found carbon monoxide elements from a relatively young supernova remnant “Cassiopeia A.” A supernova remnant is believed to be filled with high-temperature gas thus no element can exist. Therefore, the discovery this time was unexpected. Furthermore, our findings showed that the volume of solid particles (dust) created by a supernova explosion in the early space age was fewer than expected, and that is another important discovery that may lead to a reconsideration of the existing scenario of substance evolution in space.

The operation of the Infrared Imaging Satellite "AKARI" (ASTRO-F) has been completed after the sending of signals was halted from Earth on Nov. 24 (at 5:23 p.m., Japan Standard Time) following the suspension of scientific observations due to a power generation anomaly on May 24, 2011.
Since its launch on February 22. 2006, JAXA has been operating the AKARI, the first Japanese infrared-ray astronomical satellite, for well over its target life of three years. It has marked various infrared-ray astronomical achievements including capturing the first space light from a planet and compiling the all-sky infrared source catalogues (AKARI All-Sky Survey Point Source Catalogues), which cover some 1.3 million planets.

Japanese infrared astronomy satellite AKARI measured the sky brightness at the wavelength of 1 - 4 micrometers and detected large spatial fluctuation that cannot be explained by the known sources. This fluctuation can be attributed to the clustering of the first stars of the universe, which were formed 300 million years after the Big Bang. The result will provide an important clue for the investigation of star formation history in the early universe for which little observational evidence has been found. The paper will be published in the November 1st issue of The Astrophysical Journal.

The AKARI asteroid catalogue is constructed by laborious processes from the enormous quantity of data of the AKARI All-Sky Survey observations, like collecting gold dust. AKARI is the infrared astronomical satellite, which is a JAXA mission with ESA participation. The new AKARI asteroid catalogue contains 5120 asteroids and becomes the world's largest one. The catalogue will significantly contribute to progress of the asteroid research.

JAXA has been operating the Infrared Imaging Satellite “AKARI” (ASTRO-F,) which was launched on Feb. 22, 2006, past its target life of three years, and way beyond its minimum requirement operation period of one year. During those years, the AKARI compiled an astronomical catalog (an address book for a celestial body) and observed a Red Giant star with red infrared. At 5:30 a.m. on May 24, 2011 (Japan Standard Time), however, the satellite shifted its operation to energy-save mode, thus all onboard observation devices were turned off.
Currently, electricity is provided to the satellite only when the solar array paddle is generating power. JAXA is investigating the cause of the anomaly and taking necessary measures.

The Infrared Astronomical Satellite "AKARI" is observing the dusty veils of some Red Giant stars with unprecedented sensitivity and accuracy.
The dusty veils are produced by an emission of materials and elements from Red Giant stars such as carbon which the stars are composed of (mass ejection.) Using the AKARI's observation capability with mid infrared, a global first, we were able to depict when and how the mass ejection occurred. The result of the observation this time elucidated the dying stars' throes which have been mysterious, and also it became an important clue to understand the supply system of carbon, which is a basic ingredient of our body and other materials.
When more detailed image shooting and observations by mid infrared becomes possible, we can clarify the mass ejection of more Red Giant stars.

The Infrared Imaging Satellite "AKARI" and the X-ray Astronomy Satellite "Suzaku" have been observing remnants of a supernova commonly known as Tycho's supernova.
Through their observations, a possibility of dust generation due to the condensation of elements released from the supernova was found for first time in the world. The finding became very helpful and contains important data that can help reveal the origin of a planet and life, as there are still lots of mysteries in how dust, one of raw materials to help create a planet, is formulated and destroyed by supernova explosions.

AKARI's scientific achievements were specially featured in "Astronomy and Astrophysics," one of Europe's most prestigious magazines in this field, The magazine publishes 17 theses on various topics of AKARI's observations including a thesis specifically targeted on celestial bodies in the solar system and on the far-away galactic system.

AKARI All-Sky Survey Point Source Catalogues are a collection of information on about 1.3 million planets shining in infrared lights (like an address book), and today the catalogues become available to researchers world-wide.
As the catalogues issued from Japan are now open to the public, they will be used not only by international researchers on infrared astronomy, but also other astronomers in broader fields from radio waves to X-rays for various astronomical studies. They will also be useful for a variety of observation plans from ground telescopes as well as through astronomical satellites.

The initial version of AKARI all-sky infrared source catalogue is now ready for scientific analysis. We also present here three recent research results about old stars and interstellar media based on the AKARI data.

A group consisting of the University of Tokyo, JAXA, Hokkaido University, Hiroshima University and other researchers made observations through the infrared astronomical satellite AKARI of the Supernova 2006jc discovered by Koichi Itagaki. The group tried to uncover the mysteries of the supernova through cooperative and continuous observations from the ground using the Subaru Telescope, the MAGNUM Telescope and the KANATA 1.5-m telescope.
As a result, detailed images of the birth of cosmic dust were captured for the first time. A star that is about to die after a supernova explosion expels materials like cosmic dust into space, which will be the raw materials for planets and other life. At the same time, through comparisons between observation data of multiple wavelengths from visible rays to infrared rays, and the latest theoretical model, the team succeeded to capture the images of a star with a mass 40 times greater than the Sun from its repeated mass ejections to its supernova explosion at the end of its life. These serial images revealed the state of the formation of the chemically enriched space environment by cosmic dust consisting of carbon and silicon that was formed during this procedure.

Image: Infrared image of Supernova 2006jc half a year after the explosion, captured by AKARI's Near- and Mid-infrared camera. (3 micrometer wavelength)
At this point, half a year after the explosion, the supernova already appears dark with optical rays, but the AKARI clearly captured the bright infrared luminous dust that was newly born around the supernova.

We report on the initial results from the data taken by the first dedicated Japanese infrared astronomical satellite AKARI, launched in February 2006. The group in the Graduate School of Science, Nagoya University has participated in the development of an onboard instrument, the Far-Infrared Surveyor (FIS). We are delighted to introduce the unique FIS instrument along with a pair of the initial scientific results from the instrument; the observation of the nearby galaxy M101 and the deep far-infrared sky-survey programme. These results will be presented in the Annual Meeting of the Astronomical Society of Japan to be held at Gifu University in September 26th--28th, and also reported in the Publications of Astronomical Society of Japan (AKARI first results special issue). Note that AKARI's FIS instrument successfully completed its mission observations on the evening of this August 26th in Japan.

The infrared astronomical satellite AKARI ran out of its on-board supply of cryogen, liquid Helium at 08:33 (UT) on August 26th, 2007, after successful operation and observations that began on May 8th, 2006. The boil off of the liquid Helium signals the completion of observations at far-infrared and mid-infrared wavelengths with AKARI, including the All-Sky Survey.

AKARI did in fact achieve the pre-launch expected lifetime of 550 days. During this period, AKARI completed the far-infrared All-Sky Survey covering about 94 per cent of the entire sky, and also carried out mid-infrared survey as well as more than five thousand individual pointed observations. The data obtained is now being intensively analysed by the project scientists and astronomers.

AKARI plans to continue warm phase observations using the surviving instruments that can still operate under the conditions provided by the additional on-board mechanical coolers. The preparation and performance evaluation of the next phase of the mission will be carried out over the next few months.

We warmly acknowledge all the people who support the AKARI mission.

- AKARI Project Manager Professor Hiroshi Murakami -


Image:Mid-infrared Image of Reflection Nebula IC1396 (August 28, 2006)

The infrared astronomy satellite AKARI started the regular observations in May 2006. In the last one year, AKARI has carried out the All-Sky Survey observations to map the entire sky, as well as thousands of pointed observations of selected targets. Here we show the beautiful images constructed from the AKARI All-Sky Survey data; The entire sky in the mid-infrared light, the far-infrared image of the constellation Orion and the Milky Way, and the far-infrared image of the Cygnus-X region.

The infrared astronomical satellite "Akari" continues its mission to map the entire sky in infrared light. It will finish its first coverage of the entire sky in early November following almost 6 months of observations. The first scan is expected to cover about 70 percent of the entire sky excluding some areas disturbed by the moon. During the course of the first scan, the "Akari" successfully obtained detailed images of the Large Magellanic Cloud at near, mid and far infrared wavelengths. The Large Magellanic Cloud is an important observation target to study the birth of the Galaxy.

JAXA launched the 21st Scientific Satellite (ASTRO-F) aboard the M-V Launch Vehicle No. 8 (M-V-8) at 6:28 a.m. on February 22, 2006 (Japan Standard Time, JST) from the Uchinoura Space Center (USC).

The launch vehicle flew smoothly, and it was confirmed that the satellite was safely injected into its scheduled orbit.

The in-orbit ASTRO-F was given a nickname of "Akari" (meaning a "light.")

We would like to express our appreciation for the cooperation and support from all related organizations and people who helped contribute to the successful launch of the ASTRO-F/M-V-8.

The ASTRO-F underwent a thermal vacuum test for 24 hours a day for 2 weeks between Oct. 1 and 16. The test is the final climax of a series of satellite integration tests. The thermal vacuum test is to check if the satellite equipment can maintain its function and work properly in the harsh space environment. The internal walls of the vacuum chamber, which is large enough to contain a satellite, were chilled by liquid nitrogen, and each satellite part was heated either internally or by heaters set near the satellite to create the rough space conditions. The test proved that each part of the satellite properly controlled its temperature as expected, thus the normal performance was verified.

Some small issues for the actual operation were raised, and we will work on them from now until its launch. Following the completion of the thermal vacuum test, we feel that the launch of the ASTRO-F has come a step closer.

Photo 1: The ASTRO-F after it just completed the test:
You can see the wiring for the thermometers andheaters set for the test.

We would like to provide opportunities for astronomical researchers by sharing some of our observation time once the ASTRO-F is in space. We will accept applications until Nov. 18, 2005. The opportunities are provided during the "Phase 2" that starts just after its launch till about six months after the launch (until the helium coolant is used up). Some 30% of the observation time in the "Phase 2" will be allocated for publicly selected observation project(s), 10% for Europe, and 20% for Japan and Korea. We had an explanatory session for the applications in England, Spain, Korea and Japan, and that led to our high expectations for observations by ASTRO-F, as many people participated in the session in all four countries.

Photo 2: Explanatory session at the European Space Astronomy Center (Spain).

Photo 3: ASTRO-F meeting at the autumnal annual event of the Astronomical Society of Japan.

For more details, please check the following website for observers.

We performed a vibration test on the satellite that was close to its flight configuration in June 2005, and verified that all devices and equipment were working properly after the test.
In late June, we checked the direction of the light axis of the telescope by opening a cap on the cryostat, in which the telescope and observation equipment were installed, to look into the telescope (Photo1.)
We did not find any gap in the axis either before or after the vibration test, thus we confirmed that the telescope was strong enough for launch acceleration and vibrations.
The cap of the cryostat is now closed, and the devices and equipment are ready to be cooled down for future tests. The next time that the cap is opened and the light is introduced will be when the in-orbit satellite starts observations in space.

We also carried out an operation called "baking" to prevent gases with impure objects that come out from the onboard equipment and electronic mother boards from negatively impacting the devices. To bake the satellite, it was put in an air-tight chamber (vacuum chamber) and warmed in vacuum to about 50 degrees Celsius to force impure gas to be released. Photo 2 shows the satellite in the chamber and some attachments.

The observation equipment and cryostat have already been baked. After a week of baking, the satellite went back to the clean room.

Photo 1: Looking into the telescope (right) and measuring the light axis (by NIKON)
Photo 2: The satellite put in the vacuum chamber for baking. The rack came up, and went into the chamber. (by NTSpace)

In early December 2004, the observation equipment of ASTRO-F was tested at the Nihama Works of Sumitomo Heavy Industries, Ltd. (in Ehime Prefecture.) It was the first test since it had been assembled to form a flight structure, and both the coolant and observation instruments worked properly. It took over a week to measure the performance of various devices, and we were pleased to find that equivalent or better results were acquired compared with the unit-by-unit test data before the assembly. Data analysis is still going on, and when all is completed, the final estimated performance for flights will be obtained.

The tested observation equipment was immediately transported back to the Sagamihara Campus (in Kanagawa) to be tested for vibrations in the cryogenic condition by liquid helium that is set at the same environment as that at the time of launch. The vibration test was completed on the evening of Dec. 28, 2004. On Jan. 6 and 7, the observation equipment was turned on to check its operation. Both the vibration test and operation check were successful, and the equipment of the ASTRO-F was found to be strong enough to withstand launch vibrations.

We were relieved by the good test results as this marked a critical point in the observation equipment development.

Photo 1: The observation equipment under the performance evaluation test in Niihama. Pouring liquid helium on the cap of the cryostat (cryogenic vessel) to artificially make the cryogenic condition to create a "dark" condition when it is seen under infrared light.

Photo 2: ASTROF observation equipment under the vibration test in Sagamihara.

The ASTRO-F telescope passed the cryogenic vibration test. This is a very difficult test for high precision optical equipment such as telescopes, because the telescope is subjected to the equivalent vibration as that at liftoff under cryogenic conditions. The test was regarded as a critical point in the final verification test phase because an anomaly was found in the same test last year (damage to the support of the reflector) and that resulted in the re-manufacturing of the reflector.

The test was held between June 28 and July 1, 2004 at the Sagamihara Campus (ISAS). When the temperature of the telescope returned to normal after the cryogenic and harsh vibrant conditions, it underwent post test inspections, namely a surface inspection, and an inspection for cracks at the pad connection part using ultrasonic waves. The telescope passed the test as no problem was found during the inspections. In order to further review its optical performance under cryogenic conditions, we are acquiring detailed data about a focal position and other aspects by cooling the telescope down to the absolute temperature of 9 degrees (minus 264 degrees Celsius).

JAXA also carried out the final performance evaluation test for two sets of observation equipment (FIS and IRC) for a far-infrared ray and a near- to mid-infrared ray during the three cooling cycles between early June and the end of July. We overcame some small trouble when changing a module (MIR-S, mid-infrared camera system) after we found an anomaly in it during the test, and the observation equipment is now in a satisfactory condition. Along with the telescope, we are currently installing two sets of equipment into the cryostat, a container that maintains the cryogenic temperature.

Photo : ASTRO-F telescope being installed into the test chamber for the optical performance test

JAXA has been investigating the cause of an anomaly in the telescope mount that was found during the cryogenic vibration test in 2003, and consequently reviewed the design.
As part of the renovations and countermeasures, we polished a backup mirror, and that was successfully completed in early March. This mirror is to be used as a flight model.
The valid diameter of the new telescope mirror is now about 69 cm, which is 2 cm larger than the previous mirror, and that almost achieves our original goal of 70 cm.
We will perform vibration and optical tests after assembling the telescope and chilling it in order to verify the assembly state including the suitability of the mirror mount pad that is newly designed, and its comprehensive performance results in flight conditions.
As this is our second time to test the satellite with a flight model, we will use our previous experience and try to minimize the influence of thermal distortion.
JAXA also conducted a second evaluation test on the satellite attitude and orbit control system (AOCS) between mid January and mid March. The purpose of the test is to ensure the AOCS performs smoothly in its early phase, even if the launch season is changed. Through this test, we verified that the AOCS can flexibly accommodate changes in the launch season.
We were also able to carry out a more detailed performance evaluation of the system. We will further analyze test data in detail and study it further.

Photo : The ASTRO-F during the attitude control system evaluation test. This test was carried out with equipment that included a gyro detached from the satellite and placed on the fixed board (as seen in the front of the photo) so as not to be impacted by vibrations from the outside. (Photo courtesy of NT Space)

Recently a satellite integration test of the ASTRO-F satellite was completed. The satellite is now in storage.
The launch schedule of ASTRO-F has been postponed due to an anomaly found in the supporting structure of the primary mirror of the telescope during the low temperature vibration test prior to the satellite integration test which commenced from April 2003. It was found that the supporting structure was not strong enough to securely hold the primary mirror in the vibrant environment expected at liftoff and the position of the mirror would be prone to shifting.
In the successfully held satellite integration test, equipment and devices were assembled, their functions carefully checked, and an operational rehearsal carried out by simulating the launch and on-orbit observation procedures. Small anomalies and problems found during the test have been corrected.
A decision to suspend the tests for the satellite bus module (i.e., the structure excluding the observation equipment) was made after a review on the anomaly and problems held on Nov. 7, 2003. The satellite, which is mostly assembled, is now being stored in a clean room. The final assembly will begin around December 2004. The ASTRO-F project team is now renovating the mirror supporting structure. We will continue to make the utmost effort to improve the performance of the satellite by renovating its equipment so we may launch in a timely fashion.

Photo : The Satellite integration test for the ASTRO-F satellite bus module