FAQs
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FAQs about ALMA

Q1: What is ALMA?

Q2: What can we see with ALMA?

Q3: Where is ALMA constructed?

Q4: When is the completion of ALMA?

Q5: Who constructs ALMA?

Q6: Who uses ALMA?

Q7: How much does it cost to construct ALMA?

Q8: I want to know more about ALMA!

Q1: What is ALMA?

A1.1: ALMA is a gigantic high-tech array consisted of sixty-four 12-m high precision antennas and sixteen super-high precision antennas (including four 12-m antennas and twelve 7-m antennas). The array is now being constructed on a plateau at an altitude of 5,000 m above sea level in the Chilean Andes in collaboration of Japan, North America, and Europe. These antennas can be reconfigured to extend over 18.5 km at maximum, allowing a high resolution equivalent to a radio telescope of 18.5 km in diameter. The resolution to be achieved by ALMA will be 10 times higher than that of Subaru and the Habble Space Telescope. With such a high resolution, it is possible to recognize a coin left on the street in Osaka from Tokyo. ALMA aims to explore the dark and invisible universe by detecting millimeter/submillimeter waves between the radio and far-infrared spectral regions. The total construction cost of ALMA is about 100 billion yen, and its full-operation will start from 2012.

A1.2: ALMA is an abbreviation of Atacama Large Millimeter/submillimeter Array. "Alma" also means "heart", "soul", and "dear" in Spanish, the official language of Chile where ALMA is constructed.

A1.3: Millimeter/submillimeter wave has the shortest wavelength in radio waves. Radio wave of 10 mm to 1 mm in wavelength (30 GHz to 300 GHz in frequency) is called "millimeter-wave", while radio wave of 1 mm to 0.1 mm in wavelength (300 GHz to 3 THz in frequency) is called "submillimeter-wave". Wavelength of AM radio is approximately 300 mm, and that of FM radio is 4 m. On the other hand, wavelength of far-infrared ray is very short, approximately 0.05 mm. From this, millimeter/submillimeter wave is supposed to be in the wavelength band close to far-infrared ray. With millimeter/submillimeter wave, we can detect very cold interstellar matters (about -250 degrees) which do not emit light or near-frared ray by using thermography method. Objects in the solar system also can be detected by their emission, not by their reflection. It was difficult to put the observation with submillimeter wave into practical use due to its technical difficulty as well as its high absorbability into atmospheric water vapor.

A1.4: To collect weak radio waves emitted by celestial bodies, a large antenna of high precision is needed. However, the technical limit for the antenna diameter is currently 50 m, because of the deformation caused by empty weight, heat, and wind. Also, to examine the structure of celestial bodies far away from the earth, a radio telescope of 1 km or larger is needed, but it is impossible to create a single antenna of such scale. For these reasons, ALMA is created by integrating multiple antennas that are relatively small but have high precision, to realize an antenna of 14 km in diameter at maximum, with collecting area equivalent to that of an antenna of 100 m in diameter. This type of radio telescope is called "array (radio interferometer)". The array system enables high-sensitivity observation by configuring antennas in a small area, and allows high-resolution observation by reconfiguring them in a large area. In this manner, when antennas are moved in accordance with the intended use, it fulfills a function like a zoom lens of a camera.

A1.5: ALMA project was formed by merging "Large Millimeter and Submillimeter Array (LMSA)" planned by NAOJ and "Millimeter Array (MMA)" by NRAO and "Large Southern Array (LSA)" by ESO. In LMSA, the main goal was to realize submillimeter observation, as well as resolution of 0.01 arcsec and high spectral resolution. These objectives have been successively assigned to ALMA project.

A1.6: The answer is No. In contrast to 8-m optical telescopes like Subaru, which have been constructed in various parts of the world and are competing with each other, ALMA is a single large observational instrument for millimeter/submillimeter waveband planned for decades to come. There are some medium-scale projects: e.g. the Submillimeter Array (SMA) consisted of eight 6-m antennas and operated by SAO (U.S.)* and ASIAA (Taiwan)* in Hawaii, and Herschel project which is a Far Infrared and Sub-millimeter Telescope (FIRST) of 3.5m in diameter developed by ESA (Europe).

Q2: What can we see with ALMA?

A2.1: ALMA unveils invisible dark universe, including newly-born galaxies as far as 13 billion light years away, the birth of another solar system, and extraterrestrial organic molecules. See Introduction to the Universe explored by ALMA for general outline.

A2.2: ALMA achieves the resolution of 0.01 arcsec at maximum (1 arcsec=1/3600 of a degree of arc). The resolution of ALMA is 10 times higher than that of Subaru telescope and the Hubble Space Telescope. And more specifically, with such an amazing resolution, we can see a structure with the dimension of the earth's orbit, if there is another early solar system in Taurus dark nebula 400 light years away. If there are galaxies, we can recognize them wherever they are. Also, we can see a structure of only 40 km in the distance between Jupiter and the earth. Giving you more familiar example, with such a high resolution, it is possible to recognize a coin left on the street in Osaka from Tokyo. As ALMA has a field of view of 20 arcsec, this means we can obtain an image of about 2000x2000 pixels per view.

A2.3: Optical telescopes, like Subaru telescope, target structures of the universe, such as stars, planets, and galaxies. On the other hand, ALMA aims at interstellar matters that are ingredients of these structures to investigate the process in which the universe has been formed. Particularly, Subaru telescope explores giant planets, while ALMA investigates how planets were born to understand the origin of the solar system and the particularity/universality of the universe.

A2.4: Nobeyama radio telescope is still one of the world's top telescopes in millimeter wavelength after more than 20 years since its completion. It achieved remarkable results in modern science history, such as discovery of a super massive black hole, a protoplanetary disc, and a possible protogalaxy. However, the development of submillimeter-wave astronomy and the realization of high resolution and sensitivity are essential for advancement of these researches. ALMA achieves far higher performances than Nobeyama radio telescope and develops the outcome of the researches at Nobeyama. Nobeyama radio telescope is continuously used for observation of celestial bodies around north celestial pole that is not observed with ALMA.

A2.5: Since the construction site of ALMA is located just on the Tropic of Capricorn, ALMA covers mainly the southern sky, but also extensive areas of the northern sky can be investigated by ALMA. ALMA shares 60% of its observation area with Subaru telescope (at El=30 degrees or larger), and collaboration of these two telescopes is possible.

Q3: Where is ALMA constructed?

A3.1: ALMA is constructed on a plateau at an altitude of 5,000 m near the Atacama desert in the northern Chile, located in the Chilean Andes near the border with Bolivia and Argentina. The ALMA site with the average annual rainfall below 100 mm has ideal conditions for observation. And total flight hour from Japan to Chile is 36 hours (including layover), as Chile is located on the other side of Japan, however the access to the site is relatively easy compared with the Himalayas, since the base camp will be built near a village at an altitude of approximately 2,500 m, and we can get to the site within one hour by car along the paved roads from the village.

A3.2: Because it turned out candidate sites in Chile have better conditions for millimeter/submillimeter observation than those in Hawaii through the past researches. Its flat and wide land is suitable for the construction of a large-scale array. Besides, the host country, Chile, is very cooperative in accepting ALMA project, and has offered the use of their land for many telescopes so far. Another reason why Chile was chosen for the site is that there are a lot of important and unique objects in the southern sky, including the center of the galaxy and Large and Small Magellanic Clouds.

A3.3: Basically, observers do not have to travel to Chile. They can send commands for observation from Japan and analyze the data in Japan.

A3.4: The crime rate in Chile is remarkably lower than those in other countries in South America. Chile is a country that boasts high living and educational standards. Chileans are generally friendly and good, and they understand the importance of astronomy.

Q4: When is the completion of ALMA?

A4.1: ALMA is now being constructed at a fast pace. Tentative operation will start as soon as a part of antennas are installed, and the full-scale operation is scheduled to start from 2012.

A4.2: Recently, 8-m optical telescopes including Subaru have started their operation one after another. However, there is no radio telescope with the same level of resolution and sensitivity out there, and it is becoming a drag on researches. For this reason, astronomers from Japan, North America, and Europe have promoted ALMA as a large-scale telescope project of first priority in each region.

A4.3: Evaluation tests for three 12-m prototype antennas developed by Japan, North America, and Europe have been conducted in New Mexico in the US. And prospects for the most of other elemental technologies are almost confirmed. We are now in the development and manufacturing phases where Japan, North America, and Europe are individually working on the equipments of their responsibility.

Q5: Who constructs ALMA?

A5.1: ALMA is realized through international collaboration among three parties: National Astronomical Observatory of Japan (NAOJ) representing Japan and Taiwan, National Radio Astronomy Observatory (NRAO) representing North America (U.S. and Canada), and European Southern Observatory (ESO) representing its 11 member states (Belgium, Denmark, Finland, France, Germany, Italy, the Netherlands, Portugal, Sweden, Switzerland and the United Kingdom) and Spain. Chile supports this project by offering land for free and giving duty exemption. Japan provides researchers and technicians not only from NAOJ but from universities to the project.

A5.2: Japan collaborates with Taiwan, in a similar manner that U.S. collaborates with Canada. At the beginning, Japan, U.S. and Europe had their own plans separately. And then Canada joined the project sharing 10% of U.S. part, but the North American alliance is still mainly led by NRAO. As for Europe, they participate in the project through multinational alliance, but they have a single transnational entity, ESO. Japan ranks at the world's top level in research and development of millimeter-wave astronomy. The achievements attained by the Japanese engineering development team and by observation research team are as brilliant as those achieved by North America and Europe. Given the facts that NRAO, the main body of North American alliance does not have facilities for millimeter observation and that ESO is the observatory mainly used for optical observation, NAOJ can play an important role in the project with the actual achievement of submillimeter interferometer at Nobeyama. In addition, the agreements on global cooperation with Asian and Oceanian countries, including China and South Korea, are now being arranged.

A5.3: Through global cooperation, each partner can obtain higher observational efficiency than in the case of individual construction, as well as higher performance by sharing their specialized field. Moreover, we could reduce the costs to a certain degree by sharing the infrastructure.

A5.4: Japan is in charge of high-precision interferometer system composed of twelve 7-m antennas and four 12-m antennas as well as three types of receivers mainly used for submillimeter. Japan also contributes to the shared infrastructure and part of operational costs.

Q6: Who uses ALMA?

A6.1: Since ALMA will start its full-scale operation in 2012 and operate for half a century, it will be used by young generations specifically by those who are currently elementary and junior high school students. 10% of observation time will be allocated for the host country, Chile, and 90% for the partners according to their contribution. Though we publicly accept research projects from researchers worldwide, special consideration is paid for the researchers of countries financing the project. We are now discussing how to allocate the observation time; each of three parties may be individually given the right to decide the time allocation, but some key projects may be launched for international coordination regarding the important projects such as galaxy formation and planetary accretion.

A6.2: ALMA project is positioned as the highest priority plan for large-scale telescope in Japan, North America, and Europe, and it attracts great attention from the researchers globally. At Nobeyama Radio Observatory which has been used for approximately 100 research subjects a year, the number of Japanese astronomers who use the facility has been most rapidly increasing among the five most frequent user countries. It is expected that the number of users will be further on the rise at the completion of ALMA. As is the case with Hubble telescope, ALMA is designed not only for astronomers but for planetary scientists, physicists and scientists whose studies are associated with astronomy. Observation opportunity may also be given to amateurs with excellent knowledge in these fields to use ALMA as in the case of Nobeyama Radio Observatory.

Q7: How much does it cost to construct ALMA?

A7.1: The estimated cost for the overall plan is approximately one hundred billion yen or one billion US dollars. Japan will bear the cost of 30 billion yen for high precision interferometer called ACA system that is comprised of 16 high precision antennas, three receiver bands, and construction of domestic facilities for Japanese researchers. This means Japanese people pay about 30 yen per person for the construction of the telescope annually for 10 years.

A7.2: ALMA will bring us not only the scientific achievements through researches of our planet, solar system, the Galaxy and the origin of life, but also dreams and romance, especially for young generations, through realization of high technology. ALMA may contribute to reversing the tendency toward moving away from science seen among children. In addition, new technologies to be developed and introduced in the ALMA project are closely related to terahertz technology, information communication, signal processing and micromachining, which may have great impact on industrial world and our life A large-scale project such as ALMA can be a driving force for developing cutting-edge technologies for which industries wouldn't dare to take steps toward practical use. One good example of this is a device developed as part of Nobeyama radio telescope; the device is now being used for various equipments such as BS converter.

A7.3: How can we share dreams and romance of ALMA without playing active role in the project? Japan can provide leadership in this global project since the Japanese research and technology in millimeter astronomy is at the world's top level. Japanese technology is highly expected for realization of technically-difficult submillimeter observation. For Japanese astronomers, ALMA is also a good opportunity to further advance their high-level research.

A7.4: We think participation is more significant than financial contribution. Japan should practically make an appropriate level of contribution to the basic science. To cultivate human resource for further development of Japanese astronomy after ALMA, Japan needs to participate positively in making project plans, engineering development plans, and research plans. Japanese leadership is expected by North America and Europe.

Q8: I want to know more about ALMA!

A8.1: At present, there is almost nothing to be seen at the ALMA site. Visitor center is planned to be built by the completion of ALMA. You can experience the virtual tour to the site on the website.

A8.2: Please come to seminars and special open days that are held irregularly. Schedule of seminars can be obtained on the website of ALMA. In addition, you can receive more information on the progress of the project, and schedule of seminars via e-mail if you sign up for the mailing list.

A8.3: You may receive answers for your questions by sending e-mail at alma-info@nro.nao.ac.jp or by using Contact us on our website.

A8.4: We are grateful for your consideration. The signature campaign we launched for the promotion of the project was a great success and served as a great engine to gain construction budget in Japan. Your favorable messages for the project provide a great moral support for us.