Airborne telescope SOFIA rediscovers water on the Moon

Scientists from the US National Aeronautics and Space Administration (NASA) are reconfirming the existence of water on the Moon, no less than 11 years after they made such an announcement. 

What the Stratospheric Observatory for Infrared Astronomy SOFIA has just achieved is to identify water molecules in areas of the lunar surface illuminated by the Sun. However, the US Mini-SAR synthetic aperture radar installed on board India's Chandrayaan-1 space probe already detected water in small quantities on the dark side of the Moon at the end of September 2009. 

The news, which has now been widely publicised, has been given much thought at NASA headquarters in Washington by the management team chaired by Jim Bridenstine. With the backing of the White House, the Agency is immersed in the Artemis moon return project, whose first manned mission is still scheduled for 2024.

NASA is seeking the support of American taxpayers to get a triumvirate of American astronauts and men to put their feet and the star-spangled flag back on the dusty, rocky surface of Selene.

As each kilogram sent into orbit involves hundreds of thousands of euros, the discovery is accompanied by demonstrations that future manned lunar missions will be cheaper than the Apollo missions of the 1970s, if the weight of carrying water tanks can be eliminated or reduced.

Jim Bridenstine, NASA's top man, has been cautious and has stressed that scientists have not yet determined whether the water molecules found can be "used as a resource". But he acknowledges that water on the Moon "is key to our Artemis exploration plans".

Professor Casey Honniball, from the Hawaii Institute of Geophysics and Planetology, has highlighted that "if areas are located where water can be extracted in abundance", the astronauts will be able to have "a supply for their own consumption and to make rocket fuel". What is not said is the cost of the equipment to extract the moon's ore and convert it into the liquid element.  

The NASA statement is made public in the middle of the campaign for the US presidential elections, forcing Republican candidate Donald Trump and Democrat Joe Biden to take a position on Artemis and space exploration.

SOFIA is a compromise between expensive space-based telescopes, such as the Hubble, and the construction of large fixed ground-based telescopes located in high, dry places, including the European Southern Observatory. Located in the Atacama Desert in Chile, it houses the so-called Extremely Large Telescope, the world's largest eye for observing the sky. 

As opposed to space or ground-based observatory models, NASA and the German Aerospace Center (DLR) conceived the Stratospheric Observatory for Infrared Astronomy. The result is the Stratospheric Observatory for Infrared Astronomy, better known as SOFIA - acronym for Stratospheric Observatory for Infrared Astronomy - which has on board a 20-tonne, 2.5-metre aperture airborne refracting telescope, the largest in the world.

The instrument is installed on a modified Boeing 747 SP commercial four-engine aircraft from the US airline United Airlines. It houses a team of technical personnel to move it and their task from any area of the Earth is to study the Universe in the infrared spectrum - which is not visible to the human eye -, preferably the different stars of our solar system and the birth and death of stars.

Flying at night to an operational ceiling between 11.5 and 13.7 kilometres, SOFIA offers two great advantages. On the one hand, it avoids the distortions caused by water vapour in the Earth's atmosphere, which allows it to make very clear observations, especially in most of the infrared range. Secondly, the fact that it is installed on a large aircraft means that it can see the sky from anywhere in the world. However, its annual cost exceeds $80 million.

The NASA Ames Research Center in California manages the programme, science operations and flight missions, which are carried out in cooperation with the German SOFIA Institute of the University of Stuttgart and the Space Research Association of Columbia Universities in the state of Maryland.

Although the Boeing 707 SP operates from NASA's Armstrong Flight Research Center at Edwards Air Force Base, also in California, at the end of September SOFIA was moved to the Lufthansa Technical Center in Hamburg. There, a comprehensive scheduled overhaul of the aircraft and its onboard equipment, including the telescope, will be carried out until mid 2021 by NASA and DLR personnel.

SOFIA is not the first scientific telescope to be installed on a large aircraft. The Kuiper Airborne Observatory (KAO), also from the United States, has been honoured to do so. In this case the aircraft was a C-141 Starlifter military transport which housed a 91.5 centimetre aperture reflector. It entered service between 1974 and was withdrawn in 1995, when it discovered the rings of Uranus and confirmed the existence of Pluto's atmosphere.