Two different studies are under way on the International Space Station – one will observe how fuel burns in space while another is researching how medicine dissolves in water. Results from both experiments could benefit humans on Earth and in space.
Astronaut Takuya Onishi is setting up the Group Combustion experiment that will explore how flames spread across a cloud of fuel droplets. Observations may help engineers design advanced rocket engines, as well as gas turbines and industrial furnaces.
Image above: This sunrise is one of 16 the space station crew sees everyday aboard the space station. Image Credit: NASA.
NASA astronaut Kate Rubins is researching how pharmaceutical materials dissolve in water for the Hard to Wet Surfaces study. The space environment can reveal processes masked by Earth’s gravity and help scientists improve how drugs work in humans on Earth and in space.
Commander Anatoly Ivanishin was back at work studying how charged particle systems react when trapped in a magnetic field. The veteran cosmonaut, who is on his second station mission, also explored new methods to detect and target landmarks improving Earth photography techniques.
The National Advisory Committee for Aeronautics sent 13 engineers and support staff to California’s Mojave Desert in September 1946 to assist in the quest for supersonic flight.
The X-1 aircraft represented the first U.S. Air Force designated “X” or experimental vehicle. It officially exceeded Mach 1 Oct. 14, 1947. Mach is measured from 650-750 mph depending on a number of factors such as atmospheric conditions and altitude. The NACA had its first supersonic flight, also on an X-1 aircraft, March 4, 1948.
The small contingent of NACA, which became NASA in 1958, staff were expected to complete the single project and wrap up operations at the desert outpost. Now 70 years later, the NASA Armstrong Flight Research Center in California continues to test the latest aviation marvels through flight.
A number of X-planes followed, designed to find answers related to speed, temperature, structure, control and human physiology, work that continued as the agency morphed from the NACA to NASA in 1958. One such aircraft was the X-15 rocket plane program that posted a then record 199 flights, including binders of research, and an official record of speed at Mach 6.7, or more than 4,500 mph, and an unofficial altitude record at the edge of space at 67 miles, or 354,200 feet.
The center’s initial focus was aeronautics, but the X-15 bridged the worlds of high speed aircraft with the research needed to reach beyond Earth’s atmosphere. The development of reaction control systems for the legendary X-15 was critical for spaceflight, as it provided a way to control a vehicle in the absence of dynamic pressure as is encountered in space.
The Lunar Landing Research Vehicle also was tested here. After the aircraft that simulated flight of the one-sixth gravity of Earth that astronauts would face on the moon. The research contributed to construction of the Lunar Landing Training Vehicles that were built and sent to NASA Johnson Space Center in Houston (then called the Manned Spaceflight Center). Apollo astronauts used the spindly aircraft to train for landing on the moon. The practice was helpful when Neil Armstrong piloted the Lunar Module manually to the lunar surface to take the first steps.
Lifting body aircraft were designed to validate the shape of a space return vehicle that could land like an aircraft instead of descending under a parachute and landing in the ocean. When the Sierra Nevada Corporation’s Dream Chaser spacecraft returns for additional approach and landing tests at Armstrong in 2017, it will continue the center’s historic role with lifting body shaped vehicles.
Image above: The X-1B reaction control system thrusters are tested in 1958 and later proven on the X-15 as a way to control a vehicle in the absence of dynamic pressure. Image Credit: NACA Photo.
Space Shuttle Enterprise’s approach and landing tests marked another contribution to space-related technology. A large steel gantry called the Mate Demate Device slowly lifted the shuttle onto the back of a specially modified NASA 747 Shuttle Carrier Aircraft. Enterprise was then launched from the back of the large aircraft to confirm shuttles could safely land unpowered.
The center retained a role with the space shuttles during the 30-year program, often hosting landings. Most early landings and first flights of new orbiters or return to flight operations took place at the center. The shuttles concluded 54 space missions with a landing at Edwards and a return trip on the NASA 747 to Kennedy Space Center in Florida.
Also of consequence of the space program, Armstrong was involved in testing the pad launch abort test capsule for NASA's Orion spacecraft, which is intended to eventually take astronauts on a journey to Mars. The capsule’s instrumentation and wiring took place at the center, as did its weight and balance, center of gravity and combined systems testing. The center also led the construction of the launch site at White Sands Missile Range in New Mexico where the capsule successfully launched May 6, 2010.
Image above: Space Shuttle Endeavour is affixed atop NASA’s 747 Shuttle Carrier Aircraft as it prepares for a landing at Los Angeles International Airport to conclude a final flight on Sept. 21, 2012. Image Credits: NASA Photo/Jim Ross.
Software for the agency’s Space Launch System rocket, which will launch Orion into deep space, was tested onboard Armstrong’s F-18 aircraft that flew nearly vertical to simulate a rocket flight path. An Armstrong F-18 was also used to test a radar system that helped land the Mars Curiosity rover on the surface of the planet in 2012.
In fact, Armstrong manages the Space Technology Mission Directorate's Flight Opportunities program, which seeks to mature space technology development through flights on commercial suborbital launch vehicles. The program funds the flights in space-like environments of new technologies of interest to NASA’s space exploration goals. Among other successes, the program has matured a 3-D printer is now on the International Space Station that can print parts and tools.
Speed isn’t only the regime of space vehicles. Armstrong researchers explored the realm of hypersonic speed with the first integrated hypersonic scramjet engine, the X-43. The air-breathing engines propelled the vehicle to speeds of Mach 7, about 4,500 mph, and nearly to Mach 10, or roughly 6,500 mph, during separate flights in 2004.
Image above: The undamaged Pad Abort-1 flight test crew module rested in the desert after a successful flight test May 6, 2010, at the White Sands Missile Range in New Mexico. Image Credits: NASA/JSC.
A defining feature of all supersonic aircraft is a loud sonic boom created when an aircraft exceeds the speed of sound. Over the years NASA researchers have worked to mitigate or soften these booms, modifying aircraft to test theories and new technologies.
Seven decades after helping to create the first sonic boom, NASA is designing a new X-plane to demonstrate quiet boom capabilities, which could lead to supersonic flight without startling people on the ground, a key hurdle to amending rules that currently prohibit overland supersonic operations. The preliminary design review for the Quiet Supersonic Transport human-piloted X-plane is currently underway.
Unmanned Aircraft Systems, or UASs, are another major area that the center has researched with experimental vehicles since the 1960s. Engineers have continued to investigate this area of aeronautics including shapes and subsystems.
Armstrong and other NASA centers remain involved in the technology development of UAS to help in the eventual integration of Unmanned Aircraft Systems into the National Airspace System.
NASA Armstrong Flight Research Center: 70 Years of Flight Research
Video above: This video showcasing 70 years of research at NASA's Armstrong Flight Research Center in Edwards, California, began airing on NASA television Sept. 26. Armstrong, the agency's lead center for atmospheric flight research operations, began its storied history in California's high desert in September 1946. Video Credits: NASA Armstrong Video.
In the early 1990s Armstrong managed the Environmental Research Aircraft and Sensor Technology program with industry partners. The idea was to develop emerging environmentally friendly aircraft, sensors and technologies needed to fly the emerging class of aircraft safely and conduct science missions. The solar-powered Helios reached an altitude of 96,863 feet altitude during the program. Prototypes of the Predator-B aircraft later led to the NASA science platform named Ikhana, which is now used for science and aeronautical missions.
Sometimes technology advancements lead to revolutions in the way challenges are approached. For example, a specially-modified F-8 aircraft flown at Armstrong validated digital fly-by-wire control technology that replaced hydraulic systems. Military and commercial aviation companies subsequently integrated the systems into its aircraft. More recently, cars, motorcycles and boats are using systems with origins based in that research.
With an eye toward making aircraft technologies transferrable to commercial uses, the NASA Aeronautics Mission Directorate is planning to make it common for future aircraft to be more fuel efficient, quieter and produce fewer emissions. An example is the all-electric X-57 Maxwell X-plane intended to be high-efficiency, while reducing noise and emissions.
Image above: A rainbow frames the Stratospheric Observatory for Infrared Astronomy 747SP during its first Southern Hemisphere deployment in Christchurch, New Zealand, in July 2013. Image Credits: NASA Photo/Carla Thomas.
The center doesn’t fly airplanes only for aeronautics research. Specially modified aircraft based at Armstrong support NASA’s Airborne Science Program, flying scientists and specialized instruments around the world to study Earth and its changing environment. This includes a DC-8 flying laboratory, a C-20A aircraft, two ER-2 high-altitude aircraft and two Global Hawks.
Armstrong also operates and maintains the Stratospheric Observatory for Infrared Astronomy, or SOFIA. The NASA a 747SP has the world’s largest airborne infrared telescope. It flies above most of the atmosphere’s water vapor, which limits Earth-bound telescope observations. The result is clearer images of the universe and the ability to use the latest science instruments to capture extraordinary astronomical data about the solar system and far beyond.
Image above: An artist’s concept of NASA’s X-57 Maxwell aircraft shows the plane’s specially designed wing and electric motors. The X-57 is intended to demonstrate that electric propulsion can make planes quieter and more efficient and environmentally friendly. Image Credits: NASA Langley / Advanced Concepts Lab, AMA Inc.
It’s hard to predict how future aviation and space vehicles and their systems will evolve. However, it is certain that NASA Armstrong will build on its 70 years of success to validate the technologies that will drive exploration for a better tomorrow.
Leslie Williams, Christian Gelzer, Matt Kamlet and Mike Agnew contributed to this report.
Its science instruments have been powered on, and NASA’s OSIRIS-REx spacecraft continues on its journey to an asteroid. The spacecraft has passed its initial instrument check with flying colors as it speeds toward a 2018 rendezvous with the asteroid Bennu.
Last week NASA’s spacecraft designed to collect a sample of an asteroid ran the first check of its onboard instruments. Starting on Sept. 19, engineers controlling the Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer (OSIRIS-REx) spacecraft powered on and operated the mission’s five science instruments and one of its navigational instruments. The data received from the checkout indicate that the spacecraft and its instruments are all healthy.
Image above: The first-light images of star fields from OCAMS’s MapCam and PolyCam illustrate each camera’s specialized function. MapCam’s medium resolution and wider field of view will help map the entire surface of Bennu in color. While PolyCam’s field of view is much smaller, it can see much fainter objects at a higher resolution. PolyCam’s ability to act as a telescopic will help the OSIRIS-REx team spot Bennu while it is still appears as a point of light against a field of stars. Image Credits: NASA/Goddard/University of Arizona.
Instrument testing commenced with the OSIRIS-REx Camera Suite (OCAMS), provided by the University of Arizona. On Monday, OCAMS executed its power-on and test sequence with no issues. The cameras recorded a star field in Taurus north of the constellation Orion along with Orion’s bright red star Betelgeuse. The three OCAMS cameras performed flawlessly during the test.
On Monday and Wednesday, the OSIRIS-REx Laser Altimeter (OLA), contributed by the Canadian Space Agency, conducted its test sequences, which included a firing of its laser. All telemetry received from the OLA instrument was as expected.
On Tuesday, both the OSIRIS-REx Visible and Infrared Spectrometer (OVIRS), provided by NASA’s Goddard Space Flight Center, and the OSIRIS-REx Thermal Emissions Spectrometer (OTES), provided by Arizona State University, were separately powered on for tests. Data from both during the checkout showed that the instruments were healthy. The science measurements acquired from OTES exceeded the instrument’s performance requirements.
Image above: On Sept. 19, the OCAMS MapCam camera recorded a star field in Taurus, north of the constellation Orion as part of the OSIRIS-REx spacecraft’s post-launch instrument check. MapCam's first color image is a composite of three of its four color filters, roughly corresponding to blue, green, and red wavelengths. The three images are processed to remove noise, co-registered, and enhanced to emphasize dimmer stars. Image Credits: NASA/Goddard/University of Arizona.
On Wednesday, the student experiment from MIT, the Regolith X-ray Imaging Spectrometer (REXIS), executed its functional test with no problems. And on Thursday, the Touch and Go Camera System (TAGCAMS) navigational camera was powered on and tested, and it operated as expected. As part of its checkout, TAGCAMS took an image of the spacecraft’s Sample Return Capsule.
The downlink of the test data continued through Sunday via the spacecraft’s low gain antenna (LGA), which transmitted at 40 kbps to NASA’s Deep Space Network.
Goddard Space Flight Center provides overall mission management, systems engineering and the safety and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona, Tucson, is the principal investigator. Lockheed Martin Space Systems in Denver built the spacecraft and is providing spacecraft flight operations. OSIRIS-REx is the third mission in NASA’s New Frontiers Program. NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the agency’s New Frontiers Program for its Science Mission Directorate in Washington.
Astronomers using NASA's Hubble Space Telescope have imaged what may be water vapor plumes erupting off the surface of Jupiter's moon Europa. This finding bolsters other Hubble observations suggesting the icy moon erupts with high altitude water vapor plumes.
The observation increases the possibility that missions to Europa may be able to sample Europa’s ocean without having to drill through miles of ice.
Image above: This composite image shows suspected plumes of water vapor erupting at the 7 o’clock position off the limb of Jupiter’s moon Europa. The plumes, photographed by NASA’s Hubble’s Space Telescope Imaging Spectrograph, were seen in silhouette as the moon passed in front of Jupiter. Hubble’s ultraviolet sensitivity allowed for the features -- rising over 100 miles (160 kilometers) above Europa’s icy surface -- to be discerned. The water is believed to come from a subsurface ocean on Europa. The Hubble data were taken on January 26, 2014. The image of Europa, superimposed on the Hubble data, is assembled from data from the Galileo and Voyager missions. Image Credits: NASA/ESA/W. Sparks (STScI)/USGS Astrogeology Science Center.
“Europa’s ocean is considered to be one of the most promising places that could potentially harbor life in the solar system,” said Geoff Yoder, acting associate administrator for NASA’s Science Mission Directorate in Washington. “These plumes, if they do indeed exist, may provide another way to sample Europa’s subsurface.”
The plumes are estimated to rise about 125 miles (200 kilometers) before, presumably, raining material back down onto Europa's surface. Europa has a huge global ocean containing twice as much water as Earth’s oceans, but it is protected by a layer of extremely cold and hard ice of unknown thickness. The plumes provide a tantalizing opportunity to gather samples originating from under the surface without having to land or drill through the ice.
The team, led by William Sparks of the Space Telescope Science Institute (STScI) in Baltimore observed these finger-like projections while viewing Europa's limb as the moon passed in front of Jupiter.
The original goal of the team's observing proposal was to determine whether Europa has a thin, extended atmosphere, or exosphere. Using the same observing method that detects atmospheres around planets orbiting other stars, the team realized if there was water vapor venting from Europa’s surface, this observation would be an excellent way to see it.
"The atmosphere of an extrasolar planet blocks some of the starlight that is behind it," Sparks explained. "If there is a thin atmosphere around Europa, it has the potential to block some of the light of Jupiter, and we could see it as a silhouette. And so we were looking for absorption features around the limb of Europa as it transited the smooth face of Jupiter."
In 10 separate occurrences spanning 15 months, the team observed Europa passing in front of Jupiter. They saw what could be plumes erupting on three of these occasions.
Hubble Directly Images Possible Plumes on Europa
Video above: NASA's Hubble Space Telescope took direct ultraviolet images of the icy moon Europa transiting across the disk of Jupiter. Out of 10 observations, Hubble saw what may be water vapor plumes on three of the images. This adds another piece of supporting evidence to the existence of water vapor plumes on Europa; Hubble also detected spectroscopic signatures of water vapor in 2012. Video Credits: Goddard/Katrina Jackson.
This work provides supporting evidence for water plumes on Europa. In 2012, a team led by Lorenz Roth of the Southwest Research Institute in San Antonio, detected evidence of water vapor erupting from the frigid south polar region of Europa and reaching more than 100 miles (160 kilometers) into space. Although both teams used Hubble's Space Telescope Imaging Spectrograph instrument, each used a totally independent method to arrive at the same conclusion.
"When we calculate in a completely different way the amount of material that would be needed to create these absorption features, it's pretty similar to what Roth and his team found," Sparks said. "The estimates for the mass are similar, the estimates for the height of the plumes are similar. The latitude of two of the plume candidates we see corresponds to their earlier work."
But as of yet, the two teams have not simultaneously detected the plumes using their independent techniques. Observations thus far have suggested the plumes could be highly variable, meaning that they may sporadically erupt for some time and then die down. For example, observations by Roth’s team within a week of one of the detections by Sparks’ team failed to detect any plumes.
If confirmed, Europa would be the second moon in the solar system known to have water vapor plumes. In 2005, NASA's Cassini orbiter detected jets of water vapor and dust spewing off the surface of Saturn's moon Enceladus.
Scientists may use the infrared vision of NASA’s James Webb Space Telescope, which is scheduled to launch in 2018, to confirm venting or plume activity on Europa. NASA also is formulating a mission to Europa with a payload that could confirm the presence of plumes and study them from close range during multiple flybys.
“Hubble’s unique capabilities enabled it to capture these plumes, once again demonstrating Hubble’s ability to make observations it was never designed to make,” said Paul Hertz, director of the Astrophysics Division at NASA Headquarters in Washington. “This observation opens up a world of possibilities, and we look forward to future missions -- such as the James Webb Space Telescope -- to follow up on this exciting discovery.”
The work by Sparks and his colleagues will be published in the Sept. 29 issue of the Astrophysical Journal.
The Hubble Space Telescope is a project of international cooperation between NASA and ESA (the European Space Agency.) NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. STScI, which is operated for NASA by the Association of Universities for Research in Astronomy in Washington, conducts Hubble science operations.
For images and more information about Europa and Hubble, visit:
It’s small, it’s hot, and it’s shrinking. New NASA-funded research suggests that Mercury is contracting even today, joining Earth as a tectonically active planet.
Images obtained by NASA’s MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft reveal previously undetected small fault scarps— cliff-like landforms that resemble stair steps. These scarps are small enough that scientists believe they must be geologically young, which means Mercury is still contracting and that Earth is not the only tectonically active planet in our solar system, as previously thought.
The findings are reported in a paper in the October issue of Nature Geoscience.
“The young age of the small scarps means that Mercury joins Earth as a tectonically active planet, with new faults likely forming today as Mercury’s interior continues to cool and the planet contracts,” said lead author Tom Watters, Smithsonian senior scientist at the National Air and Space Museum in Washington, D.C.
Image above: It’s small, it’s hot, and it’s shrinking. Surprising new NASA-funded research suggests that Mercury is contracting even today, joining Earth as a tectonically active planet. Image Credits: NASA/JHUAPL/Carnegie Institution of Washington/USGS/Arizona State University.
Large fault scarps on Mercury were first discovered in the flybys of Mariner 10 in the mid-1970s and confirmed by MESSENGER, which found the planet closest to the sun was shrinking. The large scarps were formed as Mercury’s interior cooled, causing the planet to contract and the crust to break and thrust upward along faults making cliffs up to hundreds of miles long and some more than a mile (over one-and-a-half kilometers) high.
In the last 18 months of the MESSENGER mission, the spacecraft’s altitude was lowered, which allowed the surface of Mercury to be seen at much higher resolution. These low-altitude images revealed small fault scarps that are orders of magnitude smaller than the larger scarps. The small scarps had to be very young, investigators say, to survive the steady bombardment of meteoroids and comets. They are comparable in scale to small, young lunar scarps that are evidence Earth’s moon is also shrinking.
Image above: Small graben, or narrow linear troughs, have been found associated with small fault scarps (lower white arrows) on Mercury, and on Earth’s moon. The small troughs, only tens of meters wide (inset box and upper white arrows), likely resulted from the bending of the crust as it was uplifted, and must be very young to survive continuous meteoroid bombardment. Image Credits: NASA/JHUAPL/Carnegie Institution of Washington/Smithsonian Institution.
This active faulting is consistent with the recent finding that Mercury’s global magnetic field has existed for billions of years and with the slow cooling of Mercury’s still hot outer core. It’s likely that the smallest of the terrestrial planets also experiences Mercury-quakes—something that may one day be confirmed by seismometers.
“This is why we explore,” said NASA Planetary Science Director Jim Green at Headquarters in Washington, D.C. “For years, scientists believed that Mercury’s tectonic activity was in the distant past. It’s exciting to consider that this small planet – not much larger than Earth’s moon – is active even today.”
Managed by the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, MESSENGER launched Aug. 3, 2004 and began orbiting Mercury March 18, 2011. The mission ended with a planned impact on the surface of Mercury on April 30, 2015.
NASA & ESA - Cassini-Huygens Mission to Saturn & Titan patch.
Sept. 26, 2016
NASA's & ESA's Cassini spacecraft looks toward the brilliant disk of Saturn, surrounded by the icy lanes of its rings. Faint wisps of cloud are visible in the atmosphere. At bottom, ring shadows trace delicate, curving lines across the planet.
Prometheus (53 miles or 86 kilometers across) is just a few pixels wide in this view, barely visible as a dark speck in front of the planet, below the rings and to the left of center.
Between April and September 2017, Cassini will plunge repeatedly through the gap that separates the planet from the rings.
This view looks toward the sunlit side of the rings from about a degree above the ring plane. The image was taken in green light with the Cassini spacecraft wide-angle camera on July 21, 2016.
The view was obtained at a distance of approximately 529,000 miles (852,000 kilometers) from Saturn and at a sun-Saturn-spacecraft, or phase, angle of 37 degrees. Image scale is 30 miles (50 kilometers) per pixel.
The Cassini mission is a cooperative project of NASA, ESA (the European Space Agency) and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colorado.
Astrometry, the science of charting the sky, is one of the oldest branches of astronomy. Over the centuries, scientific and technological advancements have gradually improved the quality and information content of stellar catalogues.
Astrometry through the ages
This infographic illustrates qualitatively the progress in size and precision of measuring stellar positions and distances through the ages, featuring a series of landmarks in the history of astrometry, from ancient scientists to the space missions of our time.
The precision of stellar position measurements in the most ancient catalogues (top row) is represented with a blur around the stars, while the precision of the stellar distance measurements in the modern catalogues (bottom row) is conveyed with a linear ruler pointing towards the lower left corner of each frame – representing the location of Earth – and passing through each star. In the case of Gaia, ESA's state-of-the-art space mission currently charting over one billion stars (bottom right frame), the rulers are much smaller than the star symbols and thus not visible, to indicate the unparalleled precision of the mission.
The first documented records of systematic astronomical observations date back to the Assyro-Babylonians around 1000 BCE, and the oldest known stellar catalogue was compiled in the second century BCE by the Greek astronomer Hipparchus of Nicaea.
Hipparchus' catalogue (first frame, top row) lists the positions of 850 stars with a precision of less than one degree (one degree is twice the angular size of the full Moon) determined using only naked-eye observations and the few instruments available at the time: gnomons, astrolabes, and armillary spheres.
In the fifteenth century, Ulugh Beg of the Timurid dynasty constructed an enormous sextant with a radius of 36 metres in Samarkand, located in present-day Uzbekistan. Ruling over Central Asia, Ulugh Beg was also an astronomer and mathematician, and he compiled a catalogue of 994 stellar positions with a precision slightly better than that of Hipparchus (second frame, top row).
In the late sixteenth century, Danish astronomer Tycho Brahe measured the positions of about 1000 stars with a precision of about one arcminute, using large quadrants and sextants at the Uraniborg observatory on the island of Hven (in present-day Sweden). His catalogue (third frame, top row) was completed in 1598 and published in 1627.
In 1725, English astronomer John Flamsteed published the first stellar catalogue (fourth frame, top row) compiled with the aid of a telescope, listing the positions of almost 3000 stars with a precision of 10-20 arcseconds. French astronomer Jérôme Lalande published an even greater catalogue (fifth frame, top row) with the position of 50 000 stars and a precision of around three arcseconds, in 1801.
Not so long after that, in 1838, German astronomer Friedrich Bessel was the first to publish a reliable measurement of parallax, the yearly displacement of a star's position due to Earth's revolution around the Sun. Bessel's measurement for the star 61 Cygni amounted to 0.314 arcseconds, placing the star at a distance of about 10 light-years.
Bessel used a special type of telescope, the heliometer, originally developed to observe the Sun and consisting of a lens cut in half. Two more astronomers, the German Wilhelm Struve and the British Thomas Henderson, also successfully measured parallaxes in the late 1830s. While not strictly a catalogue, these three were the first measurements of stellar distances in the history of astronomy (first frame, bottom row).
From the 1850s onwards, the application of photography to astrometry transformed the practice of charting the sky. Compiling many photographic observations, Dutch astronomer Jacobus Kapteyn started measuring the parallax of a few hundreds of stars in the early 1900s (second frame, bottom row).
In 1924, American astronomer Frank Schlesinger made huge progress in the use of photographic plates to measure parallaxes and published a catalogue with the parallaxes of almost 2000 stars, probing stellar distances out to a few dozen light-years from Earth. His catalogue was extended to about 6000 stars by Louise Freeland Jenkins in 1952, and to over 8000 stars by William van Altena in 1995 (third frame, bottom row), but the flickering effect caused by Earth's atmosphere and the distortion of the telescopes caused by Earth's gravity prevented astronomers from reaching a precision better than about 0.01 arcseconds.
The onset of the space age brought astrometry firmly back to centre stage in astronomy. ESA's Hipparcos mission, operating from 1989 to 1993, was the first space telescope devoted to measuring stellar positions.
The Hipparcos catalogue, released in 1997, contains the position, parallax and proper motion of 117 955 stars with a precision of 0.001 arcseconds, allowing astronomers to probe stellar distances out to over 300 light-years (fourth frame, bottom row).
The Gaia mission is building on the legacy of Hipparcos to chart one billion stars – about one per cent of the content of our Galaxy. Eventually, it will measure positions and parallaxes with astrometric precisions down to 0.00001 arcseconds for the brightest stars observed (fifth frame, bottom row).
ESA's Gaia mission recently released its first batch of data, based on observations obtained with the satellite during its first 14 months of science operations. This ambitious mission is the culmination of over two thousand years of astrometry – the science of charting the sky. A new sonification demonstrates in a novel way the remarkable progress that has been made in the lead up to the first data release from Gaia. Related article:
