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By NASA
On Jan. 19, 1965, Gemini 2 successfully completed the second of two uncrewed test flights of the spacecraft and its Titan II booster, clearing the way for the first crewed mission. The 18-minute suborbital mission achieved the primary goals of flight qualifying the Gemini spacecraft, especially its heat shield during a stressful reentry. Recovery forces retrieved the capsule following its splashdown, allowing engineers to evaluate how its systems fared during the flight. The success of Gemini 2 enabled the first crewed mission to fly two months later, beginning a series of 10 flights over the following 20 months. The astronauts who flew these missions demonstrated the rendezvous and docking techniques necessary to implement the Lunar Orbit Rendezvous method NASA chose for the Moon landing mission. They also proved that astronauts could work outside their spacecraft during spacewalks and that spacecraft and astronauts could function for at least eight days, the minimum time for a roundtrip lunar mission. The Gemini program proved critical to fulfill President John F. Kennedy’s goal of landing a man on the Moon and returning him safely to Earth before the end of the 1960s.
Cutaway diagram of the Gemini spacecraft. Workers at Launch Pad 19 lift Gemini 2 to mate it with its Titan II rocket. At Pad 19, engineers verify the flight simulators inside Gemini 2. Following the success of Gemini 1 in April 1964, NASA had hoped to fly the second mission before the end of the year and the first crewed mission by January 1965. The two stages of the Titan II rocket arrived at Cape Kennedy from the Martin Marietta factory in Baltimore on July 11, and workers erected it on Launch Pad 19 five days later. A lightning strike at the pad on Aug. 17 invalidated all previous testing and required replacement of some pad equipment. A series of three hurricanes in August and September forced workers to partially or totally unstack the vehicle before stacking it for the final time on Sept. 14. The Gemini 2 spacecraft arrived at Cape Kennedy from its builder, the McDonnell Company in St. Louis, on Sept. 21, and workers hoisted it to the top of the Titan II on Oct. 18. Technical issues delayed the spacecraft’s physical mating to the rocket until Nov. 5. These accumulated delays pushed the launch date back to Dec. 9.
The launch abort on Dec. 9, 1964. Liftoff of Gemini 2 from Launch Pad 19 on Jan. 19, 1965. Engineers in the blockhouse monitor the progress of the Titan II during the ascent. Fueling of the rocket began late on Dec. 8, and following three brief holds in the countdown, the Titan’s two first stage engines ignited at 11:41 a.m. EST on Dec. 9. and promptly shut down one second later. Engineers later determined that a cracked valve resulted in loss of hydraulic pressure, causing the malfunction detection system to switch to its backup mode, forcing a shutdown of the engines. Repairs meant a delay into the new year. On Jan. 19, 1965, following a mostly smooth countdown, Gemini 2 lifted off from Pad 19 at 9:04 a.m. EST.
The Mission Control Center (MCC) at NASA’s Kennedy Space Center in Florida. In the MCC, astronauts Eugene Cernan, left, Walter Schirra, Gordon Cooper, Donald “Deke” Slayton, and Virgil “Gus” Grissom monitor the Gemini 2 flight. In the Gemini Mission Control Center at NASA’s Kennedy Space Center in Florida, Flight Director Christopher C. Kraft led a team of flight controllers that monitored all aspects of the flight. At the Manned Spacecraft Center (MSC), now NASA’s Johnson Space Center in Houston, a team of controllers led by Flight Director John Hodge passively monitored the flight from the newly built Mission Control Center. They would act as observers for this flight and Gemini 3, the first crewed mission, before taking over full control with Gemini IV, and control all subsequent American human spaceflights. The Titan rocket’s two stages placed Gemini 2 into a suborbital trajectory, reaching a maximum altitude of 98.9 miles, with the vehicle attaining a maximum velocity of 16,709 miles per hour. Within a minute after separating from the Titan’s second stage, Gemini 2 executed a maneuver to orient its heat shield in the direction of flight to prepare for reentry. Flight simulators installed where the astronauts normally would sit controlled the maneuvers. About seven minutes after liftoff, Gemini 2 jettisoned its equipment section, followed by firing of the retrorockets, and then separation of the retrorocket section, exposing the spacecraft’s heat shield.
View from a camera mounted on a cockpit window during Gemini 2’s reentry. View from the cockpit window during Gemini 2’s descent on its parachute. Gemini 2 then began its reentry, the heat shield protecting the spacecraft from the 2,000-degree heat generated by friction with the Earth’s upper atmosphere. A pilot parachute pulled away the rendezvous and recovery section. At 10,000 feet, the main parachute deployed, and Gemini 2 descended to a splashdown 2,127 miles from its launch pad, after a flight of 18 minutes 16 seconds. The splashdown took place in the Atlantic Ocean about 800 miles east of San Juan, Puerto Rico, and 25 miles from the prime recovery ship, the U.S.S. Lake Champlain (CVS-39).
A U.S. Navy helicopter hovers over the Gemini 2 capsule following its splashdown as a diver jumps into the water. Sailors hoist Gemini 2 aboard the U.S.S. Lake Champlain. U.S. Navy helicopters delivered divers to the splashdown area, who installed a flotation collar around the spacecraft. The Lake Champlain pulled alongside, and sailors hoisted the capsule onto the carrier, securing it on deck one hour forty minutes after liftoff. The spacecraft appeared to be in good condition and arrived back at Cape Kennedy on Jan. 22 for a thorough inspection. As an added bonus, sailors recovered the rendezvous and recovery section. Astronaut Virgil “Gus” Grissom, whom along with John Young NASA had selected to fly the first crewed Gemini mission, said after the splashdown, “We now see the road clear to our flight, and we’re looking forward to it.” Flight Director Kraft called it “very successful.” Gemini Program Manager Charles Matthews predicted the first crewed mission could occur within three months. Gemini 3 actually launched on March 23.
Enjoy this NASA video of the Gemini 2 mission.
Postscript
The Gemini-B capsule and a Manned Orbiting Laboratory (MOL) mockup atop a Titan-IIIC rocket in 1966. The flown Gemini-B capsule on display at the Cape Canaveral Space Force Museum in Florida. Former MOL and NASA astronaut Robert Crippen stands beside the only flown Gemini-B capsule – note the hatch in the heat shield at top. Gemini 2 not only cleared the way for the first crewed Gemini mission and the rest of the program, it also took on a second life as a test vehicle for the U.S. Air Force’s Manned Orbiting Laboratory (MOL). The Air Force modified the spacecraft, including cutting a hatch through its heat shield, renamed it Gemini-B, and launched it on Nov. 3, 1966, atop a Titan IIIC rocket. The test flight successfully demonstrated the hatch in the heat shield design during the capsule’s reentry after a 33-minute suborbital flight. Recovery forces retrieved the Gemini-B capsule in the South Atlantic Ocean and returned it to the Air Force for postflight inspection. This marked the only repeat flight of an American spacecraft intended for human spaceflight until the advent of the space shuttle. Visitors can view Gemini 2/Gemini-B on display at the Cape Canaveral Space Force Museum.
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By NASA
NASA’s Jet Propulsion Laboratory used radar data taken by ESA’s Sentinel-1A satellite before and after the 2015 eruption of the Calbuco volcano in Chile to create this inter-ferogram showing land deformation. The color bands west of the volcano indicate land sinking. NISAR will produce similar images.ESA/NASA/JPL-Caltech A SAR image — like ones NISAR will produce — shows land cover on Mount Okmok on Alaska’s Umnak Island . Created with data taken in August 2011 by NASA’s UAVSAR instrument, it is an example of polarimetry, which measures return waves’ orientation relative to that of transmitted signals.NASA/JPL-Caltech Data from NASA’s Magellan spacecraft, which launched in 1989, was used to create this image of Crater Isabella, a 108-mile-wide (175-kilometer-wide) impact crater on Venus’ surface. NISAR will use the same basic SAR principles to measure properties and characteristics of Earth’s solid surfaces.NASA/JPL-Caltech Set to launch within a few months, NISAR will use a technique called synthetic aperture radar to produce incredibly detailed maps of surface change on our planet.
When NASA and the Indian Space Research Organization’s (ISRO) new Earth satellite NISAR (NASA-ISRO Synthetic Aperture Radar) launches in coming months, it will capture images of Earth’s surface so detailed they will show how much small plots of land and ice are moving, down to fractions of an inch. Imaging nearly all of Earth’s solid surfaces twice every 12 days, it will see the flex of Earth’s crust before and after natural disasters such as earthquakes; it will monitor the motion of glaciers and ice sheets; and it will track ecosystem changes, including forest growth and deforestation.
The mission’s extraordinary capabilities come from the technique noted in its name: synthetic aperture radar, or SAR. Pioneered by NASA for use in space, SAR combines multiple measurements, taken as a radar flies overhead, to sharpen the scene below. It works like conventional radar, which uses microwaves to detect distant surfaces and objects, but steps up the data processing to reveal properties and characteristics at high resolution.
To get such detail without SAR, radar satellites would need antennas too enormous to launch, much less operate. At 39 feet (12 meters) wide when deployed, NISAR’s radar antenna reflector is as wide as a city bus is long. Yet it would have to be 12 miles (19 kilometers) in diameter for the mission’s L-band instrument, using traditional radar techniques, to image pixels of Earth down to 30 feet (10 meters) across.
Synthetic aperture radar “allows us to refine things very accurately,” said Charles Elachi, who led NASA spaceborne SAR missions before serving as director of NASA’s Jet Propulsion Laboratory in Southern California from 2001 to 2016. “The NISAR mission will open a whole new realm to learn about our planet as a dynamic system.”
Data from NASA’s Magellan spacecraft, which launched in 1989, was used to create this image of Crater Isabella, a 108-mile-wide (175-kilometer-wide) impact crater on Venus’ surface. NISAR will use the same basic SAR principles to measure properties and characteristics of Earth’s solid surfaces.NASA/JPL-Caltech How SAR Works
Elachi arrived at JPL in 1971 after graduating from Caltech, joining a group of engineers developing a radar to study Venus’ surface. Then, as now, radar’s allure was simple: It could collect measurements day and night and see through clouds. The team’s work led to the Magellan mission to Venus in 1989 and several NASA space shuttle radar missions.
An orbiting radar operates on the same principles as one tracking planes at an airport. The spaceborne antenna emits microwave pulses toward Earth. When the pulses hit something — a volcanic cone, for example — they scatter. The antenna receives those signals that echo back to the instrument, which measures their strength, change in frequency, how long they took to return, and if they bounced off of multiple surfaces, such as buildings.
This information can help detect the presence of an object or surface, its distance away, and its speed, but the resolution is too low to generate a clear picture. First conceived at Goodyear Aircraft Corp. in 1952, SAR addresses that issue.
“It’s a technique to create high-resolution images from a low-resolution system,” said Paul Rosen, NISAR’s project scientist at JPL.
As the radar travels, its antenna continuously transmits microwaves and receives echoes from the surface. Because the instrument is moving relative to Earth, there are slight changes in frequency in the return signals. Called the Doppler shift, it’s the same effect that causes a siren’s pitch to rise as a fire engine approaches then fall as it departs.
Computer processing of those signals is like a camera lens redirecting and focusing light to produce a sharp photograph. With SAR, the spacecraft’s path forms the “lens,” and the processing adjusts for the Doppler shifts, allowing the echoes to be aggregated into a single, focused image.
Using SAR
One type of SAR-based visualization is an interferogram, a composite of two images taken at separate times that reveals the differences by measuring the change in the delay of echoes. Though they may look like modern art to the untrained eye, the multicolor concentric bands of interferograms show how far land surfaces have moved: The closer the bands, the greater the motion. Seismologists use these visualizations to measure land deformation from earthquakes.
Another type of SAR analysis, called polarimetry, measures the vertical or horizontal orientation of return waves relative to that of transmitted signals. Waves bouncing off linear structures like buildings tend to return in the same orientation, while those bouncing off irregular features, like tree canopies, return in another orientation. By mapping the differences and the strength of the return signals, researchers can identify an area’s land cover, which is useful for studying deforestation and flooding.
Such analyses are examples of ways NISAR will help researchers better understand processes that affect billions of lives.
“This mission packs in a wide range of science toward a common goal of studying our changing planet and the impacts of natural hazards,” said Deepak Putrevu, co-lead of the ISRO science team at the Space Applications Centre in Ahmedabad, India.
Learn more about NISAR at:
https://nisar.jpl.nasa.gov
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Andrew Wang / Jane J. Lee
Jet Propulsion Laboratory, Pasadena, Calif.
626-379-6874 / 818-354-0307
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Last Updated Jan 21, 2025 Related Terms
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NASA, ESA, and M. Wong (University of California – Berkeley); Processing: Gladys Kober (NASA/Catholic University of America) This NASA Hubble Space Telescope image shows the planet Jupiter in a color composite of ultraviolet wavelengths. Released on Nov. 3, 2023, in honor of Jupiter reaching opposition, which occurs when the planet and the Sun are in opposite sides of the sky, this view of the gas giant planet includes the iconic, massive storm called the “Great Red Spot.” Though the storm appears red to the human eye, in this ultraviolet image it appears darker because high altitude haze particles absorb light at these wavelengths. The reddish, wavy polar hazes are absorbing slightly less of this light due to differences in either particle size, composition, or altitude.
Learn more about Hubble and how this type of data can help us learn more about our universe.
Image credit: NASA, ESA, and M. Wong (University of California – Berkeley); Processing: Gladys Kober (NASA/Catholic University of America)
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By NASA
Hubble Space Telescope Hubble Home Overview About Hubble The History of Hubble Hubble Timeline Why Have a Telescope in Space? Hubble by the Numbers At the Museum FAQs Impact & Benefits Hubble’s Impact & Benefits Science Impacts Cultural Impact Technology Benefits Impact on Human Spaceflight Astro Community Impacts Science Hubble Science Science Themes Science Highlights Science Behind Discoveries Hubble’s Partners in Science Universe Uncovered Explore the Night Sky Observatory Hubble Observatory Hubble Design Mission Operations Missions to Hubble Hubble vs Webb Team Hubble Team Career Aspirations Hubble Astronauts News Hubble News Hubble News Archive Social Media Media Resources Multimedia Multimedia Images Videos Sonifications Podcasts e-Books Online Activities Lithographs Fact Sheets Glossary Posters Hubble on the NASA App More 35th Anniversary 6 Min Read NASA’s Hubble Traces Hidden History of Andromeda Galaxy
This photomosaic of the Andromeda galaxy is the largest ever assembled from Hubble observations. Credits:
NASA, ESA, Benjamin F. Williams (UWashington), Zhuo Chen (UWashington), L. Clifton Johnson (Northwestern); Image Processing: Joseph DePasquale (STScI) In the years following the launch of NASA’s Hubble Space Telescope, astronomers have tallied over 1 trillion galaxies in the universe. But only one galaxy stands out as the most important nearby stellar island to our Milky Way — the magnificent Andromeda galaxy (Messier 31). It can be seen with the naked eye on a very clear autumn night as a faint cigar-shaped object roughly the apparent angular diameter of our Moon.
A century ago, Edwin Hubble first established that this so-called “spiral nebula” was actually very far outside our own Milky Way galaxy — at a distance of approximately 2.5 million light-years or roughly 25 Milky Way diameters. Prior to that, astronomers had long thought that the Milky way encompassed the entire universe. Overnight, Hubble’s discovery turned cosmology upside down by unveiling an infinitely grander universe.
Now, a century later, the space telescope named for Hubble has accomplished the most comprehensive survey of this enticing empire of stars. The Hubble telescope is yielding new clues to the evolutionary history of Andromeda, and it looks markedly different from the Milky Way’s history.
This is largest photomosaic ever assembled from Hubble Space Telescope observations. It is a panoramic view of the neighboring Andromeda galaxy, located 2.5 million light-years away. It took over 10 years to make this vast and colorful portrait of the galaxy, requiring over 600 Hubble overlapping snapshots that were challenging to stitch together. The galaxy is so close to us, that in angular size it is six times the apparent diameter of the full Moon, and can be seen with the unaided eye. For Hubble’s pinpoint view, that’s a lot of celestial real estate to cover. This stunning, colorful mosaic captures the glow of 200 million stars. That’s still a fraction of Andromeda’s population. And the stars are spread across about 2.5 billion pixels. The detailed look at the resolved stars will help astronomers piece together the galaxy’s past history that includes mergers with smaller satellite galaxies. NASA, ESA, Benjamin F. Williams (UWashington), Zhuo Chen (UWashington), L. Clifton Johnson (Northwestern); Image Processing: Joseph DePasquale (STScI)
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Without Andromeda as a proxy for spiral galaxies in the universe at large, astronomers would know much less about the structure and evolution of our own Milky Way. That’s because we are embedded inside the Milky Way. This is like trying to understand the layout of New York City by standing in the middle of Central Park.
“With Hubble we can get into enormous detail about what’s happening on a holistic scale across the entire disk of the galaxy. You can’t do that with any other large galaxy,” said principal investigator Ben Williams of the University of Washington. Hubble’s sharp imaging capabilities can resolve more than 200 million stars in the Andromeda galaxy, detecting only stars brighter than our Sun. They look like grains of sand across the beach. But that’s just the tip of the iceberg. Andromeda’s total population is estimated to be 1 trillion stars, with many less massive stars falling below Hubble’s sensitivity limit.
Photographing Andromeda was a herculean task because the galaxy is a much bigger target on the sky than the galaxies Hubble routinely observes, which are often billions of light-years away. The full mosaic was carried out under two Hubble programs. In total, it required over 1,000 Hubble orbits, spanning more than a decade.
This panorama started with the Panchromatic Hubble Andromeda Treasury (PHAT) program about a decade ago. Images were obtained at near-ultraviolet, visible, and near-infrared wavelengths using the Advanced Camera for Surveys and the Wide Field Camera 3 aboard Hubble to photograph the northern half of Andromeda.
This is the largest photomosaic ever made by the Hubble Space Telescope. The target is the vast Andromeda galaxy that is only 2.5 million light-years from Earth, making it the nearest galaxy to our own Milky Way. Andromeda is seen almost edge-on, tilted by 77 degrees relative to Earth’s view. The galaxy is so large that the mosaic is assembled from approximately 600 separate overlapping fields of view taken over 10 years of Hubble observing — a challenge to stitch together over such a large area. The mosaic image is made up of at least 2.5 billion pixels. Hubble resolves an estimated 200 million stars that are hotter than our Sun, but still a fraction of the galaxy’s total estimated stellar population. Interesting regions include: (a) Clusters of bright blue stars embedded within the galaxy, background galaxies seen much farther away, and photo-bombing by a couple bright foreground stars that are actually inside our Milky Way; (b) NGC 206 the most conspicuous star cloud in Andromeda; (c) A young cluster of blue newborn stars; (d) The satellite galaxy M32, that may be the residual core of a galaxy that once collided with Andromeda; (e) Dark dust lanes across myriad stars.
NASA, ESA, Benjamin F. Williams (UWashington), Zhuo Chen (UWashington), L. Clifton Johnson (Northwestern); Image Processing: Joseph DePasquale (STScI)
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This program was followed up by the Panchromatic Hubble Andromeda Southern Treasury (PHAST), recently published in The Astrophysical Journal and led by Zhuo Chen at the University of Washington, which added images of approximately 100 million stars in the southern half of Andromeda. This region is structurally unique and more sensitive to the galaxy’s merger history than the northern disk mapped by the PHAT survey.
The combined programs collectively cover the entire disk of Andromeda, which is seen almost edge-on — tilted by 77 degrees relative to Earth’s view. The galaxy is so large that the mosaic is assembled from approximately 600 separate fields of view. The mosaic image is made up of at least 2.5 billion pixels.
The complementary Hubble survey programs provide information about the age, heavy-element abundance, and stellar masses inside Andromeda. This will allow astronomers to distinguish between competing scenarios where Andromeda merged with one or more galaxies. Hubble’s detailed measurements constrain models of Andromeda’s merger history and disk evolution.
A Galactic ‘Train Wreck’
Though the Milky Way and Andromeda formed presumably around the same time many billions of years ago, observational evidence shows that they have very different evolutionary histories, despite growing up in the same cosmological neighborhood. Andromeda seems to be more highly populated with younger stars and unusual features like coherent streams of stars, say researchers. This implies it has a more active recent star-formation and interaction history than the Milky Way.
“Andromeda’s a train wreck. It looks like it has been through some kind of event that caused it to form a lot of stars and then just shut down,” said Daniel Weisz at the University of California, Berkeley. “This was probably due to a collision with another galaxy in the neighborhood.”
A possible culprit is the compact satellite galaxy Messier 32, which resembles the stripped-down core of a once-spiral galaxy that may have interacted with Andromeda in the past. Computer simulations suggest that when a close encounter with another galaxy uses up all the available interstellar gas, star formation subsides.
The Andromeda Galaxy, our closest galactic neighbor, holds over 1 trillion stars and has been a key to unlocking the secrets of the universe. Thanks to NASA’s Hubble Space Telescope, we’re now seeing Andromeda in stunning new detail, revealing its dynamic history and unique structure.
Credit: NASA’s Goddard Space Flight Center; Lead Producer: Paul Morris
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“Andromeda looks like a transitional type of galaxy that’s between a star-forming spiral and a sort of elliptical galaxy dominated by aging red stars,” said Weisz. “We can tell it’s got this big central bulge of older stars and a star-forming disk that’s not as active as you might expect given the galaxy’s mass.”
“This detailed look at the resolved stars will help us to piece together the galaxy’s past merger and interaction history,” added Williams.
Hubble’s new findings will support future observations by NASA’s James Webb Space Telescope and the upcoming Nancy Grace Roman Space Telescope. Essentially a wide-angle version of Hubble (with the same sized mirror), Roman will capture the equivalent of at least 100 high-resolution Hubble images in a single exposure. These observations will complement and extend Hubble’s huge dataset.
The Hubble Space Telescope has been operating for over three decades and continues to make ground-breaking discoveries that shape our fundamental understanding of the universe. Hubble is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope and mission operations. Lockheed Martin Space, based in Denver, also supports mission operations at Goddard. The Space Telescope Science Institute in Baltimore, which is operated by the Association of Universities for Research in Astronomy, conducts Hubble science operations for NASA.
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Facebook logo @NASAHubble @NASAHubble Instagram logo @NASAHubble Media Contact:
Claire Andreoli (claire.andreoli@nasa.gov)
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Space Telescope Science Institute, Baltimore, MD
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Last Updated Jan 16, 2025 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center Related Terms
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