Nasa's $800m Mars Exploration Rovers have accidentally drawn a penis.
The twin exploration vehicles Spirit and Opportunity were launched nine years ago, in an effort to search the surface of Mars for signs of water erosion and possibly even life.
According to Nasa, since then the rovers have driven over more than 10km of Martian land, directed by teams back on Earth combined with autonomous cameras designed to avoid potential problems with the terrain.
It appears that part of the robots' programming involves spinning in tight circles to test nearby terrain and find new routes.
The image was posted on Nasa's site and appears to be a genuine picture from the Martian surface - albeit one taken at an unfortunate angle.
It's not clear which of the rovers drew the shape, or even when it was made.
Nasa lost communication with the Spirit rover in 2009 after it became stuck in some sand. Meanwhile the Opportunity is still traversing the surface on its way to the Endeavour crater.
This handout image provided by NASA, taken Sept. 28, 2012, is a mosaic of images taken by the telephoto right-eye camera of the Mast Camera before the rover arrived at Rocknest. Mars Curiosity is about to sip its initial taste of the red planet's sand. But first, NASA's rover has to play bartender to make sure the dry dust is shaken, not stirred.The rover's scoop will dig into the sand Saturday. Then the action starts. Mission sampling chief Daniel Limonadi said the end of the rover's arm will shake vigorously and noisily for eight hours, like a Martian martini mixer gone mad. That will vibrate the fine dust grains through the rover chemical testing system to cleanse it of unwanted residual Earth grease. (AP Photo/NASA)
This undated image provided by NASA shows powdered rock in the scoop of the Mars rover Curiosity. The six-wheel rover collected the sample after drilling into a Martian rock. The next step is to transfer a portion to its onboard laboratories for analysis. Curiosity landed in August 2012 to study whether the environment was hospitable for microbes. (AP Photo/NASA)
This image released by NASA on Saturday Feb. 9, 2013 shows a fresh drill hole, center, made by the Curiosity rover on Friday, Feb. 8, 2013 next to an earlier test hole. Curiosity has completed its first drill into a Martian rock, a huge milestone since landing in an ancient crater in August 2012. (AP Photo/NASA)
This image provided by NASA shows the aftermath of a test drill by the Curiosity rover on Mars. The six-wheel rover landed near the Martian equator in August 2012 and is preparing for its first actual drill into a rock. Completion of this "mini drill" test in preparation for full drilling was confirmed in data from Mars received late Wednesday Feb. 6, 2013, at NASA's Jet Propulsion Laboratory, Pasadena, Calif. (AP Photo/NASA)
This image released by NASA shows the view of Curiositys planned first drilling site. The six-wheel, nuclear-powered rover landed five months ago on a mission to study whether Mars was habitable. Engineers are preparing Curiosity to drill into its first Martian rock. The enlargements of rocks seen on the right, and denoted by letters and boxes within the left image, represent this diversity. Each box is about 9 inches (22 centimeters) square. (AP Photo/NASA)
FILE - This Dec. 12, 2012 file image provided by NASA shows the Mars rover Curiosity at a pit stop, a shallow depression called "Yellowknife Bay." It took the image on the 125th Martian day, or sol, of the mission (Dec. 12, 2012), just after finishing that sol's drive. The Sol 125 drive entered Yellowknife Bay and covered about 86 feet (26.1 meters). The descent into the basin crossed a step about 2 feet (half a meter) high, visible in the upper half of this image. Curiosity will now head for Mount Sharp in mid-February after it drills into its first rock. (AP Photo/NASA/JPL-Caltech, File)
This image released by NASA shows the work site of the NASAs rover Curiosity on Mars. Results are in from the first test of Martian soil by the rover Curiosity: So far, there is no definitive evidence that the red planet has the chemical ingredients to support life.Scientists said Monday, Dec. 3, 2012 that a scoop of sandy soil analyzed by the rover's chemistry lab contained water and a mix of chemicals, but not the complex carbon-based compounds considered necessary for microbial life. (AP Photo/NASA)
This artist's rendering provided by NASA shows the Curiosity rover on the surface of Mars. NASA announced Tuesday, Dec. 4, 2012, it plans to send another Curiosity-like rover to Mars in 2020. (AP Photo/NASA)
This image provided by NASA shows shows a Martian rock outcrop near the landing site of the rover Curiosity thought to be the site of an ancient streambed. Curiosity landed in a crater near Mars' equator on Aug. 5, 2012, on a two-year mission to study whether the environment could have been favorable for microbial life. (AP Photo/NASA)
This handout photo provided by NASA/JPL-Caltech/MSSS, taken Oct. 15, 2012, shows part of the small pit or bite created when NASA's Mars rover Curiosity collected its second scoop of Martian soil at a sandy patch called "Rocknest." The bright particle near the center of this image, and similar ones elsewhere in the pit, prompted concern because a small, light-toned shred of debris from the spacecraft had been observed previously nearby. However, the mission's science team assessed the bright particles in this scooped pit to be native Martian material rather than spacecraft debris. (APPhoto/NASA/JPL-Caltech/MSSS)
This image from the right Mast Camera (Mastcam) of NASA's Mars rover Curiosity shows a scoop full of sand and dust lifted by the rover's first use of the scoop on its robotic arm. In the foreground, near the bottom of the image, a bright object is visible on the ground. NASA says a small bright object detected on Mars is likely a piece of plastic from the Curiosity rover. The six-wheel spacecraft captured an image of the puzzling object Monday, Oct. 8, 2012, after scooping up Martian sand and dust over the weekend. In a statement Tuesday, the space agency says the plastic bit that fell off the rover is "benign." While plans are continuing to positively identify it, NASA says it is not "Martian material." (AP Photo/NASA/JPL-Caltech/MSSS)
This image provided by NASA shows shows a Martian rock outcrop near the landing site of the rover Curiosity thought to be the site of an ancient streambed, next to similar rocks shown on earth. Curiosity landed in a crater near Mars' equator on Aug. 5, 2012, on a two-year mission to study whether the environment could have been favorable for microbial life. (AP Photo/NASA)
This Sept. 19, 2012 image provided by NASA shows a view of Mars rover Curiosity's deck showing a plaque bearing several signatures of U.S. officials, including that of President Barack Obama and Vice President Joe Biden. The image was taken by the rover's Mars Hand Lens Imager (MAHLI). The plaque is located on the front left side of the rover's deck. (AP Photo/NASA)
An image provided by NASA shows the robotic arm of NASA's Mars rover Curiosity with the first rock touched by an instrument on the arm. The rover's right Navigation Camera made the image on Sept. 22, 2012. Curiosity placed the Alpha Particle X-Ray Spectrometer instrument onto the rock to assess what chemical elements were present in the rock. The rock is named "Jake Matijevic" in commemoration of influential Mars-rover engineer Jacob Matijevic. (AP Photo/NASA)
This image provided by NASA shows shows a Martian rock outcrop near the landing site of the rover Curiosity thought to be the site of an ancient streambed. Curiosity landed in a crater near Mars' equator on Aug. 5 on a two-year mission to study whether the environment could have been favorable for microbial life. (AP Photo/NASA)
This image provided by NASA shows the Curiosity rover's three left wheels. Since landing on Mars on Aug. 5, 2012, Curiosity has driven more than the length of a football field. It will resume driving this week after it completes its health checkups. (AP Photo/NASA)
This handout photo provided by NASA/JPL-Caltech shows the surroundings of the location where NASA Mars rover Curiosity arrived on Sept. 4, 2012. It is a mosaic of images taken by Curiosity's Navigation Camera (Navcam) following the Sol 29 drive of 100 feet. Tracks from the drive are visible in the image. For scale, Curiosity leaves parallel tracks about 9 feet apart. The rover Curiosity is making its mark on Mars. Its tracks are big enough to be seen from space. In just one month, the car-sized rover has driven 368 feet on the red planet. That's slightly more than the length of a football field. Curiosity's slightly zig-zaggy tire tracks were photographed from a NASA satellite circling Mars and also from the rover's rear-facing cameras. Curiosity landed on Aug. 5. (AP Photo/NASA/JPL-Caltech) The panorama is centered to the north-northeast, with south-southwest at both ends.
In this image released by NASA on Monday, Aug. 27, 2012, An image from a test series used to characterize the 100-millimeter Mast Camera on NASA's Curiosity rover taken on Aug. 23, 2012, looking south-southwest from the rover's landing site. The 100-millimeter Mastcam has three times better resolution than Curiosity's 34-millimeter Mastcam, though it has a narrower field of view. The gravelly area around Curiosity's landing site is visible in the foreground. Farther away, about a third of the way up from the bottom of the image, the terrain falls off into a depression (a swale). Beyond the swale, in the middle of the image, is the boulder-strewn, red-brown rim of a moderately-sized impact crater. Farther off in the distance, there are dark dunes and then the layered rock at the base of Mount Sharp. Some haze obscures the view, but the top ridge, depicted in this image, is 10 miles (16.2 kilometers) away. Scientists enhanced the color in one version to show the Martian scene under the lighting conditions we have on Earth, which helps in analyzing the terrain. (AP Photo/NASA/JPL-Caltech/MSSS)
In this image released by NASA on Monday, Aug. 27, 2012, a photo taken by the Mast Camera (MastCam) highlights the geology of Mount Sharp, a mountain inside Gale Crater, where the rover landed. Prior to the rover's landing on Mars, observations from orbiting satellites indicated that the lower reaches of Mount Sharp, below the line of white dots, are composed of relatively flat-lying strata that bear hydrated minerals. Those orbiter observations did not reveal hydrated minerals in the higher, overlying strata. The MastCam data now reveal a strong discontinuity in the strata above and below the line of white dots, agreeing with the data from orbit. Strata overlying the line of white dots are highly inclined (dipping from left to right) relative to lower, underlying strata. The inclination of these strata above the line of white dots is not obvious from orbit. This provides independent evidence that the absence of hydrated minerals on the upper reaches of Mount Sharp may coincide with a very different formation environment than lower on the slopes. The train of white dots may represent an "unconformity," or an area where the process of sedimentation stopped. (AP Photo/NASA/JPL-Caltech/MSSS)
In this image released by NASA on Monday, Aug. 27, 2012, a chapter of the layered geological history of Mars is laid bare in this color image from NASA's Curiosity rover showing the base of Mount Sharp, the rover's eventual science destination. The image is a portion of a larger image taken by Curiosity's 100-millimeter Mast Camera on Aug. 23, 2012. Scientists enhanced the color in one version to show the Martian scene under the lighting conditions we have on Earth, which helps in analyzing the terrain. The pointy mound in the center of the image, looming above the rover-sized rock, is about 1,000 feet (300 meters) across and 300 feet (100 meters) high. (AP Photo/NASA/JPL-Caltech/MSSS)
In this frame of a high definition stop motion video taken during the NASA rover Mars landing provided by the space agency on Thursday, Aug. 23, 2012, the heat shield falls away during Curiosity's descent to the surface of Mars on Sunday, Aug. 5, 2012. Curiosity is the first spacecraft to record a landing on another planet. The six-wheel rover arrived on Aug. 5 to begin a two-year mission to examine whether the Martian environment was hospitable for microbial life. (AP Photo/NASA/JPL-Caltech/MSSS)
Curiosity at Work on Mars
This artist's concept depicts the rover Curiosity, of NASA's Mars Science Laboratory mission, as it uses its Chemistry and Camera (ChemCam) instrument to investigate the composition of a rock surface. ChemCam fires laser pulses at a target and views the resulting spark with a telescope and spectrometers to identify chemical elements. The laser is actually in an invisible infrared wavelength, but is shown here as visible red light for purposes of illustration.
Daybreak At Gale Crater
This computer-generated view depicts part of Mars at the boundary between darkness and daylight, with an area including Gale Crater beginning to catch morning light.
Curiosity Launch Vehicle
The Atlas V 541 vehicle was selected for the Mars Science Laboratory mission because it has the right liftoff capability for the heavy weight requirements of the rover and its spacecraft.
Mars Science Laboratory Spacecraft During Cruise
This is an artist's concept of NASA's Mars Science Laboratory spacecraft during its cruise phase between launch and final approach to Mars. The spacecraft includes a disc-shaped cruise stage (on the left) attached to the aeroshell. The spacecraft's rover (Curiosity) and descent stage are tucked inside the aeroshell.
Curiosity Approaching Mars
The Curiosity rover is safely tucked inside the spacecraft's aeroshell. The mission's approach phase begins 45 minutes before the spacecraft enters the Martian atmosphere. It lasts until the spacecraft enters the atmosphere.
Curiosity Inside Aeroshell
The Curiosity rover and the spacecraft's descent stage are safely tucked inside the aeroshell at this point. The aeroshell includes a heat shield (on the right, facing in the direction of travel through the atmosphere) and backshell. The diameter of the aeroshell is 14.8 feet (4.5 meters), the largest ever used for a mission to Mars.
Mars Science Laboratory Guided Entry At Mars
The mission's entry, descent, and landing (EDL) phase begins when the spacecraft reaches the top of Martian atmosphere, about 81 miles (131 kilometers) above the surface of the Gale crater landing area, and ends with the rover safe and sound on the surface of Mars. During the approximately seven minutes of EDL, the spacecraft decelerates from a velocity of about 13,200 miles per hour (5,900 meters per second) at the top of the atmosphere, to stationary on the surface.
Deceleration of Mars Science Laboratory in Martian Atmosphere
This artist's concept depicts the interaction of NASA's Mars Science Laboratory spacecraft with the upper atmosphere of Mars during the entry, descent and landing of the Curiosity rover onto the Martian surface.
Mars Science Laboratory Parachute
This is an artist's concept of the Mars Science Laboratory Curiosity rover parachute system.
Curiosity While On Parachute
This is an artist's concept of NASA's Curiosity rover tucked inside the Mars Science Laboratory spacecraft's backshell while the spacecraft is descending on a parachute toward Mars. The parachute is attached to the top of the backshell. In the scene depicted here, the spacecraft's heat shield has already been jettisoned.
Curiosity And Descent Stage
This is an artist's concept of the rover and descent stage for NASA's Mars Science Laboratory spacecraft during the final minute before the rover, Curiosity, touches down on the surface of Mars.
Curiosity's Sky Crane Maneuver
The entry, descent, and landing (EDL) phase of the Mars Science Laboratory mission begins when the spacecraft reaches the Martian atmosphere, about 81 miles (131 kilometers) above the surface of the Gale crater landing area, and ends with the rover Curiosity safe and sound on the surface of Mars.
Curiosity Touching Down
This artist's concept depicts the moment that NASA's Curiosity rover touches down onto the Martian surface.
A Moment After Curiosity's Touchdown
This artist's concept depicts the moment immediately after NASA's Curiosity rover touches down onto the Martian surface.
Curiosity Mars Rover
This artist concept features NASA's Mars Science Laboratory Curiosity rover, a mobile robot for investigating Mars' past or present ability to sustain microbial life.
In this picture, the mast, or rover's "head," rises to about 2.1 meters (6.9 feet) above ground level, about as tall as a basketball player. This mast supports two remote-sensing instruments: the Mast Camera, or "eyes," for stereo color viewing of surrounding terrain and material collected by the arm; and, the ChemCam instrument, which is a laser that vaporizes material from rocks up to about 9 meters (30 feet) away and determines what elements the rocks are made of.
Mars Rover Curiosity
This artist concept features NASA's Mars Science Laboratory Curiosity rover, a mobile robot for investigating Mars' past or present ability to sustain microbial life.