Why Don’t We See the Curiosity Rover’s Arm When it Takes a Selfie?

Every time the Curiosity rover takes a ‘selfie’ on Mars, we get the same questions: “How was this picture taken?” “Why isn’t the rover’s arm or the camera visible in this picture?” “In all of Curiosity’s selfies, the camera mast is never visible… why?” And (sigh) “What is NASA hiding???”

The answer is simple and quite logical. Look any selfie image you’ve taken. Does your hand show up in the picture?

No, because it is behind the camera.

The same is true with the rover’s arm. For the most part, it is behind the camera, so it isn’t part of the picture. In your own selfies, if you’ve done a good job of positioning things, your arm doesn’t appear in the photo either. For example, take a look at this selfie taken last night by Astronomy Cast co-host Pamela Gay of her co-host (and Universe Today publisher) Fraser Cain, along with their fellow speakers at the Next Frontiers Symposium at Ohio State University.

You’ll notice Pamela’s arm isn’t showing, even though she took the picture of herself, just like the rover takes pictures of itself.

Just think of the rover’s arm as the ultimate interplanetary selfie stick. The best selfie-stick pictures are where the stick doesn’t show up in the image and it appears you had your own photographer. That’s what happens with the Curiosity rover self-portraits.

It’s important to note that while the rover selfies look like they are just one single image taken by the wide-angle camera on the rover, it is actually a series of individual images stitched together. The picture above is made from dozens of images the rover took of itself with the Mars Hand Lens Imager (MAHLI) camera at the end of the rover’s robotic arm. Curiosity moves its robotic arm around and over itself and the ground, taking pictures from every angle. These pictures are then stitched, just like panoramic images are put together to form a complete image of your total view. The rover’s arm isn’t long enough to make the camera’s field of view big enough to get the entire rover in one shot (similar to how it works if you hold your camera/phone close to your face you only get one feature, like your nose or eyes, not your entire body.)

Update: As for the questions of why the rover’s arm doesn’t show up in these rover selfie images, I conferred with Guy Webster from JPL and he said that portions of the arm do show up in some of the images used to create the selfie shots, but the portion of the arm pictured is very limited, and the team feels it would be even more confusing to include the small parts of the arm that are in some of the images and so have decided to leave it out entirely.

“Some of the component images do indeed show glimpses of the arm,” Webster said via email. “There’s selectivity in choosing which parts of which component frames to use in assembling the mosaic, to avoid having discontinuous bits of arm in the scene. That would cause confusion even quicker than making choices that leave out the arm.”

For example, here is one image from the series of pictures taken by the MAHLI to create the selfie, and it shows just a small piece of the arm, near the “shoulder”:

A small portion of the Curiosity rover's robotic arm (the white 'tube' on the top left of the image) shows up in one of the original raw images used to create the montage 'selfie.' Credit: NASA/JPL-Caltech/MSSS.
A small portion of the Curiosity rover’s robotic arm (the white ‘tube’ on the top left of the image) shows up in one of the original raw images used to create the montage ‘selfie.’ Credit: NASA/JPL-Caltech/MSSS.

You can see the entire collection of MAHLI images from Sol 1126 (Oct. 6, 2015) here. You can see how few images show parts of the arm, and how little of the arm shows up in the ones that do.

For the most part, though, because of the flexibility of the robotic arm and the way it is able to move, the arm ends up behind the camera. As Curiosity’s Engineering Camera Team Leader Justin Maki explains in the video below, “The rover is imaging the deck while the arm is behind the camera, and then to image the ground … again the arm is behind the camera when taking these pictures. When we stitch them all together, you don’t see the arm in any of the pictures.”

Click on the image to start the video (which shows very well why the arm isn’t in most of the shots):

It’s interesting to note, that while the lead image above — the latest rover selfie — does not include the rover’s robotic arm, the shadow of the arm is visible on the ground. You’ll notice there seems to be an extra “joint” in the arm, which is just part of the image editing, particularly the stacking of the images where the ground is, where the image editors used more than one image for that area. For the selfie image below, taken in 2012, the imaging team chose not to include any shadow of the arm.

A color self-portrait photo of Curiosity standing on Mars, on sol 84 (October 31, 2012). The photo is a mosaic of images shot with MAHLI, the camera on the end of the robotic arm. Credit: NASA/JPL/MSSS.
A color self-portrait photo of Curiosity standing on Mars, on sol 84 (October 31, 2012). The photo is a mosaic of images shot with MAHLI, the camera on the end of the robotic arm. Credit: NASA/JPL/MSSS.

Why does the rover imaging team take these rover selfies? Are they just joining in on the selfie craze here on Earth?

These images are actually a great way for the rover team to look at all the components on Curiosity and make sure everything looks like it’s in good shape. The wheels are of particular interest because there has been some damage to them from driving over sharp rocks. These images also document various areas where the rover has worked, and often include things like the holes the rover has drilled into the Martian rocks and soil.

Emily Lakdawalla at The Planetary Society has written an extremely detailed post on how the rover takes self-portraits. She created this composite image of the 72 individual frames the Mars Hand Lens Imager (MAHLI) had to take in order to cover the 360-degree view showing the rover’s underside, a “belly selfie“:

Curiosity's arm-mounted MAHLI camera took 72 individual photos over a period of about an hour in order to cover the entire rover and a lower hemisphere including 360 degrees around the rover and more than 90 degrees of elevation. It took 2 tiers of 20 images to cover the entire horizon, and fewer images at lower elevations to cover the bottom of the image sphere. The arm was kept out of most of the images but it was impossible to keep the arm's shadow from falling on the ground in positions immediately in front of the rover. Credit: NASA/JPL/MSSS/Emily Lakdawalla.
Curiosity’s arm-mounted MAHLI camera took 72 individual photos over a period of about an hour in order to cover the entire rover and a lower hemisphere including 360 degrees around the rover and more than 90 degrees of elevation. It took 2 tiers of 20 images to cover the entire horizon, and fewer images at lower elevations to cover the bottom of the image sphere. The arm was kept out of most of the images but it was impossible to keep the arm’s shadow from falling on the ground in positions immediately in front of the rover. Credit: NASA/JPL/MSSS/Emily Lakdawalla.

Here’s another longer video from JPL that explains all the rover’s cameras.

A mosaic of images from NASA's Curiosity rover shows what appears to be a "selfie" with a Martian mountain (Aeolis Mons)in the background. Credit: NASA/JPL-Caltech /MSS/ Image editing by Jason Major.
A mosaic of images from NASA’s Curiosity rover shows what appears to be a “selfie” with a Martian mountain (Aeolis Mons)in the background. Credit: NASA/JPL-Caltech /MSS/ Image editing by Jason Major.

Philae Snaps a Spacetastic Selfie

Spacecraft “selfies” are always a treat and this one is doubly awesome: taken by the Philae lander piggybacked onto ESA’s Rosetta, it shows one of the spacecraft’s 14-meter-long (46-foot) solar arrays glinting with reflected sunlight while off in the distance is the double-lobed nucleus of Comet 67P/Churyumov-Gerasimenko!

Rosetta has been circling the comet for over a month now and returning some truly amazing images, but leave it to little Philae to put it all into perspective. Such a show-stealer! (Not that we mind, of course.)

The image above was acquired with Philae’s CIVA (Comet nucleus Infrared and Visible Analyzer) instrument on Sept. 7, 2014, from a distance of 50 km (31 miles) from Comet 67P/C-G. It’s actually a composite of two separate images made with different exposures adjusted for the lighting disparities between the spacecraft and comet.

Artist impression of Philae on the surface of comet 67P/Churyumov-Gerasimenko.  Credit: ESA/ATG medialab
Artist impression of Philae on the surface of comet 67P/Churyumov-Gerasimenko. Credit: ESA/ATG medialab

The Philae (say “FEE-lay”) lander itself weighs 100 kg (220 lbs) and is about a meter wide and 80 cm high (3.2 x 2.6 feet). The CIVA instrument, one of ten installed on the lander, is composed of seven miniature cameras that will take panoramic pictures of 67P’s surface and reconstruct its structure in 3D, as well as a microscope and a near-infrared imager to study its composition, texture, and reflectivity. (Source)

This is the second image from Philae this year to feature part of the Rosetta spacecraft (but the first to show the comet); the previous was taken in April 2014.

Back in 2007 Philae took a shot that showed Rosetta’s solar panel and Mars; check that one out here.

Currently Rosetta is being transitioned to its Global Mapping Phase (GMP). This is an incredibly intensive process that will determine how close the spacecraft will be able to get to the surface of the comet as engineers search for the best landing area to which to deploy Philae in November.

Learn more about the Rosetta mission and Comet 67P/C-G here.

Source: ESA

Selfies from Around the World Combine to Make a Portrait of Earth

On Earth Day, April 22, NASA invited people around the world to share their “selfies” on social media sites like Twitter, Facebook, Google+, and Instagram, showing where on Earth they are and marking them with the hashtag #GlobalSelfie. Well, here we are a month later and the results have just been released… proof of what a beautiful world we all make up!

The image above was built using 36,422 fan-submitted self-portraits from 113 countries, and is based upon images of Earth acquired on April 22 by NASA/NOAA’s Visible Infrared Imaging Radiometer Suite instrument aboard the Suomi National Polar-orbiting Partnership (NPP) satellite. (See the original NPP images here.)

How cool is that? A picture of Earth, as seen from space, recomposed of pictures of people on Earth taken the very same day!

Did you send in a #GlobalSelfie? I’m in there somewhere too, but I haven’t located myself (yet). They’re organized by hue and tone, not location, so I could be representing a spot in the middle of the Peruvian jungle instead of along the Providence River.

View the full zoomable 3.2-gigapixel image on GigaPan here.

The GlobalSelfie campaign was more than just a PR gimmick. 2014 is a big year for NASA Earth observation, with five missions launched to monitor our planet’s wind, oceans, soil, and atmosphere. GlobalSelfie was used to kick off the Earth Right Now campaign, helping to raise awareness about these missions and the data they’ll gather to ultimately benefit people around the world.

Source: NASA/GSFC

Hello From Mars! Curiosity Smiles in Her Latest “Selfie”

This is very cute — Curiosity’s latest “selfie,” a mosaic I assembled from about a dozen images acquired with the rover’s Mars Hand Lens Imager (MAHLI) instrument on April 27-28, 2014 (Sol 613), with the 5.5-km-high Mount Sharp (Aeolis Mons) rising in the background. Click the image for a high-res version.

While it’s far from a perfect image — there are plenty of discrepancies in the mosaic tiling, I admit — I really like the character it imparts to Curiosity, who almost seems to be giving a toothy (if slightly dusty) grin there on the left with her cylindrical RUHF antenna and a bit of her RTG visible in the lower center. And with almost 21 Earth-months on Mars and lots of discoveries already under her robot belt, Curiosity (and her team) certainly have plenty to smile about!

See these and all the raw images from the MSL mission here, and read more about Curiosity’s latest work in Gale Crater in Ken Kremer’s article here.

Rosetta’s Philae Lander Snaps a Selfie

Philae is awake… and taking pictures! This image, acquired last night with the lander’s CIVA (Comet nucleus Infrared and Visible Analyzer) instrument, shows the left and right solar panels of ESA’s well-traveled Rosetta spacecraft, upon which the 100-kilogram Philae is mounted.

Philae successfully emerged from hibernation on March 28 via a wake-up call from ESA.

After over a decade of traveling across the inner Solar System, Rosetta and Philae are now in the home stretch of their ultimate mission: to orbit and achieve a soft landing on comet 67/P Churyumov-Gerasimenko. It will be the first time either feat has ever been attempted by a spacecraft. Read more here.

Source: ESA Rosetta Blog