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Pocket Mars Reconnaissance Orbiter

The images we show on the Planet Four projects come from Mars Reconnaissance Orbiter. Although MRO won’t be coming back to Earth, you can have your very own pocket-sized MRO.

If you’ve got a 3-D printer, you can try your hand at printing out your own mini-MRO to keep you company while classifying images on Planet Four, Planet Four: Terrains, or Plant Four: Ridges.

Where Do the Images Shown on the Planet Four Projects Come From?

The images you review on the Planet Four projects (Planet Four, Planet Four: Terrains, and Planet Four: Ridges) come from two different cameras onboard NASA’s Mars Reconnaissance Orbiter (MRO). MRO has been in orbit around Mars since March 2006. Science operations commenced in November 2006. Nearly 14 years later and MRO has continued to observe and monitor the Red Planet.

Artist Impression of Mars Reconnaissance Orbiter in orbit (Image credit: NASA JPL)

MRO is equipped with several instruments :

  • HiRISE (High Resolution Imaging Science Experiment) – a high-resolution color imager
  • CTX (Context Camera) – grayscale mid-resolution imager
  • MARCI (Mars Color Imager) – color weather imager used to monitor clouds and Martian dust storms
  • CRISM (Compact Reconnaissance Imaging Spectrometer for Mars) – spectrometer that can take composition images of the surface – 2-dimensional maps of the different compositions of the surface
  • MCS (Mars Climate Sounder) – probing the conditions within the Martian atmosphere: temperature, dust, and water vapor concentrations
  • SHARAD (Shallow Radar) – ground-penetrating radar to explore the structure of the Martian subsurface

As MRO orbits Mars, it performs a complex ballet where the different images are taking observations at different times throughout the orbit. The observations are requested by the instrument science teams who are doing a wide variety of science with MRO.

On Planet Four, we use the high resolution color images from HiRISE which can see from orbit surface features down to about the size of your average. HiRISE has a resolution of about 30 cm/pixel. HiRISE is the highest resolution imager sent to another planet in Solar System. In Planet Four: Terrains and Planet Four: Ridges we’re using the grayscale CTX images which covers a wide area but at a lower resolution (6-8 m/pixel) compared to HiRISE. CTX actually provides context for where HiRISE and CRISM are observing and every time these two instrument takes an observaiton, CTX snaps an image as well. HIRISE is so high-resolution that CTX provides the context to tell researchers about what the topography and area around the HiRISE image. If you’ve ever checked out Google Mars visible imagery, you’ve seen some of CTX’s handywork. CTX has image nearly all of the Martian surface several times over.

MRO has now completed over 60,000 orbits around Mars and sent back a whopping 388 terabits of data to Earth. It’s still going strong and HiRISE and CTX are continuing to function. As long as they do, we hope to be able to put those images onto the project sites to continue exploring the current and past climate of Mars.To mark 15 year since the launch of MRO, NASA has put together a great collection of images taken by the spacecraft and its imagers and this video below to mark a decade of MRO science shows some of the striking images the cameras onboard have taken of the Red Planet.

Wind streaks in Planet Four: Ridges

Perusing Planet Four: Ridges Talk I came across the image below. I thought I’d say more about it in case you encounter similar types of images. What drew my eye was the large diffuse lighter streaker on the one side of the crater.

That’s called a wind streak. Wind streaks have been found not only on Mars but also on Venus and Earth.  As their name implies, they are formed directly by the interactions of the surface wind with the soil. The wind is impacted by obstacles in its path on the surface like crater rims. As the wind moves around the crater rim either picks up dust particles pushing them together collecting them to create bright streaks visible from orbit or the wind  excavates material exposing a darker material than the surrounding top surface layer.  Wind streaks extend into into the direction the wind is moving towards, so they are also good indicators of past wind direction.


Planet Four Poetry

Inspired by Lord Alfred Tennyson’s Locksley Hall, on Planet Four Talk  Pete (p.titchin) reflected on the arrival of Martian Southern Spring. We thought it was lovely and wanted to share with all of you. Thanks Pete:

In the Spring, the sunrise heralds changes on the Martian ice: In the Spring, a P4 classifier’s fancy lightly turns to thoughts of —-SUBLIMATION!.

Add your own verses in the comments or on Talk.

Footprints of the HiRISE observations

I’ve been learning to use JMARS  (Java Mission-planning and Analysis for Remote Sensing) to plot the coverage of the CTX images for Planet Four: Terrains. JMARS is a really nice tool for overlaying observation footprints and different maps and datasets on top of each other for Mars and other planets.

I decided to take a look at what the HiRISE Season 2 and Season 3 observations, that the science team is currently working on writing up, look like on a map of the South Pole when you plot their physical coverage on the pole . You can really see the overlap and what a small area that HiRISE covers compared to CTX.

Here’s the footprint  HiRISE observations for Seasons 2 and 3 outlined in red on the elevation and topography map of the Martian south pole (latitude and longitude lines are in 10 degree intervals).


Here’s a zoom in on one of our favorite regions, Inca City. You can really see the repeat coverage outlined in white in this case.


Screen Shot 2016-03-15 at 10.16.25 AM

Here’s another zoom in of a different area, where you can see multiple seasonal targets outlined in red:



For comparison here’s the footprints of the first set CTX images  (latitude and longitude lines are in 10 degree intervals). The colors represent geologic units, but for this comparison we’re focusing on spatial distribution and coverage.

south_pole_mola_geology_with_pointings copy


WeMartians Interview: Citizen Science on Mars

WeMartians is a brand new podcast aimed to engage the public in the exploration of Mars. The latest episode is about citizen science on Mars with  Michael talking about Planet Four and Planet Four: Terrains.  Listen to Michael (and cameos of other familiar Zooniverse voices) below or on the WeMartians website.

10 Years in Martian Orbit for Mars Reconnaissance Orbiter

Yesterday marked a decade since Mars Reconnaissance Orbiter (MRO) went into orbit around the Red Planet. A few months later science observations commenced, and since then the mission has been studying the Martian surface and atmosphere. We use MRO data on both Planet Four (HiRISE [HIgh Resolution Imaging Science Experiment] images) and Planet Four: Terrains (Context Camera [CTX]  images). Thanks to the contributions of those at NASA and the instrument teams (including engineers, scientists, software programmers, and other operations support  team members) who make these observations happen and keep the spacecraft and its suite of instruments happy and healthy.

With 10 Earth years (or ~5 Mars years) of observations, we can look for long term changes in the geyser formation process, and this summer we’ll be pointing HiRISE to new regions of the South Pole thanks to the contributions from Planet  Four: Terrains volunteers for monitoring for several more Mars years.

Below is a highlight reel compiled by NASA of MRO’s greatest science hits and images over the last decade.

There have been so many iconic moments from the MRO’s mission, but I think two moments are HIRISE capturing the descent stage of the the Curiosity rover with the parachute and the parachute of the Phoenix lander several years before.

Image Credit: Credit: NASA/JPL/University of Arizona

HiRISE captures the descent of NASA’s Curiosity rover Image Credit: Credit: NASA/JPL/University of Arizona


Image Credit: Credit: NASA/JPL/University of Arizona

Parachute of the Phoenix lander snapped by HiRISE during the entry, landing, and descent of the polar lander – Image Credit: Credit: NASA/JPL/University of Arizona – original image

Happy Anniversary MRO! – Here’s to the next decade around Mars! Celebrate by classifying a few images on Planet Four and Planet Four: Terrains

Mars and the Planetary Gang in the Early Morning Sky

Wake up early and view our planetary neighbors in all their glory. Starting this weekend you’ll be able to find Mars and four other planets from our Solar System visible in the early morning sky. In addition to the Red Planet,  this planetary alignment includes Mercury, Venus, Jupiter, and Saturn. Some of the planets will continue be visible for over two or three weeks, but the best time to see all five is from  Saturday, January 23 through the first week of February.

Below is a guide to help direct you to the right spot. Just before dawn (about 45 minutes before) while the sky is is still dark will be the best time to look.

 Credit: NASA/JPL-Caltech

Credit: NASA/JPL-Caltech

Most of the  planets are bright compared to stars in the sky so you should be able to glimpse them without the need of a telescope or binoculars, though you’ll likely need binoculars to spot tiny Mercury. If you’re having trouble identifying the planets from the backgrounds stars in the patch of sky, this (below) might help.

Mars should stand out as it will have a reddish tint thanks to all the iron oxide dust (or maybe better to say rusty dust) that covers it surface and swirls in its atmosphere. The bright star Spica will be in the middle between Jupiter and Mars, but  our own Moon will also join this cosmic display, so if you’re having a hard time finding the planets, then try on the morning around February 1st. That’s when our  Moon will be visible near Mars.

You can find more details on how to spot this early morning show here and here.   If you do spot Mars, take a moment to think about the fact that you’re viewing a world that you can help better understand how the atmosphere/climate of this distant world works. You can explore Mars and help map seasonal fans on the South Pole of Mars with the Zooniverse’s Planet Four project (, and if you do get a glimpse of Mars, post your photos in the comments section and we’ll post them here in a future blog post.

Where Are We Looking?

Image Credit: Andy Martin - Image credit: Adapted from Tanaka et al. (2014) ISSN 2329-132X

Image Credit: Andy Martin – Image credit: Adapted from Tanaka et al. (2014) ISSN 2329-132X

Thanks to Talk moderator Andy (wassock), we have a handy map that overlays previous plots I’ve made of the locations of the HiRISE images being focused on by Planet Four and the CTX images that are being searched on Planet Four: Terrains.  He’s also marked some of the target of interest areas like Ithaca, Inca City, Manhattan, and Giza that we’ve been trying to focus on over the past two years on Planet Four.

Andy overlays the plot on top of the geologic map of the Martian South Pole produced by the United States Geological Survey that’s been discussed on Planet Four: Terrains Talk. You can find more details about it here.

Dust Devil Tracks or a Jackson Pollock Painting?

A subframe CTX image on Planet Four: Terrains showing many dust devil tracks. Discuss this image at

A subframe CTX image on Planet Four: Terrains showing many dust devil tracks. Discuss this image at

You might have seen an image like the one above while classifying on Planet Four: Terrains. It reminds me of Jackson Pollock’s painting style. Those dark lines crisscrossing the image are actually dust devil tracks. Dust devils are mini-tornadoes on the surface of Mars, kicking up and clearing dust in their paths. Dust devils exist in the plains and deserts on Earth. The Martian equivalent can be considerably bigger than those found on Earth. Their tracks can be seen from orbit in images from CTX and other cameras.

Here’s what dust devils look like from orbit. This image was captured by the HiRISE camera on Mars Reconnaissance Orbiter.

A dust devil spotted from orbit. Image credit: NASA/JPL-Caltech/Univ. of Arizona - More info at

A dust devil spotted from orbit. Image credit: NASA/JPL-Caltech/Univ. of Arizona – More info at

Dust devils have been caught in the act  on the ground in the mid-latitudes by several robotic rovers and landers  including the  Mars Exploration Rovers (Opportunity and Spirit). Actually Spirit and Opportunity have had dust devils  pass over them, cleaning their solar panels. Below was a series of dust devils passing through nearby the Spirit rover in Gusev crater.

Dust devils in Gusev Crater spotted by the Spirit rover - Image credit: NASA/JPL - /Texas A&M - More info at

Dust devils in Gusev Crater spotted by the Spirit rover – Image credit: NASA/JPL – /Texas A&M – More info at

You might be wondering why we don’t ask you to mark these in the main Planet Four: Terrains interface. The reason is because they’re so ubiquitous that a full map of their locations isn’t needed, but if you’re interested you can identify images like this on Talk using the #dustdeviltracks hashtag.

Thanks to volunteer o0ohando0o for spotting this image and posting about it on Planet Four: Terrains Talk. You can find more examples of dust devil tracks as well as other things you might encounter in the Planet Four: Terrains images in our Site Guide.