Archive | July 2015

Gravity Waves in Mars’ Atmosphere

Today we have a guest post Dr. Nicholas G. Heavens. He is a Research Assistant Professor of Planetary Science at Hampton University in Hampton, Virginia. He studies the weather of present day Mars, the climate of late Paleozoic Earth, and the atmospheric evolution of Earth-like planets outside the Solar System. He is a member of the Mars Climate Sounder science team.

Dear Explorers of the Fourth Planet,

Chances are, at some point, you have found yourself by a still body of water on a rainy day. Entranced by the smooth surface of this lake or pond, you began to feel the rain fall on your head and shoulders. And as the rain fell on the water, you noticed circular ripples radiating out from each raindrop and moving toward the shore.

Those ripples are a particularly beautiful and elegant example of a type of wave known as a gravity wave (or sometimes buoyancy wave). The raindrop’s impact depresses the surface of the water, upsetting the balance between the force of gravity and the pressure exerted by the water. Water then moves into the hole to restore this balance, creating a further imbalance that spreads the energy of the impact (but not the water itself) outward as circular rings.

Gravity waves in water are a familiar sight in our everyday lives, but gravity waves are common in atmospheres as well, including Mars’s. On average, gravity and air pressure in Mars’s atmosphere are in balance, meaning that less dense air is higher in the atmosphere than more dense air. However, in some situations, denser air can be forced over less dense air, resulting in gravity waves that can propagate to higher altitudes and grow in amplitude as they do so. Some of those waves can be quite inconvenient, since they make up much of aircraft turbulence.

When you look at Planet Four images, you stare at high-resolution, mostly cloudless images of Mars near its poles. What I want to show you today is what might be happening in the atmosphere above, as seen in cloudy, low-resolution images of Mars. It is common to see visible indications of gravity waves in the winter hemisphere around 45 degrees south, but gravity waves are likely active at other times and places.


Circular gravity waves near 45 degrees south late in Mars’s northern summer. This Mars Orbiter Camera Daily Global Map is freely available to download at

 Nearly linear gravity waves near 45 degrees north late in Mars's northern autumn. This Mars Orbiter Camera Daily Global Map is freely available to download at

Nearly linear gravity waves near 45 degrees north late in Mars’s northern autumn. This Mars Orbiter Camera Daily Global Map is freely available to download at

In the first image, do you see circular, whitish ripples near the center of the image? Something analogous to raindrops dropping in a pond has happened there. In the parts of the waves that correspond to rising air, water vapor is cooled and condenses into ice to clouds that trace out the waves.

In the second image, the wave fronts are not strongly curved and appear to be radiating in one direction, probably indicating that a strong wind is affecting the waves. In each case, the wavelength of the waves can be easily measured, around 40 km in the first case and around 20 km in the second case. The source of the first set of waves is unclear (at least to me). The source of the second set of waves is probably the interaction of dense cold air from the pole moving over less dense warmer air at lower latitudes. In some images, the source of the waves can be traced to wind dropping down into a crater.

Studying gravity waves can tell us much about how Mars’s atmosphere works from bottom to top. Future Martian glider pilots also might appreciate knowing when they occur and the conditions they will create. But I will admit that my interest in Mars’s atmospheric gravity waves continues to be fed by the disturbing beauty they bring to Mars’s thin atmosphere.

A Planet Four Science Poster

ASIAA, my institute in Taiwan had its 5 year external review where a panel of experts in the field  from outside the institute come in and give a critique and highlight both the positive things that are going well and also the potential areas to be strengthened.  At this review there was a poster session for postdocs and other researchers to present their projects. Last week was the poster session. I gave an update on Planet Four and presented Planet Four: Terrains. I thought I’d share (typos and all) the poster with you.  You might find that some of the figures are familiar and that you’ve seen them on this very blog in one form or another.

Click on the image to get a higher resolution versionSchwamb_P4_poster_preview

Summer Student 2015 Update: Coding with Loading

Today we have a  post from Gauri Sharma who will be working on Planet Four this summer as part of the ASIAA Summer Student Program.

So the second week has passed in the ASIAA Summer program. I would like to call this week “coding with loading.”  This past week, I played with python. Don’t be scared, I will reiterate for you again it is not a snake, it’s a kind of language like java, C, C++ etc.

As the week was running likewise my work was also running. On the 3rd day of week, my supervisor said “let’s go and have some drink”. It sounds so awesome right!, I was thinking: ” Yipee! I am going to spend some time with my supervisor “. But beside all this imagination, I am gonna tell you truth. No doubt that was the wow time but along with that I got full week tasks. And finally I got all those tasks, that what I wanted to get completed. This is called ‘loading.’ Now time to talk about coding…

On 17 July, again meeting with Meg, and fully working on debugging my code. Oh! My God, my code!! full of errors. She spent almost 2 hours with me. In between more than two time My Mind said: ” Gauri Sharma you gone, she is gonna kick you in few mins, you wasted this much of her time”. I was literally soo scared. But we got through the debugging (and she didn’t kick me).

Before I tell, what’s the use of my code.  I would like to let you know some key points like HiRISE image and Planet Four images. HiRISE images: High Resolution Imaging Science Experiment (HiRISE) is a camera on board the Mars Reconnaissance Orbiter , which allows it to take pictures of Mars with resolutions of 0.3 m/pixel. So that, image is so big that HiRISE images are diced  into tiles (Planet Four images) that are shown on the Planet Four website that you classify.  Right now, I am working to correlate Planet Four images to full HiRISE images, so I can easily find out a particular interesting area in the larger HiRISE image. So now I can tell you, my code works by converting Planet Four image (x, y) position into HiRISE_image (x, y) pixel position.

There is a  happy ending, my first master code is working. And as usual Meg always makes me happy and her line ” you are making progress ” always left a pretty smile on my face and helps me keep calm and cool in such a HOT Summer of Taipei.

Then, I moved forwarded for new task, I got in my loading season .This new code has taken much more time then expected, but it is finally done. It works by  “converting corners of Planet Four image (x, y) position into corners of HiRISE image (x, y) pixel position. So on Monday, I am ready with my second master code. I gather so much python tricks, finally I am enjoying with them. One thing , I would like to say for coding, “its awesome!, its kind of magic!!!!”

That’s all for this week. See you next week.

Where Exactly on Mars are the Terrains You’re Looking At?

With our new addition Planet Four: Terrains, we need your help to review CTX  (Context Camera) images and identify ‘spiders’ (radially organized channels carved in the surface), craters, pitted sheets of carbon dioxide ice nicknamed Swiss Cheese Terrain, and channel networks carved by carbon dioxide gas trapped below the thawing ice sheet and also by the freezing and thawing of water ice permafrost.

The CTX images are of the South Pole, but you might be wondering where exactly we’re looking. One of the main aims of Planet Four: Terrains is to identify new areas of interest to point HiRISE, the higher resolution camera on Mars Reconnaissance Orbiter. CTX is named the Context Camera because it provides the larger picture or context for HiRISE’s detailed but narrow image swaths. Anya’s gone in to more detail about this, so check out her blog to learn more.

To find new areas of interest,  for Planet Four: Terrains we wanted to extend beyond the regions we know have spiders because they’ve been imaged by HiRISE during the seasonal processes campaign. To give you some sense, here are  the regions targeted by HiRISE that are currently uploaded in the Planet Four database. This compromises  all imaged locations from Seasons 1,2,3 and Manhattan Season 4 and Inca City Season 4 and a small part of 5.

P4_locationsFor picking the first set of CTX images, I went through and found what we think are ice free images from the end of Summer and early Fall, and selected as much of a random uniformly distributed sample south of -75 degree latitude. The reason we didn’t want ice if possible is that if there’s ice, there’s a chance for carbon dioxide  geysers and fans (the ones we ask you to mark on the original Planet Four). The fans would block you from seeing surface features in the ground below them.

ctx_random_select_centersAbove are plotted the locations of the full frame CTX images used to make the  subframes that you see on Planet Four: Terrains (Note: we cut up the CTX images into 800 x 600, width x height,  pixel images). We currently have a random third of this set live on the site. We’ll be add the remaining subimages to the site over the next month or so.

For comparison, here again the previous HiRISE seasonal monitoring images locations uploaded on the original Planet Four, plotted on the same scale as the CTX plot above.

P4_locations_zoomAs you can see most of the HiRISE images from the seasonal monitoring campaign are focused south of -80 degrees. As you can see , we’re looking at much more of the Martian South Pole with Planet Four: Terrains.  Soon the South pole will be in darkness again, and the temporary carbon dioxide cap will start growing again. Our hope is that we can have these images reviewed before the start of the Spring on the South Pole to add new locations to the target list for Season 6 of the HiRISE monitoring campaign that starts around July 2016.

Check out Planet Four: Terrains, and classify an image or two today at

Summer Student 2015 Update: My First Blog Post of Summer 2015

Today we have a  post from Gauri Sharma who will be working on Planet Four this summer as part of the ASIAA Summer Student Program.

As a part of my summer project , I am  planning to write a blog weekly. Today is 13/07/2015. So I have completed 13 days in ASIAA and 15 days in Taipei, Taiwan. Taipei is beautiful and my surroundings are just wow. Humans in Taipei are so nice, although we don’t understand each other languages we still try to help each other with a friendly face.  All this made me feel at home here.

Now it’s time to tell you something about my research at ASIAA. I am working with Meg Schwamb on ” Exploring the Seasonal Processes and Wind Directions of Mars’ South Pole. ” This project title itself creates excitement  in my full body.  I am looking  at how fans evolve by boulders. i am possibly exploring how fan direction changes over time for few locations  on south pole.

In this project, I have to write a toolkit to be able to analyze markings coming from Planet Four (P4). I am writing a code right now to be able to do that.I am going to look evolution of fans near boulders in some of the Planet Four images. For all this purpose, my first task is to deal with huge database of P4, and write a code that can transform x_tile and y_tile of P4  to x,y position of HiRISE image. Slowly slowly I learned the basics of MySQL (a kind of database), and I am still learning. I started coding in python (coding language like C) . I wrote my first python code for  my project on the 9th day. I am writing and rewriting codes from morning til night.  Meg says I am making progress and  that make me happy at the end of my day.

This is my first real time project focused on Mars. On first few days, I was like… How to do this ? I was not getting anything. But then my supervisor made me calm and then I started getting confidence. My supervisor says learning everyday is itself  research, so don’t feel bad if you are not reaching a conclusion every day.  Just keep trying towards the conclusion,,, “THAT  IS  RESEARCH”. So, the more we know, the more we grow.

See you next week

Planet Four AMA Today!

Today is the day! The Planet Four AMA is now live on /r/science, and you can start contributing your questions right away. (See the last blog post for more details about the AMA.)

You can post your questions here. Michael, Anya, Meg, and Darren will be back at 1:00 p.m. EDT to start answering, and will continue to post answers and follow-ups for the next few hours.

Remember, you need a Reddit account to post, but it’s free and quick to make.

We’re looking forward to conversing with our volunteers and other Reddit users!

Save the Date: A Planet Four Reddit Science AMA

We’re happy to announce that the science team behind Planet Four and Planet Four: Terrains will be hosting a Science Series Ask Me Anything (AMA) session on Reddit’s /r/science subreddit this coming Friday on July 17, 2015! The post will go live at 8 a.m. EDT to collect questions, and the team will begin answering them at 1 p.m. EDT.

The Science AMA Series is, according to Reddit, “a unique format that allows scientists to speak about their work in a manner that is not possible within the confines of traditional short-form journalism.” Essentially, anyone with a Reddit account can post a question for the team—about Mars, the Martian climate, citizen science, the Zooniverse, the Planet Four projects, or anything else relevant—and the team will be providing answers and follow-ups to as many as possible.

Science team members Michael Aye, Anya Portyankina, and Meg Schwamb will be joined by Zooniverse community builder Darren McRoy for the AMA.

We’ll post another blog on July 17 with a link to the AMA, as well. Save the date, start preparing your questions, and make a Reddit account if you don’t have one. We hope to see you there!

Why we need Planet Four: Terrains?

Hi there!

I want to talk why we created the new project Planet Four: Terrains if we have Planet Four already.

The very high resolution images of HiRISE camera are really impressive and one might think that there is no reason to use a camera with lower resolution anymore. Wrong!

First, high resolution of HiRISE image means large data volume. To store on-board and to download large data from MRO spacecraft to Earth is slow (and expensive) and this means we are always limited in the number of images HiRISE can take. We will never cover the whole surface of Mars with the best HiRISE images. Sadly. so we use different cameras for it. Some – with very rough resolution and some – intermediate, like context camera (CTX). We can use CTX, for example, to gain statistics on how often one or the other terrain type appears in the polar areas. This is one point why Planet Four: Terrains is important.

Second, because HiRISE is used for targeted observations, we need to know where to point it! And we better find interesting locations to study. We can not say “let’s just image every location in the polar regions!” not only for the reason 1 above, but also because we work in a team of scientists and each of them has own interests and surely would like his/her targets to be imaged as well. We should be able to prove to our colleagues that the locations we choose are truly interesting. To show a low-resolution image and point to an unresolved interesting terrain is one of the best ways to do that. And then, when we get to see more details we will see if it is an active area and if we need to monitor it during different seasons.

Help us classify terrains visible in CTX images with Planet Four: Terrains at

A Summer on Mars

Today we have a  post from Gauri Sharma who will be working on Planet Four this summer as part of the ASIAA Summer Student Program.


Meet Gauri


What is your current position and where/institution?

I am undergraduate in MATHEMATICS from jiwaji university, INDIA. I was working as research assistant in Indian institute of astrophysics. This year going to pursue my master’s in astrophysics from Aix Marseille university, France.

Where are you originally from/where did you grow up?

I grew up in Gwalior, madhya pradesh India

What are your research interests/what do you work on?

Right now I am interested to know about whole astronomy , and after my master’s, I am going to select one if them, for my further research.

Why are you interested in Mars?

It’s my first planet from where I started my first sky watch, my celestial object, from where I am going to start my research. And it’s a planet if my dream where, I wanted to be land  so finally I got it… At least for look up deeply.

What is your favorite movie?

Any fairytale …..

What is your favorite book?

Mahabharata, by vedvyas

What is the song you currently can’t get out of your head?

Mangal bhawan yaa mangal hari, drabhu su dashrath ajar bhiri

What three albums would you bring with you to a desert island?

No songs

Favorite cocktail or beverage?

Ginger tea