An Introduction to HiRISE
Today we have a guest post from Chuhong Mai, an undergraduate student working on Planet Four this summer as part of the ASIAA Summer Student Program.
By now, you may have helped the Planet Four team classified hundreds of thousands of cutouts produced from HiRISE season 1 to 3 products, and you may have voted for a region target for HiRISE to be observe in season 5, however, but how well do you know about this camera that makes the whole Planet Four project possible? And that’s what this blog post is going to talk about.
The High Resolution Imaging Science Experiment (HiRISE) camera is carried on the Mars Reconnaissance Orbiter (MRO) spacecraft and since the spacecraft entered Mars orbit in 2006, HiRISE has produced a large amount of beautiful images in unprecedented detail. It was in a 2-year Primary Science Phase (PSP) during 2006 and 2007, corresponding to season 1 in Planet Four project. Later, it had two 2-year Extended Science Phases (ESP) in 2008-2009 (season 2) and 2010-2011 (season 3). HiRISE continues today to operate under an extended mission taking images of unprecedented detail. So if you notice the images’ names (not the cutouts’ names), you’ll find all of them begin with PSP or ESP, which indicates the mission phase HiRISE were in when a certain picture was taken. The rest of their names tell you some other information of HiRISE’s orbit.
The HiRISE camera mainly consists of a telescope with 50 cm diameter and a focal plane system right behind it. This plane might be one of the most important parts of HiRISE since 14 CCD detectors are installed on it, each with 2 separated output channels and 2048 pixels. 10 of these CCDs are for the Red band (RED0 to RED9), 2 are for the Infrared (IR) band (IR10, IR11) and the rest 2 are for the Blue-Green (BG) band (BG12, BG13). They overlap each other by around 48 pixels. Their positions are shown in Fig.1. So as you see, the red band will cover a much wider range (5.0-6.4 km wide) of Mars surface than the other two bands, but only RED4 and RED5, which locate at the center, can cooperate with IR and BG band to generate color products (1.0-1.3 km wide). The HiRISE team also use Time Delay Integration (TDI) to increase SNR (Signal-Noise Ratio). The basic idea of TDI is to image the same small patch of surface many times and add up together to improve SNR. Different numbers of TDI lines (8, 32, 64, 128) are used under different conditions. In addition, six pixel binning modes can be used to increase coverage and SNR, either. Click here to learn more about how binning works. On the whole, HiRISE is able to reach a high resolution: 0.25m/pixel with low SNR exceeding 100:1. This makes sub-meter surface study of Mars possible.
The three bands are selected to differentiate a broad classes of surface materials like bedrocks, frost or ice, sand, dust and other minerals and to avoid ambiguities between shades and different materials, which is often the case in grayscale products. Typically, frost and ice appear bright white and blue, sand and rocks appear bluer and darker, while the dust are the reddest material in these images. Therefore, with these bands combined together, a final color product you see are usually not a true-color images (like what you see through naked eyes), it is either an IRB product, which combines the 3 bands mentioned above, or a RGB product, which combines the Red, BG and synthetic blue band. The latter one is used by Planet Four to make cutouts for you, as RGB images usually do better in contrasting RED with BG color variations. Note again that these images are false-color products and the true Mars surface appear relatively bland and red. Sorry about that because how beautiful these cutouts are!
Fig 1. Schematic of the focal plane system on HiRISE (from A.S. McEwen et al [Reference 2])
References:
W. Alan Delamere, and 15 colleagues, 2009. Color imaging of Mars by the High Resolution Imaging Science Experiment (HiRISE). Icarus, 205, 38-52
Alfred S. McEwen, and 14 colleagues, 2007. Mars Reconnaissance Orbiter’s High Resolution Imaging Science Experiment (HiRISE). J. Geophys. Res., 112, E05S02
Update on the Season 5 Sneak Peak Vote
On August 1st, we announced a public vote in partnership with the HiRISE team. It is your chance to decide which of the 3 regions we have featured on Planet Four in the first half of this year will have its first observation from the new HIRISE monitoring season prepared for public release by the HiRISE team.
You can help determine which of one these 3 regions on the South Pole will have its first observation of the Season 5 HiRISE monitoring campaign prepared for public release.
Below is the breakdown of the tallied votes as they stand right now. Inca City has the lead with Ithaca trailing not that far behind in second. Manhattan is a distant third.
Cast your vote (as often as you like) until September 1st for Inca City, Ithaca, or Manhattan at www.planetfour.org/vote , and while you’re at it if you can spare some time, help map the seasonal fans and blotches today at www.planetfour.org
Meet the Planet Four Team: Brian Carstensen
Today we have the next installment of our Meet the Planet Four Team series, featuring Brian Carstensen from the Zooniverse development team.
Name: Brian Carstensen
What is your current position and where/institution?
Front end web developer at the University of Oxford
Where are you originally from/where did you grow up?
I’m originally from Chicago.
In 3 lines explain what you do as part of the Zooniverse development team?
I used to build user interfaces for various projects.
Now I’m working on the UI for the new Zooniverse-as-a-platform infratructure.
I’m also taking on some graphic design responsibility for the new system.
What was your role in Planet Four?
I built the part of the site our volunteers interact with. The marking tools in Planet Four were actually the first prototype of the drawing library now used in most of the more recent Zooniverse projects.
Why do you find interesting about Mars?
I’m just waiting patiently for someone to start terraforming it so my great-great-great-etc. grandbabies can hang out there.
What is your favorite movie?
Primer (2004)
What is your favorite book?
Anathem by Neal Stephenson
What is the song you currently can’t get out of your head?
Ella Fitzgerald’s botched recording of Mack the Knife.
What three albums would you bring with you to a desert island?
Six Demon Bag by Man Man
The Milk Eyed Mender by Joanna Newsom
Milo Goes to College by Descendent
Favorite cocktail or beverage?
Moscow mule!
The Sun is back!
Planet Four at ZooCon 2014
Image Credit: Grant Miller
The Zooniverse UK HQ hosted ZooCon 2014 this past Saturday at Oxford University with an afternoon inspired by Zooniverse projects. There was representation from science team members (physically and virtually) from many of the projects as well as some of the core Zooniverse team in attendance.
I was invited to give a talk at this year’s ZooCon virtually. I gave an update on Planet Four, and I talked about the progress the science team has been making towards the project’s first paper. You can find the recorded video below:
If you were at ZooCon or just watched the video and have questions, I’ve started a thread on Talk for further discussion.
There is also going to be a second ZooCon called ZooCon Portsmouth hosted at the University of Portsmouth. It will take place on September 13th. There will be some talks as well as an editathon to improve coverage of Citizen Science on Wikipedia. They have a schedule set for the day that you can check out. More details here (Like the Oxford event, tickets are free, but there is limited space at both the lecture hall and the pub) so do register.
Inca City, Ithaca, Manhattan: Which part of the Martian Arctic do you want to see first?
Image credit: Adapted from Tanaka et al. (2014) ISSN 2329-132X http://pubs.usgs.gov/sim/3292/
Mars Reconnaissance Orbiter and the HiRISE camera will soon begin the 5th Season of the South Pole seasonal processes monitoring campaign, and now’s your chance to decide which region will have its first observation from the new season prepared for public release by the HiRISE team. Often these first images are striking, and though the Sun is low in the sky and close to the horizon, there may be active carbon dioxide jets present and already starting to create the first springtime fans and blotches!
Since January, we’ve been focusing on targets of interest from the Season 1 campaign asking you to help map fans and blotches in the areas nicknamed ‘Inca City‘, ‘Ithaca‘ (currently live on the site), and ‘Manhattan‘. To celebrate the start of the new monitoring season, Planet Four is partnering with the HiRISE team to organize a public vote where you get the chance to decide which of these three regions you want to see first.
Voting will be open from August 1, 2014 9am GMT – September 1, 2014 9am GMT. We will be announcing the results on September 2nd. When the winning region’s first Season 5 observation is ready, we’ll post the image here on the blog.
Whether it be the boulders of Inca City, the fans of Ithaca, or the lace terrain of Manhattan that strikes your fancy, cast your vote today (as often as you like) at http://www.planetfour.org/vote.
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