Help Shape the Future of Space Exploration

Join The Planetary Society Now Join Now!

Join our eNewsletter for updates & action alerts

   Please leave this field empty
Blogs

Headshot of Emily Lakdawalla

High tau for Spirit and Opportunity

Posted by Emily Lakdawalla

30-07-2007 12:26 CDT

Topics: pretty pictures, amateur image processing, Spirit, Mars Exploration Rovers, Mars, animation

Over the weekend I fiddled with the "tau" images that Mars Exploration Rover Pancam lead Jim Bell gave me, and I produced a couple of different ways to visualize the darkness of the rovers' skies. Typically, the rovers turn to find the Sun, cover their Pancam eyes with dark solar filters (like welders' glasses), and take photos, several times a day. These photos, when calibrated, provide a direct measurement of how much sunlight is getting through Mars' atmosphere to the rovers. The opacity of the atmosphere is referred to by the Greek letter tau (τ). Atmospheric opacity increases exponentially with increasing tau. So here are two animations, one for Spirit and one for Opportunity, covering pretty much the same time period. Opportunity's skies get darker faster than Spirit's skies do, and the opacity is also more variable. Spirit now has skies as dark as Opportunity's. For several sols, Opportunity wasn't able to muster enough power to take any tau measurements at all, so I substituted in images with an "X" to indicate that.

Spirit's dimming Sun

NASA / JPL-Caltech / Cornell / animation by Emily Lakdawalla

Spirit's dimming Sun

There have been more tau images returned to Earth from both rovers since I requested these from Jim last week. I hope to update these animations, but I won't pester Jim for new pictures daily.

Here's a different way of looking at the same data:

Spirit's dimming Sun

NASA / JPL / Cornell / Emily Lakdawalla

Spirit's dimming Sun

Both rovers are still OK. I've been using Midnight Mars Browser to check on their progress, and there were images returned from Spirit on sol 1269 (Sunday) and from Opportunity on sol 1249 (early this morning). For Opportunity, the newest images are still just focused on the sky, but Spirit is occasionally returning more science-y pictures. This series of forward Hazcam images documents some cool motions in the sand near Spirit's wheels: a track that its left front wheel made when it moved is being destroyed as wind shifts sand around.

Sand ripples in motion near Spirit

NASA / JPL-Caltech / Fredk

Sand ripples in motion near Spirit
Eight Hazcam images captured over a period of 17 days show how forcefully the winds are blowing across Spirit in Gusev Crater. In the first image, captured on sol 1250 / July 10, 2007, Spirit's left wheel has left a track in the sand. Over the subsequent sols, wind obliterates the track.
 
See other posts from July 2007

 

Or read more blog entries about: pretty pictures, amateur image processing, Spirit, Mars Exploration Rovers, Mars, animation

Comments:

Leave a Comment:

You must be logged in to submit a comment. Log in now.
Facebook Twitter Email RSS AddThis

Blog Search

LightSail - Flight by Light

Support LightSail!

In 2016, The Planetary Society’s LightSail program will take the technology a step further.

I want to help!

Featured Images

Drill hole at Confidence Hills, Curiosity sol 759

Drilling at Confidence Hills, Curiosity sols 755-759
Curiosity at Pahrump Hills, sol 753
The Base of Mount Sharp, Curiosity sol 752
More Images

Featured Video

View Larger »

Fly to an Asteroid!

Travel to Bennu on the OSIRIS-REx spacecraft!

Send your name

Join the New Millennium Committee

Let’s invent the future together!

Become a Member

Connect With Us

Facebook! Twitter! Google+ and more…
Continue the conversation with our online community!