OH MY GOD!
Do you mean that when NASA hires an undergrad to put images on its rah-rah public websites, they don’t make sure he sets all the sliders in Photoshop exactly the same way on every image?
This is indeed evidence of a deep and troubling conspiracy.
You’d be surprised. 
As you said, NASA is not just a monolith. I think this point cannot be stressed enough. It’s not just all the scientists, who are an ornery bunch not inclined to rule-following. Add in all the engineers who would need to be in on it, all the computer people writing programs to take raw data from instruments and turn it into images and other data, all the people looking at all the data, and * all the people who will ever look at the data in the future *…
NASA is not like the CIA.
Those two images (which appear to actually be the same image*) are both GIF images.
GIF is 8-bit or less images only, meaning that any color on the image will have to fit onto at 256 color pallete. You lose a great deal of color information through this process. There are different methods for deciding what colors wind up in the pallete, and what the individual pixels in the image map to. Because of that, you could take the same image, pick different methods for determining the color map and have what is essentially the same image look very different.
*Which I agree with Podkayne is probably just a mistake made by whatever poor shmuc^?^?^? grad student they got to work on the website.
I trying to figure out to what end this would be for. I mean, is there some crazy-haired scientist in the bowels of NASA jumping about with glee shouting, “The FOOLS! We have them all under our thumb! They all think Mars is red when anyone can plainly see it’s more of a yellowish-green!” I just don’t get it.
I don’t either. Yet…
I’m not exactly sure what the point is. However, there is some lively debate about whether Mars currently has any life on it (I believe it probably does) and whether Mars could have had any life on it in the past. For a long time “science” taught us that Mars was an old cold lifeless planet. Lately, though, as we look more closely at Mars there has been evidence of water. Lots of water. To some that means life.
So perhaps the color debate ties in with the larger debate about life on Mars. I’m still learning.
Good point. I hate it when other people use a term like “the White House said”, and then I did it myself! 
Thank you for stressing that point.
It’s not? Well, perhaps that’s a topic for another thread…
GOM, I think the place for this discussion is in this thread, because the sort of deception you’re attributing to NASA would require the agency to be something completely different from what it is in reality. Anyone who says NASA is like the CIA is probably a disgruntled contractor or an attention whore who gets off on stringing the lunatic fringe along with tales of mysterious disappearing files and visits from men in black.
From the scientist’s point of view, NASA is, at times, a source of money, an irritating bureaucracy, a facilitator of great things, and an interface with the government and thus, to some extent, the taxpayer. It most certainly is not a secretive, all-powerful, draconian mafia with a stranglehold on information flow and a shadowy secret agenda.
NASA’s greatest sins (again, from the point of view of a scientist) are the inevitable consequences of drawing together a large number of freethinking, independent, smart people to try to do science by committee. Nobody gets exactly what he wants from a mission or an instrument or a program. Mistakes are made and it’s not always clear who to blame. NASA also has these weird hangups about accountablity to the public that are very inconvenient to accomodate sometimes. (:))
“Science,” whether you distainfully put it in quotes or not, is not a static entity. It’s not fair to demand that scientists be right about everything all the time! We aren’t omniscient. All we can do is make the best guesses we can based on the information we have in hand. If you can you think of a better way to do things, I’d be delighted to hear it.
There is a long traditition of great hope for life on Mars, and the Viking missions, to many, were a great disappointment. However, Viking never proved that there was no water on Mars. All it showed was that there was very little water at the landing sites, and at the resolution of the Viking orbiters there was no evidence for suface water in the present epoch. Given the absence of evidence of the copious amounts of surface water that we were hoping for, the picture Viking painted of a bone-dry, dead Mars was very sobering to the scientific community.
Is it surprising that with better missions and higher resolution imagery, we’re finding new information? Isn’t that the whole point of exploration? It’s hardly evidence of a conspiracy that, given new data, scientists come to different conclusions! If NASA really was falsifying data from Mars, wouldn’t they have presented a more consistent picture of Mars, rather than an inconsistent one, filled with mistakes, false starts, revisions, and retractions?
Is there life on Mars? I have to give the scientist’s answer: I don’t know. We do not have any solid evidence for the existence of life there, but what we do have is evidence that Mars may be more hospitable to life than we thought in the post-Viking era. To say that there is evidence for “lots” of liquid water at the surface of Mars today might be overstating the case a bit, but many scientists are quite enthusiastic about the possibility of near-surface aquifers.
For most scientists, Mars is a fascinating place to study with or without life. The focus of interest by NASA on life and water is in some ways a boon, and in some ways a nuisance. There’s a lot of money available for the study of Mars, and lots of good missions in the pipeline, which makes the Marsies happy. On the other hand, if you take the money to study the martian geology, atmosphere, weather, and so forth, there’s this irritating wink-wink, nudge-nudge thing going on where you have to come up with something to put in a press release about your work that relates to life on Mars, water on Mars, or climate change on Mars.
The possiblity of life on Mars is exciting, but most of the Mars people I know feel that we don’t have the kind of data in hand to make any strong conclusions on the subject and it’s a poor allocation of money and effort to be chasing after life and water at the expense of expanding our basic understanding of the planet. If we improve our understanding Mars as a whole, we’ll naturally understand water and climate change on Mars. If there are traces of life on Mars, we will find it, sooner or later. I think NASA is making a bit of a gamble here. What if there isn’t life on Mars? How are the taxpayers going to react when years and years and years drag by, without The Big Discovery?
Sorry to be so long and rambling, but if the “outsider’s” perspective is that NASA a) has all the answers and b) is powerful and organized enough to keep them from the public, I feel like I should offer a bit of the “insider’s” point of view: NASA is a rag-tag crew of imperfect and ignorant but enthusiastic and curious human beings who are doing their best to work on very hard problems.
“Rag-tag”. I like that. It makes us sound like we’re in Battlestar Galactica.
I think there’s really a lack of understanding of what “NASA” is, which is pretty widespread. I get paid out of grants from NASA, which I spend (an alarming amount of) time writing. But I’m employed at a university. If I wanted, I could spend some of the grant money on hiring an undergrad to do some work. That may make the student a “NASA scientist” in the eyes of the public. Peter Smith, who built IMP, works at the University of Arizona, but received money from NASA to build the camera. People can move from NASA-funded grants to NSF-funded ones and back.
What leverage NASA does have is almost entirely slanted toward more disclosure, more quickly. Raw data from all missions are available after a short period designed to allow the people who invested their time to get first crack at the data. Many telescopes are moving toward making all data public a few years after it was taken. It is extremely common for people to be denied funding if they don’t publish their results (ever hear of “publish or perish”?)
I don’t want to overstate the case-- NASA policies have very little day-to-day influence in my work. But I suppose that really is the point. There are no directives telling me what to work on or what to publish. If I can convince my peers that the work I’m doing is interesting and worth doing, the money gets allocated.
Boy, Podkayne, I don’t think you were rambling at all. Certainly not compared to me…
Battling the Cylon Centurians of ignorance. 
Thanks for adding your perspective. Unfortunately, Phil Plait (the Bad Astronomer) is at AAS now, or he could chime in.
I don’t think it was mentioned (maybe I missed it), but some missions to Mars (IIRC) included color calibrators attached to the landers. Basically, it was a color wheel carried to Mars and that the camera could photograph once there. Then, since we know what that is supposed to look like, the rest of the photos could be adjusted by the same amount (if a true color photo was needed).
Or was that on one of the missions that missed?
(p.s. Hi Lib & asrivkin! long time, no speak)
Pathfinder and Viking had calibration targets, but unresolved questions about the spectrum of sunlight transmitted through the martian atmosphere prevented a rigorous color calibration.
The calibration target on Mars Exploration Rover will be a sundial. Super cool.
Hello Podkayne,
Thanks for your response. Sorry it’s taken me so long to get back to you, but every time I attempt to post here my machine locks up. I can post fine at a number of other boards. Strange.
Quick reply, before my machine freezes again:
a) As I’m sure you know, NOBODY has all the answers.
b) I’m not sure about your powerful and organized comment. Some secrets have been, can be, and will continue to be kept. I don’t mean NASA in particular, but our government in general. Secrets are a necessary way of life in a dangerous world. As curious as I am about some things, I still realize the need for secrets.
P.S. I’m glad to hear the NASA crew is pretty much like the rest of us!
Later.
FWIW, I checked my copy of The Pale Blue Dot and found Sagan’s account of the blue-and-salmon Mars story, on pg 162.
The first photo of Mars wasn’t destroyed by the corrupt and secret bureaucracy of NASA. It was released to the press, and you can see it yourself in Sagan’s book. The sky is definitely blue, and the sand is salmon colored. Beneath it Sagan also reproduces the same picture with the correct color balance, showing a red-orange sky and sand.
I’ll second this (and everything Podkayne said), and add that many astronomical missions are moving towards making all data public immediately. It’s especially true in my field (solar astronomy) where scientists don’t have to write proposals for observations. (The instruments are always pointed to the sun anyway so we don’t have to fight for targets.) Anybody with Internet access can download yesterday’s data from the RHESSI, TRACE or SOHO satellites, as well as all the software and calibration information to make full use of the data. The people who made the instrument still benefit in two ways: they get the credit for building them in the first place, and they have the expertise to make better use of the data.
Sssshhhhhhhh
Let’s not go there! Okay?
Hello again Polkayne,
What can you tell us about the Martian atmosphere? At one time it was supposedly reported at about 10% of Earth’s. Now the number is reported at around 1% of Earth’s atmosphere. How was that measured?
Also, do you remember that big dust storm on Mars some time ago? It might have even been a year or two. I lose track of time…
This storm was over almost all of Mars for a while. IIRC, the storm was blocking our view almost completely. I admit it’s just my gut feeling but a 1% atmosphere, compared to Earth’s, doesn’t sound quite right to create such a gigantic storm. I suppose it’s possible if the dust is extremely fine though. Do you remember this event?
Thanks in advance.
The atmospheric pressure at the surface of Mars is indeed about 1% of the Earth’s atmospheric pressure at sea level, though it can vary by up to 30% depending on season due to the fact that in winter it gets cold enough for, CO[sub]2[/sub], the major constitutent, to freeze. The atmospheric pressure indicates the total mass of the atmosphere, and it has been measured a lot of ways: you can us a telescope to watch a star disappear behind Mars and see how much its light is dimmed and bent by the atmosphere, for example. But the most straightforward measurement is from barometers on a lander.
I can’t speak to the 10% figure unless you tell me where it’s coming from. I’ve never heard an estimate that high, but I certainly am not an expert on historical observations of Mars.
There are several reasons why Mars experiences global dust storms. One is the fierce winds. Though the air is thinner, the winds can be much faster, due in part to the big difference in pressure between the summer and winter hemispheres. The winds can be up to 300 mph, though you should divide that number by 10 to get a sense of how strong the wind would feel, due to the thinness of the atmosphere.
Also, as you suggest, the dust on Mars is very fine, composed of particles around 2 microns in size–that’s comparable to the particles in cigarette smoke!
Another thing to keep in mind that the gravity on Mars is weaker, allowing particles to stay aloft longer.
A subtler point is that when the atmosphere is filled with dust, it absorb’s the Sun’s heat, and very little reaches the ground. This heating of the atmosphere contributes more energy to the storm.
Dust storms, the global ones and smaller ones, seem to happen in southern summer, which is extra hot because that’s when Mars is at perihelion, its closest approach to the Sun. As the Sun heats the southern CO[sub]2[/sub] ice cap (that’s the dry ice that covers the polar cap! Brrrr!) the gas come streaming away from the poles in strong winds, which kicks up dust, which heats the atmosphere, which perpetuates the dust storm.
There was a global dust storm in 2001, and there was also one in 1971 at the time of the Mariner 9 orbiter mission. Luckily, they could shut down the orbiter to conserver resources, or else we would have just had lots of pictures of dust, showing no surface detail. After a month, the storm cleared, and the spacecraft was reawakened to continue its mission.
Thanks.
How much good is a parachute in an atmosphere that thin?
It’ll make a nice burial shroud when you hit the ground.
Seriously, you can use a parachute to slow yourself down - the Mars Pathfinder did. They are especially useful at higher speeds where even in the thin atmosphere a significant load can be put on the canopy, absorbing that energy.
The big problem is that the parachute can’t slow the spacecraft enough for a soft touchdown. It would have to be immense to do that. So instead, parachutes are used to slow the spacecraft down to a speed where braking rockets can take over, or slow it down enough that big airbags around the spacecraft can protect it from high impact speeds.
Right, what Sam said. The Viking landers used parachutes and rockets, Pathfinder used a parachute and airbags. The failed Mars Polar Lander misson used a parachute and rockets. It may have crashed because the jolt of its spring-loaded landing legs popping into place was mistaken by the sensors for the jolt of landing, cutting the rockets when it was a good distance above the ground. Sad, huh? Close only counts in horseshoes and handgrenades. Mars Exploration Rover will use a parachute and airbags (which are 100% succsessful so far, as compared to only 67% for rockets. )
Here’s a brief note on the test of the MER parachute. They use a normal (but huge) wind tunnel, and scale down the wind speed to compensate for the thicker atmosphere.
