Archive for the ‘Oddysey’ category

Watching out for Dust Storms

April 15, 2009

NASA just sent out this press release discussing the various ways that we watch out for dust storms that might be dangerous to the rovers. I have actually used data from the Mars Color Imager (MARCI) that they mention in the release, but I used it for the exact opposite task! I wrote programs that search through the images taken by that camera (there are a lot of them, it gets global coverage every day!) over a certain timeframe and choose the least dusty ones. This is useful for removing the effect of the atmosphere and tracking changes on the surface: for example, if I run my program before and after the huge dust storm in 2007, you can see the wind streaks in Gusev crater changing.

Anyway, here’s the NASA press release. You may also be interested in Emily’s post about recent dust activity on Mars.

PASADENA, Calif. — Heading into a period of the Martian year prone to major dust storms, the
team operating NASA’s twin Mars rovers is taking advantage of eye-in-the-sky weather reports.

On April 21, Mars will be at the closest point to the sun in the planet’s 23-month, elliptical orbit.
One month later, the planet’s equinox will mark the start of summer in Mars’ southern
hemisphere. This atmospheric-warming combination makes the coming weeks the most likely
time of the Martian year for dust storms severe enough to minimize activities of the rovers.

“Since the rovers are solar powered, the dust in the atmosphere is extremely important to us,” said
Bill Nelson of NASA’s Jet Propulsion Laboratory, Pasadena, Calif., chief of the engineering team
for Spirit and Opportunity.

Unexplained computer reboots by Spirit in the past week are not related to dust’s effects on the
rover’s power supply, but the dust-storm season remains a concern. Spirit received commands
Tuesday to transmit more engineering data in coming days to aid in diagnosis of the reboots.

After months of relatively clear air, increased haze in March reduced Spirit’s daily energy supply
by about 20 percent and Opportunity’s by about 30 percent. Widespread haze resulted from a
regional storm that made skies far south of the rovers very dusty. Conditions at the rovers’ sites
remained much milder than the worst they have endured. In July 2007, nearly one Martian year
ago, airborne dust blocked more than 99 percent of the direct sunlight at each rover’s site.

The rovers point cameras toward the sun to check the clarity of the atmosphere virtually every
day. These measurements let the planning team estimate how much energy the rovers will have
available on the following day. Observations of changes in the Martian atmosphere by NASA’s
Mars Reconnaissance Orbiter, which reached Mars in 2006, and NASA’s Mars Odyssey, which
reached Mars in 2001, are available to supplement the rover’s own skywatch.

The Mars Color Imager camera on Mars Reconnaissance Orbiter sees the entire planet every day
at resolution comparable to weather satellites around Earth.

“We can identify where dust is rising into the atmosphere and where it is moving from day to
day,” said Michael Malin of Malin Space Science Systems, San Diego, principal investigator for
Mars Color Imager. “Our historical baseline of observing Martian weather, including data from
the Mars Global Surveyor mission from 1998 to 2007, helps us know what to expect. Weather on
Mars is more repetitive from year to year than weather on Earth. Global dust events do not occur
every Mars year, but if they do occur, they are at this time of year.”

Two other instruments — the Thermal Emission Imaging System on Mars Odyssey and the Mars
Climate Sounder on Mars Reconnaissance Orbiter — monitor changes in airborne dust or dust-
related temperatures in Mars’ upper atmosphere. Orbiters also aid surface missions with radio
relays, imaging to aid drive plans, and studies of possible future landing sites.

When orbital observations indicate a dust-raising storm is approaching a rover, the rover team can
take steps to conserve energy. For example, the team can reduce the length of time the rover will
be active or can shorten or delete some communication events.

In recent weeks, frequent weather reports from Bruce Cantor of Malin’s Mars Color Imager team
let the rover team know that the March increase in haziness was not the front edge of a bad
storm. “Bruce’s weather reports have let us be more aggressive about using the rovers,” said Mark
Lemmon, a rover-team atmospheric scientist at Texas A&M University, College Station. “There
have been fewer false alarms. Earlier in the mission, we backed off a lot on operations whenever
we saw a small increase in dust. Now, we have enough information to know whether there’s
really a significant dust storm headed our way.”

At other times, the weather reports prompt quick precautionary actions. On Saturday, Nov. 8,
2008, the rover team received word from Cantor of a dust storm nearing Spirit. The team deleted
a communication session that Sunday and sent a minimal-activity set of commands that Monday.
Without those responses, Spirit would likely have depleted its batteries to a dangerous level.

Winds that can lift dust into the air can also blow dust off the rovers’ solar panels. The five-year-
old rover missions, originally planned to last for three months, would have ended long ago if
beneficial winds didn’t occasionally remove some of the dust that accumulates on the panels. A
cleaning event in early April aided Opportunity’s power output, and Spirit got two minor
cleanings in February, but the last major cleaning for Spirit was nearly a full Martian year ago.

Nelson said, “We’re all hoping we’ll get another good cleaning.”

JPL, a division of the California Institute of Technology, Pasadena, manages the Mars
Exploration Rovers, Mars Odyssey and Mars Reconnaissance Orbiter for NASA’s Science
Mission Directorate, Washington. More information about the rovers is at
http://www.nasa.gov/rovers .  Dust reports from the Thermal Emission Imaging System,
operated by Arizona State University, Tempe, are at http://themis.asu.edu/dustmaps/ . Weather
reports from the Mars Color Imager team are at
http://www.msss.com/msss_images/latest_weather.html .

Advertisements

An Ancient Ocean on Mars?

November 17, 2008

slide2_040820205548

Bad Astronomy has a post today about possible evidence for an ancient ocean on Mars, based on this press release. It’s an interesting post, but all the hype confused me. The results that supposedly suggest an ocean on Mars are old, it’s just the interpretation that is new, and that is not very convincing to me. The basis of the argument is that potassium, thorium and iron were transported to the northern lowlands, leeched out of the rocks and re-deposited in a thin layer. The detections of these elements tend to be below the “shorelines” that people have drawn on Mars, and therefore this is claimed as support for an ocean.

My questions is: why not just put the volcanic rocks in the lowlands to begin with and skip the whole business with the transport, leaching and re-deposition? It’s certainly possible that the elements were deposited by oceanwater, but I don’t think it’s necessarily the best explanation.

Don’t get me wrong, I love the idea of an ocean on Mars. But that’s why I’m so cautious about people claiming to discover one. There are so many scientists (and others) who want Mars to once have been Earth-like, that they start to see evidence for it everywhere, even if it isn’t really there, or isn’t very compelling. The more you want to find something, the more cautious you need to be when claiming that you have found it.

I know, I know. The headline: “Oceans on Mars are One of Many Possible Explanations for Observations” doesn’t have quite the same ring to it. But I think it’s important to save the big headlines for the big discoveries. These results and their interpretation are fascinating! But I’m not convinced yet.

How to Look at Mars

August 20, 2008

There is so much Mars data out there that it hard to keep track of all of it! Thankfully there are some useful tools that let anyone look easily look at orbital data of anywhere on the planet.

The first is a program called “jmars“. This java-based program distributed by Arizona State University lets you overlay all sorts of global datasets, from MOLA topography to THEMIS nighttime infrared maps to H2O abundance from the Odyssey gamma ray spectrometer. It also shows the location of high-resolution images from MOC, HiRISE and CTX, and lets you either load a low-resolution version of the images right in jmars, or click a link and web-browse to a higher-resolution version. I use this program all the time. Here’s a screenshot of what I’m (supposed to be) working on right now. It shows a THEMIS day-IR map of the Meridiani region of Mars with CTX images overlaid on top and outlines of the locations of all the HiRISE (red) and MOC (pink) images of the area. (click for a bigger version)

I also discovered yesterday that you can generate a 3D view of Mars with jmars also! Check out this view of Valles Marineris (no vertical exaggeration).

The second tool that I often use is Google Earth. “But wait!” you say, “I thought we were talking about Mars!” Oh, we are. The trick is, you just drape earth in Mars data and everything works great! Here’s a link to a website describing how to set up Google earth to display all sorts of Mars data. Follow the directions and soon you too can click and zoom on a globe that looks like this:

Have fun!

Rescinded

March 25, 2008

I don’t have time to write a long post, but I thought I should share the latest about the rover cuts. The NASA administrator Mike Griffin has stated unequivocally that shutting down a rover is not an option. The letter directing the budget cuts to MER and Odyssey has been rescinded, and we are essentially pretending that the last week didn’t happen.

There’s still a budget problem with MSL, and the money still has to come from somewhere, but the official word at this moment is to go ahead as if none of this happened.

I’ll post more about this as I learn more…

Mars Budget Cuts

March 24, 2008

Exploring another planet is an expensive business. We all know this, but sometimes it hits home harder than others. Today was one of those times. This afternoon at an all-hands meeting of the Mars Exploration Rovers team, we heard about some particularly bad budget news. The situation is this: the Mars Science Laboratory mission is costing more than expected. It is common for this to happen with spacecraft missions because there are so many unexpected difficulties to overcome. Due to the overruns with MSL, the powers-that-be at NASA have decided that, rather than hurt other missions in space science, the money should come from the Mars Exploration program’s budget.

Starting immediately, $4 million is going to be cut from the remaining $11 million in the MER budget for the rest of fiscal year 2008. The remaining $7 million is not enough to operate both rovers on Mars.

The Mars Odyssey mission is also facing a devastating $4 million cut, with the stipulation that the spacecraft must remain safe and operational to be used as a communications relay with landers on the surface. I am not directly involved with Odyssey, so I can’t comment on what has been going on within their team today, but I will say this: if this cut goes through, it will reduce a spacecraft doing revolutionary science at Mars to a communications satellite.

As for the Rovers, it is entirely possible that one of the rovers will be put into hibernation mode from now until the end of this fiscal year (October). Coincidentally, from now until October happens to be winter at Spirit’s site, and the rover was already going to be very limited in its activities. However, “very limited” activities are still scientifically valuable, and are certainly better than none at all. A lot of people are very upset about this.

Not only will this likely eliminate the valuable science from the Spirit winter campaign, it may also result in members of the MER team leaving to pursue other projects with more stable budgets, and some team members may simply be let go to cut costs. Once those team members leave, there is no simple way to get them back. It is possible (but extremely difficult) to recover from a cut and get a healthy budget again, but trained members of the MER team are irreplaceable.

At the meeting today, Steve Squyres made it clear that there are three assets that cannot be replaced and that he is going to fight tooth and nail to preserve: the two rovers and the MER team.

The heads of the MER team also called upon everyone listening not to get negative about these cuts and not to take out our frustration with pot-shots against other missions or against the NASA administrators. Nobody at headquarters or on the teams affected wants to see things like this happen, but sometimes hard decisions have to be made.

The Rovers and Odyssey are extremely successful and extremely valuable missions, returning never-before-seen data from Mars every day. To cut their budgets and halt the science operations of perfectly good spacecraft just to scrape together a little money for a future mission seems like a bad way of doing things. The problem is, if all the money has to come from the Mars budget, there is no way to win. Either you sacrifice current missions to keep MSL on track, or you maintain current missions and delay MSL, and that delay costs more money than you save. All in all, it’s a bad state of affairs.

With all the uncertainty in these events, things may change minutes after I post this. We will be doing our best to keep you up to speed. Check back here for the latest…