I almost didn't get to drive the rovers.
As one of the five developers of the software used to build the command sequences and rehearse and visualize the rover activities, I really wanted to be one of the people using it in flight. Unfortunately, only three members of the team were selected to be Rover Planners (a job title we believe was chosen in place of Rover Drivers to make the job sound very boring and reduce competition for it). I was not one of them.
I was originally slated to be a downlink analyst looking at the telemetry from the rover to assess the driving and arm operations. This entailed months of training to learn how to run somebody else's software, a much more difficult task than using your own. Fortunately for me, and unfortunately for someone else, a position opened up on the Rover Planner team and I was transferred over. This entailed more months of training to learn the procedures, but the fuse was very short since Spirit was careening towards its landing. The fact that I knew the software tools already was the saving grace that allowed me to be ready to go on landing day.
Looking back on these six years, I'm tired, but amazed, when I think about how much we've accomplished and continue to accomplish. During the prime mission, I remember hearing Steve Squyres say how much we would like Spirit to go explore the hills in the distance but that we would never get there. Well, we have driven to the top of those hills and down the other side.
I remember when Opportunity drove into Purgatory and the Rover Planners immediately said that we needed to back out of the sand dune. After months of testbed activities and review, the decision was made to back out of the sand dune. I can remember looking over at Scott Maxwell, another Rover Planner, and saying to each other "This is so cool!!" (We still say that).
Some of my favorite memories are of giving talks to school kids about what I do, though one of my saddest was being asked by one of the kids, an honor student, if the moon landings were faked. I especially enjoyed calling up Car Talk and asking the guys how to keep our electric vehicle running through the winter on Mars. I laugh when I think about a recent talk I had with Scott when the right front wheel of Spirit seemed to work again after four years of being dragged around. Scott said he didn't know if we were driving with six wheels or only five. Immediately I jumped in, Dirty Harry-style, with, "I know what you're thinking punk. Are we driving with six wheels or only five? To tell the truth, I don't know myself. The question you have to ask yourself is, 'Do I feel lucky?' Well, do ya', punk?"
As we work on getting Spirit out of the current sand trap, I feel manic-depressive about our chances. One day I am sure we will have no problem but the next day I am equally convinced that all is lost. This is about the toughest situation we have ever had to get out of. When we are stuck, it seems as if we are always running out of daylight, which translates to power. It happened at Tyrone, it happened at Tartarus, and it has happened at Troy.
Hmmm, maybe we should stop giving names to locations that start with T.
Updated Aug. 26, 2010
If you're like me, you may have received an e-mail this summer telling you to go outside on August 27 and look up in the sky. The e-mail, most likely forwarded to you by a friend or relative, promises that Mars will look as big as the moon on that date and that no one will ever see this view again. Hmmm, it looks like the same e-mail I received last summer and the summer before that, too. In fact this same e-mail has been circulating since 2003, but with a few important omissions from the original announcement.
I'm Jane Jones, an amateur astronomer and outreach specialist for the Cassini mission at Saturn, and I'm here to set the record straight on when and how you can actually see Mars this month.
1. How did the "Mars in August" e-mail get started in the first place?
In 2003, when Mars neared opposition -- its closest approach to Earth in its 22-month orbit around the sun -- it was less than 56 million kilometers (less than 35 million miles) away. This was the closest it had been in over 50,000 years. The e-mail that circulated back then said that Mars, when viewed through a telescope magnified 75 times, would look as large as the moon does with the unaided eye. Even back in 2003, to the unaided eye, Mars looked like a reddish star in the sky to our eyes, and through a backyard telescope it looked like a small disc with some dark markings and maybe a hint of its polar ice cap. Without magnification, it never looked as large as the moon, even back in 2003!
2. Can the moon and Mars ever look the same size?
No. The moon is one-quarter the size of Earth and is relatively close -- only about 384,000 kilometers (about 239, 000 miles) away. On the other hand, Mars is one-half the size of Earth and it orbits the sun 1-1/2 times farther out than Earth's orbit. The closest it ever gets to Earth is at opposition every 26 months. The last Mars opposition was in January and the next one is in March 2011.
At opposition, Mars will be 101 million kilometers (63 million miles) from Earth, almost twice as far as in 2003. So from that distance, Mars could never look the same as our moon.
3. Is Mars visible in August 2010?
Mars and Saturn made a dramatic trio with brighter Venus this month. Skywatchers enjoyed seeing the three planets closely gathered on the 12th and 13th with the slender crescent moon nearby. On the 27th, you'll see Venus shining brightly in the west. If you look above Venus, you may find faint Mars. Saturn is barely visible above the horizon, getting ready for its solar conjunction next month.
4. Can I see Mars and the moon at the same time this month?
Both the moon and Mars were next to one another on the 12th and 13th, but now you can see both planets a few hours apart. Look for Mars in the west at sunset, and watch the moon rise in the east a few hours later. On August 26th and 27th you can see the nearly full moon rising in the east at about 10 p.m. The bright planet below the moon on the 26th is Jupiter! On the 27th, the moon is to the left of the planet.
5. Will the "Mars in August" e-mail return next year?Most certainly! But next year, you'll be armed with facts, and perhaps you will have looked at the red planet for yourself and will know what to expect. And you will know exactly where to put that email. In the trash!
A theme of Mars exploration is "Follow the Water," since understanding the history of water on our planetary neighbor will help us understand if there were environments favorable for life to occur and how climate has changed over time. This is because all life on Earth requires water and we assume the same applies elsewhere in the universe. The Mars Reconnaissance Orbiter has made numerous discoveries that have provided new insights into past wet environments on Mars, water vapor in the planet's current atmosphere and ice in the subsurface. However, so far, liquid water remains elusive.
The Shallow Radar, or "SHARAD" instrument is the only one on the Mars orbiter that was designed with a goal of discovering liquid water below Mars' surface. This ground-penetrating radar instrument, which was supplied by the Italian Space Agency, transmits a radar signal at approximately 20 megahertz, and receives any radar waves that bounce off the surface or subsurface layers. The radar instrument has sufficient strength to see layers to a depth of about one kilometer (a little more than one-half mile), and even deeper in the polar caps. Layers in the subsurface reflect the radar wave if there is sufficient contrast in their dielectric properties (their bulk electrical properties), as for example between dry sand and ice-filled sand. Water is a much better conductor than other geologic materials, and thus should be readily detected if present.
Of all the features believed to be formed by water on Mars, we have found only two gullies known to have recent flows – within the last 5-10 years. Gullies are narrow channels that emanate from cliff walls, starting well below the local ground surface. Dr. Michael Malin used the Mars Orbital Camera on Mars Global Surveyor to repeatedly image these features because of their fresh, unweathered appearance. These efforts led to the discovery of the two relatively new gullies.
To date, the Shallow Radar instrument's observations of dozens of regions containing gullies show no evidence of liquid water. Since slopes of the cliffs where the two new gullies occur are extremely steep, some scientists put forth an alternate hypothesis in which dry debris tumbling downhill could have formed the latest channels. Yet many of the features observed at these and other gullies strongly suggest that liquid water had at least some role in carving the channels. These channels may have formed when a past climate change caused subsurface ice to melt. Or perhaps liquid water was trapped in a past aquifer. But for now, liquid water, if it exists today on Mars, remains out of reach of the Mars Reconnaissance Orbiter.
The Mars Exploration Rovers, Spirit and Opportunity, have been exploring the geology of Mars for nearly five years - well beyond their expected lifetime of three to six months. In that time they have made amazing discoveries, most importantly finding proof that Mars was once a much wetter planet that may have been capable of supporting life. Spirit has been exploring a region around a small mountain range that seems to have once had hot water or steam, the very kind of place life might have originated on Earth. Opportunity has been investigating craters in the plains that provide views deep underground and show evidence of flowing water in the ancient past.
I am a roboticist at JPL, and just one member of the large team of people who work together to enable Spirit and Opportunity to explore. My work focuses on getting robots to do things intelligently, both by developing software for robot autonomy and by operating our two spacecraft on the surface of Mars. Spirit and Opportunity have become like old friends to the operations team. Every day we are anxious to hear the latest news and see the snapshots taken from the new places they are visiting. Working with the rovers never gets routine as each new location brings new circumstances and new problems to solve.
The challenges of operating Spirit and Opportunity have continued to grow and change as they age, and we have had to develop new ways of driving and operating the robotic arm as capabilities decrease. We are discovering how to operate these rovers in ways for which they were never designed. The discovery process requires a lot of imagination and a lot of practice, both on Earth with our engineering rover and on Mars. It’s this kind of completely new and unanticipated problem that is the most fun for engineers like myself to solve.
Both rovers are now starting to show their old age of 4¾ years (that’s at least 300 in rover-years!), and some parts do not function quite as well as they used to. Spirit has to drive more slowly and constantly monitor her progress to make sure she is staying on the right path to compensate for a broken right front wheel that tends to dig into the soil. Opportunity has limited reach with her instrument arm due to a failed shoulder joint, and has to approach science targets in a very precise way. Despite these limitations, both rovers are now about to embark on difficult journeys which will require them to set new milestones and we will need to learn new ways of driving yet again.
After surviving a very difficult winter, Spirit is soon going to be heading south toward some interesting geological features: a hill called von Braun and a depression called Goddard. Scientists hope investigating these unique features will provide insights into the Martian past. They are looking for additional evidence of hot springs or steam vents that have been hinted at by other observations in this region. Based on comparisons to similar locations on Earth (like deep sea vents), this could be an ideal place for life. Reaching these exciting features requires a long drive through sandy terrain in a very short period of time before next winter arrives. This will mean pushing Spirit to new levels of performance.
Opportunity is finishing up her observations of the 800-meter Victoria crater and then will begin a 12-kilometer, two-year odyssey toward a huge crater (about 22 kilometers across) to the southeast. As this means more than doubling the total distance Opportunity has driven in her lifetime, we are excited to be developing new methods to make record distance drives safely. This will require relying on the rover’s onboard autonomy to keep her safe more than ever before as we drive each day well past what we can see.
Spirit and Opportunity’s story of continued exploration - boldly striking out after one new goal after another, far beyond their design lifetimes - is a genuinely inspiring one. It’s as if Magellan circumnavigated the Earth, then paused and said, ‘You know, that’s not good enough. Let’s go to the moon, too.’
Mars Science Laboratory is a mission to create and send to Mars the largest, most capable and most exciting rover that has been sent to another planet to date. It will be a remote robotic scientist that will help us investigate our most Earth-like neighbor in the solar system. It is literally a mobile laboratory -- the size of a car, with a wide array of science instruments that will help us determine whether Mars has the capability to support life, both in the past and in the present.
Most of my work at JPL has been in the area of research robotics, small projects with very focused goals, such as the Urban Robot project, the Spiderbot, and many others. These robots were created using a small team of engineers who each covered a wide area of responsibility such as mechanical, electrical, and different areas of computer science for perception and navigation.
At times, to get one of these robots working right we would “hack” together a solution, and get it implemented in a very short amount of time! By throwing our energy and ideas into each project, we could push the cutting edge of different technologies and robotic capability that could then be used by future projects and researchers.
In contrast I’m now working on the motor control system of the Mars Science Laboratory mission, which as opposed to research is a “flight project” (it’s going to fly!). This is quite a different experience than the research area - the mission is kind of like taking the goal or purpose of the robot, breaking it down into a million pieces, and putting every piece under a microscope to make sure everything will work absolutely perfectly. Instead of 10 or fewer engineers each working on the different subsystems of the robot, we have hundreds of engineers and scientists who are planning, designing, developing, manufacturing, testing and in general creating a very complicated remote-sensing system.
Sending a robot of any kind to another planet is a completely different story than running any such thing on Earth. For one thing, the robot must operate within very extreme temperatures and handle harsh exposure to the sun’s rays. Future robots may have to deal with steep or challenging terrain, or even a lack of a solid surface such as on Titan, Saturn’s largest moon. And throughout all this, the robot has to work perfectly and stay in communication with Earth. There is no control-alt-delete button to handle software crashes, and no technician around who can run out to push the big red reset button. In other words, if you’re going to run a robot on another planet, it has to land unharmed, work the first time, and run correctly every time you command it to do something, so that you’re guaranteed to get back the vital science data you’re after.
Since Phoenix landed in the northern hemisphere of Mars, the spacecraft has discovered:
1. Water ice near the surface of Mars! And it is really close to the surface, as the orbiting Odyssey spacecraft predicted, and Phoenix confirmed. This demonstrates science in action: data, hypothesis, confirmation of hypothesis.
2. The pH of Martian arctic soil is basic (or alkaline), rather than acidic. On Earth, soil pH is important because most food plants prefer an acidic or neutral soil to grow. Bacteria usually thrive in acidic soils as well. So what we found on Mars is not necessarily the best news for the search for life. One thing I think astrobiologists would agree upon, however, is that life is very adaptable and can exist in many extreme environments!
3. Unlike the landing sites of the Spirit and Opportunity rovers near the planet’s equator, there are no soils with sulfur compounds, or sulfates, in this part of Mars. Spirit and Opportunity found that the soils at their landing sites were cemented together with sulfur compounds. Sulfates do not act as cementing chemicals where Phoenix landed in the Martian arctic.
4. The soil grains Phoenix found are a mixture of angular and rounded particles, with a myriad of colors from rust to white to black. They show degrees of weathering and different chemical compositions.
5. There are high level clouds and ground fogs every night, and the general weather patterns are repeatable.
6. A chemical called perchlorate appears to be prevalent in the soil. On Earth, perchlorate forms in arid areas where there is very little rainfall. The team is still working to understand how perchlorate affects whether life could have existed in this region on Mars.
What does all of this mean? Well for starters, Mars has a diverse geology and geochemistry, much like Earth. Making generalizations about Mars planetwide is probably not the right approach, because of the planet’s diversity. What does it all mean for the bigger picture? Ah, that’s where the difficult science comes in. This takes time. Many members of the science team expect to have their findings ready by December, to coincide with a big science conference in San Francisco. So stay tuned!
Who ever thought that being in the desert in the middle of summer would be so much fun?!
I'm working on a mission called the Mars Science Laboratory, the next rover that NASA is going to send to Mars. Its mission is to help us find out whether or not Mars might have offered a favorable environment for life at one point in time (read more about the mission).
I'm part of the group designing the mission's entry, descent, and landing phase, also known as the "7 minutes of terror." This is a really exciting part of the mission because we're trying to slow the spacecraft down from over 12,500 mph (about 5 times as fast as a speeding bullet) to a screeching halt in about 7 minutes! To do this, so many things have to go right in such a small amount of time. Once the spacecraft enters the Martian atmosphere, and because it's going so fast, the spacecraft gets hotter than the surface of the sun. Then we deploy a parachute supersonically (faster than the speed of sound), fire retro-rockets at a very precise altitude, and gently lower the rover to the surface of Mars on a bridle. No one ever said rocket science was easy!
Since so many things need to happen perfectly, we test things here on Earth before we launch the spacecraft to Mars. One of my responsibilities includes field testing the radar, which will tell the spacecraft how far off the ground it is and how fast it is going during its descent. If the radar doesn’t work properly, the spacecraft could fire its rockets at the wrong time and crash on the surface of Mars. That would be a very, very bad day.
To make sure the radar will work on Mars, a group of us went out to the desert two weeks ago to test it out. The weeks leading up to the test were pretty frantic, with numerous hurdles along the way as we were trying to get the system working in the lab. After we got it working, we took it out to the desert where we attached our radar to a cable, which was attached to a pulley, and all of this in turn was suspended between two towers about 400 feet tall. The other end of the cable was attached to a truck. When the truck drove forward, the radar was lowered at about the speed that it will be descending on Mars just prior to landing.
The testing was so successful that we finished a day early, and were able to leave the really hot desert. We ended up with great data that will help us improve our radar so that it will work flawlessly on Mars. The success of this test made the hard work and desert heat all worth it. But when it was all said and done, we were all pretty glad to go back home, rest and then come back to work to start the cycle over for our next two sets of radar tests–on a helicopter and an F-18 jet!
We've been steadily learning about what it takes to run this thing called the Phoenix lander. As expected, not everything has gone exactly as planned. But that in its own way was planned -- we work to maintain flexibility in our schedule and our design, so that we can absorb new things that happen without throwing the whole team into a tizzy! So what have we been doing?
The Robotic Arm Camera on Phoenix captured this image underneath the lander on the fifth Martian day of the mission. The abundance of excavated smooth and level surfaces adds evidence to a hypothesis that the underlying material is an ice table covered by a thin blanket of soil.
The wet chemistry experiment in one of the lander's instruments called the Microscopy, Electrochemistry and Conductivity Analyzer, or MECA, also found salts in the soil samples. Salts are only formed when water has been present! So that is another indicator that there was abundant water in this region of Mars. What are these salts? They appear to be chemicals containing sodium, magnesium, potassium and chlorine. The soils were found to be alkaline, with a pH greater than 7 -- similar to soils in the upper dry valleys of Antarctica.
But, like I said, everything hasn't been totally smooth. The team discovered that the Martian soil is lumpy and sticks together. That made the first sample difficult to deliver! So the team thought about how to make the process easier, and we figured out various ways to break up the lumps. We tried three methods: de-lumping, sprinkling and agitation.
De-lumping refers to shaking the acquired material in the scoop by running a Dremel-like tool that vibrates the entire scoop, breaking up clumps. Then there is sprinkling: By running the rasp while slightly tipping the scoop, the team can command Phoenix to send a small shower and sift particles down into the TEGA (Thermal and Evolved-Gas Analyzer ) and MECA instruments rather than dumping a whole load of clumped-up dirt onto each instrument. As for agitation, the TEGA instrument has a method to shake itself -- it has an agitator which shakes the sample loose if anything has stuck to its entry port. The sprinkle and agitation methods have been routinely adopted for sample delivery.
The neat consequence of this is that it solves what had always been our worry about how to deliver the same sample to each instrument for comparison of science results. The sprinkle delivery method enables us to put a large sample into the scoop and deliver part of it to MECA microscopy, part to MECA wet chemistry and part to the TEGA instrument. Same sample problem: solved!!
When life gives you lemons, make lemonade! Or in this case, Marsade!
Thanks to all those who posted comments! I'm glad to see that there is so much interest in the Phoenix mission! I wanted to address a few key items.
First off, some staff from the Mars Science Laboratory project will be writing blog entries, so please hold your questions about that mission until the end of summer, when those blogs begin!
Phoenix's Thermal and Evolved-Gas Analyzer, or TEGA, has given the team some head-scratchers, and those challenges continue. In my last blog I talked about lumpy soil, sprinkling and delivery mechanisms. TEGA has been using a method to agitate its cells to help move the soil down from the collection area into the oven as well. Well, it turns out there was a short circuit in a TEGA cell number four when we used the agitator on that cell in June. We used that same agitator for repeated periods of many minutes each time while we were getting the first soil sample into TEGA. Project engineers determined the likely cause was running the screen-agitator longer than we ever had done in pre-launch testing. Running the circuit for such a long time caused some wire insulation to get too warm, causing a short. That short in itself did not cause or threaten any problem with operating TEGA, just on the "grounded" portion of the circuit. It was on the return part of the circuit, between where the current does its work and the ground connection. And then that short apparently healed itself when doors for cell number zero were opened on July 19! However, the occurrence of any short raised concerns that another short circuit might possibly occur, and if it did, it might be a more harmful one. That concern still exists, and has prompted at least two precautions -- a decision to change sampling strategy to treat each TEGA sample as if it could be the last, and an operational rule to avoid running a screen-agitation for more than three minutes without a cool-down period before resuming.
Trying to get samples into the chemistry experiment was a big topic during development. When Peter Smith proposed to send Phoenix to the Martian arctic, the intention was to use as many already-developed pieces as possible. New methods of delivering material to the chemistry experiments on the lander deck had to be simple, because the original design was to use the scoop to dump soil. However, based on pre-launch testing, the original method of scraping/scooping the soil to generate a sample didn't appear to work on ground that is frozen so hard that the ice and soil behaves like cement! The Phoenix team has been doing many tests to ensure that the alternative method, using a little Dremel-like tool called the rasp, works. These tests were done on analogs of extra-hard Martian soil, but there is still nothing like testing with the real stuff on Mars. The Phoenix team had established that the rasp will acquire enough icy soil to deliver a proper sample to TEGA. Those on-Mars tests have taken a long time, as expected. Mars continues to amaze the science and engineering team - the Martian soil is behaving unlike any sample the team used in practice back on Earth! The exciting news is that the team was able to get a sample with a bit of ice into TEGA after all!
Another item came up regarding better ways to clear off the ice table. I'll tell you that the Phoenix development team wrestled with this topic for quite some time. Field studies show that a brush is the best way to remove loose soil from a region a geologist wishes to sample. The problem of course, is that then the brush gets dirty! The ability to clean the brush for further use becomes the problem. The soil on Mars is very, very sticky due to small particle sizes, salts and ice that appear to be acting as cements, and electrostatic properties that cause dust-sized particles to be charged and stick to each other that way too. The team could not come up with a reasonable, relatively inexpensive brush/cleaning mechanism in the short development cycle that the Phoenix mission undertook. (Remember that the mission was only approved in August 2003!) The notion of using the scraping blade on the robotic arm was deemed the most expedient, least costly way to clean surfaces.
Hope this answers some of your questions. Thanks for all of your interest!