Cassini Will Switch to Back-up Thrusters

Cassini Will Switch to Back-up Thrusters

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In a move reminiscent of Star Trek’s Scotty fine-tuning the Enterprise’s performance, engineers working with the Cassini spacecraft will begin work to switch the spacecraft’s thrusters to a back-up set after noticing a degradation in performance from the main thrusters that have been in use for over 11 years, since the spacecraft launched in October of 1997. The thrusters are used for making small corrections to the spacecraft’s course and for attitude control. In mid-March, the current set of eight thrusters, referred to as branch A, will be swapped over to a redundant and identical set, branch B. In a forward thinking move, almost all Cassini engineering subsystems have redundant backup capability. And in a testament of the spacecraft’s robustness and reliability, this is only the second time during Cassini’s 11-year flight that the engineering teams have gone to a backup system.

“Ay, Captain. Auxiliary thrusters engaged!”

Cassini’s propulsion engineers began to see a lower performance from one of the thrusters on branch A in October, and recently a second branch A thruster also began now showing some degraded performance.

An extensive review with the propulsion system contractor, Lockheed Martin Space Systems, Denver, Colo., the thruster manufacturer, Aerojet, Sacramento, Calif., and propulsion experts at NASA’s Jet Propulsion Laboratory, Pasadena, Calif., was completed last week. The recommendation was made to swap to side B as soon as is practical.

Nine of Saturn's moons are in this image.  Can you find them? Credit: NASA/JPL/Space Science Institute
Nine of Saturn's moons are in this image. Can you find them? Credit: NASA/JPL/Space Science Institute


Mid-March is the earliest practical opportunity to make the swap. This allows time for the team to properly test and prepare the sequence of commands that will be sent to the spacecraft. Science planners have identified a period where no high-priority science will be lost during the switch, which will be done over a seven-day window. It also is a time when no navigation maneuvers are required to maintain the spacecraft’s trajectory.

The swap involves commanding a latch valve to open hydrazine flow to the B side, and powering on some thruster control electronics. No pyrotechnic devices are involved in the swap, and the action is fully reversible if necessary.

A few years ago, the backup reaction wheel was brought online and is currently functioning as one of the three prime wheels.

Cassini successfully completed its four-year planned tour and is now in its “Equinox” extended mission operations.

Source: JPL

Spirit Rover Having Memory, Mobility Problems

Special-Effects Spirit Silhouetted on "Jibsheet" Image Note: Rover model by Dan Maas; synthetic image by Koji Kuramura, Zareh Gorjian, Mike Stetson and Eric M. De Jong. Image credit: NASA/JPL-Caltech/Cornell

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The Spirit rover appears to have some memory and mobility problems. Yes, she’s getting old, and it appears she has symptoms of aging similar to humans. On Sunday, during her 1,800th Martian day, or sol, information radioed from Spirit indicated the rover had received its driving commands for the day but had not moved. That can happen for many reasons, including the rover properly sensing that it is not ready to drive. However, other behavior on Sol 1800 was even more unusual: Spirit apparently did not record the day’s main activities into the non-volatile memory, the part of its memory that persists even when power is off. It’s almost five years to the day when Spirit had memory problems with her “flash drive,” but back then, she was just a youngster.

The team operating NASA’s Mars Exploration Rover Spirit plans diagnostic tests this week to see why she did not report some of its weekend activities, including a request to determine its orientation after an incomplete drive.

On Monday, Spirit’s controllers at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., chose to command the rover on Tuesday, Sol 1802, to find the sun with its camera in order to precisely determine its orientation. Not knowing its orientation could have been one possible explanation for Spirit not doing its weekend drive. Early Tuesday, Spirit reported that it had followed the commands, and in fact had located the sun, but not in its expected location.

“We don’t have a good explanation yet for the way Spirit has been acting for the past few days,” said JPL’s Sharon Laubach, chief of the team that writes and checks commands for the rovers. “Our next steps will be diagnostic activities.”

Among other possible causes, the team is considering a hypothesis of transitory effects from cosmic rays hitting electronics. On Tuesday, Spirit apparently used its non-volatile memory properly.

Despite the rover’s unexplained behavior, Mars Exploration Rovers’ Project Manager John Callas of JPL said Wednesday, “Right now, Spirit is under normal sequence control, reporting good health and responsive to commands from the ground.”

Spirit has a history of being a drama queen, but just the same, I’m keeping my fingers crossed that she pulls through this latest mess alright.

Source: JPL

Space Telescope of the Future: SIM

Artist's concept of the current mission configuration. Credit: JPL

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Two of the hottest and most engaging topics in space and astronomy these days are 1.) exoplanets – planets orbiting other stars – and 2.) dark matter—that unknown stuff that seemingly makes up a considerable portion of our universe. There’s a spacecraft currently in development that could help answer our questions about whether there really are other Earth-like planets out there, as well as provide clues to the nature of dark matter. The spacecraft is called SIM – the Space Interferometry Mission. “We’ll be looking for other Earths around other stars,” said Stephen Edberg, System Scientist for the mission, “and by making accurate mass measurements of galaxies, we should be able to measure dark matter, as well.”

Listen to the January 20, 2009 “365 Days of Astronomy” Podcast and my interview with Steve Edberg, and/or read more about the SIM Lite mission below!

The concept for this mission has been around for awhile, and the concept has changed over time, with the telescope going through different incarnations. Currently, the mission is being called SIM Lite, as the spacecraft itself has gotten smaller, however the mirrors for the interferometer have gotten bigger.

While interferometry at radio wavelengths has been done for over 50 years, optical interferometry has only matured recently. Optical interferometry combines the light of multiple telescopes to perform as a single, much larger telescope. SIM Lite will have two visible-wavelength stellar interferometer sensors – as well as other advanced detectors, that will work together to create an extremely sensitive telescope, orbiting outside of Earth’s atmosphere.

“These are instruments that can measure positions in the sky to almost unbelievable accuracy,” said Edberg. “Envision Buzz Aldrin standing on the moon. Pretend he’s holding a nickel between thumb and forefinger. SIM can measure the thickness of that nickel as seen by someone standing on the surface of the Earth. That is one micro arc second, a very tiny fraction of the sky.” Watch a video depicting this — (Quicktime needed)

Having the ability to make measurements like that with SIM, it will be possible to infer the presence of planets within about 30 light-years from Earth, and those planets can be as small and low mass as Earth. As of now, the SIM team anticipates studying between 65 and 100 stars over a five year mission, looking for Earth analogs, planets roughly the same mass as Earth orbiting their stars in the habitable zone, where liquid water could exist.

So, for example, SIM Lite would be able to detect a habitable planet around the star 40 Eridani A, 16 light-years away, known to fans of the “Star Trek” television series as the location of Mr. Spock’s home planet, Vulcan. See a movie depicting this possible detection — (QuickTime needed).

SIM will not detect a planet directly, but by detecting the motion it causes in the parent star. “That’s a difficult task, there’s no question,” said Edberg, “but it gets complicated, based on what we see with our own solar system and what we’ve seen in other planetary systems. We know there are other systems out there that have more than one planet. Multiple planets can confound the measurements.”

But SIM should be able to detect the different sized planets orbiting other stars. SIM Lite recently passed a double blind study conducted by four separate teams who confirmed that SIM’s technology will allow the detection of Earth-mass planets among multiple-planet systems, by having the ability to measure the mass of different sized planets, to as low as Earth-mass.

“With a few exceptions all the planets we know about were detected using a method called radial velocity,” said Edberg, “where we look at the periodic motion of the star coming toward us and moving away from us on a regular basis. But when you make measurements like that, when you have no other information, you don’t know the orientation of the planets’ orbit with respect to the star, or the mass of either the star or the planet.”

With the hottest stars, radial velocity can’t be used to look for planets. But SIM Lite will be able to look at stars clear across the diagram from the coolest to the hottest stars.

“So far, we haven’t found any other Earth-sized planets,” said Edberg. (See our article from 1/19/2009 about a planet that could possibly be 1.4 times the mass of Earth.) “So, finding Earth analogs around stars like the sun is really the big goal.”

“It’s a big question mark in the other planets we know about now – I believe we know only about 10% of the masses of extrasolar planets,” said Edberg.

A second planet search program, called the “broad survey,” will probe roughly 2,000 stars in our galaxy to determine the prevalence planets the size of Neptune and larger.

Graphic illustrating the mass and quantity of planets SIM Lite could potentially detect. Number of terrestrial planets assumes 40% of mission time divided evenly between 1-Earth mass and 2-Earth mass surveys.  Credit:  JPL
Graphic illustrating the mass and quantity of planets SIM Lite could potentially detect. Number of terrestrial planets assumes 40% of mission time divided evenly between 1-Earth mass and 2-Earth mass surveys. Credit: JPL

SIM will also be used to measure the sizes of stars, as well as distances of stars, and be able to do so several hundred times more accurately than previously possible. SIM Lite will also measure the motion of nearby galaxies, in most cases, for the first time. These measurements will help provide the first total mass measurements of individual galaxies. All of this will enable scientists to estimate the distribution of dark matter in our own galaxy and the universe.

“Dark matter is known for its gravitational affects,” said Edberg. “It doesn’t seem to interact with normal matter as we know it. To get more clues on it, we want to know where it is.”

SIM will measure on two different scales. One is within the Milky Way Galaxy, making measurements of stars and globular clusters, and making measurements of stars that have been torn out of smaller galaxies that orbit the Milky Way.

“We can do mass model of our galaxy and find out where that mass is, including what has to be a lot of dark matter,” said Edberg. “When we make measurements of how our galaxy rotates, you find that it rotates like a solid. Instead of being Keplerian, where you think of Mercury going around the sun faster than Pluto, from all the way inside the galaxy as close as we can measure to the center, out to beyond the sun’s distance, the Milky Way rotates like it’s a solid body. It’s not a solid body, but that means it must have a density that is constant all the way through and that means there is far more matter than we can see.”

“Another thing we’d like to know is the concentration of dark matter in cluster of galaxies,” Edberg continued. “The Milky Way is part of the Local Group of galaxies, and SIM has the capability to measure stars within the individual galaxies, which in turn can be modeled to tell us where the dark matter is within the Local Group. This is cutting edge. This is one of the big mysteries right now in astrophysics and cosmology.”

Extra solar planets and dark energy may seem like two completely different things for one spacecraft to be looking for, but Edberg said this is an example of how everything is tied together.

“To get planet masses we need to know the masses of the parent stars,” he said. “SIM will make measurements of stars, particularly binary stars, and determine the masses of stars for a wide variety of star types, and be able to estimate the sizes of the planets that are causing the reflex motion. To make the measurements, and because stars with planets are going to be scattered around the sky, we need to have a grid of stars that are the fixed points to give us latitude and longitude, so to speak. If you know exactly where St. Louis and Los Angeles are, then it’s much easier to triangulate where things between them are. We need to do this all around the sky, and to do that we tie that down to the stars, and SIM can do that. These are fundamental questions that we don’t know the answers to, but SIM will help us find the answers.”

So, SIM Lite will be searching from within our neighborhood to the edge of the universe.

What’s the status of this future spacecraft?

“We’re on hold right now,” said Edberg. “We recently passed the double blind test to show that SIM can find Earth-like planets in systems that have multiple planets. SIM is also undergoing a decadal review to make the case that the astronomical science community needs to have a mission like SIM to strengthen the foundations enormously.”

Technical work is being done to prepare to build the actual instruments, but due to budgetary reasons, NASA has not set a launch date. “We think we could be ready to launch by 2015 once we get the go-ahead from NASA,” said Edberg, “and the go ahead depends on the decadal review, and the reports should be out in about a year.”

SIM Lite would provide an entirely new measurement capability in astronomy. Its findings would likely stand firmly on their own, while complimenting the capabilities of our current, as well as other planned future space observatories.

For more information about SIM check out the mission website.

Russia Proposes Mission to Search for Evidence of Astroengineering

An artistic rendering of Larry Niven's Ringworld

[/caption]It is probably the most seductive urge for mankind: search for extraterrestrial life. There are many ways to look for life; from digging into the Martian dirt with robotic landers looking for pre-biotic compounds, to building vast radio antennae to “listen” out for distant communications either leaked or transmitted deliberately from a distant star system from a developed, intelligent civilization. However, despite our best efforts, we appear to be the only form of life for hundreds of lightyears around. It is eerily quiet out there

Although we appear to be drawing blanks so far, it doesn’t stop us from trying to work out what we should be looking for. In the quest to find a vastly advanced alien civilization, a forthcoming Russian space telescope hopes to bridge the gap between science fiction and science fact, attempting to find evidence (or lack thereof) of observable attempts of astroengineering by an alien race…

New and exciting ways are being formulated to work out whether intelligent life does exist beyond our blue oasis. Programs such as the famous Search for Extra-Terrestrial Intelligence (SETI), Messaging to Extra-Terrestrial Intelligence (METI) and the tongue-in-cheek Wait for Extra-Terrestrial Intelligence (WETI) are conceived to somehow interact with a sufficiently advanced alien culture (one that has the ability to communicate via radio, at least). In an engrossing entry I read in last week’s Carnival of Space Week 86, Dr Bruce Cordell (21st Century Waves) discussed the apparent paradox between UFOs and Fermi’s Paradox (in a nutshell: if aliens have visited our planet, as UFO sightings would lead us to believe, why haven’t we intercepted any kind of signal via SETI?). I was most interested with Cordell’s thoughts on optical communications that could be used by extraterrestrials to communicate with a pre-radio communication human era. Apparently, in 40 years, mankind could be generating very bright signals using 30 terrawatt optical beacons for pre-radio civilizations to see over 10 light years away, brighter than their brightest star. If there are advanced civilizations out there, why have we not seen their optical transmissions?

To summarize, we are a little confused by the lack of life in our Universe (intelligent life in any case).

So, perhaps we can find other ways to spy on our hypothetical alien neighbours. Could we build a powerful telescope to seek out structures built by alien civilizations? Possibly, according to a forthcoming Russian space-based telescope project: The Millimetron Space Telescope.

On reading an article about this subject on the Daily Galaxy, I thought I’d heard of something like this before. Sure enough, during my research on the Infrared Astronomical Satellite, IRAS (surrounding the whole Planet X controversy), I found out that work was being done to try to find the infrared signature of the hypothetical Dyson Sphere. The Dyson Sphere is a theorised example of an astroengineered structure by a significantly advanced alien race. There are many variations on this theme, including science fiction ideas of an engineered “ring” straddling a host star (as pictured top). In the case of the Dyson Sphere, this megastructure would generate infrared radiation, and analysis of IRAS data has been done to establish an upper limit on the existence of these objects. So far, no Dyson Sphere candidates have been found (within 300 light-years from Earth in any case).

To build on the IRAS survey, in 2017, Russia hopes to launch the Millimetron to observe distant stellar systems in millimeter, sub-millimeter and infrared wavelengths. This instrument has a long list of aims, but one of the extreme results that could come from this project is the detection of astroengineered megastructures.

The goal of the project is to construct space observatory operating in millimeter, sub-millimeter and infrared wavelength ranges using 12-m cryogenic telescope in a single-dish mode and as an interferometer with the space-ground and space-space baselines (the later after the launch of the second identical space telescope). The observatory will provide possibility to conduct astronomical observations with super high sensitivity (down to nanoJansky level) in a single dish mode, and observations with super high angular resolution in an interferometric mode. – The Millimetron Project.

By combining the orbiting telescope with observatories on the ground, it may be possible to create a very long baseline interferometer (VLBI) with huge baselines beyond 300,000km. This will provide unprecedented angular resolution. Alone, the large 12 metre dish will allow astronomers to probe emissions at the nano-Jansky level, where radio astronomers usually operate from <1-100 Janskys (the Jansky is a non-SI measurement of electromagnetic flux density).* With a system like this, very weakly radiating sources may be detected, possibly revealing structures such as the Dyson Sphere, or possibly sci-fi concepts like Larry Niven’s “Ringworld”.

Although I am dubious as to whether our persistent efforts to find intelligent extraterrestrial life will ever turn up positive, the search is exciting and certainly boosts the scientific process in directions we wouldn’t have necessarily examined…

Sources: The Millimetron Project, Daily Galaxy

*Thanks to Don Alexander for tightening up a couple of points in this article

Latest Chandrayaan-1 Images

A Mini-SAR strip overlain on an Earth-based, Arecibo Observatory radar telescope image. Taken Nov. 17, 2008, the south-polar SAR strip shows a part of the moon never seen before: a portion of Haworth crater that is permanently shadowed from Earth and the sun. Credit: ISRO/NASA/JHUAPL/LPI/Cornell University/Smithsonian

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A few “new” images have been released from the Chandrayaan-1 lunar orbiter mission. The latest are the first images from NASA’s radar instrument that’s hitching a ride on board the Indian Space Research Organization’s (ISRO) spacecraft. Called the Mini-SAR (synthetic aperture radar), NASA’s instrument recently passed initial in-flight tests and sent back its first data from Nov. 17, 2008, showing the first look inside one of the Moon’s coldest, darkest craters. The image above shows a swath from the Mini-SAR overlaid on a ground-based telescope image of Haworth Crater. The swath shows the floor of this permanently-shadowed polar crater on the moon that isn’t visible from Earth. The instrument will map both polar regions to search the insides of craters for water ice.

“The only way to explore such areas is to use an orbital imaging radar such as Mini-SAR,” said Benjamin Bussey, deputy principal investigator for Mini-SAR, from the Johns Hopkins University Applied Physics Laboratory. “This is an exciting first step for the team which has worked diligently for more than three years to get to this point.”

Bright areas represent surface roughness or slopes pointing toward the spacecraft. The data cover an area approximately 50 kilometers (31 miles) by 18 kilometers (11 miles).

The two north-polar strips have been mosaicked to show the western rim of Seares crater.Credit: ISRO/NASA/JHUAPL/LPI  Click for larger image
The two north-polar strips have been mosaicked to show the western rim of Seares crater.Credit: ISRO/NASA/JHUAPL/LPI Click for larger image

Two more radar swaths from the Moon’s north pole have been stitched together to show the western rim of Seares crater. The mosaic covers an area roughly 80 kilometers (50 miles) long by 20 kilometers (12.5 miles) wide.

“During the next few months we expect to have a fully calibrated and operational instrument collecting valuable science data at the moon,” said Jason Crusan, program executive for the Mini-RF Program, which also includes a radar instrument on the upcoming Lunar Reconnaissance Orbiter mission

Mini-SAR is one of 11 instruments on Chandrayaan 1. Not setting any speed records in making the images available to the public, a few other images were recently released that were also taken in November 2008. Mission managers have had to deal with the spacecraft overheating slightly due to orbiting in almost continual sunlight, and therefore they decided to use only one instrument at a time. Normal operations should begin soon, where all the instruments will be able to function normally and together.

Moon 3D from the TMC.  Credit:  ISRO
Moon 3D from the TMC. Credit: ISRO

This Digital Elevation Model of the lunar surface was generated by using imagery from India’s Terrian Mapping Camera. The TMC will map topography on both sides of the Moon and prepare a 3-dimensional atlas with high spatial and altitude resolution.
Lunar crater from the TMC.  Credit:  ISRO
Lunar crater from the TMC. Credit: ISRO

This image, also from the TMC, shows details of a lunar crater.
3D anaglyph from the TMC.  Credit:  ISRO
3D anaglyph from the TMC. Credit: ISRO

Here’s one of several 3D images of different regions of lunar surface captured by TMC. By looking through 3D glasses, you get a grasp of the height of features shown here. More 3D anaglyph images are available on the ISRO site.

Chandrayaan-1 launched from India on Oct. 21, 2008 and began orbiting the moon Nov. 8.

Sources: NASA, ISRO,

Latest Images From HiRISE (More Eye Candy)

Gullies on the dunes of Russell Crater on Mars. Credit: NASA/JPL/University of Arizona

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I don’t know about the rest of you, but I could look at images from the HiRISE camera on the Mars Reconnaissance Orbiter all day…and there are days I have spent a great deal of time perusing through the gorgeous, high-resolution images. Here are just a few of the latest images the HiRISE team has released. This first one is one of the most stunning yet. It’s part of a dune field in a crater called Russell Crater (53.3S and 12.9E.) The dune field itself is roughly 30 kilometers long, and appears to have formed from windblown material trapped by the local topography. The image was taken in October 2008, during the Mars’ southern hemisphere’s deep winter, where temperatures are low enough to allow the carbon dioxide frost to be stable. Looking closely, you can see the frost, visible on the slopes that don’t get full sunlight. The team says this region is the target of a long term monitoring program by HiRISE.

And there’s more…

Features in Moreau Crater. Credit: NASA/JPL/UA
Features in Moreau Crater. Credit: NASA/JPL/UA

This image is of a so called “flow feature” within Moreux Crater, located at 42N and 44.6E on the edge of Mars’ highlands/lowlands boundary. The crater itself is roughly 135 kilometers in diameter. During an impact event that creates a crater, central uplifts or mounds form on the floor of the crater in craters larger than 7km in diameter. This image focuses on a portion of the Moreux central uplift that apparently broke off and slid away, forming a type of giant landslide. Interesting hummocks, swirls and ridges are found on the surface of the landslide. There are also distinct, almost circular depressions of unknown origin near the foot of the flow. Both light and dark toned dunes later formed on this landform.
Features in a volcano, Hecates Tholus.  Credit: NASA/JPL/UA
Features in a volcano, Hecates Tholus. Credit: NASA/JPL/UA

This image shows features on a volcano called Hecates Tholus. This volcano is located in the northern hemisphere of Mars and is the northernmost of three volcanoes within Elysium Planitia. The “braided” channels seen in this image appear to have formed by water carving into young lava flows. Like braided rivers on Earth, they consist of a network of small channels, often separated by small streamlined “islands.” The fact that they are braided and have streamlined islands has led scientists to interpret these landforms as being created by water (fluvial) rather than by volcanic activity, and perhaps even more than one water-related event created these features, since there are fine sediments and multiple channels.

The water that potentially formed the braided channels may have been released when hot lava came into contact with ground ice.

For more images, as well as more information on these images and high resolution versions, see the HiRISE site. But watch out, you might be there for awhile — there’s lots to look at!

Source: HiRISE

Happy Birthday Spirit!

Full panorama of Spirit's location in Bonestell. Image Credit: NASA/JPL/Cornell University/New Mexico Museum of Natural History and Science

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What were you doing five years ago today? I remember trying to watch NASA TV on my computer in an effort to monitor the status of the Spirit rover that was on its way to land in Gusev Crater on Mars. The feed kept cutting out, and I know it was way behind what was happening in real time at the Jet Propulsion Laboratory. The scientists and engineers there were certainly more anxious than I, but even I had butterflies in my stomach. During the entry and landing, the spacecraft with Spirit aboard maintained radio contact with flight controllers at JPL through a series of tones designed to transmit the status of the lander. The flight team was even able to detect that the lander was bouncing on the surface of Mars, secure in the inflated airbags. But the tones suddenly stopped and there was no signal from the lander for several minutes. The flight control room erupted when the spacecraft sent the signal that it was sitting safely on the Red Planet.

“There was a lot of jumping, hugging and even a few tears of relief here at JPL,” said Chris Potts, who was the MER Deputy Navigation Team Chief back in 2004. “There were definitely some tense moments when we lost the signal after confirmation of bouncing on the surface. Mars just wanted us to wait a bit longer.” The wait was definitely worth it, and now five years later, Spirit and her twin rover Opportunity are still working hard on Mars’ surface. That fact is truly cause for celebration, and there are a few ways you can join in celebrating…

One way to celebrate is to read the three part-article here on Universe Today where we talked with rover driver Scott Maxwell about 1. the rovers’ current status, 2. what its like to drive the rovers, and 3. what the past five years have been like.

Another way to celebrate is to check out Scott Maxwell’s blog, “Mars and Me.” Tonight (Saturday) he is going to start making public his “diary” of the past five years, “The diary of a Mars rover driver, I suppose you could say,” Scott writes in his blog. “I’ve decided to make them public now, as a thank-you to everyone who’s followed the mission for so long, everyone who’s dreamed of being part of it. This is what it was like for one person who was, and still is, part of that mission. This is what it was like to be one person living a small part of a grand, historic adventure.”

Spirit on top of Husband Hill.  Credit: NASA/JPL/Dan Maas
Spirit on top of Husband Hill. Credit: NASA/JPL/Dan Maas

Still another way to celebrate is to listen to Emily Lakdawalla on the Jan. 3rd 365 Days of Astronomy Podcast talk about Spirit’s five years on Mars. The transcript is also available on the site if you’d rather read it.

You can also enjoy Stuart Atkinson’s blog (we’re not related, but he’s a great guy nonetheless!) Cumbrian Sky, where he has put together a great birthday Photoshop image of Spirit, and shares what the last five years have been like for him.

If you haven’t seen JPL’s Five Years on Mars video, I highly recommend it.

Also, the image at the top of this article is a full 360-degree panorama from Spirit’s panoramic camera (Pancam). Click on the image to get the full resolution, and to read the notations which indicate locations for several events of the first five Earth years since Spirit landed inside Gusev Crater.

Happy Birthday Spirit!

Phoenix Not Covered With Ice — Yet

Phoenix landing site, Dec. 21, 2008. Credit: NASA/JPL/UA

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The HiRISE Camera on board the Mars Reconnaissance Orbiter is keeping an eye on the Phoenix lander, and took the above image of the landing site on Dec. 21, 2008. Phoenix, its heatshield, parachute and backshell are still visible on the Martian arctic plains, providing evidence that the spacecraft hasn’t been covered with ice as of yet. Via the HiRISE Blog, scientists say the conditions are hazy and dark because northern winter summer is turning to autumn on Mars. They will keep imaging the site as long as there is enough light to see the lander. Compare this image to previous photos of the Phoenix site, below.

Phoenix and accoutrements from May 2008. Credit: NASA/JPL/UA
Phoenix and accoutrements from May 2008. Credit: NASA/JPL/UA

This color image was taken just after Phoenix landed in late May 2008. Insets show the backshell, parachute and heatshield.
Phoenix site July 08. Credit: NASA/JPL/UA
Phoenix site July 08. Credit: NASA/JPL/UA

In these images, top one taken in July of 2008, and bottom taken in October 2008, you can compare the lighting conditions between late summer and early fall, and now winter (first image) in the northern arctic regions on Mars.
Phoenix September 08. Credit: NASA/JPL/UA
Phoenix September 08. Credit: NASA/JPL/UA

Source: HiRISE Blog, HiRISE site

How to Drive a Mars Rover, Part 3: Five Years on Mars

Santorini Panorama. Credit: NASA/JPL/Cornell/James Canvin

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In preparation of celebrating Spirit and Opportunity’s fifth anniversary on Mars in January, we’ve been talking with rover driver Scott Maxwell, getting updates on the two Mars Exploration Rovers and learning about what it really is like to drive the rovers. Today, Scott will share some of the highlights of the past five years, and his outlook for the future. But first, in the latest updates from Scott via Twitter, he says Spirit tried to back-up off of ‘Home Plate’ but encountered quite a bit of slippage. It looks like she’ll probably end up driving forward and taking the long way around the low plateau to the next target objects, a hill called Von Braun, and a crater-like feature nearby called Goddard. Meanwhile, Opportunity is studying “cobbles” or loose rocks at a region called Santorini, where she has been stationed during solar conjunction. Now that radio transmissions are improving, Oppy will start receiving commands from the rover drivers to hit the road again. The image above is a panoramic image of Santorini, put together by James Canvin at his website, Martian Vistas.

Scott has actually been with the MER mission for longer than just the five years since the rovers landed. He joined the team early on, about three-and-a-half years before the rovers launched. He was part of the development team, helping to write the software used to drive the rovers. Back then, did he ever fathom the rovers would last this long?

How to Drive a Mars Rover, Part 1

How to Drive a Mars Rover, Part 2

“I think back, to that time, and we did all that work where we sat in our cubicles, had meetings and argued with each other about the best way to program the software,” said Scott. “We slaved away working on the mission, never knowing if the mission would succeed or not. We did all that work just for the chance, the hope, that the rovers would be working on Mars for three months. And it was worth it.”

The rover planners include Rich Morris, Scott Maxwell, Sharon Laubach, Joseph Carsten, John Wright and Brian Cooper; and (front row) Tara Estlin, Paolo Bellutta and Ashley Stroupe. Credit: PBS

“And then to do all that work and have the rovers on Mars for five years, it’s like you’re playing a slot machine and you put in your quarter and pull the lever, and not only do a few quarters come out, they keep coming and coming and coming, and it fills up your cup, and overflows. That’s what it’s like to work on this mission.”

OK, Scott, now we want to know the highlights for you from the past five years. Certainly there’s at least one or two memorable moments!

“Certainly for me, there are two things I think of,” Scott said. “One is the first time I ever drove the rover. There was the period early on where we lost contact with Spirit. But then we were able to recover her. But that was a month into the mission where we thought it was only going to last three months, and it delayed the time until I got my first chance to drive her.”

“I still remember the day. We planned and planned and rehearsed the drive. I checked over the sequence a million times before sending it. Then I went home and I should have gone to sleep, but I couldn’t. I just laid there in my bed and stared at the ceiling, and couldn’t get past the thought that right then, at that moment, there was a robot on another planet, doing what I had told it to do. It was just an awesome feeling to imagine that, and that feeling has never left me. I still feel like that every time I drive the rover.”

Scott says it’s an incredible feeling to go outside and look up and see Mars in the sky, and on that red dot way out there is an object, placed there by humans, and humans are telling it what to do. “And I’m one of the people doing that. It’s an absolutely amazing feeling. I feel that way all the time.”

Scott Maxwell, rover driver.  Image courtesy Scott Maxwell
Scott Maxwell, rover driver. Image courtesy Scott Maxwell

Its obvious Scott has a soft spot in his heart for Spirit, as another memorable aspect of the mission involves her, too. Scott tells the story so well and with such passion, I’ll just let him go:

“The other thing I always think about is that Spirit travels the 300 million miles to Mars, she gets to Mars, drives off the lander, and she’s gone all that way with the hope of finding evidence of past liquid water on Mars,” Scott said. “But instead, when she drives around, there’s nothing: just lava as far as the eye can see. She drives around the area and looks at rocks, and then drives over to Bonnevillle crater, which is her best chance of finding evidence of liquid water, thinking maybe if she goes down far enough into this crater there will be something there, but there’s nothing.”

“But way off in the east, there are a range of hills, the Columbia Hills, and (principal investigator) Steve Squyres says clearly the hills may be too far for us to get to, but maybe we can get some images that can tell us something. But Spirit takes off for those hills anyway, even though they are too far away, and never gives up and gets there; she actually makes it all the way to the bottom of the hills.”

“And then,” Scott continued, “she’s at the bottom of the hill, looking up at them, and it’s now twice as long as she should have survived and she has driven three times as far as she was supposed to be able to drive, and she’s tired and her wheels are sore, now is when the real challenge will begin. Now she won’t just be driving over flat terrain, like she was meant to drive on. She’s going to have to climb the hill, which is taller than the Statue of Liberty, and everyone thinks it’s way too tall for this poor little rover to climb. But she does it anyway.”

“She starts climbing up the hill and there are times when she can’t make any progress, so we have to turn her around and give up some of the altitude she’s won and go back and find another path, but she never gives up and goes all the way to the top of that hill that was just impossibly far away when she started.”

A special effect image of Spirit sitting on Husband Hill.  Credit: NASA/JPL/Cornell.  Rover model by Dan Maas
A special effect image of Spirit sitting on Husband Hill. Credit: NASA/JPL/Cornell. Rover model by Dan Maas

“When we came into work that day and we saw that image of Spirit standing on top of Husband Hill with the beautiful panorama of the world around her –she stood there for a long time and took the images of the area around her — to me, that’s one of the achievements, not just of this mission, but of engineering excellence in our whole civilization, to be able to do that. To be able to go so far and do so many impossible things, that image just says all of that for me. I know what it took to get there and be able to take that image, and I feel the pride of being part of the team that made it happen. It is just an amazing experience.”

As incredible as the MER mission has been, we all know the rovers won’t last forever. Someday – and we don’t know when – the rovers will eventually quit working. It’s hard to think about life without the rovers, but has Scott given any thought to what mission he would like to work on next?

“It’s all downhill from here!” Scott laughed. “But, really there’s a lot of cool and exciting stuff going on at JPL. We’ve got another rover we’re working on, the Mars Science Laboratory, and I’ve been working on that. I’m also involved with ATHLETE, which is a 12-ft. tall six legged robot spider on roller skates that we are going to send to the moon. There’s always so much like that going on here at JPL, it’s just like being an engineer in Disneyland. You come to work and say, ‘What cool stuff can I work on today?’ It’s just awesome, and there’s just no end to it.”

Scott says he has nothing against orbiter missions, but to be honest they’re not top on his list. “I’m not putting them down,” he said, “but orbiters don’t really float my boat. I kind of get into rovers, I kind of relate to them, in a way. But you look at a mission like Cassini and it’s amazing! Cassini is finding liquid water spewing out of Enceladus, and dropping a probe onto Titan and getting the first view beneath the thick clouds that cover that moon! It’s just amazing stuff. So even though orbiters aren’t my thing, I might end up on one of them, too, you never know.”

Scott has definitely shown his worth with the rovers, so, even though the MSL launch has slipped to 2011, the rover fans out there are secretly hoping Scott will have a place on the MSL team when the time comes.

Spirit heading off into the sunset.  Special effects image by NASA/JPL/Cornell
Spirit heading off into the sunset. Special effects image by NASA/JPL/Cornell

But in the meantime, Spirit and Opportunity, the Energizer Bunnies of Mars exploration keep going and roving, and sending back loads of data and images.

JPL has put out a video to celebrate the rovers’ five years on Mars, where Scott says it best: “It seems like every day is better than the day before. The mission keeps getting better and better the longer it goes.”

Happy birthday Spirit and Opportunity! We’ll take as many years as you can give us!

How to Drive a Mars Rover, Part 2

Scott Maxwell, using his 3-D simulation software. Courtesy Scott Maxwell

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The Mars Exploration Rovers have been traversing the surface of the Red Planet for almost five years now. But how exactly are the two rovers, Spirit and Opportunity, “driven” from Earth, about 150 million km away? Many of us might have visions of joysticks, similar to what are used for remote control toys, but it’s not like that at all. However, being a “Rover Driver” is one job where having experience with video games and simulation software looks good your resume! Scott Maxwell is one of fourteen rover drivers, or planners as they are also called, who last week gave us an update on Spirit and Opportunity’s status. Today, Scott provides the details of how to drive a Mars rover.

“The way we wished it would work,” said Scott in a phone interview from JPL, “is if we could have a joystick where if we pushed forward on the joystick the rover would go forward, or push back and the rover would stop. But, with lag time delays in the radio signals, you would push forward on the joystick and 10 minutes later the rover would get the signal to go. But on Earth, you won’t know if it worked for another 10 minutes after that because of the time it takes for the signal to get back to you.”

This would create a nightmare in logistics, planning and operations, because the drivers can’t “see” what the rover is doing in real time. So instead, the rover drivers work the Martian nightshift.

Recent view from Opportunity's hazard camera.  Credit: NASA/JPL/Cornell
Recent view from Opportunity's hazard camera. Credit: NASA/JPL/Cornell

“We take advantage that our solar powered rovers have to shut down for the night,” said Scott. “So as the sun is going down in the Martian sky, the rover is commanded to take pictures of the world around them and send it before they go to sleep. When we get that data back on Earth, we go to work. We take all the images and put them into a simulation. We have a 3-D simulation world — kind of like a video game — on our computers. Then, we have a simulated rover that we put down in that 3-D world and we drive that rover around instead.”

So in that 3-D world, the rover drivers can test every possibility, make all the mistakes (tip the rover, get stuck, drive off a precipice, crash into a big rock) and perfect the driving sequence while the real rovers are dozing securely and peacefully. This certainly has helped with the long life the rovers have led, as in five years the rover drivers have safely and successfully guided the rovers to drive in and out of craters, climb a challenging hill, and put on more mileage than anyone ever thought possible. The biggest driving calamity has been getting stuck in a sand dune, but now the driving team has a few tricks up their sleeves to avoid that (see Part 1).

So then, when the drivers perfect the commands inside the simulation and hone the exact sequence of movements for the rover, they upload those commands and send it to the real rover. Then as the sun is coming up on Mars, the rover wakes up, receives a communications uplink from Earth, processes the commands and it goes to work while the rover drivers go to sleep. “At the end of the rover’s day, it sends us more pictures and data, and we start the cycle all over again,” Scott said.

Rover test bed.  Credit: JPL
Rover test bed. Credit: JPL

If there’s a particularly difficult situation, such as how much tilt can the rover withstand without tipping over, a test rover can go through the same sequences in a simulated Mars environment out in JPL’s Mars Yard.

Back in 2004 during the “prime mission,” the first three months of the mission (the original length of time the rovers were slated to last) everyone who worked with MER lived on Mars time. Since the two rovers are on opposite sides of the planet, that meant operations going on 24 hours a day. And since a Mars day is 40 minutes longer than Earth’s day, that meant a perpetually shifting sleep/wake cycle, a difficult situation where your body continually feels “jet-lagged.” But now that the mission has been ongoing for such a long time, the planners operate in a more Earth-normal mode and even take some weekends off. But still, a planner’s eight- hour shift can start anywhere from 6:00 a.m. to noon.

So what’s an average drive for the rovers? “It varies widely,” Scott said, “but an average drive is in the neighborhood of a few meters.” Right now Spirit is struggling her way up the side of “Home Plate,” a low plateau, which for a rover is a steep hill. The crumbly soil gives out beneath her wheels as she makes the climb, making it difficult to drive father than a few centimeters in a day. Plus, Spirit is dealing with low power levels from dust-covered solar panels, providing limited energy for any big drives. Just after a recent dust storm, Spirit’s solar panels were producing only 89 watt hours, which is about the energy needed to run a small light bulb for an hour and half.

Spirit's dusty solar panels.  Credit:  NASA/JP
Spirit's dusty solar panels. Credit: NASA/JP

But Opportunity’s power levels are much better, and she recently had drives as long as 216 meters, as she puts the pedal to the metal in an attempt to reach Endeavour Crater, about 12 km away.

Some of the rover drivers work mainly with one rover (Steve Squyres has said it’s easy to get attached to one rover or the other, depending which one you’re working with) but Scott goes back and forth between the two. “That’s in part because I’m a team lead, and part because I’m the kind of person who wants to run around and be part of everything all the time!” he said. When we talked with Scott last week, he was working with Spirit, and thought that this week he will probably do a drive or two with Opportunity.

Currently Spirit’s total odometry is at about 7,530 meters (over 4.6 miles), while Opportunity’s odometer reads almost 14,000 meters (about 9 miles).

JPL has some wonderful videos of the rover’s treks, travails and progress, and you can keep track of the rovers’ progress by checking for regular updates on the MER website.

Tomorrow: What have you been doing the past five years? Scott Maxwell shares what five years of driving the Mars rovers has been like.


How to Drive a Mars Rover, Part 1

How to Drive a Mars Rover, Part 3