Sol 225: Science ops continue

Finally, Curiosity's beaming back science data again! Hooray!

Sol 215, one of the first images beamed back from Curiosity about fifteen days
after sol 200's anomaly happened. The view was shot by the lower-mounted front hazard
avoidance cameras (right 'B' eye) and shows 'John Klein' in the foreground with
Aeolis mons in the distance. (NASA/JPL)

Of course one of the first things that happens after such prolonged episodes without any data returns is to take images for vehicle orientation verification. This will allow scientists and engineers on Earth to quickly assess the rover's position especially arm position, see if other data sources follow and thereafter plan their next move. They do this with the navigation cameras which shoot in black and white and are mounted 2m above the ground alongside the colour science cameras.

Sol 223 360 degree navigtion mosaic panorama. It was a rough
set up so forgive the saw-like horizon though that isn't the point of
this image as explained above (NASA/JPL/panorama by Abraham Samma)

More samples of John Klein are planned to be processed for SAM to refine the measurements presented to us 2 weeks ago. Conjunction will slow things down for the time being but with a working B-side computer and a restored A-side as back up, Curiosity is set to restart her mission of exploration. Let's roll!

Solar conjunction... what's it all about?

Yet another brilliant addition to JPL's 'Mars in a minute' video for all my readers who still don't understand why its such a big deal for Curiosity and other missions operating at Mars. Enjoy!

The 44th Lunar and Planetary Science Conference

Its March and that can only mean one thing; the annual Lunar and Planetary Science Conference (LPSC) 2013 is here! This conference is important to all of us space geeks because its where all planetary scientists come together to discuss the latest in researches into the inner workings of the planetary bodies and other objects in our solar system. An amazing amalgam of the Earth sciences, engineering, astronomy and public outreach, the LPSC is as good as it gets in terms of a hot bed for new discoveries and insights into our solar system.

One of the most wonderful things about the LPSC is its generous publication of extremely informative abstracts which actually look more like mini-papers than abstracts per se. The most anticipated papers (atleast for me) would be from Curiosity this year given the mission's importance as a flagship mission and the amount of data returned over the last 200 sols. This year is especially interesting as the conference planners are becoming more social than ever before; a facebook and twitter page are available as well as a list of microbloggers who will tweet all the latest from the proceedings. I only follow one blogger and that's Planetary Society's ever esteemed Emily Lakdawalla (she has written a post on the website's blog about the whole conference; be sure to follow her on twitter @elakdawalla for excellent tidbits). There is also a youth program somewhere which helps to highlight the commitment these men and women of science have made to help bring pure science to the public.

Lunar and Planetary Science Conference 2013

Though I won't be attending, I'm definitely going through lists abstracts on Curiosity's mission. There's so much I can hardly breathe! I'll select one or two and maybe talk about them on the blog while we wait for Curiosity to resume her science ops which according to the latest press release should happen by the end of this week.

The conference is already halfway through (it runs up to Friday this week). Already there have been two video press briefings on the discoveries made by two missions, one of them being Curiosity which you can read about here. It talks about the observation by Mastcam and the DAN instruments of hydrated minerals in the rock veins that the rover encountered on entering the Yellowknife bay area.

For the curious ones, go to the conferences site here to experience so much more on the absolute fine cutting edge of planetary exploration! Onwards!

The Mount

Just when I wanted to start fooling around with mastcam raw images, out pops this gorgeous sol 45 view of the more than 5km high Mount Sharp aka Aeolis Mons on the mission's website!

True colour image of Mount Sharp taken by Curiosity's 100mm Mastcam.
Click the picture to see the full size version. (NASA/JPL/MSSS)

As you may notice there is a bit of a problem when it comes to discerning details under natural colour on Mars. Everything just seems... beige with no diversity in shade. In fact, on the scientist's side, the natural colour reveals very little about something on Mars. So to reveal a little more detail in this beige nightmare, the picture is usually white-balanced to make the scene look like its under a more balanced, Earth-like setting.

White-balanced version. Click to see a full size. (NASA/JPL/MSSS)

There is a lot of compensation on the blue side of the spectrum hence the colour of the sky. You can even clearly see colour differences in the rocks that make up the lower slopes. These are more ancient, Noachian era rocks that should contain more smectite like at John Klein. As you move up the slope towards the lighter-toned rocks we should be seeing more sulphate rich content as we move into the more acidic Hesperian era of Mars and finally the more modern, arid Amazonian rock at the summit. Welcome to Mars' central library of history! Or natural history for that matter!

Mission Discovery!

The Mars Curiosity mission has uncovered multiple lines of evidence to suggest that the past Mars was once a wet world just like ours with a thicker atmosphere and environment conducive to support life as we know it! This is an achievement that sees the mission fulfilling its prime objective of determining the habitability of the past environment at Gale crater instead of just finding evidence for water per se which other previous missions to Mars have done many times.

Listing down the evidence from the most prominent one to the minor ones from different instruments aboard the rover:

1. First from the Chemical and Mineralogical instrument; this instrument investigates concentrations of chemical compounds and minerals in the sample it receives. By the use of the X-ray diffraction instrument which I explained about here, we see a spectrum that is similar to the previous site of investigation called 'Rocknest' which contained plagioclase feldspar, olivine and pyroxene with small amounts of anhydrite, magnetite and about 25-35% of amorphous (non-crystalline) material. None of these minerals are asscoiated with hydrological activity. Roughly the same was found at John Klein except for a signal that proved to be the holy grail of the mission, atleast 20% phyllosilicates (which in this case; smectite). These are clay minerals whose presence cannot be explained without invoking lots of neutral pH water or normal water that you would drink without high acidity or alkalinity. Here my friends is the turning point in the mission. Although Gale was chosen for a landing site by having a lot of this stuff to study, Curiosity's discovery has forced the mission team to reshuffle their priorities by making the study of the area John Klein lies in (an alluvial fan) a primary objective instead of a secondary objective.

X-ray diffraction spectrum  of Rocknest and John Klein comparison.
The signal for clays is annotated. (NASA/JPL/Ames)

     2. To confirm CheMin's signal, we turn to SAM, the sample analysis at Mars instrument which also says              the same. For a reminder of how SAM works go here. The evidence comes from the quadropole mass spectrometer which detects chemicals based on their mass and measures their abundances by signal intensity. The result was this graph that shows signal intensity against temperature at which the volatiles were released.

(NASA/JPL/GSFC)

Diagnostic of clay is the presence of a high water release. So both of Curiosity's analytical instruments show evidence for this mineral class which is excellent. But apart from that we see certain interesting features in the data. We see sulphur containing minerals of 2 kinds; oxidised and reduced forms. These are probably sulphur dioxide and and hydrogen sulphide as far as the masses go. This is extremely interesting to the scientists:

Scientists were surprised to find a mixture of oxidized, less-oxidized, and even non-oxidized chemicals, providing an energy gradient of the sort many microbes on Earth exploit to live. This partial oxidation was first hinted at when the drill cuttings were revealed to be gray rather than red.  

"The range of chemical ingredients we have identified in the sample is impressive, and it suggests pairings such as sulfates and sulfides that indicate a possible chemical energy source for micro-organisms," said Paul Mahaffy, principal investigator of the SAM suite of instruments at NASA's Goddard Space Flight Center in Greenbelt, Md.

 Usually organisms require reduced chemicals to oxidise and release energy here on Earth. So what we're seeing may constitute a potential energy source for a microbe finding itself on Mars.

     3. From SAM again we see from the tunable laser spectrometer a new deuterium to hydrogen ratio which is higher than what we have seen at Rocknest. At that location it was taken as evidence that Mars has lost a lot of its atmosphere since it was formed. A higher ratio means that John Klein is giving us a window further into the past (older rocks are supposed to contain more clays indicative of a wetter past 3 billion years ago) when Mars may have had a thicker atmosphere than what we have today. Again this is conducive for habitability.

     4. The final line of evidence comes from comparing images of rocks seen by Curiosity with those taken of rocks by the Opportunity rover over at Meridiani planum where it too is investigating smectite rich rocks. The rocks are similar in appearance and both contain concretions it seems, indicating a history of water transport, cementation and alteration of the rocks. Beautiful!

The left rock lies near Endurance crater at Meridiani planum. Its called 'Wopmay'. The right one is
at Gale and is called 'Sheephead'. See the concretions sticking out of the surface? (NASA/JPL/Cornell/MSSS)

Overall this has been an amazing mission update and it all begs the question; what's next for the rover? Yellowknife bay has proven to be quite an interesting place to visit. The geology is incredible and its helping to achieve mission objectives at the moment. So Curiosity will be sticking around for a while. But despite the geological diversity of the area, Mount Sharp still beckons with its layers of history, something that the current area of investigation cannot contribute; understanding how Mars progressed from being a grey-white planet full of clay and water and everything nice for life to a red, dry, dead world we see today.

The high thermal inertia area comprising Yellowknife bay is highlighted in red.
(NASA/JPL/ASU)

Mars is approaching conjunction where it will be behind the sun as seen from the Earth. This will make communications difficult so that, together with continued tests being conducted on the rover's A side computer, images and data returns will be at an all time low. Curiosity is now, however, a fully commissioned rover and the next drilling activity is scheduled for no earlier than May (again because of conjunction). Recent memory tests show that the A side is on the verge of recovery so the mission is safe. Ready to study the history of Mars and the mystery of its habitability.

View of the inner solar system from above with the Celestia program illustrates the current
beginnings of planetary comjunction of the Earth, sun and Mars. Direct comms will be
interfered by the sun.

Resumption of Operations

Last week it was announced that Curiosity would resume surface science operations with its B side computer. Delay in resuming operations was caused by a solar storm directed at Mars on March 6 or around sol 206 (this storm was not directed towards Earth) which forced the mission team to put the rover to sleep to prevent any stray charged particle from the sun from damaging the delicate electronics. Mars' thin atmosphere, a lack of ozone and weak magnetic field means electronics need protection from radiation. Nevertheless, better safe than sorry. We certainly don't want a repeat of sol 200.

Fortunately the storm was less intense than anticipated and Curiosity was woken up the next day on sol 209 for operations. I expected images to be relayed for the first time since sol 200's anomaly during last weekend but the plan was apparently scrubbed for some unknown reason. So far there is nothing new on the ground.

Curiosity uses RAD750 flight computers like these ones. They
are slower than your average laptop (100MHz versus 2000MHz or 2GHz processing
respectively) but the RAD750 is designed for highly radiation environment. Besides
we're not running any video games aboard Curiosity! Credit: BAE systems

Spaceref.com provided new insights into the computer problem in an article dated March 8. Here they say that the side A computer, which is independent of side B and is now being salvaged to serve as a back-up in the future, suffered a memory-corruption event triggered by a stray charged particle(s) that managed to penetrate the shielding. Nevertheless the team is at work to patch things up and maybe introduce software updates to prevent such things from becoming an issue should it occur again.

These computers are tough as mentioned in the article:

As journalist William Harwood of CBS wrote in a CNET article just after the rover landed last August, "The RAD750s also meet lifetime dosage standards that are up to a million times more extreme than those considered fatal for a human being. As a result, over a 15-year period, the RAD750 chips aboard Curiosity would not be expected to suffer more than one external event requiring intervention from Earth. 

"The RAD750 card is designed to accommodate all those single event effects and survive them," Vic Scuderi, BAE business manager for satellite electronics, said in an interview with Harwood. "The ultimate goal is one upset is allowed in 15 years. An upset means an intervention from Earth - one 'blue screen of death' in 15 years. We typically have contracts that (specify) that."

The blue screen of death is well known amongst Windows users. But so far we aren't there... yet. Should B side wink out and side A is unavailable, it may be curtains for our big girl.

Tomorrow there will be a televised press conference about updates from Curiosity. I expect it will be about data from the analytical labs SAM and CheMin which managed to analyse a bit of core sampling before sol 200's fiasco. Hopefully there will be some good news if not brilliant news. The conference will take place at 1700hrs GMT or 1pm EDT Tuesday 12 March, 2013. You can watch it via NASAtv online or ustream. Brief details are here. It is now sol 212, half past twelve midday at Curiosity's locality. Stay tuned!

Catching up with bad news

The last time I heard from the rover was two weeks ago in the middle of exams when the mission team announced the successful drilling operation made by the rover on Feb. 8 with its powerful drilling tool into the target dubbed 'John Klein'. Subsequent transfer of the inner rocky material collected by the drilling tool was made on Feb. 20 to the CHIMRA (pronounced 'chimera') instrument via an internal mechanical transfer using the drills flutes and a series of tubing right inside the instrument turret. CHIMRA is designed to process the material using a set of fine sieves to separate fine materials on the order of 150microns in diameter (about as fine as flour) which the analytical instruments CheMin and SAM can use. Sample deliveries to these two occurred on Feb. 22 and 23 respectively. Subsequent days were dedicated to managing power for analysis on the material by SAM and CheMin up to sol 200 (Feb. 27) along with other scientific activities.

The following video is a computer animation showing the various movements that the arm has to do to drill and get the material into CHIMRA. Its sort of like shaking the salt out of a salt pot, same principle.

Mastcam picture taken of the rock material in CHIMRA's scoop, Feb. 20 or sol
193 of operations (NASA/JPL/MSSS)

Except for some concern about the remote possibility of CHIMRA's sieve coming off after long use as seen on one flight copy here on Earth (there are 2 flight copies used for tests. The other did not show such a problem.), everything seemed to be going swimmingly for Curiosity. Then Feb. 28 came which was sol 201 for the mission. The rover had trouble saving data in its flash memory (solid state memory or 'flash' is much more sturdy for space flight than hard disks) so it went into a state called 'safe mode' where the machine stops running whatever plan it was following at the time, cancels all activities for the day and awaits further instructions from Earth. The team responded with telemetry data analysis from up to when the fault happened to see what caused the problem (which was found to be a flash problem). The plan then was to move to Curiosity's back up computer (with these kinds of projects where you cannot reach your asset, you need to have maximum redundancy) called side B which has its own set of of subsystems including its own, unaffected and independent flash memory. Although Curiosity can continue operations on this redundant flight computer, side A needs to be restored to working order or its potentially curtains for the mission.

Diagnostics continue so far as no scientific data or images have come down since sol 200. Operations are set to resume soon according to the latest bulletin on the mission's site. Such memory issues tend to happen with space missions and they are usually dealt with quickly and expertedly. If anyone will find a solution to Curiosity's current woes, it'll be JPL's code monkeys!

One of the last few images from the rover taken on sol 200. This
shot was taken by the lower-mounted front hazard avoidance cameras showing
the John Klein formation and Mount Sharp in the horizon.
(NASA/JPL)