The Sol 2115 wheel imaging went well, and we received the images needed to plan a drive back to "Sgurr of Eigg," near the Sol 1999 rover position. The >50-meter drive dominates the Sol 2116 plan, but leaves time for continued atmospheric and other scientific observations. Before the drive, Right Mastcam will image the ChemCam target selected by AEGIS on Sol 2115 and Navcam will monitor the opacity of the atmosphere. After the drive and the standard post-drive imaging needed to plan weekend activities, Mastcam will measure the atmospheric opacity and ChemCam will observe another target selected by AEGIS. Early in the morning of Sol 2117, Mastcam and Navcam will again monitor opacity, and Navcam will look for clouds overhead and near the horizon to measure wind velocity.

Earth and Mars are getting closer to each other this month, and by the end of this month Mars will be closer to Earth than it has been since 2003! Mars is visible low in the southeast after evening twilight. If you have a good telescope, you can monitor the progress of the global dust storm that is being intensely studied from spacecraft orbiting Mars as well as by MSL.

The priorities for Sol 2115 are to image the rover's wheels and acquire the images needed to plan a drive back to the Sol 1999 location, where we might start another drilling campaign. The MAHLI images of the wheels taken on Sol 2114 with the dust cover closed show that there is enough dust on the cover to make it difficult to see the wheels, so a different approach to wheel imaging was planned for Sol 2115. To minimize the risk of dust contamination of MAHLI's optics while the cover is open, MAHLI will image only the wheels on the left side of the rover from above the wheels, keeping MAHLI pointing downward while the dust cover is open. The wheels on the right side of the rover will be imaged by the left Mastcam rather than MAHLI. Then the rover will turn in place to allow imaging in the direction of the next drive, toward the southwest. After acquiring the standard post-drive data, Mastcam will observe the Sun and crater rim to continue the monitoring of the dust opacity over Gale Crater. These observations will be repeated twice early in the morning on Sol 2116 to look for short-term changes in opacity. In addition, ChemCam will use the AEGIS software to autonomously select a bedrock target for a 3x3 LIBS raster. Tactical planning went smoothly, so it was an easy day for me as SOWG Chair!

After our attempt to drill the Voyageurs target did not reach sufficient depth due to the impressive hardness of the rock , the team is beginning to finish up its activities at this location before heading a bit further uphill to find a more suitable (i.e., softer) drill target. All evidence suggests that this rock target is one of the hardest yet observed in Gale crater, a property that may be indicative of this entire section of the Vera Rubin Ridge. To a geologist, variations in rock hardness could indicate several different physical and chemical properties about a rock. It is important for us to further characterize and understand why this rock unit is so much harder than the underlying rocks within the Murray formation. Could this increased hardness be related to changes in water chemistry as the sedimentary rocks were being deposited? Or, could this increased hardness be due to subsequent cementation as iron-rich water was injected into the previously deposited sedimentary rocks? In order to address these possible formation mechanisms (and countless others), we must continue to gather data on the physical, chemical, and mineralogical properties of this portion of the Vera Rubin Ridge.

Today's rover activities contain a combination of scientific investigations and engineering activities. The plan starts with a short imaging science block around 11:30am local time, where Mastcam will be used to acquire images of the surrounding landscape to search for short-term changes to the surface, including sand migration and changes to dust cover. Navcam will also be used to investigate the atmospheric dust content and to search for nearby dust devils. Following this block of observations, Curiosity will use the Mars Hand Lens Imager (MAHLI) high-resolution camera to investigate the shallow Voyageurs drill hole and to image the rover wheels with its dust cover closed (to avoid dirtying the camera lens). After a short nap and a data uplink to the Mars Reconnaissance Orbiter as it passes overhead, Curiosity will embark on another block of science activities beginning around 3:00pm local time. This second suite will include Mastcam images of the dusty atmosphere, a ChemCam laser-induced breakdown spectroscopy (LIBS) chemical analysis of the Voyageurs drill hole, a LIBS measurements of the ChemCam calibration target, and a follow-up Mastcam documentation image of the drill hole. This will conclude the sol 2114 science activities.

I served as the geology science theme lead during yesterday's plan, when the team first had to deal with the realization that the drill activities at the Voyageurs target did not penetrate deep enough into the target to acquire materials for analysis onboard the rover. While disappointing, the information gathered about the rock properties and drill activities led to a deluge of productive scientific discussions about how to proceed and what these observations tell us about the geologic environment that Curiosity is investigating. It's moments like these that remind me of how lucky I am to be working with such an impressive group of scientists and engineers, who can collectively turn a frustrating sigh into a gasp of excitement as we think about our next observations and what more we have to learn about this interesting and foreign environment.

Unfortunately, we found out this morning that the "Voyageurs" drill target was a much harder rock than expected. While our drill plan executed perfectly, our bit stopped short of the full depth we need for sampling. The engineers are still evaluating the data to better understand the target. I had a busy morning as SOWG Chair, as the team had to come up with a new plan for today while thinking about our longer-term strategy. Ultimately, we decided to focus on contact science and documenting the mini drill hole in today's plan.

The plan kicks off with several Navcam observations to monitor atmospheric opacity during the ongoing dust storm. Then we'll take several Mastcam change detection observations to characterize the movement of sand, followed by several ChemCam observations to assess the diversity of color and composition in the bedrock here. We'll also take a ChemCam RMI image of the "Voyageurs" target, which will help with targeting the drill hole with ChemCam in tomorrow's plan. The afternoon includes a few more environmental monitoring activities, including a Navcam line-of-sight image, Mastcam tau, and crater rim extinction observation. Then Curiosity will image the drill chuck, drill bit, and turret, to monitor our tools. In the evening, we'll acquire an APXS integration on the drill tailings, and overnight we'll get a longer APXS integration on the drill hole. Today is a reminder that it's hard to operate a rover and drill on another planet, but I'm hopeful that we'll find a way to sample this part of the ridge!

Drilling on another planet is no easy feat, and each time we have the opportunity to do so on Mars feels pretty special. The focus of the weekend three-sol plan is to drill the target "Voyageurs," which is part of an outcrop that shows a high hematite signature in orbital data.

The weekend plan kicks off with several Navcam and Mastcam observations of the atmosphere to continue to monitor the ongoing dust storm from our unique vantage point on the ground. Then ChemCam will analyze the "Voyageurs" target, followed by Mastcam multispectral imaging. Curiosity will continue several important environmental monitoring observations later in the afternoon and first thing the next morning, and throughout the second and third sols. The second sol also includes more Mastcam change detection observations of three different targets to look for changes and the movement of fine material. Then we'll acquire MAHLI pre-drill images, and APXS on the future dump locations. With those observations complete, we'll be "go" for the full drill of the "Voyageurs" target on Sol 2112! I'll be on duty on Monday, so I'm anxiously awaiting the results of the drilling attempt and look forward to finding out what this rock is made of!

I first became involved with Curiosity shortly after starting my third year of graduate school in the fall of 2011. My graduate advisor was selected to join the mission as a Participating Scientist, and he enlisted me to help analyze orbital data over Mt. Sharp as part of that role. In particular, I was tasked to examine data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) to see what minerals Curiosity might find when she landed and, importantly, where exactly she should drive to visit the best exposures.

One of the most the significant things I found was the signature of the mineral hematite (Fe2O3) associated with the feature we now call Vera Rubin Ridge. Many collaborators and I spent the winter and spring of 2012 -- the time between launch and landing -- working out the geological implications of this discovery as best we could using orbital data, and beginning to ponder the specific observations Curiosity should make when she reached the ridge. I first presented these findings to the Curiosity science team on sol 15 of the mission (or August 20, 2012 Earth time).

Almost 2100 sols and countless exciting discoveries later, Curiosity is now poised to drill at the exact spot we first detected the strongest hematite signature over seven years ago. We've named the new drill target "Voyageurs" after a National Park in northern Minnesota. I love this name because it reminds me we truly are a team of voyagers, participating in a mission of exploration and discovery. The data we collect from this sample will help us better understand the environments that shaped Mt. Sharp over time, and, on a personal level, it will allow me to test some of the hypotheses I first started to formulate as a graduate student back in 2012.

Sol 2109 will be the first sol of our drilling campaign at Voyageurs (very close to the former target "Stranraer" that we examined back around sol 2004). The main focus of the sol's plan will be contact science of the site, including DRT, MAHLI, and APXS observations. We'll also take a Mastcam documentation of yesterday's AEGIS target and do some ChemCam calibration activities. As always, we will continue to take environmental science observations to monitor the ongoing dust storm. As you can imagine, I am quite anxious and excited to see what we find!

After being out of commission for over a year, Curiosity's drill is making not just a comeback, but a strong one, with imminent plans for a second drill hole within the span of 60 sols. The rover is heading back to a place it visited on Sol 2005, looking to drill near target Stranraer. Curiosity has just been climbing back up Vera Rubin Ridge from drill target Duluth, which was drilled on Sol 2057 at the base of the ridge. If the rover succeeds with another drill target within the next few sols, it will be quite a rapid turn-around. Previous instances when drill holes were made within rapid succession include the combination of Mojave and Telegraph Peak (sols 882 and 908) at Pahrump; the trio of Lubango, Okoruso, and Oudam on Naukluft Plateau between sols 1320 and 1361; and Quela and Sebina between sols 1464 and 1495.

Curiosity still has about six meters to go to the area around Stranraer, so the short drive will be a feature of today's activities. Along with that, and still using target names from northern Minnesota, ChemCam will analyze targets "Fort_Francis and "Icarus_Lake". APXS and MAHLI will analyze a dark rock named "Orr". (A MAHLI image of nearby bedrock target "Dumbarton_Rock" is shown in the above image. Laser pits and crystal forms can be seen in the red rock.) After the drive, Navcam will take images of the region in front of the rover, and the onboard computer will select a new target for ChemCam to shoot. Mastcam will take an image for the clast survey, and will check the sky conditions with a tau measurement and a view out to the crater rim (if it shows up through the dusty air). RAD, REMS, and DAN will get data, including a DAN Active measurement, and MARDI will take an image of the ground beneath the rover.

The image above shows the Mastcam view as of Sol 2104, in which the nearby terrain is clearly visible, but nothing beyond the foreground, and the entire scene looks a murky red-brown color due to the dust storm. Unhampered by the storm, Curiosity is heading back toward a site visited on Sol 2005 for what we hope will be the next drill target. Jupiter is known for its "Great Red Spot", which is a swirling storm thousands of kilometers in diameter. The rover drive destination could perhaps be called the "Great Red Spot on Mars" as it seems to indicate the presence of a reddish mineral, hematite, as seen from orbit and in rover spectra. Of course this spot is not at all as prominent from orbit as Jupiter's Great Red Spot, but the orbital spectra do predict this location to have one of the highest surface hematite abundances in this part of Gale crater.

ChemCam was marked healthy over the weekend after repetition of a known event last week. REMS lost a small amount of science data over the weekend in a slight anomaly, but the instrument remains healthy.

Today we will uplink a one-sol plan. Activities will include a drive to cover most of the 50 meters remaining to our planned drill target. There are three targets in the pre-drive workspace. The arm will deploy MAHLI and APXS to target "Chippewa". APXS will get two 15-minute integrations; MAHLI will image from 25 and 5 cm distances. ChemCam will target "Animikie" nearby. Mastcam will document that target plus "Barnum", a piece of bedrock in between the other two. Navcam will continue checking the atmospheric opacity and Mastcam will collect a 4-image mosaic of "Taconite_crater." DAN, REMS, and RAD will continue taking environmental data.

Tomorrow is a "soliday" or effectively a leap day in which Earth has an extra day relative to Mars. Our next sol of uplink will be on Wednesday.

Our primary goal for today's planning was to continue to approach our next drill location on the Vera Rubin Ridge by paralleling the north side of the ridge (seen on the left side of this image) during this plan's drive while documenting the geochemistry of the bedrock we're currently parked on and continuing to study the ongoing planet-encircling dust storm. A warning from ChemCam received early this morning prevented us from employing ChemCam for both of those purposes, but it was cleared up later and will be ready for Monday's planning. We therefore took advantage of the unexpected availability of science time to include some routine Mastcam calibration activities and additional observations of the dust storm.

The amount of dust over Gale Crater has been slowly declining over the last two weeks and it's possible the dust storm has reached its "peak". Whereas on Earth we have thousands of surface weather stations and a constellation of spacecraft observing the weather, on Mars we are comparatively blind to global conditions. But based on what data we do have, we may now be entering (or soon entering) the period where the massive amount of dust in the atmosphere will slowly settle out and Mars' shrouded surface may once again be clearly visible from space.

While the rest of us are enjoying fireworks, BBQs, and spending time with friends and family, Curiosity will remain hard at work over this Fourth of July holiday. On Monday, the science team planned Monday and Tuesday activities on Mars, while today (Tuesday) they planned Wednesday and Thursday activities. This will allow the rover team to take a well-deserved holiday break on Wednesday!

Because of this interesting planning timeline, however, the science team had to make today's plan before Curiosity executed the plan that was created yesterday. This is no problem though, as we're in the same location, so we have plenty of activities to do and know which targets to focus on.

In yesterday's plan, Curiosity used her arm to acquire Alpha Particle X-Ray Spectrometer (APXS) measurements on three targets - one brushed with the Dust Removal Tool (DRT) and two unbrushed targets. Today's plan will use the arm to acquire high-resolution images of these three targets (named "Dumbarton Rock," "Duntarvie Castle," and "Duntelchaig") using the Mars Hand Lens Imager (MAHLI). There was quite a bit of discussion about how much time the MAHLI and other images acquired by Curiosity would take in the middle of this dust storm, now that the sky is much darker than usual and the illumination conditions are very different from the typically clearer skies that Curiosity has been used to for the past several years. In the end, it was determined that imaging would not be significantly influenced by the darker and dustier skies. A ChemCam LIBS analysis was also planned on the "Callanish" target, which is a layered block just off the right front wheel of the rover. This observation will help in our continued documentation of the chemical variations observed as we climb back up the Vera Rubin Ridge.

Following these operations, Curiosity will tuck her arm back into its stored position and continue her drive up the ridge. During her drive, Curiosity will acquire frequent images of the ground using the Mars Descent Imager (MARDI). This imaging sequence is referred to as a "sidewalk video," as the final stitched mosaic looks like sidewalk blocks moving across the martian landscape. These sequences help us to see how the terrain under the rover changes as we progress across the surface. After her drive, Curiosity will undertake a standard post-drive imaging campaign to characterize the surrounding landscape, which can be used by the rover team to plan subsequent scientific and navigational activities. On the second day of the plan, Curiosity will obtain automated chemistry measurements using the ChemCam LIBS instrument. These data will be sent down to the rover team before the next planning session.