“I spy with my big eye…” and landing a rocket on Earth

CuriosityNASA’s Curiosity rover has been a busy bunny on Mars. Currently still parked in the “Pahrump Hills” terrain on the lower slopes of “Mount Sharp”, the Mars Science Laboratory (MSL) rover has now completed its latest drilling activity, collecting samples from a rock dubbed “Mojave 2”.

This isn’t actually the rock from which the science team had originally hoped to gather samples. That rock, dubbed “Mojave” broke apart as a result of the percussive action of the rover’s drill during a “mini-drill” test. As a result, the rock was ruled out as a sample gathering target. “Mojave” was of particularly interest to scientists as Curiosity had images tiny, rice-grain sized crystalline minerals that might have resulted from evaporation of a drying lake, thus presenting the science team with a further insight into environmental conditions within Gale Crater.

To counter this loss, the team relocated Curiosity to  “Mojave 2”, another rock within the same outcrop as “Mojave”, and which exhibits similar crystalline features. In doing so, the team were able to bring into play software improvements only recently uploaded to the rover as a part of an overall systems upgrade, which was deployed to one of the rover’s two computer systems at the end of January.

The software improvements for the drill are the result of investigations into the fracturing of a rock during a previous attempt to obtain samples prior to the rover arriving on “Mount Sharp”. Like an Earth-based hammer drill, the rover’s drill uses a percussive action, so that as well as drilling into a rock, the drill bit effectively hammers its way into the rock. In all, there are six settings governing the amount of percussive energy used during drilling, which range from a gentle tapping (level 1) through to hammering at the rate of 30 times a second with a 20-fold increase in energy imparted (level 6).

During early drilling operations the software monitoring these percussion settings “learned” that defaulting to the “level 4” setting best met the needs of gathering samples in the harder rock types the rover initially encountered. However, this was proving too forceful for the softer rocks closer to, and on, “Mount Sharp”, but the software was unable to switch down to a lower setting.

The drill hopes on "Mojave 2" captured by Curiosity's Mastcam. Towards the top is the small, "mini drilling" test bore, just a couple of centimetres deep, created on Sol 881 (January 28th, 2015, PDT) and some 10 centimetres below it, the sample-gathering bore hole, some 6.5 centimetres deep, cut on Sol 882 (January 29th, 2015, PDT).
The drill holes on “Mojave 2” captured by Curiosity’s Mastcam. Towards the top is the small, “mini drilling” test bore, just a couple of centimetres deep, created on Sol 881 (January 28th, 2015, PDT) and some 10 centimetres below it, the sample-gathering bore hole, some 6.5 centimetres deep, cut on Sol 882 (January 29th, 2015, PDT).

The new update causes the drill software to reset to “level 1” after each drilling operation, and then step through the levels incrementally until the ideal is found. As a result, a sample was gathered from “Mojave 2” without the drill needing to step beyond the “level 2” percussion action.

Drilling operations on “Mojave 2” took place on Sol 881 and Sol 882 (January 28th and 29th, PDT, respectively). As per standard operating procedure, the first drilling operation was a test “mini drilling” to see how the rock responded to encroachment and cutting. The second, which took the dill to a depth of around 6.5 centimetres (2.6 inches). The gathered samples were then sifted and sorted through the CHIMRA system in the rover’s turret, prior to being transferred via the surface scoop to Curiosity’s primary laboratory systems, ChemMin and SAM.

At the same time as Curiosity was carrying out its initial analysis of the “Mojave 2” rock, NASA released an image captured by the HiRise (High Resolution Imaging Science Experiment) carried aboard the orbiting Mars Reconnaissance Orbiter (MRO), which forms the mainstay of the rover’s communications with Earth. The image, which was taken on December 13th, 2014, reveals Curiosity mid-way through its “walkabouts” in “Pahrump Hills”, when it was seeking potential targets of interest for further study.

While not the first time the rover has been imaged from orbit, this is one of the clearest pictures from the rover yet capture from an altitude of around 280 kilometres (175 miles) above the surface of Mars.

"I see you!" - MRO's HiRise image of the curiosity rover, obtained on December 13th, 2014, as the rover explores the "Pahrump Hills" region on a basal slopes of "Mount Sharp"
“I see you!” – MRO’s HiRise image of the curiosity rover, obtained on December 13th, 2014, as the rover explores the “Pahrump Hills” region on a basal slopes of “Mount Sharp”

Initial results from ChemMin (the Chemical and Mineralogy) instrumental has shown that the rock was likely effected by water that was much more acidic in nature than evidenced through the analysis of other rock samples obtained by the rover. The still-partial analysis shows a significant amount of jarosite, an oxidized mineral containing iron and sulphur that forms in acidic environments. This raises the question of whether the more acidic water was part of environmental conditions when sediments were being deposited to form “Mount Sharp”, or the result of fluids soaking the rocks at a later time.

ChemMin was also unable to identify a clear candidate mineral for the crystalline deposits which first attracted the science team to the outcrop; this presents the possibility that the minerals responsible for originally forming the crystals may have been leached away over time and replaced by other minerals during later periods of wet environmental conditions.

It is hoped that SAM – the Sample Analysis at Mars – suite of instruments may be able to reveal more about the nature and composition of the samples once they have completed their round of analysis. Depending on the outcome of this work, Curiosity may be ordered to gather a further rock sample from “Pahrump Hills”, or may be ordered to continue upwards and into new territory on “Mount Sharp”.

SpaceX Sets Out To Land a Rocket

The Falcon 9 carrying the DSCOVR satellite stands ready for launch – note the landing legs folded against the base of the first stage (SpaceX)

Update, February 11th: SpaceX have called off attempts to recover the first stage of the Falcon 9 ahead of the anticipated launch of the DSCOVR mission. Extreme weather conditions, coupled with a failure of one of the ADS’s station-keeping engines have ruled-out any attempt to recover the rocket through a landing on the ship. 

Update, February 10th: Unfavourable winds again caused a launch scrub. The next attempt will be Wednesday, February 11th, at 18:03 EDT (23:03 GMT).

Update, February 9th: Unfavourable weather conditions over the Cape caused a further delay of the DSCOVR mission, which has been re-scheduled for Tuesday, February 10th at 18:07 EDT (23:07 GMT).

Update: due to an issue with the radar transmitter on the first stage of the Falcon 9, the DSCOVR launch has been delayed until 18:07 EDT (23:07 GMT) on Monday, February 9th.

On Sunday February 8th, SpaceX, the private venture space company founded by billionaire Elon Musk, and which is very much at the forefront of spaceflight development and innovation, will attempt to further their goal of developing an almost fully reusable rocket system.

SpaceX is perhaps best known for their role in resupplying the International Space Station with consumables, an activity they took on in partnership with Orbital Sciences as a result of NASA’s decision to retire the space shuttle, and because Europe’s heavy-lift Automated Transfer Vehicle has reached the end of its contracted operations for resupplying the ISS. However, the February 8th launch is that of a solar weather satellite, the Deep Space Climate Observatory (DSCOVR), which will be operated by the  US National Oceanic and Atmospheric Administration. (NOAA).

DSCOVR is a part of the NOAA’s on-going NESDIS (National Environmental Satellite, Data, and Information Service) programme. It will operate around 1.6 million kilometres (1 million miles) from Earth, DSCVR will join NASA’s ACE and SOHO missions in monitoring surface activity on the Sun and providing early warning of potentially damaging solar coronal mass ejections that might be directed towards the Earth.

However, the launch is also significant in that it will mark SpaceX’s second attempt to recover the first stage of the Falcon 9 launch vehicle.

Used during the initial launch phase to boost a payload through the densest part of the Earth’s atmosphere during orbital ascent, the first stage of a rocket is generally discarded. However, SpaceX has been working on a means of recovering the stage so it can be refurbished and reused a number of times, thus reducing the overall cost of individual launches.

By their nature, rocket stages aren’t exactly aerodynamic. Once engine thrust has ceased, there is nothing to stop a 14-storey cylinder from tumbling through the air. To prevent this, SpaceX has come up with an innovative approach. By re-lighting the engines a number of times during descent, the company has shown it can both keep the stage upright, and gently reduce its velocity. The technique has been tested over land, where it has been used to demonstrate the Falcon 9’s hover, manoeuvring and landing capabilities, and has been used to successfully return a Falcon 9 first stage for an eventual splashdown.

However, bringing a rocket stage down over land is considered too great a risk if something goes wrong, and a splashdown is hardly ideal as it exposes the entire stage to immersion in salt water, making refurbishment harder. So SpaceX have come up with the idea of landing their Falcon 9 first stage on a floating platform some 92 metres (300 feet) by 31 metres (100 feet) in size. Called the autonomous spaceport drone, the platform will be sited some 590 kilometres (370 miles) off the Florida coast.

A similar attempt to recover a Falcon 9 first stage on January 10th only just failed when the booster ran out of hydraulic fuel just seconds (and a few metres) away from a successful landing. With its landing legs deployed, the stage abruptly drifted sideways prior to toppling over and exploding. Or as Elon Musk later referred to it, in a sideways poke at NASA’s love of acronyms, the vehicle suffered a pre-touchdown RUD – Rapid Unscheduled Disassembly (!). fortunately, while the stage was lost, the landing platform escaped almost entirely unscathed.

It is hoped that the landing on February 8th, which should take place shortly after the DSCOVR launch from Cape Canaveral Air Force Station at 6:10 p.m. EST (2310 GMT), will be far more successful.

NASA TV will be covering the launch live, and SpaceX will be covering the launch and recovery via their own webcast.

All images via NASA / JPL unless otherwise stated. Videos courtesy of NOAA and SpaceX.

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