Visible at the bottom (the thick vertical rod) is the Rover Environmental Monitoring Station (REMS) built by the Centro de Astrobiologia (CAB) in Madrid, Spain. The pencil-like instrument sticking out to the left is Boom 1 which houses a suite of infrared sensors to measure the intensity of infrared radiation emitted by the ground. The large structure at the top includes the Mastcam (Mast Camera) and the white rectangular-shaped ChemCam (Chemistry & Camera) instruments. Credit: NASA/JPL/MSSS/Ed Truthan
<!-- image -->Curiosity began a second two-year extended mission on 1 October 2016, continuing its explorations of lower Mount Sharp. At that point, the rover had returned more than 180,000 images to Earth; NASA declared that the mission "has already achieved its main goal of determining whether the landing region ever offered environmental conditions that would have been favorable for microbial life." Engineers put a halt on using the rover's drill soon after, while taking what would have been the seventh drill sample of the year. On 1 December, the Curiosity team discovered that the rover had not completed the commands for drilling; apparently, the rover had detected a fault in the "drill feed mechanism" which was supposed to extend the drill to touch the rock target. This problem remained unresolved until May 2018 when a new method of "percussive" drilling finally opened the path to further use of the instrument. Despite the problem with the drill, Curiosity was once again investigating active sand dunes (the so-called Bagnold Dunes). As of 23 February 2017, Curiosity had driven 15.63 kilometers since landing. By this time, it was clear to NASA engineers that the zig zag treads on Curiosity's wheels were suffering damage, jeopardizing the wheels' ability to carry the weight of the rover. Damage to only three treads (or "grousers") would indicate that the wheel had reached 60% of its lifetime. Lessons from damage to Curiosity's wheels will play a major role in the design of future Mars rovers. In March 2017, JPL controllers uploaded a software for traction control that helped the rover adjust wheel speed depending on the rocks it is climbing. The traction control algorithm uses real-time data to vary the wheel speed, thus reducing pressure from the rocks. "Armed" with the new software, in July, Curiosity began a campaign to study a ridge on lower Mount Sharp, informally named Vera Rubin Ridge after the recently departed astronomer, Vera Florence Cooper Rubin (1928–2016). The ridge was thought to be rich in an iron-oxide mineral known as hematite that can form under wet conditions. Two months later, the rover began making a steep ascent toward the ridge top. On 17 October 2017, for the first time in 10 months, the rover cautiously touched its sampler drill to a surface rock. While it was still several months away from resuming full-scale drilling operations on the Martian surface, this and subsequent tests allowed ground controllers to test techniques, including using the motion of the robotic arm directly to advance the extended bit into the rock, thus working around the mechanical problem that suspended drill work. NASA made some significant attempts to involve the public in the Curiosity mission. On the third anniversary of landing on Mars, in August 2015, the Agency made available two online tools for public engagement. Mars Trek was a free web-based application that provides high-quality visualizations of the planet derived from 50 years of NASA exploration of Mars, while Experience Curiosity was a platform to allow viewers to experience in 3D, movement along the surface of Mars based on data from both Curiosity and MRO. Around the time of Curiosity's third anniversary on Mars, in August 2016, NASA also released a social media game, Mars Rover, for use on mobile devices where users can drive a rover through Martian terrain while earning points.
232 LADEE
Nation: USA (98) Objective(s): lunar orbit Spacecraft: LADEE Spacecraft Mass: 383 kg Mission Design and Management: NASA / ARC / GSFC Launch Vehicle: Minotaur V (no. 1) Launch Date and Time: 7 September 2013 / 03:27:00 UT Launch Site: Mid Atlantic Regional Spaceport (MARS) / Pad 0B
Scientific Instruments:
- ultraviolet and visible light spectrometer (UVS)
- neutral mass spectrometer (NMS)
- lunar dust experiment (LDEX)
- lunar laser communications demonstration experiment (LLCD)
Results: The Lunar Atmosphere and Dust Environment Explorer (LADEE), the first mission in the Lunar Quest series, was designed to orbit the Moon and study its thin atmosphere and the lunar dust environment, specifically to collect data on the global density, composition, and time variability of the exosphere. By studying the Moon's exosphere—an atmosphere that is so thin that its molecules do not collide with each other—LADEE's instruments helped further the study of other planetary bodies with exospheres such as Mercury and some of Jupiter's moons. After insertion into low parking around Earth after launch from the Wallops Flight Facility—the first lunar launch from that location—Minotaur's fifth stage (with a Star 37FM solid motor) fired at 03:43 UT to boost the payload into a highly elliptical Earth orbit of 200 × 274,600 kilometers at 37.7° inclination.
<!-- image -->LADEE took a path to lunar orbit used by several other recent lunar spacecraft that involved flying increasingly larger Earth orbits (in this case, three orbits) over a period of a month, with the apogee increasing until it was at lunar distance. On the third orbit, on 6 October, as LADEE approached the Moon, it fired its own engine and entered into an initial elliptical lunar orbit with a 24-hour period. On 9 and 12 October, further burns brought LADEE down into a 235 × 250-kilometer orbit. These events occurred exactly during the period when the U.S. Government—and therefore NASA—shut down briefly, opening back up on 16 October. One of the early experiments was use of the LLCD system, carried out on 18 October 2013 when the spacecraft, using the optical laser system, transmitted good data to a ground station 385,000 kilometers away. Finally, on 20 November, LADEE successfully entered its planned equatorial orbit of 20 × 60 kilometers, allowing the probe to make frequent passes from lunar day to lunar night. When the Chinese Chang'e 3 lunar lander arrived at the Moon, LADEE (more specifically, its NMS neutral mass spectrometer) was used to observe the specific masses of the substances (such as water, nitrogen, carbon monoxide, and hydrogen) that would be expected to be found given the operation of Chang'e's operation in near-lunar space. In the event, LADEE's data found no effects—no increase in dust, no propulsion products, etc.—that could be attributed to Chang'e 3. Another experiment that involved another spacecraft was NASA's Lunar Reconnaissance Orbiter (LRO) taking a photo of LADEE in orbit at 01:11 UT on 15 January 2014. Its 100-day science mission, during which LADEE collected an enormous amount of data, came formally to an end by early March 2014. The three science payloads worked full-time during this period: the UVS instrument acquired more than 700,000 spectra of the exosphere. The NMS instrument positively identified argon-40 in the atmosphere (first identified by an Apollo surface experiment 40 years before). Finally, the LDEX recorded more than 11,000 impacts from dust particles from a dust cloud engulfing the Moon. In early 2014, LADEE began to gradually lower its orbital altitude in anticipation of its final impact on the Moon. Controllers lowered LADEE's orbit to within 2 kilometers of the lunar surface to ensure impact. On its penultimate orbit, on 17 April, LADEE swooped down to as low as 300 meters of the lunar surface, and contact was lost at 04:30 UT on 18 April when it moved behind the Moon. Controllers estimated that the spacecraft probably struck the Moon on the eastern rim of Sundman V crater between 04:30 and 05:22 UT at a speed of 5,800 kilometers/hour. Later, on 28 October 2014, NASA announced that its LRO spacecraft had successfully imaged the impact location of LADEE on the far side of the Moon.
233 Mangalyaan / Mars Orbiter Mission (MOM)
Nation: India (2) Objective(s): Mars orbit Spacecraft: Mars Orbiter Spacecraft Spacecraft Mass: 1,337 kg Mission Design and Management: ISRO Launch Vehicle: PSLV-XL (no. C25) Launch Date and Time: 5 November 2013 / 09:08 UT Launch Site: SHAR / PSLV pad
Scientific Instruments:
- Mars color camera (MCC)
- thermal infrared imaging spectrometer (TIS)
- methane sensor for Mars (MSM)
- Mars exospheric neutral composition analyzer (MENCA)
- Lyman alpha photometer (LAP)
Results: India's first interplanetary spacecraft was designed and built in a relatively short period of time, with a total development time of 4 years and 2 months, although official government approval came as late as August 2012. The main spacecraft bus was a modified I-1 bus used on the lunar Chandrayaan-1 mission. The mission was essentially a technology demonstrator although it carried a set of modest scientific instruments to study the surface features, morphology, mineralogy, and Martian atmosphere. With the mission, India accomplished a remarkable feat, becoming only the fourth nation or agency to have a spacecraft orbit Mars, after the former Soviet Union, the United States, and the European Space Agency. Japan had tried and failed, while a Chinese rocket had yet to launch a probe to Mars (although its Yinghuo-1 orbiter launched by the Russians failed to leave Earth orbit due to the malfunctioning Russian upper stage). The name Mangalyaan was formally attached to the mission before launch while in the development period the spacecraft was known variously as the Mars Orbiter Spacecraft, the Mars Orbiter Satellite, or the Mars Orbiter Mission. Mangalyaan entered an initial orbit around Earth at 251 × 23,892 kilometers at 19.4° inclination. The mission profile to Mars involved six engine burns (the fourth on 10 November was partially successful) over a month in progressive larger Earth orbits to accumulate sufficient velocity to escape Earth's sphere of influence. A seventh engine burn lasting over 22 minutes, beginning at 19:19 UT on 30 November, inserted Mangalyaan into heliocentric orbit. On the way to Mars, the spacecraft conducted three mid-course corrections (on 11 December 2013, 11 June, and 22 September) before a successful burn (lasting over 23 minutes) of the main 44.9 kgf thrust engine put the probe into Mars orbit on 24 September 2014. This was a highly elliptical orbit at 421.7 × 76,993.6 kilometers with an orbital period of nearly 73 hours. Mangalyaan returned its first global image of Mars, a spectacular picture captured by the MCC instrument, on 28 September 2014 from an altitude of 74,580 kilometers with about a 4-kilometer resolution that showed various morphological features and thin clouds in the Martian atmosphere. The ground team maneuvered the spacecraft to avoid a possible encounter with Comet C/2013 A1 (Siding Spring) which passed by Mars on 19 October 2014, one of seven spacecraft on or around Mars that had to take measures to prevent damage. The comet passed by Mars at a range of about 132,000 kilometers shedding material around Mars, some at a velocity of 56 kilometers/second putting many of these spacecraft in danger. Mangalyaan's instruments remained fully operational through late 2014, and on 1 January 2015 ISRO scientists marked 100 days of successful operations around Mars. Mission planners were confident that the spacecraft would meet its planned lifetime of six months or 180 days in orbit around Mars. As with many other spacecraft in and around Mars, Mangalyaan was subjected to a communications blackout in June 2015 when Mars' orbit took it behind the Sun relative to Earth. Mangalyaan commemorated a successful operational year orbiting Mars in September 2015 although at the time, scientific results from its instruments had yet to be publicly shared. The 13 pictures released by that time were largely taken in September and October 2014 although, because of MOM's unique orbit, they show the kind of wide-angle images have rarely been seen from Mars orbit. Finally, in March 2016, scientists published the first results (in Geophysical Research Letters) of the MENCA instrument. Further results from other instruments were made available in the fall of 2016. Newly released images included some of the most spectacular views from orbit showing many surface patterns. One note of concern was a possible problem with the MSM methane sensor, data from which has yet to be released. There were some reports that the sensor itself had a design flaw. NASA Goddard Space Flight Center scientists had apparently briefed ISRO personnel on the problem in February 2016 and suggested that the instrument instead be repurposed for albedo mapping and measuring reflected sunlight. On 17 January 2017, ISRO controllers changed Mangalyaan's orbit as a strategy to avoid the eclipse season when the spacecraft would be in Mars' shadow for as much as 8 hours per day. The burn used about 20 kilograms of propellant, leaving 13 kilograms remaining for further maneuvers. It is hoped that the spacecraft can transmit data until 2020.