Beyond_Earth-_A_Chronicle_of_Deep_Space_Exploration_1958-2016.pdf

LISA Pathfinder operates from a vantage point in space about 1.5 million kilometers from Earth towards the Sun, orbiting the first Sun–Earth Lagrange point, L1. Credit: ESA-C. Carreau

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Almost simultaneously, on 21–22 June, ESA approved a mission extension, beginning 1 November, for seven months, during which investigators will be working with LTP. The mission was finally concluded on 30 June 2017. Earlier, in June 2016, mission scientists published the first results of the LISA Pathfinder experiments, confirming that the two cubes were falling freely under the influence of gravity alone, to a precision level more than five times better than originally expected.

244 ExoMars Trace Gas Orbiter / Schiaparelli EDM Lander

Nation: ESA / Russia (1) Objective(s): Mars orbit and landing Spacecraft: TGO / EDM Spacecraft Mass: 4,332 kg total including 3,755 kg TGO and 577 kg Schiaparelli EDM Mission Design and Management: ESA / Roskosmos Launch Vehicle: Proton-M + Briz-M (8K82M no. 93560 + Briz-M no. 99560) Launch Date and Time: 14 March 2016 / 09:31 UT Launch Site: Baikonur Cosmodrome / Site 200/39

Scientific Instruments:

TGO:

1. Nadir and Occultation for Mars Discovery spectrometer (NOMAD)
2. Atmospheric Chemistry Suite spectrometers (ACS)
3. Color and Stereo Surface Imaging System (CaSSIS)
4. Fine-Resolution Epithermal Neutron Detector (FREND)

EDM:

1. Dust Characterization, Risk Assessment, and Environmental Analyzer on the Martian Surface (DREAMS)
2. Atmospheric Mars Entry and Landing Investigation and Analysis (AMELIA)
3. Descent Camera (DECA)
4. Combined Aerothermal Sensor Package (COMARS+)
5. Instrument for Landing – Roving Laser Retroreflector Investigations (INRRI)

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Results: The first in a series of joint missions under the ExoMars program between ESA and Roskosmos, the Russian space agency, the ExoMars Trace Gas Orbiter (TGO) is designed to study methane and other atmospheric trace gases present in small concentrations in the Martian atmosphere. Despite their relative scarcity (less than 1% of the atmosphere), studying these gases could provide evidence for possible biological or geological activity. Organisms on Earth release methane when they digest nutrients, although geological processes (such as the oxidation of certain minerals) can also release methane. ExoMars TGO was originally a collaborative project with NASA but the latter's contribution was cut due to lack of support in 2012, leading to cooperation with the Russians. As currently envisioned, the two ExoMars missions involve the TGO and Schiaparelli (first mission) and a lander-rover (second mission) in 2020, both launched by the Russians, who also are contributing hardware to both missions. Besides its primary mission, ExoMars TGO also had two secondary missions: to deliver the Schiaparelli Entry, Descent, and Landing Demonstrator Module (EDM), an Italian-built lander designed to test technologies planned for use in future soft-landings on Mars; and to serve as a data relay to support communications for the ExoMars 2020 rover and surface science platform. The orbiter included instruments developed by Belgium (NOMAD), Russia (ACS and FREND), and Switzerland (CaSSIS). EDM's scientific mission was limited to measurements of several atmospheric parameters (such as wind speed and direction, humidity, pressure, etc.). Its small technical camera, weighing 0.6 kilograms, was a refurbished spare flight model of the Visual Monitoring Camera flown on ESA's Herschel and Planck spacecraft. Teams from Italy, France, the Netherlands, Finland, Spain, and Belgium contributed to EDM. The Russian Proton-M + Briz-M combination inserted the payload stack into an initial 185 × 185-kilometer orbit at 51.5° inclination. A second Briz-M firing after one orbit raised the orbit to 250 × 5,800 kilometers, and a third burn raised it further to 696 × 21,086 kilometers. A final fourth firing sent the payload to escape velocity with spacecraft release from Briz-M occurring at 20:13 UT on the day of the launch. On 14 March 2016, ExoMars adjusted its trajectory with a 52-minute burn. Finally, on 19 October, TGO fired its engine for 139 minutes from 13:05 to 15:24 UT to enter its planned initial orbit around Mars of 346 × 95,228 kilometers at 9.7° inclination. Three days earlier, at 14:42 UT on 16 October, the orbiter had released the EDM that was programmed to autonomously perform an automated landing sequence. After it entered the atmosphere at 14:42 UT on 19 October, the sequence would include parachute deployment, front heat shield release (at between 11 and 7 kilometers altitude), retrorocket braking (starting at 1,100 meters altitude), and a final freefall from a height of 2 meters, cushioned by a crushable structure. During this phase, Schiaparelli was to have captured 15 images of the approaching surface. Unfortunately, the signal from the lander was lost a short time before the planned landing sequence initiated. Later analysis showed that the parachute deployed normally at an altitude of 12 kilometers and the heatshield was released as planned at 7.8 kilometers. However, at some point, an inertial measurement unit sent an incorrect reading of the vehicle's rotation, which in turn generated an incorrect estimated altitude (in fact, a negative altitude) which triggered premature release of the parachute and backshell, firing of the thrusters and activation of ground systems even though the lander was still at an altitude of 3.7 kilometers. As such, the Schiaparelli simply plummeted from that altitude to the ground at near terminal velocity and was destroyed. During atmospheric entry, some data was collected by the COMARS+ instrument. The day after the crash, NASA's Mars Reconnaissance Orbiter (MRO) photographed the crash site in Meridiani Planum. Higher resolution images taken on 25 October and 1 November (the latter in color) showed more detail. Impact coordinates were 6.11° W / 2.07° S. The orbiter, meanwhile, began several months of aerobraking to reach its nominal 400-kilometer circular orbit for its primary science mission slated to begin in late 2017. In November 2016, TGO was in a highly elliptical 230–310 × 98,000-kilometer orbit with an orbital period of 4.2 days. Between 20 and 28 November, it tested and calibrated its four scientific instruments for the first time. In January 2017, the orbiter carried out three maneuvers by firing its main engine to adjust inclination to 74°, necessary for its primary science mission to begin later in the year. By March 2017, TGO was in a one-day 200 × 33,000-kilometer orbit and was using the atmosphere to adjust the orbit by a process of gradual aerobraking. The goal was to achieve a final operational circular orbit at 400 kilometers by March 2018 at which time full-scale science operations would begin. Earlier, in December 2016, ESA announced the formal approval of the second joint European-Russian ExoMars mission, tentatively slated for launch in 2020.

245 OSIRIS-REx

Nation: USA (101) Objective(s): asteroid sample return Spacecraft: OSIRIS-REx Spacecraft Mass: 2,110 kg Mission Design and Management: NASA GSFC / University of Arizona Launch Vehicle: Atlas V 411 (no. AV-067) Launch Date and Time: 8 September 2016 / 23:05 UT Launch Site: Cape Canaveral / SLC-41

Scientific Instruments:

1. Camera Suite (PolyCam, MapCam, SamCam) (OCAMS OSIRIS-REx)
2. Laser Altimeter (OLA OSIRIS-REx)
3. Visible and IR Spectrometer (OVIRS OSIRIS-REx)
4. Thermal Emission Spectrometer (OTES OSIRIS-REx)
5. Regolith X-Ray Imaging Spectrometer (REXIS OSIRIS-REx)
6. Touch-And-Go Sample Acquisition Mechanism (TAGSAM)

Results: The Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRIS-REx) mission is the third major planetary science mission falling under NASA's New Frontiers Program (after New Horizons launched in 2006 and Juno launched in 2011). The goal of the mission is to reach a near-Earth asteroid 101955 Bennu (formerly known as 1999 RQ36), collect a 59.5-gram sample, and then return it to Earth. The science mission, developed by scientists at the University of Arizona, will open up the possibilities to glean more information on how planets formed and how life began and help scientists understand asteroids that could impact Earth in the future. About 55 minutes after launch, after a boost by the Centaur upper stage, OSIRIS-REx separated from the Atlas V and the solar arrays deployed. At 17:30 UT, on 9 September, the spacecraft crossed the orbital path of the Moon at a range of 386,500 kilometers. Three days later, it was in heliocentric orbit at 0.77 × 1.17 AU. Beginning 19 September, the mission team activated all of its scientific instruments. The larger Trajectory Correction Maneuver (TCM) thrusters were fired (for 12 seconds) for the first time on 7 October for a mid-course correction. The spacecraft also carries three other sets of thrusters—the Attitude Control System (ACS), a Main Engine (ME), and Low Thrust Reaction Engine Assembly (LTR) thrusters—thus providing significant redundancy for maneuvers. On 28 December 2016, the spacecraft conducted its first Deep Space Maneuver (DSM-1), firing the main engine to position it properly for an Earth gravity-assist encounter in late 2017.

NASA's OSIRIS-REx spacecraft is shown here in an artist's impression. OSIRIS-REx is the third mission in NASA's New Frontiers Program. Credit: NASA/University of Arizona

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A second firing, the first to use the spacecraft's Attitude Control System (ACS) thrusters, on 25 August 2017, further sharpened its trajectory by changing the velocity by 47.9 centimeters/second. About a month later, on 22 September, OSIRIS-REx passed over Earth at a range of 17,237 kilometers as part of a gravity-assist maneuver that tilted its orbit to match Bennu. During the encounter, the spacecraft took several high-resolution pictures of both Earth and the Moon. The actual asteroid encounter is scheduled to begin in August 2018, culminating in a rendezvous with Bennu. OSIRIS-REx will survey the asteroid for about a year beginning October 2018 and select a final touchdown site. The actual sample collection will be carried out by the TAGSAM instrument which will release a burst of nitrogen gas to blow regolith particles into a sampler head at the end of a robotic arm. The spacecraft is capable of returning to the asteroid in case of a first failed attempt at sample collection. In March 2021, there will be a window to depart from Bennu, allowing OSIRIS-REx to begin its Earthward return trip. If all goes well, the spacecraft will return to Earth in September 2023, when the sample return capsule will separate from the main spacecraft and enter Earth's atmosphere, landing at the Utah Test and Training Range.

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237 Chang’e 5-T1

Nation: China (5) Objective(s): circumlunar flight, Earth–Moon L2 Lagrange Point, lunar orbit Spacecraft: Zhongguo tanyue gongcheng san qi zai ru fanhui feixing shiyan qi Spacecraft Mass: 3,300 kg Mission Design and Management: CNSA Launch Vehicle: Chang Zheng 3C/G2 (or Chang Zheng 3C/E) Launch Date and Time: 23 October 2014 / 18:00:04 UT Launch Site: Xichang

Scientific Instruments:

1. cameras
2. biological payloads

Results: This mission, called Chang'e 5 Flight Test Device (or CE 5-T1), was a precursor to the planned Chang'e 5 mission, which, at the time of writing, is slated to land on the Moon and return lunar samples (at least 2 kilograms) back to Earth in 2019. The spacecraft consists of a bus (DFH-3A) similar to the CE-1 and CE-2 lunar orbiters, but with a large descent vehicle, resembling a scaled-down version of the piloted Shen Zhou descent module. During this flight, the reentry module carried a complement of biological payloads. The goal of the test mission was to fly a full-scale circumlunar mission so as to flight-test the reentry vehicle—particularly the heatshield—in real conditions before the actual sample return mission. This was the first circumlunar mission and recovery of a spacecraft since the Soviet Zond 8 mission in 1970. The payload entered into a parking orbit around Earth after successful firing of the launch vehicle's first three stages. The third stage then reignited for about 3 minutes to send the payload on a translunar trajectory of 209 × 413,000 kilometers. Soon after TLI, the spacecraft deployed its solar arrays and implemented at least two mid-course corrections (on 24 and 25 October). Chang'e 5-T1 entered the Moon's gravitational influence at 13:30 UT, before flying around the far side of the Moon, with the closest distance of approximately 12,000 kilometers reached at 19:03 UT on 27 October. Throughout its voyage to the Moon, the spacecraft relayed back spectacular pictures of both Earth and the Moon. On the four-day trip home, the spacecraft performed one mid-course correction. Before entry into Earth's atmosphere, at 21:53 UT on 31 October, the headlight-shaped descent vehicle separated from the service module when about 5,000 kilometers from Earth; 5 minutes later, the service module fired its engine (for about 12 minutes) to go back into a translunar orbit. The descent vehicle, meanwhile, completed a "double-dip" reentry into Earth's atmosphere to reduce g-loads.