Beyond_Earth-_A_Chronicle_of_Deep_Space_Exploration_1958-2016.pdf

212

Artemis P1 and Artemis P2

Nation: USA (89)

Objective(s): Earth–Moon L1 and L2 Lagrange points, lunar orbits

Spacecraft: THEMIS B / THEMIS C

Spacecraft Mass: 126 kg (each)

Mission Design and Management: NASA / University of California–Berkeley

Launch Vehicle: Delta 7925-10C (no. D323)

Launch Date and Time: 17 February 2007 / 23:01:00 UT

Launch Site: Cape Canaveral Air Force Station / SLC-17B

Scientific Instruments:

• 1. electric field instruments (EFI)
• 2. fluxgate magnetometer (FGM)
• 3. search coil magnetometer (SCM)
• 4. electrostatic analyzer (ESA)
• 5. solid state telescope (SST)

Results: The two Artemis lunar orbit missions were repurposed from the original Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission that involved five NASA satellites, THEMIS A, B, C, D, and E, which studied a type of magnetic phenomena ("substorms") in Earth's magnetosphere that tend to intensify auroras near Earth's poles. Each of the five satellites carried identical instrumentation. After a burn of the third stage, the five THEMIS spacecraft—initially joined but soon separated—were deposited into a 469 × 87,337 km × 16.0° orbit around Earth. In its "string-of-pearls" configuration, the five THEMIS satellites carried out its initial mission without any significant anomalies. On 19 May 2008, Space Sciences Laboratories, developer of the spacecraft at University of California–Berkeley, announced that NASA had extended the THEMIS mission to 2012 and that two of the THEMIS satellites, B and C, would venture into lunar orbit as part of a new mission under the name ARTEMIS (Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon's Interaction with the Sun).

<!-- image -->

In this new mission, THEMIS B and C were renamed ARTEMIS P1 and ARTEMIS P2, respectively, and redirected to study the Earth–Moon Lagrange points, the solar wind, the Moon's plasma wake, and the interaction between Earth's magnetotail and the Moon's own weak magnetism. (The "P1" and "P2" designations were leftover terminology from the THEMIS mission which used "P1" and "P2" to denote the operational orbits of THEMIS B and C). On the 40th anniversary of the Apollo XI landing, on 20 July 2009, ARTEMIS P1 and P2 officially began low thrust maneuvers that, over the course of the following year-and-a-half, led them to the L2 and L1 Lagrange points, opposite the near and far sides of the Moon, respectively. (This phase included a lunar flyby on 28 March 2010 by ARTEMIS P2.) On 25 August 2010, an engine burn propelled ARTEMIS P1 into orbit around the Earth–Moon L2 Lagrange point, located on the far side of the Moon, about 61,300 kilometers above the lunar surface. This was the first time that a spacecraft had successfully entered orbit around an Earth–Moon libration point. The second spacecraft, ARTEMIS P2 arrived at L1 on 22 October 2010 by which time P1 had completed about four revolutions around L2. Although the stationkeeping at the Lagrange points on the way to the Moon was motivated to avoid Earth's long shadows in its original orbits (thus keeping the spacecraft operational), here at the two Lagrange points, the two spacecraft collected magnetospheric data from opposite sides of the Moon, critical for simultaneous measurements of particles and electric and magnetic fields to build a three-dimensional map of the acceleration of energetic particles near the Moon's orbit. On 27 June 2011, ARTEMIS P1 successfully entered lunar orbit with an initial orbit of roughly 3,543 × 27,000 kilometers while its sister vehicle, ARTEMIS P2 arrived on 17 July 2011, after a two-year journey from Earth orbit. Over the next three months, mission controllers implemented a series of maneuvers to move the second spacecraft into an orbit with a period of 27.5 hours, similar to its companion, but moving in the opposite direction. The two spacecraft, orbiting in opposite directions around the Moon, began to provide the first 3D measurements of the Moon's magnetic field to determine its regional influence on solar wind particles. More specifically, the two spacecraft revealed new information on the lunar "wake" that extends about 12 lunar radii and in particularly how its void distorts the interplanetary magnetic field causing it to bulge moonward. As of January 2016, the two spacecraft remained in good health and operating in their stable but highly elliptical lunar orbits. Mission scientists marked the tenth anniversary of the launch in February 2017, with the spacecraft still in good health.

213

Phoenix

Nation: USA (90)

Objective(s): Mars landing

Spacecraft: Phoenix Lander

Spacecraft Mass: 664 kg (350 kg lander)

Mission Design and Management: NASA / JPL / University of Arizona

Launch Vehicle: Delta 7925-9.5 (no. D325)

Launch Date and Time: 4 August 2007 / 09:26:34 UT

Launch Site: Cape Canaveral Air Force Station / SLC-17A

Scientific Instruments:

• 1. robotic arm (RA)
• 2. microscopy, electrochemistry, and conductivity analyzer (MECA)
• 3. robotic arm camera (RAC)
• 4. surface stereo imager (SSI)
• 5. thermal and evolved gas analyzer (TEGA)
• 6. Mars descent imager (MARDI)
• 7. meteorological station (MET)

Results: The Phoenix mission was a landing mission to Mars, the first under NASA's new Mars Scout Program to send a series of small, low-cost, low complexity, and higher frequency robotic missions to Mars. (The second and last mission in the series was MAVEN launched in 2013; Mars missions were then folded into the Discovery Program where they would compete with missions to other planetary destinations). Its science goals included studying the history of water on Mars in all its phases, searching for evidence of habitable zones, and assessing the biological potential of the ice–soil boundary. More broadly, the lander was designed to determine whether life ever existed on Mars, characterize the climate and geology of the Red Planet, and help prepare for future human exploration of its surface. The spacecraft was essentially built on the basis of the abandoned and never-launched Mars Surveyor 2001 Lander and contained other instruments built in support of the unsuccessful Mars Polar Lander mission. It was the first NASA mission to Mars that was led directly from a public university, the University of Arizona, more specifically its Lunar and Planetary Laboratory. The primary mission was designed to last 90 sols (Mars days) or approximately 92 Earth days. After two burns of the Delta's second stage, the PAM-D upper stage (with a Star 48 motor) fired at 10:44 UT on 4 August 2007 to send the Phoenix lander towards Mars. It conducted mid-course corrections on 10 August and 30 October 2007, and 10 April and 17 May 2008, the latter two directing it toward the northern polar region of Mars. As it approached Mars, the orbits of three other spacecraft orbiting Mars—Mars Reconnaissance Orbiter (MRO), 2001 Mars Odyssey, and Mars Express—were adjusted so that they could observe Phoenix's entry into the atmosphere. In addition, MRO's HiRISE instrument was used to thoroughly scout out the landing area, with some images identifying rocks smaller than the lander itself. Phoenix entered the Martian atmosphere at nearly 21,000 kilometers/hour on 25 May 2008 and touched down safely on the surface at 23:38:38 UT in the Green Valley of Vastitas Borealis. It was the first successful landing of a stationary soft-lander on Mars since Viking 2, 32 years before. During its descent, MRO's HiRISE camera clearly photographed Phoenix suspended from its parachute, the first time one spacecraft photographed another during a planetary landing. The lander waited 15 minutes for the dust to settle before unfurling its solar panels. The first images showed a flat surface marred by pebbles and troughs, but no large rocks or hills as expected given its northern position. Within four days, Phoenix had transmitted a complete 360° panorama of the cold Martian surface, deployed the nearly 2.5-meter robotic arm, and started returning regular weather reports. On 31 May, the robotic arm scooped up dirt and began sampling Martian soil for ice. Already by 19 June 2008, mission scientists were able to conclude that clumps of bright material in the so-called "Dodo-Goldilocks" trench dug by the robotic arm were probably water ice: the material had vaporized in four days after the scoop. On 31 July 2008, NASA officially announced that, based on an analysis (by TEGA's mass spectrometer) of a sample collected by the lander, that there is water on Mars. William Boynton of the University of Arizona noted that such data adds to the claims from the 2001 Mars Odyssey orbiter whose data also indicated likewise. On 5 August, in response to media rumors about the possibility of life on Mars, the Phoenix team announced that they had found perchlorates on the surface of Mars that neither confirmed nor refuted the possibility of life on Mars. The results also led scientists to revisit the data from the Viking Landers. By the end of August, Phoenix had completed its originally planned 90-day mission, which was extended to 30 September. On 12 September, the lander scoop delivered a new soil sample to its Wet Chemistry Laboratory that mixed an aqueous solution from Earth to the soil as part of a process to identify soluble nutrients and other chemicals in the soil. Early results suggested that the soil was alkaline, composed of salts and other chemicals such as perchlorate, sodium, magnesium, chloride, and potassium. On 13 October, Phoenix weathered a dust storm and recovered another soil sample, the sixth, into the TEGA instrument. But as the Martian winter was upon the landing site, the lander went into safe mode on 28 October 2008 due to insufficient sunlight and poor weather conditions. During safe mode, non-critical activities were suspended while the spacecraft awaited further instructions from mission control. There was daily communication with the lander from 30 October to 2 November but no signals were received after that. On 10 November, NASA announced the lander had "finishe[d its] successful work on [the] Red Planet," and on 1 December, the Agency announced that NASA "had stopped using its Mars orbiters to hail the lander." The loss of the spacecraft was a combination of low power and the dust storm. During the cold harsh winter, CO2 ice—some of it as thick as 19 centimeters—probably built up on the lander, sufficiently heavy to break the fragile solar arrays. Because of this kind of damage, subsequent communications attempts with the lander, in early 2010, were unsuccessful. On 24 May 2010, NASA announced that the project was formally ended. Images from MRO conclusively showed that Phoenix's solar panels were severely damaged by the freezing during the Martian winter.

214

Kaguya

Nation: Japan (6)

Objective(s): lunar orbit

Spacecraft: SELENE plus Okina (Rstar) and Ouna (Vstar)

Spacecraft Mass: 2,900 kg

Mission Design and Management: JAXA

Launch Vehicle: H-IIA 2022 (no. 13)

Launch Date and Time: 14 September 2007 / 01:31:01 UT

Launch Site: Tanegashima / Area Y1

Scientific Instruments:

• 1. x-ray spectrometer (XRS)
• 2. gamma-ray spectrometer (GRS)
• 3. multi-band imager (MI)
• 4. spectral profiler (SP)
• 5. terrain camera (TC)
• 6. lunar radar sounder (LRS)
• 7. laser altimeter (LALT)
• 8. lunar magnetometer (LMAG)
• 9. charged particle spectrometer (CPS)
• 10. plasma energy angle and composition experiment (PACE)
• 11. radio science experiment (RS)
• 12. upper atmosphere and plasma imager (UPI)
• 13. four-way Doppler measurements by relay satellite and main orbiter transponder (RSAT)
• 14. differential VLBI radio source experiment (VRAD)
• 15. high-definition television (HDTV)

Results: SELENE (Selenological and Engineering Explorer), named Kaguya ("Moon princess") after launch as a result of a public poll, was the second Japanese lunar probe, whose goal was to orbit the Moon and collect data on the origins and geological evolution of Earth's only natural satellite, study the lunar surface environment, and carry out radio science experiments. The Japanese noted it was "the largest lunar mission since the Apollo program." Besides the main lunar satellite, SELENE, the mission also included two small spin-stabilized sub-satellites, each weighing 53 kilograms. These were the Relay Satellite (Rstar) and the VRAD satellite (Vstar). Upon launch, they were renamed Okina and Ouna, which mean "honorable elderly man" and "honorable elderly woman," respectively. Originally slated for launch in 2003 but delayed to 2007 due to problems with the H-II launch vehicle, the probe was launched into a highly elliptical parking orbit of 282 × 232,960 kilometers. On 3 October 2007, Kaguya entered into an initial polar orbit around the Moon at 101 × 11,741 kilometers, the first time that a Japanese spacecraft had done so. The two subsatellites, Okina and Ouna, were released on 9 October at 00:36 UT and 12 October at 04:28 UT into corresponding orbits: 115 × 2,399 kilometers and 127 × 795 kilometers. The orbiter itself attained its operational circular orbit at 100 kilometers by 19 October. Soon, on 31 October, Kaguya's two main HDTV cameras—each a 2.2 megapixel CCD HDTV camera—took the first high definition images of the Moon. A week later, on 7 November, the satellite took spectacular footage of an "Earthrise," the first since the Apollo missions in the 1970s. The fully operational phase of the mission began on 21 December following a successful checkout of all the onboard instruments. By 9 April 2008, JAXA was able to announce that Kaguya, using its Laser Altimeter, had been able to collect enough data to construct the topography of the entire lunar surface, with data points 10 orders larger than the previous model of the lunar surface, produced by the Unified Lunar Control Network in 2005, based largely on the American Clementine spacecraft. Its subsequent achievements include detecting gravity anomalies on both the near and far side of the Moon (based on Doppler data from both Kaguya and the Okina spacecraft) and the first optical observation of the permanently shadowed interior of the Shackleton Crater. Kaguya completed its original planned mission by late October 2008, with hopes to continue to March 2009 followed by impact in August 2009. However, because of a faulty reaction wheel, the extended mission was ended early. On 1 February 2009, Kaguya's orbit was lowered to approximately 50 kilometers. The orbiter then impacted the Moon at 18:25 UT on 10 June 2009 at 65.5° S / 80.4° E near Gill Crater. Okina had already impacted the Moon at 10:46 UT on 12 February 2009.