Throughout the inner solar system in 2016, NASA, ESA, JAXA, Roscosmos, and ISRO built upon their prior year successes and demonstrated a coordinated and cooperative approach toward advancing scientific returns from around Earth\u2019s immediate neighbors. For these agencies, non-Earth orbital exploration yielded surprising and dramatic changes to our views of the Sun, Venus, the Moon, and Mars via arrivals, discoveries, and cooperative investigations.<\/p>\n<\/p>\n
The Sun \u2013 The Transit of Mercury; new insights on solar waves and coronal heating:<\/b><\/p>\n
The oft forgotten but wholly important element of our solar system has the largest number of operational spacecraft and instruments dedicated to its round-the-clock study, including the Solar Dynamics Observatory (SDO), DSCOVR, PICARD, the Solar Monitoring Observatory, the Solar Terrestrial Relations Observatory, Hinode, the Reuven Ramaty High Energy Solar Spectroscopic Imager, the Advanced Composition Explorer, the Solar and Heliospheric Observatory (SOHO), and the Global Geospace Geoscience WIND.<\/p>\n
![\"\"](\"\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2016\/12\/Screen-Shot-2016-12-17-at-14.04.00-350x287.png\")
In a relatively quiet solar year, one that satellites and instruments again spent continuously peering at the sun, the year afforded an opportunity for space-based craft to observe and study the transit of Mercury and potentially unlock a solar question that has puzzled scientists for decades.<\/p>\n
Occurring roughly 13 times each century, the transit of Mercury is far more common though less celebrated than the transit of Venus. Regardless, Mercury\u2019s transit of the sun is equally valuable in terms of stellar observation.<\/p>\n
Historically, the transits of Mercury were used to measure the apparent size of Mercury and help estimate the distance from Earth to the sun.<\/p>\n
This year, the transit of Mercury occurred on 19 May and was observed cooperatively by SDO, Hinode (a JAXA led and NASA, ESA, and UK supported mission), and SOHO (a joint operation of NASA and ESA) \u2013 for which two of SOHO\u2019s dormant instruments were turned back on: the Extreme Ultraviolet Imaging Telescope and the Michelson Doppler Imager.<\/p>\n
Rocket building kits (adsbygoogle = window.adsbygoogle || []).push({});<\/p>\n Likewise, SDO used the transit to help with instrument alignment, made possible because scientists know with such precision where Mercury should be in relationship to the sun that they can use it as a marker to fine tune exactly how SDO\u2019s instruments should be pointed.<\/p>\n For SDO, the Mercury transit observation campaign was not the only significant return this year, with the craft also providing a new understanding of solar waves and, in connection, a revelation about a long-standing mystery of the sun\u2019s coronal temperature.<\/p>\n For the solar waves, the sun is constantly changing as charged material courses through not only the star itself, but throughout its expansive atmosphere.<\/p>\n In a scientific paper announced in October, scientists revealed that SDO, along with the Interface Region Imaging Spectrograph and Big Bear Solar Observatory, had tracked a particular kind of solar wave as it swept upward from the sun\u2019s surface through its atmosphere. <\/p>\n Scientists have long suspected that the solar waves seen on the sun\u2019s surface, the photosphere, are linked to those seen in the lowest reaches of the sun\u2019s atmosphere, the chromosphere. But never before had scientist been able to track a wave up through the various layers into the sun\u2019s atmosphere.<\/p>\n Until now.<\/p>\n The implications of this study are twofold. First, the technique for watching solar waves gives scientists a new tool to understand the sun\u2019s lower atmosphere, and second, it provides an avenue to potentially answer a long-standing question in solar physics: the coronal heating problem.<\/p>\n For the first implication, \u201cWatching waves move upwards tells us a lot about the properties of the atmosphere above sunspots \u2013 like temperature, pressure, and density,\u201d said Ruizhu Chen, a graduate student scientist at Stanford. <\/p>\n \u201cThe magnetic field [acts] like railroad tracks, guiding the waves as they move up through the atmosphere,\u201d said Dean Pesnell, SDO project scientist at NASA\u2019s Goddard Space Flight Center.<\/p>\n For the second implication, the coronal heating problem, models have always suggested that each layer of the sun should be cooler the further out they are. But the corona is roughly one hundred times hotter than the region directly below it \u2013 counter to what the models suggest.<\/p>\n Presently, no one has been able to pinpoint the source of the extra heat in the corona, but solar waves may play a small role.<\/p>\n \u201cWhen a wave travels upwards, a number of different things can happen,\u201d said Zhao. \u201cSome may reflect back downwards or contribute to heating \u2013 but by how much, we don\u2019t yet know\u201d. <\/p>\n Venus shines in new exploration from Akatsuki:<\/b><\/p>\n The only spacecraft at Venus, JAXA\u2019s Akatsuki vehicle marked the completion of its first Earth-year at Venus this month on 7 December.<\/p>\n Following initial confirmation of Akatsuki\u2019s health and orbital parameters, JAXA controllers fired Akatsuki\u2019s thrusters on 26 March to lower the probe\u2019s apoapsis to 330,000 km (210,000 mi).<\/p>\n Lowering of the apoapsis resulted in a 9 day, stable orbit, well off the pre-mission planned 30 hour orbit that would have resulted had orbit insertion occurred as planned in 2010.<\/p>\n Throughout the preliminary orbit and first month of the refined orbit, Akatsuki\u2019s controllers powered up the craft\u2019s onboard observation instruments.<\/p>\n Following final checkout of its instruments, Akatsuki was taken to full operational mode and began its two Earth-year primary science mission on 28 April 2016.<\/p>\n With Venus\u2019 orbital period of 225 Earth-days, Akatsuki marked its first full Venusian year on 19 July, at which point JAXA confirmed that the spacecraft was operating well and was gathering information as intended to study the stratification of Venus\u2019 atmosphere and the complex meteorology of the planet.<\/p>\n The Moon:<\/b><\/p>\n Churning away in lunar orbit for its seventh year, NASA\u2019s Lunar Reconnaissance Orbiter (LRO) continued to reveal more secrets of our closest celestial neighbor.<\/p>\n The discovery was made via LRO\u2019s observation of the lunar ice trapped in craters at the Moon\u2019s poles. When the spin axis of the moon shifted, it allowed sunlight to reach areas that were previously in constant shadow \u2013 evaporating ice present at those locations.<\/p>\n Researchers have now discovered that the ice that survived this axis shift \u201cpaints\u201d a path along which the axis moved. <\/p>\n The researchers matched this ice path with models predicting where ice could remain stable and inferred the moon\u2019s axis had moved by approximately five degrees. <\/p>\n This is the first physical evidence that the Moon underwent such a dramatic change in orientation and implies that much of the lunar polar ice is billions of years old.<\/p>\n \u201cThe new findings are a compelling view of the moon\u2019s dynamic past,\u201d said Dr. Yvonne Pendleton, director of the Solar System Exploration Research Virtual Institute. \u201cIt is wonderful to see the results of several missions pointing to these insights.\u201d<\/p>\n While a celestial body\u2019s spin axis can change for a number of reasons, the change to the Moon\u2019s is likely the result of a large change in mass in the interior Procellarum region on the lunar near-side. <\/p>\n Concentrations of radioactive material in the Procellarum region were found to be sufficient enough to have heated a portion of the lunar mantle, causing a density change significant enough to reorient the Moon.<\/p>\n Following this announcement, NASA revealed findings from LRO related to how the Moon received its 100+ distinctive \u201ctattoos\u201d \u2013 swirling patterns of lightly colored regions found across the lunar surface.<\/p>\n Previous observations held two significant clues about their formation \u2013 1. They occur where ancient bits of magnetic field are embedded in the lunar crust, and 2., the bright areas in the swirls appear to be less weathered than their surroundings. <\/p>\n Those observations led to three prominent theories about how the swirls formed, one of which being that particles in the solar wind, being electrically charged, respond to magnetic forces around the Moon and formed shields \u2013 the lighter colored \u201ctattoo\u201d areas \u2013 on the surface that prevent surface weathering by the solar wind.<\/p>\n This magnetic shield theory was tested with new observations by LRO and revealed that the lunar magnetic field can create a strong enough electric field \u2013 when the solar wind flows through it \u2013 to deflect and slow particles in the solar wind and therefore reduce the weathering from the solar wind, leaving brighter regions over protected areas.<\/p>\n An analysis of LRO data led researchers to understand that the lunar surface experiences a heavier bombardment by small meteoroids than models had previously predicted. <\/p>\n By comparing early mission and more current high resolution images from LRO, researchers were able to directly measure the rate of heavier bombardment as well as the rate at which the lunar regolith (top 1 inch of surface material) was overturned from micrometeorite impacts.<\/p>\n Prior to LRO, scientists had estimated that it took 8.1 million years for 99% of the Moon\u2019s surface to be overturned \u2013 made new. The new LRO data adjusts that estimate to just 81,000 years \u2013 100 times faster than previously thought.<\/p>\n Mars \u2013 MOM, Mars Express, Mars Odyssey, MRO, and MAVEN welcome TGO:<\/b><\/p>\n Most of the major coverage and attention on Mars this year focused on the Trace Gas Orbiter (TGO \u2013 from ESA and Roscosmos) and Schiaparelli (ESA) lander missions\u2019 launch and arrival at the red planet. <\/p>\n As with Mars Express and MRO, one of TGO\u2019s functions is to increase and enhance the telecommunications network present at Mars ahead of the arrival of future spacecraft \u2013 notably the ExoMars 2020 mission by ESA and Roscosmos.<\/p>\n With its successful arrival, TGO joined the five already operational Mars orbiters that continued to churn away in orbit and unlock Mars\u2019 mysteries and perform technology demonstration for future Mars missions.<\/p>\n ISRO \u2013 MOM at Mars:<\/p>\n In the realm of technology demonstration, the Indian Space Research Organisation\u2019s (ISRO\u2019s) Mars Orbiter Mission (MOM) saw the release of its first scientific results this year.<\/p>\n While simply confirming another spacecraft\u2019s discovery might not seem like a banner achievement, it certainly is for MOM, whose primary purpose is to serve as a technology demonstration for ISRO\u2019s goal of placing a more robust scientific investigation orbiter around Mars in the coming years.<\/p>\n The corroboration from MENCA also validated returns from ISRO\u2019s Chandrayaan-1 mission to the Moon, which carried the CHACE (Chandra\u2019s Altitudinal Composition Explorer) instrument that first detected ice on the surface of the Moon but whose results were preliminarily dismissed due to the unproven nature of the CHACE instrument.<\/p>\n ESA \u2013 Mars Express marks 13 years at the Red Planet:<\/p>\n For ESA, 2016 marked the 13th year of operations for Mars Express and the continued return of information regarding Mars\u2019 geologic past.<\/p>\n However, the coup de grace for Mars Express this year came in May via a series of observations from the craft in 2012 that have potentially shed new light on mysterious high-rise clouds observed periodically on Mars. <\/p>\n The cloud-like plumes are seen at an altitude of ~250 km (~155 mi). However, none of the recorded plumes have been observed in situ by Mars orbiters \u2013 only from Earth ground- and space-based telescopes.<\/p>\n The extreme altitude\/elevation of the clouds in the Martian ionosphere is unusual. Typical clouds consisting of frozen carbon dioxide and water are not able to form that high in Mars\u2019 atmosphere.<\/p>\n Review of this data showed that a massive Coronal Mass Ejection (CME) from the Sun struck the Martian atmosphere at the same place and at relatively the same time as the 2012 cloud\u2019s appearance.<\/p>\n \u201cOur plasma observations tell us there was a space weather event large enough to impact Mars and increase the escape of plasma from the planet\u2019s atmosphere,\u201d says David Andrews of the Swedish Institute of Space Physics.<\/p>\n However, information from Mars Express did not conclusively prove that the CME event was the cause of the mysterious cloud.<\/p>\n \u201cOne problem is that the plume was seen at the day-night boundary, over a region of known strong crustal magnetic fields where we know the ionosphere is generally very disturbed, so searching for \u2018extra\u2019 signatures is rather challenging.\u201d<\/p>\n However, like the 2012 event, no spacecraft at Mars in 1997 observed that cloud, nor did they carry instruments sufficient to judge the CME\u2019s impact on Mars.<\/p>\n This, coupled with the fact that CMEs hit Mars many times without the appearance of these mysterious high-rise clouds creates a case for scientific doubt as to the relationship of the two events.<\/p>\n Presently, Mars Express\u2019 study of the Martian atmosphere will continue for several more years as the mission has been formally extended through at least the end of 2018 with enough fuel to remain operational until 2026.<\/p>\n If Mars Express remains operational until 2026, it will enjoy roughly one year as the reigning longest-operational craft at Mars \u2013 taking the title from NASA\u2019s Mars Odyssey orbiter which arrived two years before Mars Express but only has enough fuel to last until 2025.<\/p>\n NASA \u2013 Mars Odyssey marks unprecedented 15th year at Mars:<\/p>\n Mars Odyssey and its teams celebrated the 15th anniversary of the craft\u2019s launch on 7 April and the 15th anniversary of its arrival at Mars on 24 October.<\/p>\n Mars Odyssey is currently in an orbit that not only permits it to pass directly overhead of the Curiosity rover twice daily for communication relay with Earth but to also observe the Martian surface during sunrise hours to collect data on morning clouds and fog.<\/p>\n Moreover, observations of the briny water flows on Mars by Mars Odyssey\u2019s THEMIS instrument allowed scientists to determine an upper limit on the amount of water contained at these deposits, which were discovered by MRO and announced last year.<\/p>\n Data from Mars Odyssey indicates that the briny areas contain 30 grams of water per kilogram of soil, or about as much water contained in the driest sands on Earth.<\/p>\n Importantly, this discovery does not contradict what scientists announced last year in the discovery of the salt water flows but rather lends a greater understanding to their composition and our growing knowledge of the nature of present-day water on Mars. <\/p>\n Mars Reconnaissance Orbiter \u2013 10 years on:<\/p>\n","protected":false},"excerpt":{"rendered":" Throughout the inner solar system in 2016, NASA, ESA, JAXA, Roscosmos, and ISRO built upon their prior year successes and demonstrated a coordinated and cooperative approach toward advancing scientific returns from around Earth\u2019s immediate neighbors. For these agencies, non-Earth orbital exploration yielded surprising and dramatic changes to our views of the Sun, Venus, the Moon, […]<\/p>\n","protected":false},"author":1,"featured_media":30245,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"inline_featured_image":false,"footnotes":"","_links_to":"","_links_to_target":""},"categories":[2],"tags":[2297,4129,367,3370,4273],"class_list":["post-38896","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news","tag-exomars","tag-jpl","tag-mars","tag-maven","tag-mom"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/38896"}],"collection":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/comments?post=38896"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/38896\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media\/30245"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=38896"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=38896"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=38896"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}![\"\"](\"\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2016\/12\/Screen-Shot-2016-12-17-at-14.06.00-350x324.png\")
During the transit event, SOHO measured the sun\u2019s rotation axis \u2013 part of a long line of observations which help scientists better understand how the sun changes over hours, days, years and decades.<\/p>\n![\"\"](\"\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2016\/12\/bbso4-350x350.gif\")
Understanding the path this charged material (the solar wave) takes through the sun\u2019s multiple layers, how it heats up the sun\u2019s atmosphere, how it creates a steady flow of solar wind streaming outward in all directions, and how magnetic fields create regions that can explode in giant eruptions is a key element to SDO\u2019s mission. <\/p>\n![\"\"](\"\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2016\/12\/Screen-Shot-2016-12-17-at-14.09.58-350x250.png\")
\u201cThis research gives us a new viewpoint to look at waves that can contribute to the energy of the [sun\u2019s] atmosphere,\u201d said Junwei Zhao, a solar scientist at Stanford University. <\/p>\n![\"\"](\"\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2016\/12\/Screen-Shot-2016-12-17-at-14.11.10-350x262.png\")
\u201cMore importantly, we can figure out the magnetic field strength and direction\u201d because the effect of the magnetic field on these waves is so pronounced that instead of traveling straight upwards through the sun, the waves veer off and take a curved path through the atmosphere.<\/p>\n![\"\"](\"\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2015\/12\/2015-12-27-162755-350x259.jpg\")
Last December, the mission settled into its preliminary orbit, but because of a five-year delayed insertion, recovery efforts, and investigation findings, JAXA controllers were forced to insert Akatsuki into a highly elliptical 440,000 km (270,000 mi) x 400 km (250 mi) 13 day 14 hour orbit of Venus.<\/p>\n![\"\"](\"\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2016\/12\/Screen-Shot-2016-12-17-at-14.16.33-350x282.png\")
In early April, JAXA confirmed that all of Akatsuki\u2019s instruments were functioning properly and had already conducted enough observations to meet minimum mission success criteria \u2013 which included capturing Venus\u2019 all-globe cloud structure via continuous imaging from Venusian orbit. <\/p>\n![](\"\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2016\/12\/Screen-Shot-2016-12-17-at-14.19.25-314x350.png\")
In March, NASA announced that new information from LRO revealed that the spin axis of the Moon shifted by five degrees roughly 3 billion years ago.<\/p>\n![](\"\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2016\/12\/Screen-Shot-2016-12-17-at-14.21.49-340x350.png\")
While the primary data came from LRO and its instruments, corroborating evidence of the spin axis shift came from previously gathered data of the Gravity Recovery And Interior Laboratory (GRAIL) and the Lunar Crater and Observation Sensing Satellite (LCROSS) missions. Additional confirmation came from present-day observations of lunar ice concentrations that are displaced from each pole by the same distance but exactly opposite directions. <\/p>\n![](\"\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2016\/12\/Screen-Shot-2016-12-17-at-14.24.25-350x338.png\")
\u201cThese patterns, called lunar swirls, appear almost painted on the surface of the moon,\u201d said John Keller of NASA\u2019s Goddard Space Flight Center. \u201cThey are unique; we\u2019ve only seen these features on the moon, and their origin has remained a mystery since their discovery.\u201d<\/p>\n![](\"\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2016\/12\/Screen-Shot-2016-12-17-at-14.29.31-350x242.png\")
Moreover, in October, NASA announced a drastic alteration to scientists\u2019 understanding of the age of the lunar surface.<\/p>\n![\"\"](\"\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2016\/10\/Screen-Shot-2016-10-18-at-14.51.31-350x228.png\")
While Schiaparelli was not successful in its attempt to land, TGO was successful in inserting itself into Martian orbit \u2013 all while Mars Express and the Mars Reconnaissance Orbiter (MRO) provided telecommunication relay and real-time monitoring of Schiaparelli\u2019s and TGO\u2019s approach and arrival sequences.<\/p>\n![\"\"](\"\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2014\/09\/2014-09-23-22_01_44-India-MOM-PSLV-Google-Search-350x257.jpg\")
The results, published in the journal Geophysical Research Letters, related to the Mars Exospheric Neutral Composition Analyser (MENCA) \u2013 which, while not making a discovery on its own, did corroborate MRO\u2019s detection of briny water solutions on the Martian surface. <\/p>\n![\"\"](\"\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2016\/12\/Screen-Shot-2016-12-17-at-14.34.58-350x350.png\")
This year, ESA released information from Mars Express regarding an ancient flood on Mars (evidence for which can be seen from orbit in the form of dendritic drainage patterns and formerly muddy sediments that have since dried and partially collapsed), observations of ancient tectonic stress and fault fractures, and evidence for ancient glaciers.<\/p>\n![\"\"](\"\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2016\/12\/Screen-Shot-2016-12-17-at-14.38.14-350x350.png\")
Nonetheless, the ionosphere is where the Martian atmosphere directly interacts with the solar wind, and this led scientists to look at plasma and solar wind measurements collected by Mars Express at the time of the most recent high-rise cloud in 2012.<\/p>\n![\"\"](\"\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2016\/12\/Screen-Shot-2016-12-17-at-14.37.13-350x251.png\")
Corroborating evidence for a CME cause does exist, however, via the 1997 high-rise cloud observed by the Hubble Space Telescope at the same time that a well-studied CME hit both Earth and Mars.<\/p>\n![\"\"](\"\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2016\/12\/Screen-Shot-2016-12-17-at-14.41.02-350x279.png\")
With this longevity, Mars Odyssey has observed Mars through seven complete solar orbits and full seasonal variations \u2013 which has allowed scientists to begin constructing normal and varying climate maps and models of Mars through its four seasons.<\/p>\n