There was recent exciting news last month about the landing of the Curiosity Rover on Mars. JPL has an excellent web site. Follow both links to keep up to date on the most recent news of the mission. There are five other missions I have been watching as well. Each of them has some recent news I want to share. If you are a fan of space missions, I hope these will interest you. A lot of science about the Moon, planets, and protoplanets is coming.
Thanks for your patience with the rather long diary. A lot of updates were posted by NASA recently. I figured they all needed some attention. |
Dawn and the Protoplanets
This week the
Dawn spacecraft will depart from the large asteroid
Vesta and begin its journey to the largest asteroid
Ceres. It is to arrive at Ceres in February 2015. It will orbit Ceres first at high altitude, then descend to low altitude gathering images and data as it did with Vesta. Dawn has been at Vesta from July 2011 until now. This orbit trajectory diagram shows the long curving journey. Dawn is equipped with an ultra efficient ion engine. The thrust is very weak. But, it can thrust for a very long time. Dawn was originally to depart in August. But some problems with gyroscopic stabilizing fly wheels has cause a delay. The mission success should not be impacted by this problem.
Vesta, Ceres, Earth's Moon
What we knew of Vesta prior to Dawn was limited. Hubble Telescope views were stitched together into this rotation movie. It takes 5.34 hours to rotate. Astronomers combined 146 exposures. The images were taken in near-ultraviolet and blue wavelengths. It is not representative of what the human eye would see. Dark areas were thought to be basalt. Red areas thought to be dust. They were made February 25 and 28, 2010.
Come below the squiggle to see what Dawn did for our view of Vesta.
The movie below is of Vesta from Dawn images when it arrived in July 2011. What a difference. And it only got better as the months went by. See the details in the links below. Dawn first maintained a high orbit to survey the body. It then descended to low orbit for higher resolution imaging and to make closer measurements with instrumentation. It also could feel the accelerations caused by variations in mass at, and below the surface, to get information about internal structure and density.
Dawn has found that the asteroid's southern hemisphere boasts one of the largest mountains in the solar system. Vesta's surface, viewed by Dawn at different wavelengths, has striking diversity in its composition, particularly around craters. The surface appears to be much rougher than most asteroids in the main asteroid belt. Indications are that areas in the southern hemisphere are as young as 1 billion to 2 billion years old, much younger than areas in the north.
Scientists do not yet understand how all the features on Vesta's surface formed. After analysis of northern and southern troughs, results are consistent with models of fracture formation due to giant impact.
One of the most impressive views comes from this low altitude simulated flyover made from a large number of images. I suggest you watch it in full screen mode and change the quality to HD with the little gear-like ✲ symbol toward the lower right part of the window.
This coming week Dawn begins the journey to Ceres. This optimized image below is our current best view of Ceres from Hubble in January 2004. It was the first object discovered in the asteroid belt in 1801 by Sicilian astronomer Father Giuseppe Piazzi. It and other objects were found in the region between Mars and Jupiter. They were called asteroids or minor planets. Ceres was first called as a planet and later an asteroid. In recognition of its planet-like qualities, Ceres was designated a dwarf planet in 2006 along with Pluto and Eris.
Dawn will give us unprecedented views of Ceres and answer a lot of questions about its makeup and history. It is believed to be quite different from Vesta. We shall see.
Links to past Dawn and Vesta diaries and science reports.
• Ministry of Space Exploration Dawn Blog
• Dawn @ Vesta in Low Altitude Orbit Dec. 2011
• Dawn @ Vesta Science Report Oct. 2011
• Dawn Visits the Protoplanets July 2011
GRAIL
The Gravity Recovery And Interior Laboratory (GRAIL) mission is designed to create a gravity map of the moon, using two spacecraft that orbit the moon at very precise distances. The mission will enable scientists to learn about the moon's internal structure and composition, and give scientists a better understanding of the moon's origin. Accurate knowledge of the moon's gravity could also be used to help choose future landing sites on the moon.
During the GRAIL mission's science phase which was completed this spring, spacecraft (Ebb and Flow) transmitted radio signals precisely defining the distance between them as they orbited the moon in formation.
Ebb and Flow were named by school children in Bozeman, Montana in January.
During the mission from March 1 to May 29, Ebb and Flow, orbited at an average altitude of 34 miles (55 kilometers). GRAIL returned 99.99% of the data that could have been collected. It also did so ahead of schedule. As of August 30, GRAIL entered the extended mission phase.
"Orbiting at an average altitude of 14 miles (23 kilometers) during the extended mission, the GRAIL twins will be clearing some of the moon's higher surface features by about 5 miles (8 kilometers)," said Joe Beerer of JPL, GRAIL's mission manager. "If Ebb and Flow had feet, I think by reflex they'd want to pull them up every time they fly over a mountain."
Along with mission science, GRAIL's MoonKAM (Moon Knowledge Acquired by Middle school students) education and public outreach program is also extended. To date over 70,000 student images of the moon have been obtained. The MoonKAM program was led by Sally Ride, America's first woman in space, and her team at Sally Ride Science in collaboration with undergraduate students at the University of California in San Diego.
Links to past GRAIL diaries and science reports.
• NASA GRAIL MoonKAM Middle School Science Mission Has Begun Mar. 2012
• GRAIL A B Renamed Ebb Flow Jan. 2012
• GRAIL A & B Lunar Mission Update Jan. 2012
MESSENGER
The MESSENGER spacecraft launched eight years ago on August 3, 2004 on a six-and-a-half year journey to become the first spacecraft to orbit Mercury. The spacecraft's 4.9-billion mile (7.9-billion kilometer) cruise to history included 15 trips around the Sun, a flyby of Earth, two flybys of Venus, and three flybys of Mercury.
MESSENGER made history on January 14, 2008, when it flew over a portion of Mercury that had never before been seen at close range. In this first of three flybys of the planet, the probe's cameras took 1,213 images and other sophisticated instruments made the first spacecraft measurements of the planet and its environment since Mariner 10's third and final flyby on March 16, 1975.
On March 17, 2012, MESSENGER successfully completed a year-long campaign to perform the first global reconnaissance of the geochemistry, geophysics, geologic history, atmosphere, magnetosphere, and plasma environment of the solar system's innermost planet. The following day, March 18, 2012, marked the official start of an extended mission phase designed to build upon those discoveries. Two orbit-correction maneuvers on April 16 and April 20, 2012 shortened the orbit period from 12 to 8 hours, allowing MESSENGER an even closer look at the planet.
"Our small spacecraft has been a hardy traveler," says MESSENGER Principal Investigator Sean Solomon, of the Lamont-Doherty Earth Observatory at Columbia University. "Across billions of miles, during more than 1,000 orbits about the planet with the greatest extremes in surface temperature, and in the face of streams of energetic particles from an increasingly active Sun, MESSENGER has continued to surpass expectations. Mercury, too, has continued to surprise the scientific community, and the MESSENGER team looks forward to learning more about one of the nearest yet least studied worlds."
Links to past MESSENGER diaries and science reports.
• Ministry of Space Exploration MESSENGER Blog. An excellent link.
• Messages from ☿ Mercury - MESSENGER Science Update Sep. 2011
• Update: Messages from ☿ Mercury June 2011
• Update: Messages From ☿ Mercury May 2011
NEW HORIZONS
In 2006, NASA dispatched an ambassador to the planetary frontier. The New Horizons spacecraft is now well more than halfway between Earth and Pluto, on approach for a dramatic flight past the icy planet and its moons in July 2015. New Horizons will shed light on new kinds of worlds we've only just discovered on the outskirts of the solar system.
With New Horizons, NASA set out a list of things it (and the planetary science community) wanted to know about Pluto: What is its atmosphere made of, and how does it behave? What does the surface of Pluto look like? Are there big geological structures? How do particles ejected from the sun (known as the solar wind) interact with Pluto's atmosphere?
The Kuiper Belt and KBO
Arrival at Pluto in just over 1000 days is approaching with great anticipation. But, that will not be the end of the mission. The spacecraft will continue to coast from the Sun into a region called the Kuiper Belt.
The Kuiper Belt is a region of space in our solar system, shaped more like an ellipse than a circle, which is similar to an asteroid belt. While the asteroid belt is mostly metal and rock, the Kuiper Belt is composed almost entirely of icy chunks of various substances. Actually, the makeup of Kuiper Belt Objects KBO is similar to the composition of comets – a mixture of frozen water, ammonia and various hydrocarbons, such as methane.
This region is located approximately 30 to 50 AU (astronomical units) from the Sun. Each astronomical unit is equivalent to the distance from the Earth to the Sun, so the region is 4.5 billion km to 7.4 billion km from the Sun. Scientists believe that there are over 70,000 objects in the Kuiper Belt, although astronomers have found a fraction so far. Some of these Kuiper Belt objects, KBOs, are massive. In fact, the dwarf planet Pluto is thought to be one of the objects in the Kuiper Belt. Pluto is the largest known KBO, but there are a number of other objects of substantial size. Quaoar is more than half the size of Pluto, and Makemake and Haumea are much closer in size to Pluto. A number of KBOs, including Pluto and Haumea, also have satellites.
JUNO
The
Juno Mission is of particular interest to me for a couple of reasons. First, it has an experiment on board from the
University of Iowa Physics and Astronomy Dept. Secondly, Son in IA had a summer job in the lab that was building some of the hardware for the experiment. Here are some details about the mission
Mission Timeline
• Launch - August 5, 2011
• Deep Space Maneuvers - August/September 2012
• Earth flyby gravity assist - October 2013
• Jupiter Orbital Insertion (JOI) - July 2016
• Spacecraft will orbit Jupiter for about one year (33 orbits)
• End of mission (deorbit into Jupiter) - October 2017
In this graphic of the trajectory there are Deep Space Maneuvers set for August 30 and September 4. As of this writing, the maneuver went well on the 30th. Based on telemetry, the Juno project team believes the burn was accurate, changing the spacecraft's velocity by about 770 mph (344 meters a second) while consuming about 829 pounds (376 kilograms) of fuel.
This image of Earth (on the left) and the moon (on the right) was taken by NASA's Juno spacecraft on Aug. 26, 2011, when the spacecraft was about 6 million miles (9.66 million kilometers) away. It was taken by the spacecraft's onboard camera, JunoCam. Image credit: NASA/JPL-Caltech/SwRI
A second deep space maneuver, of comparable duration and velocity change, is planned for Sept. 4. Together, they will place Juno on course for its Earth flyby, which will occur as the spacecraft is completing one elliptical orbit around the sun. The Earth flyby will boost Juno's velocity by 16,330 mph (about 7.3 kilometers per second), placing the spacecraft on its final flight path for Jupiter. The closest approach to Earth, on Oct. 9, 2013, will occur when Juno is at an altitude of about 310 miles (500 kilometers).
Specifically, Juno will…
• Determine how much water is in Jupiter’s atmosphere, which helps determine which planet formation theory is correct (or if new theories are needed)
• Look deep into Jupiter’s atmosphere to measure composition, temperature, cloud motions and other properties
• Map Jupiter’s magnetic and gravity fields, revealing the planet’s deep structure
• Explore and study Jupiter’s magnetosphere near the planet’s poles, especially the auroras – Jupiter’s northern and southern lights – providing new insights about how the planet’s enormous magnetic force field affects its atmosphere.