NASA to Launch “Dawn” Spacecraft to Ceres and Vesta, Asteroid Belt Denizens

The National Aeronautics and Space Administration (NASA), because of highly limited launch opportunities and protection of the Phoenix Mars Lander mission launch in August, has rescheduled the launch of its Dawn mission “to the heart of the asteroid belt” from July 2007 to September 2007 at Cape Canaveral Air Force Station, Florida. (1)

Dawn is the ninth of 10 missions in NASA’s Discovery Program. The previous eight missions were Near-Earth Asteroid Rendezvous (February 17, 1996), Mars Pathfinder (December 4, 1996), Lunar Prospects (January 6, 1998), Stardust (February 7, 1999), Genesis (August 8, 2001), Comet Nucleus Tour (July 3, 2002), Mercury Surface, Space Environment, Geochemistry and Ranging Messenger (August 3, 2004), and Deep Impact (January 12, 2005). NASA plans the tenth Kepler mission for an October 2008 launch. (1a)

Depiction of Asteroid belt. Source: http://www.tqnyc.org/NYC063368/AsteriodBelt.jpg; accessed July 11, 2007.	Depiction of Asteroids in belt. Source:  http://www.tqnyc.org/NYC063368/orbit.bmp; accessed July 11, 2007.

Dawn’s two targets in the asteroid belt, located between the planets Mars and Jupiter, are the minor planets Vesta and Ceres, the two most massive residents of the belt.

The Dawn spacecraft is 5.4 feet long, 4.2 feet wide and 5.8 feet high. Its high-gain antenna is 5 feet in diameter and when deployed, its solar array is 65 feet long, tip to tip. (2) It will carry three instruments: a framing camera, a visible and infrared mapping spectrometer, and a gamma ray and neutron spectrometer. (3)

The framing camera will acquire detailed optical images for scientific purposes and navigation in the vicinities of Vesta and Ceres. Dawn carries two identical and physically separate cameras for redundancy, each with its own optics, electronics and structure. The Max Planck Institute for Solar System Research, Germany, designed and fabricated the cameras, in cooperation with the Institute of Planetary Research of the German Aerospace Center and the Institute for Computer and Communication Network Engineering of the Technical University of Braunschweig. (3a)

Artist concept of Dawn. Image credit: William K. Hartmann Courtesy of UCLA. Source: http://www.jpl.nasa.gov/images/dawn/dawn-concept-browse.jpg; accessed July 11, 2007.	Two-inch meteorite fragment of Vesta asteroid. Source: http://www.nasa.gov/images/content/175953main_vesta-meteorite-browse.jpg; accessed July 11, 2007.

The visible and infrared mapping spectrometer will measure the surface mineralogy of Vesta and Ceres. Pictures taken by the instrument record the light intensity at more than 400 wavelength ranges in every pixel. Scientists can determine the minerals on the surfaces of Vesta and Ceres by comparing the pictures with laboratory measurements of minerals on Earth. The instrument has 6 gigabits of internal memory. The Italian Space Agency provided the spectrometer, which Galileo Avionica designed and built in collaboration with Italy’s National Institute for Astrophysics. (3a)

The gamma ray and neutron detector will measure the elemental composition of Vesta and Ceres (down to three feet from their surfaces) by quantifying the energy from gamma rays and neutrons that bounce off, or are emitted by, Vesta and Ceres. The neutron and gamma ray maps will show the degree to which oxygen, magnesium, silicon, calcium, titanium and iron exist on the surfaces of Vesta and Ceres. In addition, the maps will show the presence of gadolinium and samaritium (trace elements) and long-lived radioactive elements (potassium, thorium and uranium). Gamma rays are a form of light, while neutrons are particles that normally reside in the nuclei of atoms. This instrument will tell scientists whether Ceres is rich in water. The instrument has no internal memory storage. Los Alamos National Laboratory, Los Alamos, New Mexico, USA, developed the instrument.

In addition to these three instruments, notes NASA, “radiometric and optical navigation data will provide data relating to the gravity field and thus bulk properties and internal structure of the two bodies.” (3)

Ceres. Source: http://www.nasa.gov/images/content/175956main_ceres-keck-browse.jpg; accessed July 11, 2007.	Dawn atop rocket. Source:  http://dawn.jpl.nasa.gov/images/fairing_300.jpg; accessed July 11, 2007.

The distance between Earth and Vesta at the time of launch (for the July 7-11, 2007 launch) calculates to 121 million miles. To reach Vesta from Earth, however, Dawn will need to travel 1.9 million miles with a gravity assist from Mars (originally scheduled for April 10, 2009). The arrival of Dawn to Vesta on October 1, 2011 and to Ceres on February 1, 2015, will occur slightly later because of the delayed launch from Earth. Dawn’s prime mission ends in July 2015 (probably advanced to September 2015 with the rescheduling of the launch).

NASA’s Deep Space Network complexes in California’s Mojave Desert, near Madrid, Spain, and near Canberra, Australia will provide tracking and telecommunications throughout the Dawn mission,

The cost of the Dawn mission is $343.5 million total (not including the launch vehicle), consisting of $267 million spacecraft development and $76.5 million for mission operations.

Asteroid Belt Residents

The up-close study of Vesta and Ceres interests NASA staff for three reasons. First, Vesta and Ceres are considered proto-planets, remnant debris from the processes that formed the bodies of the inner solar system. Second, some asteroids have the capacity to cross Earth’s orbit and collide with Earth, an occurrence that has happened in the past and will happen again, with obvious significance for Earth’s living things and the need to deflect or otherwise degrade infalling near-Earth objects. (4-7) Third, asteroids offer natural resources, including volatile compounds and a rich supply of minerals useful for human exploration of the solar system.

Vesta and Ceres, like other bodies in the asteroid belt, formed about 4.5 billion years ago, at the same time and in similar environments as the bodies that grew (accreted) to become the rocky inner planets, Mercury (closest to the Sun), Venus, Earth, and Mars. All the matter in the asteroid belts added up would produce a “healthy planet”.

Astronomers believe that Jupiter’s gravitational pull prevented accretion of the asteroids and other bodies in the asteroid belt. Ceres and Vesta are the two most massive remnants of the failed accretion. Ceres alone accounts for about one-third of the estimated mass of all of the solar system’s asteroids, while Vesta’s mass is almost one-third of Ceres’ mass. (8) 

Drawing of Dawn. Source: National Aeronautics and Space Administration Dawn Press Kit (ed. Susan Watanabe), p. 10. Available at:  http://www.nasa.gov/mission_pages/dawn/news/index.html; accessed July 11, 2007.	Dawn’s journey to the asteroid belt: Source: National Aeronautics and Space Administration Dawn Press Kit (ed. Susan Watanabe), p. 11. Available at:  http://www.nasa.gov/mission_pages/dawn/news/index.html; accessed July 11, 2007.

Vesta, Dry Proto-Planet

The German Heinrich Wilhelm Olbers discovered Vesta (official name is 4 Vesta because it was the fourth asteroid discovered) on March 29, 1807. The dimensions of its nearly spheroid shape are about 359 by 348 by 285 miles (length as long as the length of Arizona), with a massive chunk (crater) out of its south pole. It rotates once every 5 hours, 20 minutes. Its surface appears as basaltic rock, frozen lava, which oozed out of the asteroid’s presumably hot interior shortly after its formation 4.5 billion years ago. Minerals vary across its surface. (9)

Scientists are interested in Vesta’s giant crater, about 285 miles across and 8 miles deep, located at its south pole. The collision that produced this crater blasted over one-half million cubic miles of rock into space. If Earth had a crater that was proportionately as large as the one on Vesta, it would fill the Pacific Ocean. (9) Scientists believe that about 5% of all meteorites found on Earth are a result of this single ancient crash in deep space. (10) Astronomers currently believe that Vesta is the parent body for the class of stony meteorites known as howardite, eucrite and diogenite, or “HED” meteorites. (9a)

Ceres, Wet Proto-Planet

Giuseppe Piazzi of Italy discovered Ceres (1 Ceres because it is the very first minor planet discovered, according to NASA) on January 1, 1801. Also spheroid, Ceres measures 606 by 585 miles, about as big across as the state of Texas. It rotates once ever 9 hours, 4.5 minutes. Its interior, like the Earth, has denser material at the core and lighter minerals near the surface. Astronomers believe that Ceres’ crust may harbor water ice because its density is less than that of the Earth’s crust, and because the dust-covered surface bears spectral evidence of water-bearing minerals. Ceres could even possess polar caps. If Ceres mass contains 25% water, thought to be in the form of water ice in its mantle, it may have more water than all the fresh water on Earth. Astronomers are very interested in understanding the role of water in controlling asteroid evolution.

Summary

Immanuel Velikovsky is smiling somewhere. (4)

Notes:

1. NASA Dawn Portal: “Dawn Mission Rescheduled for September Launch”, July 7, 2007. Available at: http://dawn.jpl.nasa.gov/; accessed July 11, 2007.
   1. National Aeronautics and Space Administration Dawn Press Kit (ed. Susan Watanabe), pp. 7-8. Available at:  http://www.nasa.gov/mission_pages/dawn/news/index.html; accessed July 11, 2007.
2. “Quick Facts”, National Aeronautics and Space Administration Dawn Press Kit (ed. Susan Watanabe), p. 2. Available at:  http://www.nasa.gov/mission_pages/dawn/news/index.html; accessed July 11, 2007.
3. Ibid, p. 3.
   1. Ibid, p. 18.
4. SEMP Biot Report #423: “Worlds in Collision: Velikovsky on Earth’s Catastrophic History” (June 13, 2007). Available at:  http://www.semp.us/publications/biot_reader.php?BiotID=432; accessed July 11, 2007.
5. SEMP Biot Report #433: “What is a Comet?” (June 20, 2007). Available at: http://www.semp.us/publications/biot_reader.php?BiotID=433; accessed July 11, 2007.
6. SEMP Biot Report #434: “What is a Near-Earth Object” (June 20, 2007). Available at: http://www.semp.us/publications/biot_reader.php?BiotID=434; accessed July 11, 2007.
7. SEMP Biot Report #435: “What is the ‘Torino Scale’ for Near-Earth Objects? (June 20, 2007). Available at: http://www.semp.us/publications/biot_reader.php?BiotID=434; accessed July 11, 2007.
8. National Aeronautics and Space Administration Dawn Press Kit (ed. Susan Watanabe), p. 4. Available at:  http://www.nasa.gov/mission_pages/dawn/news/index.html; accessed July 11, 2007.
9. Ibid, p. 5.
   1. Ibid, p. 20.
10. “NASA Mission Overview: Dawn’s Target: Vesta and Ceres”. Available at: www.nasa.gov/mission_pages/dawn/ceresvesta/index.html; accessed July 11, 2007.