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Craft lifts off to asteroid belt

Sept. 27, 2007
Courtesy NASA
and World Science staff

In a mis­si­on as­tro­no­mers are hail­ing as an his­tor­ic first, a NASA space­craft called Dawn is on its way to study two as­ter­oids af­ter de­part­ing Thurs­day from Flori­da’s Cape Ca­nav­er­al Air Force Stati­on, the agen­cy an­nounced.

Near­ly en­vel­oped by the smoke af­ter ig­ni­tion, the Del­ta II rock­et car­ry­ing NA­SA's Dawn space­craft rises from the smoke and fire on the launch pad. (Cour­tesy NA­SA)

“Dawn has ris­en, and the space­craft is healthy,” said mis­si­on proj­ect man­ag­er Keyur Pa­tel of NASA’s Je­t Pro­pul­si­on Lab­o­r­a­to­ry in Pas­a­de­na, Ca­lif. “About this time to­mor­row [Fri­day morn­ing], we will have passed the moon’s or­bit.” 

Dur­ing the next 80 days, space­craft con­trollers plan to test and cal­i­brate the myr­i­ad of space­craft sys­tems, en­sur­ing Dawn is ready for its long jour­ney. 

“This is a mo­ment the space sci­ence com­mun­ity has been wait­ing for since in­ter­plan­e­tary space­flight be­came pos­si­ble,” said Chris­to­pher Rus­sell of the Un­ivers­ity of Ca­lifornia, Los An­ge­les, the mission’s prin­ci­pal in­ves­ti­ga­tor. “Dawn will trav­el back in time by prob­ing deep in­to the as­ter­oid belt.” 

The as­ter­oid belt is a zone in which most of the small, rocky and me­tal­lic ob­jects known as as­ter­oids are found, or­bit­ing the Sun be­tween the or­bits of Mars and Ju­pi­ter.

Art­ist con­cept show­ing the Dawn space­craft with Ce­res and Ves­ta. (Wil­liam K. Hart­mann Cour­te­sy of UCLA)

Dawn’s 4.8-billi­on-kilometer (3-billi­on-mile) od­ys­sey in­cludes ex­plor­ati­on of as­ter­oid Ves­ta in 2011 and the so-called dwarf plan­et Ce­res, a large mem­ber of the as­ter­oid belt, in 2015. These two bod­ies have been wit­ness to much of our so­lar sys­tem’s histo­ry, re­search­ers said. 

By us­ing Dawn’s in­stru­ments to study both, sci­en­tists hope to be able to com­pare and con­trast them. The in­stru­ments are to meas­ure the bod­ies’ com­po­si­ti­on, shape and tec­ton­ic histo­ry, and al­so seek wa­ter-bear­ing min­er­als. In ad­di­ti­on, the Dawn space­craft and how it or­bits Ves­ta and Ce­res would be used to meas­ure the ce­les­tial bod­ies’ mass­es and gra­vity fields.

The space­craft’s en­gines use a un­ique, ef­fi­cient sys­tem called ion pro­pul­si­on. The 30-centimeter-wide (12-inch) ion thrusters pro­vide less pow­er than conventi­onal en­gines but can main­tain thrust for months. 

The mis­si­on is man­aged by Je­t Pro­pul­si­on Lab­o­r­a­to­ry, a divisi­on of the Ca­lifornia In­sti­tute of Tech­nol­o­gy in Pas­a­de­na, for NASA. The Un­ivers­ity of Ca­lifornia, Los An­ge­les, is re­spon­si­ble for over­all Dawn mis­si­on sci­ence.

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In a mission astronomers are hailing as an historic first, a NASA spacecraft called Dawn is on its way to study two asteroids after departing Thursday from Florida’s Cape Canaveral Air Force Station, the agency announced. “Dawn has risen, and the spacecraft is healthy,” said mission project manager Keyur Patel of NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “About this time tomorrow [Friday morning], we will have passed the moon’s orbit.” During the next 80 days, spacecraft controllers plan to test and calibrate the myriad of spacecraft systems, ensuring Dawn is ready for its long journey. “This is a moment the space science community has been waiting for since interplanetary spaceflight became possible,” said Dawn Principal Investigator Christopher Russell of the University of California, Los Angeles. “Dawn will travel back in time by probing deep into the asteroid belt.” The asteroid belt is a zone in which most of the small, rocky and metallic objects known as asteroids are found, orbiting the Sun between the orbits of Mars and Jupiter. Dawn’s 4.8-billion-kilometer (3-billion-mile) odyssey includes exploration of asteroid Vesta in 2011 and the so-called dwarf planet Ceres, a large member of the asteroid belt, in 2015. These two bodies have been witness to much of our solar system’s history, researchers said. By using Dawn’s instruments to study both, scientists hope to be able to compare and contrast them. The instruments are to measure the bodies’ composition, shape and tectonic history, and also seek water-bearing minerals. In addition, the Dawn spacecraft and how it orbits Vesta and Ceres would be used to measure the celestial bodies’ masses and gravity fields. The spacecraft’s engines use a unique, hyper-efficient system called ion propulsion. The 30-centimeter-wide (12-inch) ion thrusters provide less power than conventional engines but can maintain thrust for months at a time. Management of the Dawn launch was the responsibility of NASA’s Kennedy Space Center, Fla. The mission is managed by Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena in Calif., for NASA. The University of California, Los Angeles, is responsible for overall Dawn mission science.