Spacecraft Returns Seven Particles From Birth of the Solar System

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Required fields are indicated by an asterisk (*) Country * Afghanistan Aland Islands Albania Algeria Andorra Angola Anguilla Antarctica Antigua and Barbuda Argentina Armenia Aruba Australia Austria Azerbaijan Bahamas Bahrain Bangladesh Barbados Belarus Belgium Belize Benin Bermuda Bhutan Bolivia, Plurinational State of Bonaire, Sint Eustatius and Saba Bosnia and Herzegovina Botswana Bouvet Island Brazil British Indian Ocean Territory Brunei Darussalam Bulgaria Burkina Faso Burundi Cambodia Cameroon Canada Cape Verde Cayman Islands Central African Republic Chad Chile China Christmas Island Cocos (Keeling) Islands Colombia Comoros Congo Congo, the Democratic Republic of the Cook Islands Costa Rica Cote d’Ivoire Croatia Cuba Curaçao Cyprus Czech Republic Denmark Djibouti Dominica Dominican Republic Ecuador Egypt El Salvador Equatorial Guinea Eritrea Estonia Ethiopia Falkland Islands (Malvinas) Faroe Islands Fiji Finland France French Guiana French Polynesia French Southern Territories Gabon Gambia Georgia Germany Ghana Gibraltar Greece Greenland Grenada Guadeloupe Guatemala Guernsey Guinea Guinea-Bissau Guyana Haiti Heard Island and McDonald Islands Holy See (Vatican City State) Honduras Hungary Iceland India Indonesia Iran, Islamic Republic of Iraq Ireland Isle of Man Israel Italy Jamaica Japan Jersey Jordan Kazakhstan Kenya Kiribati Korea, Democratic People’s Republic of Korea, Republic of Kuwait Kyrgyzstan Lao People’s Democratic Republic Latvia Lebanon Lesotho Liberia Libyan Arab Jamahiriya Liechtenstein Lithuania Luxembourg Macao Macedonia, the former Yugoslav Republic of Madagascar Malawi Malaysia Maldives Mali Malta Martinique Mauritania Mauritius Mayotte Mexico Moldova, Republic of Monaco Mongolia Montenegro Montserrat Morocco Mozambique Myanmar Namibia Nauru Nepal Netherlands New Caledonia New Zealand Nicaragua Niger Nigeria Niue Norfolk Island Norway Oman Pakistan Palestine Panama Papua New Guinea Paraguay Peru Philippines Pitcairn Poland Portugal Qatar Reunion Romania Russian Federation Rwanda Saint Barthélemy Saint Helena, Ascension and Tristan da Cunha Saint Kitts and Nevis Saint Lucia Saint Martin (French part) Saint Pierre and Miquelon Saint Vincent and the Grenadines Samoa San Marino Sao Tome and Principe Saudi Arabia Senegal Serbia Seychelles Sierra Leone Singapore Sint Maarten (Dutch part) Slovakia Slovenia Solomon Islands Somalia South Africa South Georgia and the South Sandwich Islands South Sudan Spain Sri Lanka Sudan Suriname Svalbard and Jan Mayen Swaziland Sweden Switzerland Syrian Arab Republic Taiwan Tajikistan Tanzania, United Republic of Thailand Timor-Leste Togo Tokelau Tonga Trinidad and Tobago Tunisia Turkey Turkmenistan Turks and Caicos Islands Tuvalu Uganda Ukraine United Arab Emirates United Kingdom United States Uruguay Uzbekistan Vanuatu Venezuela, Bolivarian Republic of Vietnam Virgin Islands, British Wallis and Futuna Western Sahara Yemen Zambia Zimbabwe THE WOODLANDS, TEXAS—After a massive, years-long search, researchers have recovered seven interstellar dust particles returned to Earth by the Stardust spacecraft. The whole sample, reported here this week at the Lunar and Planetary Science Conference, weighs just a few trillionths of a gram, but it’s the first time scientists have laid their hands on primordial material unaltered by the violent birth of the solar system.The Stardust spacecraft, launched in 1999, has already accomplished its prime objective: collecting dust particles in the tail of comet Wild 2 and returning them in a reentry capsule ejected as Stardust passed by Earth in 2006. NASA went to all that trouble because comets were supposed to be the repository of the primordial ice and rock—the product of eons of star birth and death—that went into building the solar system. But it turned out that the minerals in the comet dust that Stardust managed to collect weren’t that pristine: They had been heated, melted, and totally transformed somewhere near the nascent sun and then carried outward to be incorporated into comets in the ultradeep freeze far beyond the outermost planets.That left the hunt for pristine star stuff to Stardust’s other mission, collecting dust streaming in from interstellar space. For a total of 200 days in 2000 and 2002, Stardust stuck out its tennis racket-like dust collector panel to catch interstellar dust as the solar system and the spacecraft with it plowed through the galaxy. The panel’s centimeter-thick blocks of aerogel—“frozen smoke” made of airy silica that is 99.8% empty space—were intended to slow and retain dust particles without vaporizing them. That would be no mean feat, as interstellar particles are a thousandth the mass of comet dust and can be traveling well in excess of 15,000 kilometers per hour. Once the sample panel was back on Earth, the problem quickly became finding any collected particles embedded in the aerogel. Out of desperation, Stardust team members called on 30,714 members of the general public. “We really did not know how else to find” the embedded particles, says Stardust team member Andrew Westphal of the University of California, Berkeley. The “dusters” of the [email protected] project—who as a group were listed as authors of the talk—volunteered to examine microscopic images taken down through the aerogel. They used the world’s best pattern-recognition system—the human eye and brain—to pick out the telltale tracks left by speeding particles.One hundred million searches later, Stardust team members had seven “probable” dust impacts on the collector. Two particles weighing in at about 3 trillionths of a gram each—100 billion of them would equal a grain of sugar—drove into the aerogel at less than 18,000 kilometers per hour and lodged there. A third came in so fast that it didn’t even leave a chemical residue, only a track. Four more particles serendipitously blasted into thin aluminum foil around the edges of the aerogel, leaving measurable material in their craters.“It’s an enormous achievement that the Stardust team got this far,” says cosmochemist Scott Messenger of NASA’s Johnson Space Center in Houston, Texas, who is not on the team. He agrees with Westphal that these “are the most challenging extraterrestrial samples ever.” To be sure that the grains are truly interstellar, researchers must next transfer the infinitesimal specks of dust from inside the aerogel into instruments for further analysis, in particular of their isotopes. Developing the techniques “will be fundamentally boring but necessary,” Westphal says. “It would be very easy to lose them.” Sign up for our daily newsletter Get more great content like this delivered right to you! Country Email

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