Sökning: "Asteroid"

Visar resultat 1 - 5 av 20 avhandlingar innehållade ordet Asteroid.

1. 1. The flux of extraterrestrial spinels to Earth associated with He-3 anomalies in Cenozoic and Ordovician sediments

   Författare :Samuele Boschi; Kärnfysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Chromite; He-3 anomaly; Cenozoic; mid-Ordovician; asteroid breakup; ordinary chondrites; Popigai ejecta; iridium anomaly; Zircons; ice age;

   Sammanfattning : The main goal of this thesis is to reconstruct the flux of extraterrestrial matter to Earth in specific time intervals of our past in order to add an astronomical dimension to the understanding of Earth's history. To accomplish this, extraterrestrial chrome-spinel grains have been extracted and analysed. LÄS MER

3. 2. The micrometeorite flux to Earth through the Phanerozoic Eon : Reconstructed using sediment-dispersed extraterrestrial spinels

   Författare :Ellinor Martin; Kärnfysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; chromite; chrome spinel; micrometeorites; Phanerozoic; asteroid breakup; ordinary chondrites; 3He anomalies; lunar impacts; ice age; impact craters; zircons;

   Sammanfattning : The purpose of this thesis is to add an astronomical component to the history and evolution of Earth by reconstructing the micrometeorite flux to Earth at different time intervals during the Phanerozoic Eon, using sediment-dispersed extraterrestrial spinel group minerals as a proxy. Chromite and chrome spinel are common refractory members of the spinel group, occurring in both extraterrestrial and terrestrial rocks. LÄS MER

4. 3. Extrasolar Kuiper and asteroid belts Modelling far-infrared dust emission

   Författare :Joachim Wiegert; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Stars: binaries - Stars: circumstellar matter - Infrared: stars - Infrared: planetary systems - Submillimeter: stars;

   Sammanfattning : The first detections of circumstellar dust emission were announced in the mid 1980s. Direct observations of the edge-on disc of beta Pictoris provided evidence that the dust was part of possible planetary systems. About a decade later, in 1995, the first confirmed extrasolar planet around a main sequence star (51 Pegasi b) was announced. LÄS MER

5. 4. Guidance and Control for Multiple Spacecraft Formation

   Författare :Sumeet Gajanan Satpute; George Nikolakopoulos; Per Bodin; Kazuya Yoshida; Luleå tekniska universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Spacecraft Formation; Concurrent maneuver planning; Co-location; Geostationary satellite; Asteroid visual coverage; Trajectory planning; Traveling salesman problem; Onboard space systems; Rymdtekniska system;

   Sammanfattning : Multiple spacecraft formation forms a distributed space system where multiple spacecraft cooperatively exhibit the functionality of a single monolithic spacecraft or work in a cooperative way towards the completion of a common goal. This possibility of distributing the workload between different spacecraft provides the ability to work in parallel, enable economic and simple solutions in terms of spacecraft design, while is redundant towards partial or complete failure of a spacecraft. LÄS MER

7. 5. Laser Interaction with Minerals Common on Asteroids

   Författare :Niklas Anthony; Mikael Granvik; Christina Wanhainen; Olle Norberg; Christopher Dreyer; Luleå tekniska universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Onboard space systems; Rymdtekniska system;

   Sammanfattning : Asteroids are worth studying for three reasons: planetary protection, industrial applications, and scientific knowledge. It is critical we develop technologies capable of diverting objects on collision courses with our planet. LÄS MER