[{"id":998,"title":"Space Debris Fingerprint Definition and Identification","sha":"b34c6d6a9469b415652a946a19f2c4cd","user_id":null,"state":"published","body":"The amount of space debris is increasing, and the threat to normal human space activities is also increasing. The concept of fingerprints of space debris is proposed here. It is necessary to define the fingerprints of space debris, and identify different debris characteristics according to the fingerprints of the debris fragments. The definition of debris fingerprints depends on ground-based and space-based cameras, radars, laser ranging and other related data. By defining the debris fingerprints, based on the uniqueness and stability of the debris fingerprints, a space debris fingerprint identification technology is created to verify the identity of the debris. Fragment fingerprint features include global features and local features. The overall features include direct and easy-to-identify features, including track inclination, track height, size, volume, shape cusp features, and the number of fingerprint lines. The number of fragment fingerprint lines is defined as the number of connecting lines between the center of the fragment and the cusp of the shape. The local features of fragment fingerprints include the position, direction, curvature, area and other features of non-smooth points, bifurcation points, fractures, zigzags, etc. of space debris.","created_at":"2022-08-24T07:30:15.843Z","updated_at":"2022-09-10T06:00:10.743Z","zenodo_id":7064100,"doi":"https://doi.org/10.5281/zenodo.7064100","subject":null,"tags":["space debris","space science","aerospace","astrophysics"],"vote_count":0,"view_count":1,"score":0.1,"deleted":false,"muted":false,"tweeted":false,"attachment_file_name":null,"attachment_content_type":null,"attachment_file_size":null,"attachment_updated_at":null},{"id":1005,"title":"Calculation of multi-dimensional information acquisition in space potential disintegration target","sha":"20787d7ed0801b4042c1c0c190157bcc","user_id":null,"state":"published","body":"Some space debris belongs to the upper stage of the rocket, and propellant remains inside the debris, which may explode and generate more space debris. In order to identify potential disintegration targets in space, understand the remaining amount of propellant, fracture location and degree of fracture, aging degree, etc., and predict when space targets will disintegrate. Based on this information, we can carry out debris removal in advance, which plays an important role in the governance of the space debris environment. Here we propose to use an X-ray camera to image the space target, use the computer X-ray tomography technology to obtain the multi-dimensional information inside the space target, and establish a multi-dimensional model of the space target's internal information. Relevant technologies can also help us troubleshoot spacecraft on-orbit and help humans solve potential space risks.","created_at":"2022-09-10T14:34:51.753Z","updated_at":"2022-10-21T06:00:46.840Z","zenodo_id":7232610,"doi":"https://doi.org/10.5281/zenodo.7232610","subject":null,"tags":["space debris","space science","aerospace","astrophysics","breakup"],"vote_count":0,"view_count":1,"score":0.1,"deleted":false,"muted":false,"tweeted":false,"attachment_file_name":null,"attachment_content_type":null,"attachment_file_size":null,"attachment_updated_at":null},{"id":194,"title":"Shovel-ready for Gaia DR2: Find hypervelocity stars from M31/LMC","sha":"eb7a8d07127ffeba69ff871c1b95d32d","user_id":null,"state":"published","body":"Hypervelocity stars move with extremely large Galactocentric velocities (~1000 km/s) and are found from their anomalous velocities, ages, and metallicities. These stars are thought to have interacted with the supermassive black hole at the center of the Milky Way, given that they are seen moving at large radial velocities relative to the Galactic center. Presumably, the SMBH's in M31 and the LMC (if it exists) should also produce hypervelocity stars, some of which may be moving at large velocities through the Milky Way but not necessarily along the line-of-sight relative to the Galactic center. Step one is to find the stars, next is to measure the mass of the SMBHs in M31 and the LMC by the rate of extragalactic hypervelocity stars.","created_at":"2015-07-24T10:06:02.331Z","updated_at":"2015-07-25T06:00:48.385Z","zenodo_id":39226,"doi":"http://dx.doi.org/10.5281/zenodo.21345","subject":null,"tags":["astronomy","astrophysics"],"vote_count":0,"view_count":1,"score":0.1,"deleted":false,"muted":false,"tweeted":true,"attachment_file_name":null,"attachment_content_type":null,"attachment_file_size":null,"attachment_updated_at":null},{"id":327,"title":"The NASA K2 Mission has yet to observe an analog of Tabby's Star","sha":"59bde655f99d29f685702717316e06f3","user_id":null,"state":"published","body":"Tabby's Star is a main sequence F-class star ([KIC 8462852](https://en.wikipedia.org/wiki/KIC_8462852)) observed by the NASA Kepler spacecraft to undergo significant aperiodic dimming activity across a four year baseline. The light curve was noted as novel amongst a pool of ~150,000 targets through visual inspection performed by participants of the [PlanetHunters.org](https://www.planethunters.org/) project. [Boyajian, et al. (2015)](http://arxiv.org/abs/1509.03622) reported an analysis which attempted to model the enigmatic behavior under various scenarios, with a swarm of exo-comets offered as a potential (but problematic) leading explanation. Subsequent follow-up studies failed to detect a significant IR excess or the presence of close stellar companions. [Wright, et al. (2015)](http://arxiv.org/abs/1510.04606) offered an alternative explanation invoking transits of alien-megastructures, which may not produce a detectable IR excess or radial velocity signal. \r\n\r\nTo date, a robust model to explain the behavior of Tabby's Star remains elusive.\r\n\r\nThe Kepler spacecraft is now observing a series of new ecliptic fields ([K2](http://keplerscience.arc.nasa.gov/)) and has accumulated observations of ~165,000 additional targets. Continued visual inspection of these public data has failed to recover an analog to KIC 8462852. Lack of such a detection suggests that the aperiodic dimming indeed represents a rare astrophysical phenomenon, regardless of the true root cause mechanism involved. Future photometric surveys by K2 and TESS will offer additional opportunity to search for such analogs.\r\n\r\n","created_at":"2016-08-04T03:36:28.126Z","updated_at":"2016-08-15T21:57:38.941Z","zenodo_id":143398,"doi":"http://dx.doi.org/10.5281/zenodo.59494","subject":null,"tags":["astronomy","kepler","astrophysics","crowdsourcing"],"vote_count":2,"view_count":1,"score":3.1,"deleted":false,"muted":false,"tweeted":true,"attachment_file_name":"8462852_LC_img.png","attachment_content_type":"image/png","attachment_file_size":145799,"attachment_updated_at":"2016-08-04T03:36:58.456Z"}]