OrbitalHub

ESA dixit:

“The AIM spacecraft will be launched in October 2020 on board a Soyuz-Fregat launch vehicle from Kourou. After launch and one or more deep-space manoeuvres, AIM will arrive at Didymos in June 2022, some months before DART’s impact.After arrival, the AIM spacecraft will transition into a heliocentric co-flying orbit, from which it will observe the binary system to derive a high-resolution 3D model of the asteroid, determine its mass and dynamical state, and characterise its surface and shallow sub-surface properties by means of a thermal infrared imager and high-frequency radar. This first characterisation phase would last for a couple of months and be conducted from a distance of between 35 to 10 km from the asteroid. Following this, the AIM spacecraft will release a number of CubeSats and a lander which is based on DLR’s MASCOT lander used for the JAXA Hayabusa-2 mission. The lander will carry out a detailed characterization of the deep-interior structure of the asteroid by means of a low-frequency bistatic radar. Approximately two weeks before DART impact, the AIM spacecraft would be moved to an orbit about 100 km from the asteroid to safely conduct impact observations. After the impact, a second characterisation phase would conclude the mission.

The AIM spacecraft is based on a very simple design with fixed solar arrays and a fixed high-gain antenna. The baseline propulsion system uses a bi-propellant (MMH/MON) fuel with 24 thrusters each capable of producing 10 N of thrust. A separate Helium tank would keep the four 60 l propellant tanks pressurized. Power is generated by two deployable, fixed solar arrays with an output of 165 W each at a distance of 2.2 AU from the Sun, and a total panel surface of 5.6 m². The total spacecraft dry mass would be about 420 kg and the propellant mass about 292 kg.

The target of the AIM mission is asteroid 65803 Didymos (1996 GT), an Apollo-type near-Earth orbit (NEO) with a perihelion that is just below the aphelion radius of Earth orbit. Didymos is a binary body; the primary body has a diameter of around 750 m and a rotation period of 2.3 hours, while the secondary body had a diameter of around 170 m and rotates around the primary at a distance of 1.2 km in 12 hours. Study of the Didymos moon should offer valuable insights into the origins of our Solar System, and help scientists develop planetary defence strategies against any incoming asteroids in the future. Informally called ‘Didymoon’, the asteroid is nearly three times larger than the body thought to have caused the 1908 Tunguska impact in Siberia, the largest impact in recorded history. An equivalent asteroid striking Earth would be well into the ‘city-killer’ class, leaving a crater of at least 2.5 km diameter and causing serious regional and climate damage. The 2013 Chelyabinsk airburst, whose shockwave struck six cities across Russia, is thought to have been caused by an asteroid just 20 m in diameter.”

Video credit: ESA

NASA dixit:

“New imagery from NASA’s Hubble Space Telescope is revealing details never before seen on Jupiter. High-resolution maps and spinning globes (rendered in the 4k Ultra HD format) are the first products to come from a program to study the solar system’s outer planets each year using Hubble. The observations are designed to capture a broad range of features, including winds, clouds, storms and atmospheric chemistry. These annual studies will help current and future scientists see how such giant worlds change over time.”

Video credit: NASA Goddard

NASA dixit:

“In this video, Karl Battams of the Naval Research Lab talks us through a visualization of the comets that SOHO has witnessed. Since its launch nearly 20 years ago, NASA and the European Space Agency’s Solar and Heliospheric Observatory has spotted 3000 comets. The mission’s The Large Angle and Spectrometric Coronagraph (LASCO) instrument blocks out the bright solar disk, making it easier to see the corona of plasma and dust around the Sun, normally only visible during solar eclipses. This instrument also provides a very large field of view of the region around the Sun.

This visualization utilizes SOHO data from 1998 – 2010 and shows over 2000 comets. Comets that were first observed by SOHO carry no labels, and comets witnessed but not discovered by the spacecraft are represented with their labels. Trails on the comets are color coded based on family: yellow – unaffiliated comets, red – Kreutz group, green – Meyer group, blue – Marsden, cyan – Kracht, and magenta – Kracht 2.”

Video credit: NASA

Wikipedia dixit:

“(85989) 1999 JD6 is an Aten asteroid, near-Earth object, and potentially hazardous object in the inner Solar System that makes frequent close approaches to Earth and Venus. […] Although 1999 JD6 in its current orbit never passes closer than 0.047 AU to Earth, it is listed as a potentially hazardous object because it is large and might pose a threat in the future. The asteroid is well-observed, having been observed over 1,500 times over a length of over 25 years, and was assigned a numeric designation in August 2004.”

NASA JPL:

“Radar data of asteroid 1999 JD6 revealed the object is a contact binary consisting of two lobes. The data was collected over seven and a half hours on July 25, 2015, when the asteroid was about 4.5 million miles (7.2 million kilometers) from Earth.”

Video credit: NASA JPL

Wikipedia dixit:

“Ceres is the largest object in the asteroid belt, which lies between the orbits of Mars and Jupiter. Its diameter is approximately 945 kilometers (587 miles), making it the largest of the minor planets within the orbit of Neptune. The thirty-third largest known body in the Solar System, it is the only one within the orbit of Neptune that is designated a dwarf planet by the International Astronomical Union (IAU). Composed of rock and ice, Ceres is estimated to comprise approximately one third of the mass of the entire asteroid belt. Ceres is the only object in the asteroid belt known to be unambiguously rounded by its own gravity. From Earth, the apparent magnitude of Ceres ranges from 6.7 to 9.3, and hence even at its brightest, it is too dim to be seen with the naked eye, except under extremely dark skies.

Ceres was the first asteroid discovered, by Giuseppe Piazzi at Palermo on 1 January 1801. It was originally considered a planet, but was reclassified as an asteroid in the 1850s when many other objects in similar orbits were discovered.

Ceres appears to be differentiated into a rocky core and icy mantle, and may harbor a remnant internal ocean of liquid water under the layer of ice. The surface is probably a mixture of water ice and various hydrated minerals such as carbonates and clay. In January 2014, emissions of water vapor were detected from several regions of Ceres. This was unexpected, because large bodies in the asteroid belt do not typically emit vapor, a hallmark of comets.

The robotic NASA spacecraft Dawn entered orbit around Ceres on 6 March 2015. Pictures with a resolution previously unattained were taken during imaging sessions starting in January 2015 as Dawn approached Ceres, showing a cratered surface. Two distinct bright spots (or high-albedo features) inside a crater, incorrectly reported as observed in earlier Hubble images, were seen in a 19 February 2015 image, leading to speculation about a possible cryovolcanic origin or outgassing. On 3 March 2015, a NASA spokesperson said the spots are consistent with highly reflective materials containing ice or salts, but that cryovolcanism is unlikely. On 11 May 2015, NASA released a higher resolution image showing that, instead of one or two spots, there are actually several.”

Video credit: NASA JPL

Credits: ASPERA

When Einstein was awarded the Nobel Prize in Physics in 1921, he did not receive it for his contributions to the understanding of gravity through his theory of relativity… actually he received it for a paper he wrote in annus mirabilis 1905 on the law of the photoelectric effect.

At that time, relativity and the new perspective on gravity offered by Einstein’s theory was so controversial that the Nobel Prize Committee members chose to protect their reputations and felt that it would be appropriate to award Einstein the Nobel Prize for “his services to theoretical Physics, and especially for his discovery of the law of the photoelectric effect”. One hundred years later, the theory of relativity is part of second-year University curriculum and reputations are safe.

Classical astronomy relies on the fact that cosmic events generate electromagnetic radiation in different regions of the electromagnetic spectrum (radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays). This electromagnetic radiation is recorded with telescopes or other instruments and the details of the astronomic events are revealed to observers. The limitations of the early ground astronomical observatories are quite obvious: the eyes of the astronomers were used as sensors and they were able to receive only the electromagnetic radiation passing through the atmospheric window. Many secrets have been revealed to us only after the telescope sensors were able to record data across all regions of the spectrum and when the astronomic observatories have been moved in orbit around Earth.

But the strength of our space telescopes is also their weakness… there are astronomical events that do not generate electromagnetic radiation, or to be more exact, they keep it for themselves. And the example is just beyond the event horizon: a black hole. This is where Einstein’s theory of relativity comes to the rescue. Even if the electromagnetic radiation cannot escape the gravitational grip of a black hole, gravitational waves can. A black hole cannibalizing another black hole will generate gravitational waves that cause distortions in the space-time.

The question is how to detect the gravitational waves. The first generation of gravitational wave detectors is already deployed, and the second generation is currently being designed by scientists. They are based on interferometers and the principle on which they rely is very simple: they detect tiny variations in the relative positions of sensors located far away from each other. The Advanced Laser Interferometer Gravitational Wave Observatory (LIGO), which is a first-generation instrument, consists in two perpendicular four-kilometer tubes in which LASER light enters through a splitter. Each tube has mirrors located at their ends so the light can bounce back and forth between the end points of the tubes many times. The two beams of light eventually return to the splitter and if the two tubes have different lengths (they are designed and built identical) the splitter will not be able to reconstruct the initial LASER beam.

Gravitational waves passing through the gravitational wave observatory would affect the two tubes in different ways so a photodetector exposed to the reconstructed LASER beam would record the variations. In order to validate such observations and rule out false signals caused by earthquakes, tides, and even human activity, LIGO consists of three interferometers.

A third-generation observatory, ten times more sensitive than the second-generation instruments, was proposed by a team of European scientists. This third-generation observatory is called the Einstein Telescope. Similar to LIGO, the Einstein Telescope will consist of three interferometers. An improvement of the new instrument is the ten-kilometer arms, and a cryogenic system that will cool the elements of the instrument so that the noise caused by molecular motion will not affect the measurements. In addition, the interferometers are located 150 meters underground and away from coast lines.

The project is supported by the European Commission and there are eight research institutions involved in the study and the conceptual design of the telescope. The design study project is organized in four working groups: WP1 (Site Identification), WP2 (Suspension Requirements), WP3 (Topology Identification), and WP4 (Astrophysics Issues).

We are witnessing the emergence of a new field of astronomy — Gravitational Wave Astronomy. You can find more details about Gravitational Wave Astronomy and the Einstein Telescope on the telescope home website.