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Featured B "Space and Stuff"

  1. Oct 27, 2016 #81

    1oldman2

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    The Hi-res images are released.

    http://www.esa.int/Our_Activities/S...Schiaparelli_and_its_descent_hardware_on_Mars

    27 October 2016

    A high-resolution image taken by a NASA Mars orbiter this week reveals further details of the area where the ExoMars Schiaparelli module ended up following its descent on 19 October.

    The latest image was taken on 25 October by the high-resolution camera on NASA’s Mars Reconnaissance Orbiter and provides close-ups of new markings on the planet’s surface first found by the spacecraft’s ‘context camera’ last week.

    Both cameras had already been scheduled to observe the centre of the landing ellipse after the coordinates had been updated following the separation of Schiaparelli from ESA’s Trace Gas Orbiter on 16 October. The separation manoeuvre, hypersonic atmospheric entry and parachute phases of Schiaparelli’s descent went according to plan, the module ended up within the main camera’s footprint, despite problems in the final phase.

    The new images provide a more detailed look at the major components of the Schiaparelli hardware used in the descent sequence.

    The main feature of the context images was a dark fuzzy patch of roughly 15 x 40 m, associated with the impact of Schiaparelli itself. The high-resolution images show a central dark spot, 2.4 m across, consistent with the crater made by a 300 kg object impacting at a few hundred km/h.

    The crater is predicted to be about 50 cm deep and more detail may be visible in future images.

    The asymmetric surrounding dark markings are more difficult to interpret. In the case of a meteoroid hitting the surface at 40 00080 000 km/h, asymmetric debris surrounding a crater would typically point to a low incoming angle, with debris thrown out in the direction of travel.


    But Schiaparelli was travelling considerably slower and, according to the normal timeline, should have been descending almost vertically after slowing down during its entry into the atmosphere from the west.

    It is possible the hydrazine propellant tanks in the module exploded preferentially in one direction upon impact, throwing debris from the planet’s surface in the direction of the blast, but more analysis is needed to explore this idea further

    An additional long dark arc is seen to the upper right of the dark patch but is currently unexplained. It may also be linked to the impact and possible explosion.

    Finally, there are a few white dots in the image close to the impact site, too small to be properly resolved in this image. These may or may not be related to the impact, they could just be ‘noise’. Further imaging may help identify their origin.

    Zooming_in_on_Schiaparelli_components_on_Mars_large.jpg
     
  2. Oct 27, 2016 #82

    davenn

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    cool :)
     
  3. Oct 27, 2016 #83

    1oldman2

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    I see Opportunity rover is only 54 km's away from the crash site, I know it's not practical but it would be very cool to take a drive over and get an up close look at the debris field. :cool:

    A little more detail here.
    http://spaceflight101.com/faulty-software-suspect-in-schiaparelli-landing/

    The data quickly revealed that Schiaparelli enjoyed a normal entry, hitting the atmosphere 121.5 Kilometers in altitude at a speed of 5.83 Kilometers per second. Slowing down, Schiaparelli was to deploy its parachute at a speed of Mach 1.95, going almost twice the speed of sound. Parachute deployment and the jettisoning of the heat shield to expose the lander’s radar altimeter were also as expected according to teams at the European Space Operations Center.

    Where Schiaparelli ran into trouble was the separation of the Surface Platform from the back shell that was expected to occur between 600 and 1,250 meters in altitude at a speed of 60 to 85 meters per second - to be followed by a thirty-second rocket-powered descent to deliver Schiaparelli to a point two meters above the surface for a short free fall to the ground.

    According to data from Schiaparelli, the surface platform cut itself loose four minutes and 41 seconds after the onset of re-entry - 41 seconds before the planned time. The nine rocket engines that were to slow Schiaparelli for landing ignited after separation from the chute but only fired for three seconds, before shutting down and leaving the lander plummeting to the surface.

    ESA believes Schiaparelli fell from an altitude of two to four Kilometers and impacted at a speed of over 300 Kilometers per hour.
     
    Last edited: Oct 27, 2016
  4. Oct 28, 2016 #84
    It seems reasonably clear now that for whatever reason the craft decided it was close to the ground and initiated parachute release and retrorocket firing prematurely.
    A fault with the radar-altimeter is the first thing that crossed my mind, but I gather now that the radar isn't activated until after the heat shield and parachute release.
    So there must have been some other system responsible for the parachute detaching too early.
    I guess the radar altimeter couldn't make much sense of the situation after that because the craft should have been a few hundred meters above ground, whereas actually it was at a kilometer or more.
    Maybe it just couldn't 'see' any ground while at that altitude
     
  5. Oct 28, 2016 #85

    Jonathan Scott

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    The Martian atmosphere density is somewhat variable, and in addition there may be wind effects, so I wonder how they allowed for that when timing the heat shield and parachute release. Perhaps inertial guidance calculations based on accelerometers? And I've also wondered about whether the radar altimeter could be confused by seeing something spurious such as its own heat shield or ionized atmospheric gases. I'd hope they would have enough telemetry to narrow it down a lot.
     
  6. Oct 29, 2016 #86

    1oldman2

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    http://spaceflight101.com/faulty-software-suspect-in-schiaparelli-landing/

    A navigation software miscommunication appears to have played a central role in last week’s Schiaparelli crash landing on the surface of Mars, initial analysis of data recorded during the lander’s descent reveals.

    Where Schiaparelli ran into trouble was the separation of the Surface Platform from the back shell that was expected to occur between 600 and 1,250 meters in altitude at a speed of 60 to 85 meters per second - to be followed by a thirty-second rocket-powered descent to deliver Schiaparelli to a point two meters above the surface for a short free fall to the ground.

    According to data from Schiaparelli, the surface platform cut itself loose four minutes and 41 seconds after the onset of re-entry - 41 seconds before the planned time. The nine rocket engines that were to slow Schiaparelli for landing ignited after separation from the chute but only fired for three seconds, before shutting down and leaving the lander plummeting to the surface.

    The timing of the premature surface platform separation (~40 seconds after heat shield jettison) and the altitude given by ESA (2-4km) suggest trouble arose at some point in the Radar Doppler Altimeter Acquisition and Validation Sequence. At this point, RDA data was not to be processed as part of closed loop navigation and should not have been able to influence flight events.

    How a timeout on the radar side commanded a separation of the lander before closed loop navigation was planned to start will be a central question to answer. Even more puzzling is Schiaparelli switching to ‘landed mode’ when the Inertial Measurement Units were still showing it in a fast decent.
     
  7. Oct 29, 2016 #87
    was that Elon Musk? 00:05. had no idea he had/has anything to do with space angencies
     
  8. Oct 29, 2016 #88

    1oldman2

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    Several good examples in this thread. :thumbup:
     
  9. Oct 30, 2016 #89
    Good point.
     
  10. Oct 30, 2016 #90

    Jonathan Scott

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    The update on spaceflight101.com confirmed that they used Inertial Measurement Units to help determine the timing for parachute deployment and the point where the heat shield was discarded.

    It seems that something went wrong at the point where the navigation system was supposed to be trying to match up the landing radar input with the IMU information, and it somehow happened long before the point where the matching process should have started to take any action on the results. They describe the problem as being due to a "timeout" on communication between the radar and the general navigation computer. It sounds as if the "timeout" resulted in the extremely premature assumption that the radar processing was complete and that landing had occurred.
     
  11. Oct 30, 2016 #91
    "Timeout" hmm
     
  12. Oct 30, 2016 #92
    Does anyone think the Soyuz design is a bit un -dynamic is it just me?
     
  13. Oct 30, 2016 #93
    In computer systems the term usually means that an expected signal did not occur within a given timeframe, so the system switches to a default mode.
    The default mode usually is designed to place the system in 'safe' idling condition, but it can be anything, including a reboot.
    The details of what happens in case of a timeout should be part of the system spec, and the code which executes is decided by programmers.
     
    Last edited: Oct 30, 2016
  14. Oct 30, 2016 #94

    1oldman2

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    I'm not qualified for commenting on spacecraft Dynamics but the Soyuz does have a very good track record and seems to be good at doing what its designed to do, I only mentioned the rough docking because usually there doesn't seem to be the "rough" contact you see in this video, usually a lot smoother, that one likely sent a pretty good bang throughout the ISS.
     
  15. Oct 31, 2016 #95
    Thank you. I have no qualifications commenting on the Soyuz's design but I found an article that said that the Soyuz could be designed better in terms of dynamics so I was just getting a second opinion.
     
  16. Oct 31, 2016 #96

    1oldman2

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  17. Nov 1, 2016 #97

    OmCheeto

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    I can't remember seeing this posted:

    https://exoplanets.nasa.gov/alien-worlds/galaxy-of-horrors/

    Pretty interesting stuff, with a Halloween theme.
    6 different exoplanets.
    Cool interactive graphics.
    One of which is comparing our solar system to theirs.

    One example:
    Rains of Terror
    HD 189733 b: This nightmare world is the killer you never see coming. Any space traveler confusing its blue color with the friendly skies of Earth would find themselves in howling 5,400 mph winds where it rains glass– sideways.

     
  18. Nov 1, 2016 #98

    1oldman2

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    This is about "Stuff" as much as it's about "Space", thought I'd throw it in and see what the consensus is on the articles. o_O
    http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.117.192001
    Ultrahigh energy cosmic ray air showers probe particle physics at energies beyond the reach of accelerators. Here we introduce a new method to test hadronic interaction models without relying on the absolute energy calibration, and apply it to events with primary energy 6-16 EeV (ECM=110-170 TeV), whose longitudinal development and lateral distribution were simultaneously measured by the Pierre Auger Observatory. The average hadronic shower is 1.33±0.16 (1.61±0.21) times larger than predicted using the leading LHC-tuned models EPOS-LHC (QGSJetII-04), with a corresponding excess of muons.

    http://physics.aps.org/articles/v9/125
    The Large Hadron Collider at CERN produces proton collisions with center-of-mass energies that are 13 thousand times greater than the proton’s rest mass. At such extreme energies these collisions create many secondary particles, whose distribution in momentum and energy reveals how the particles interact with one another. A key question is whether the interactions determined at the LHC are the same at higher energies. Luckily, nature already provides such high-energy collisions-albeit at a much lower rate-in the form of cosmic rays entering our atmosphere. Using its giant array of particle detectors, the Pierre Auger Observatory in Argentina has found that more muons arrive on the ground from cosmic-ray showers than expected from models using LHC data as input [1]. The showers that the Auger collaboration analyzed come from atmospheric cosmic-ray collisions that are 10 times higher in energy than the collisions produced at the LHC. This result may therefore suggest that our understanding of hadronic interactions (that is, interactions between protons, neutrons, and mesons) from accelerator measurements is incomplete.

    http://www.astrowatch.net/2016/11/physicists-leapfrog-accelerators-with.html
    An international team of physicists has developed a pioneering approach to using Ultrahigh Energy Cosmic Rays (UHECRs)-the highest energy particles in nature since the Big Bang-to study particle interactions far beyond the reach of human-made accelerators. The work, outlined in the journal Physical Review Letters, makes use of UHECR measurements by the Pierre Auger Observatory (PAO) in Argentina, which has been recording UHECR data for about a decade.

    The study may also point to the emergence of some new, not-yet-understood physical phenomenon at an order-of-magnitude higher energy than can be accessed with the Large Hadron Collider (LHC), where the Higgs particle was discovered.

    The origin of UHECRs remains a mystery, in spite of decades of work aimed at discovering their sources. Yet even before the UHECRs’ sources are identified, the particle showers they create in the Earth’s atmosphere can be used for exploring fundamental physics.

    The cosmic rays are atomic nuclei. When they collide with air particles, hundreds of additional particles are created, which then further interact to produce a cascade of particles in the atmosphere. PAO telescopes measure how the shower develops as it travels through the atmosphere, and the PAO surface detectors gauge the particle content of the shower on the ground. The difficulty of using UHECR air showers to study particle physics, up to now, stemmed from the uncertainty in an individual ray’s energy and not knowing exactly what nucleus it is.

    New York University Physics Professor Glennys Farrar and Jeff Allen, her graduate student and postdoctoral researcher at the time of the study, circumvented this by using the atmosphere similar to the way a particle detector is employed in laboratory experiments. For the Physical Review Letters study, they compared the PAO data for 441 UHECR showers, with computer-simulated showers based on particle physics models derived from experiments at accelerator energies.

    "State-of-the-art particle physics models seriously underestimate a key component of these UHECR showers," explains Farrar. "This may point to the emergence of unanticipated physical processes at higher energy than the LHC. Future studies, and planned upgrades to the PAO, should reveal what produces the extra signal, providing a window on particle physics far beyond the reach of accelerators."

    Credit: nyu.edu
     
  19. Nov 2, 2016 #99

    1oldman2

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    Regarding post #83.
    http://www.space.com/34574-mars-newest-crater-a-target-for-science.html
    Scientists and engineers had hoped Europe's Schiaparelli Mars lander would just be running out of power about now, following a successful mission on the planet's surface.

    Instead, Schiaparelli landed with a bang on Oct. 19, victim of a possible software glitch that jettisoned its parachute and shut down landing thrusters woefully early.

    Europe has tried to put a happy face on the test flight, which was intended as a trial run before a larger and much more sophisticated rover touches down on Mars in 2021 to search for life.

    While impacts to the joint European-Russian ExoMars rover are being sorted out, scientists have cast their eyes on the planet's newest crater, wondering if they may make use of the unexpected glimpse into a freshly unearthed subsurface.

    The 660-pound Schiaparelli hit the ground at more than 180 mph, leaving a small crater about 8 feet in diameter and about 20 inches deep.

    Satellites circling Mars have been trying to get a look as they pass overhead.

    "We might see a shallow crater, which could provide some (information) on Mars surface properties, but it's complicated," University of Arizona astronomer Alfred McEwen, lead scientist for the Mars Reconnaissance Orbiter high-resolution camera, wrote in an email to Seeker.

    Others were more pessimistic.

    "The crater could still be interesting even if small, but in our case it is likely to be contaminated by all kinds of material from the lander and its fuel. So I would not recommend any effort to study this place from that point of view," project scientist Håkan Svedhem said.

    NASA and Europe released the first high-resolution MRO images of the crash site on Thursday. The pictures were taken on Tuesday.

    "This first HiRISE observation does not show topography indicating the presence of a crater," the European Space Agency said in a statement. "Stereo information from combining this observation with a future one may provide a way to check."

    Schiaparelli hit near its intended landing site, a flat region about 2 degrees south of the equator known as Meridiani Planum. The region is not high on scientists' lists of sites that potentially could have hosted and preserved life, but still of interest.

    NASA's Opportunity rover has been exploring Meridiani for almost 13 years, but it is too far away to visit Mars' newest impact basin, Schiaparelli crater.
     
  20. Nov 2, 2016 #100

    mfb

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    Concerning cosmic rays: the showers are mainly collisions with larger nuclei, while the LHC mainly studies proton-proton collisions. Nuclei are messy, I can imagine that some model there is not very accurate. New physics is always the least likely explanation until everything is understood really well.
     
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