Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Featured B Space Stuff and Launch Info

  1. Oct 21, 2016 #76


    User Avatar
    Science Advisor
    Gold Member
    2017 Award

    Schiaparelli crash site identified.
  2. Oct 21, 2016 #77
    Whatever went wrong appears to related to the retrorocket control, which ultimately is decided by the onboard computer.
    That still leaves a number of possibilities open.
  3. Oct 22, 2016 #78
    Here's ESA's latest statement.

    21 October 2016

    NASA’s Mars Reconnaissance Orbiter has identified new markings on the surface of the Red Planet that are believed to be related to ESA’s ExoMars Schiaparelli entry, descent and landing technology demonstrator module.

    Schiaparelli entered the martian atmosphere at 14:42 GMT on 19 October for its 6-minute descent to the surface, but contact was lost shortly before expected touchdown. Data recorded by its mothership, the Trace Gas Orbiter, are currently being analysed to understand what happened during the descent sequence.

    In the meantime, the low-resolution CTX camera on-board the Mars Reconnaissance Orbiter (MRO) took pictures of the expected touchdown site in Meridiani Planum on 20 October as part of a planned imaging campaign.

    The image released today has a resolution of 6 metres per pixel and shows two new features on the surface when compared to an image from the same camera taken in May this year.

    One of the features is bright and can be associated with the 12-m diameter parachute used in the second stage of Schiaparelli’s descent, after the initial heat shield entry. The parachute and the associated back shield were released from Schiaparelli prior to the final phase, during which its nine thrusters should have slowed it to a standstill just above the surface.

    The other new feature is a fuzzy dark patch roughly 15 x 40 metres in size and about 1 km north of the parachute. This is interpreted as arising from the impact of the Schiaparelli module itself following a much longer free fall than planned, after the thrusters were switched off prematurely.

    Estimates are that Schiaparelli dropped from a height of between 2 and 4 kilometres, therefore impacting at a considerable speed, greater than 300 km/h. The relatively large size of the feature would then arise from disturbed surface material. It is also possible that the lander exploded on impact, as its thruster propellant tanks were likely still full. These preliminary interpretations will be refined following further analysis.

    A closer look at these features will be taken next week with HiRISE, the highest-resolution camera onboard MRO. These images may also reveal the location of the front heat shield, dropped at higher altitude.

    Since the module’s descent trajectory was observed from three different locations, the teams are confident that they will be able to reconstruct the chain of events with great accuracy. The exact mode of anomaly onboard Schiaparelli is still under investigation.

    The two new features are located at 353.79 degrees east longitude, 2.07 degrees south latitude on Mars. The position of the dark mark shows that Schiaparelli impacted approximately 5.4 km west of its intended landing point, well within the nominal 100 x 15 km landing ellipse.

    Meanwhile, the teams continue to decode the data extracted from the recording of Schiaparelli descent signals recorded by the ExoMars TGO in order to establish correlations with the measurements made with the Giant Metrewave Radio Telescope (GMRT), an experimental telescope array located near Pune, India, and with ESA’s Mars Express from orbit.

    A substantial amount of extremely valuable Schiaparelli engineering data were relayed back to the TGO during the descent and is being analysed by engineers day and night.

    The ExoMars TGO orbiter is currently on a 101 000 km x 3691 km orbit (with respect to the centre of the planet) with a period of 4.2 days, well within the planned initial orbit. The spacecraft is working very well and will take science calibration data during two orbits in November 2016.

    It will then be ready for the planned aerobraking manoeuvres starting in March 2017 and continuing for most of the year, bringing it into a 400-km altitude circular orbit around Mars.

    The TGO will then begin its primary science mission to study the atmosphere of Mars in search of possible indications of life below the surface, and to act as a telecommunications relay station for the ExoMars 2020 rover and other landed assets.

  4. Oct 24, 2016 #79
    Working off of https://arxiv.org/abs/1209.0343
    This project, http://www.jb.man.ac.uk/research/BINGO/ may shed some light on Dark Energy.

    The BINGO experiment is a project to build a special purpose radio telescope to map redshifted neutral hydrogen emission between z = 0.13 and 0.48. It is an international project with collaborators in Brazil, Saudi Arabia, Switzerland, United Kingdom and Uruguay. It is the only radio telescope which aims at mapping neutral gas, as traced by the 21cm line, on large angular scales and at redshift z~0.3. We call this method HI intensity mapping. Using the Baryon Acoustic Oscillations (BAOs) as a standard ruler allows to measure the expansion of the universe as a function of redshift and so, to constrain the properties of dark energy. The telescope will have no moving parts and consist of a primary mirror of about 40 m diameter and a secondary a bit smaller. It will have around 50 "pixels". With this design, the accuracy on the measurement on the acoustic scale will be 2.4% for one year of integration time, by performing a drift scan survey of 15 deg x 200 deg, with a resolution of 40 arcmin at 1 GHz. The plan is to build the telescope in a disused open-caste gold mine in Uruguay.

    One of the main challenge of the today cosmology is to explain the late-time acceleration of the expansion of the Universe. This acceleration, which has been measured by two independant collaborations studying Supernovae Ia (Perlmutter et al. 1998, Riess et al. 1998), could be explained by a negative pressure from a new component, known as dark energy. There are different ways of trying to determine the properties of the dark energy as Baryonic Acoustic Oscillations (BAO), weak and strong gravitational lensing, cluster counts and supernova. But, BAO measurements appear to be the most powerful tool in order to contrain the properties of Dark Energy (Eisenstein et al. 1998, Eisenstein 2003). The BAOs arise because the coupling of baryons and photons by Thomson scattering in the early universe allows acoustic oscillations at early times, which leads to a feature in the distribution of matter and the anisotropies of the cosmic microwave background radiation. The distance that acoustic waves can propagate in the first million years of the universe becomes a characteristic comoving scale. This acoustic signature has been detected in different optical galaxy surveys (Cole et al. 2005, Percival et al. 2009, Blake et al. 2011, Anderson et al. 2012). HI intensity mapping is an efficient alternative to measure a large number of galaxies individually. It allows to measure the fluctuations of the HI signal and to obtain the power spectrum of these fluctuations as a function of frequency. This method is complementary to optical galaxy surveys (BOSS, WiggleZ, SDSS-II, 6dFGS) in terms of systematics. The figure on the right shows the predicted sensitivity of BINGO to the BAOs for 1-year observation for 70 horns and 15 degree FOV. The experiment will allow to measure the acoustic scale at z~0.3 with an accuracy ~2.4% and the equation of state of the dark energy with 16%, which is a level comparable with the current state-of-the-art large optical surveys. We use the Fisher Matrix code of (Bull et al. 2014) to compute the likelihoods for cosmological parameters given various cosmological data. These figures show the joint constraints for the equation-of-state of the dark energy with w0 and wa (1st time derivative of w0) given for various datasets (BINGO, CHIME and BINGO). It shows the improvement obtained with the combination of different intensity mapping experiments BINGO compared to the current constraints given by Planck + WMAP (polarisations) + highL (SPT, ACT) + BAO (BOSS, WiggleZ, 6dF).

    The guiding principle in the design of BINGO has been for all components to be as simple as possible to minimize the cost, and also to allow repetitive observations so that they are simple to model and the redundancy is optimized. The design of BINGO instrument is a 40 m transit telescope with an offset focus. To minimise the cost, the telescope will have no moving parts. The instrument will realise a drift scan on the sky during two years in order to have one year of full integration time. The telescope is designed for having a good detection of the BAO at low resolution. The angular resolution of the instrument will be 40 arcmin at 1000 MHz. The instrument will operate in the frequency range between 960 to 1260 MHz which is relatively RFI free band and corresponds to a redshift range between 0.13 and 0.48. The frequency resolution will be about 1 MHz over a bandwidth of about 300 MHz. To reach the required sky coverage, the focal plane will contain 50 dual polarisation feeds, each horn will have an aperture diameter of 2 m and a length of 6 m. With this configuation, the focal plane will be 16 m x 15 m and the instantaneous field of view will be 10 deg x 10 deg. The volume survey will be 10 deg x 200 deg. The design and the fabrication of these large feeds represent a key technical challenge for the project and different methods are explored. The receiver modules will need to present a high stability. We will use the experience of the CMB experience (WMAP, Planck) and choose the same approach in using correlation receivers. Each receiver module will produce a spectrum of the difference between the observed region of the sky and a reference signal. The reference feed will have to present the same spectrum of the science beam and no variations. It will point at a Celestial Pole.

    We will build the BINGO telescope in Uruguay because of its favourable latitude and topography. Our two reflector systems have to be positioned in a quarry which has two parallel walls and the local topography has to support the dish and feed structure. The chosen site is the Quarry Castrillon located in Minas Corrales in the north of Uruguay. This site also presents good results according to RFI measurements.

    Manchester will lead the horn design and testing and the production of a prototype receiver-unit. Brazil and Uruguay will lead the telescope construction, receiver integration and site operations while Switzerland will design and construct the digital backend. The calibration and data analysis be a joint effort. Early receiver prototypes are already being tested and working on simulations and analysis software is well underway. The project is able to start as soon as fundings are available. The construction phase is expected to start in the beginning of 2015 and last 1.25 yr. Operations will last for a further 4 years.

    Salvaging a $340,000,000 spacecraft. :woot:

    The U.S. Navy’s MUOS 5 mobile communications satellite is closing in on its operational orbit after an extended orbit-raising campaign following a failure within the satellite’s main propulsion system that required an alternate maneuvering scenario to be worked out for the $340 million satellite

    The Lockheed Martin-built MUOS 5 satellite lifted off on June 24 atop the most powerful Atlas V version currently available, enlisting the help of five Solid Rocket Boosters to get the 6,740-Kilogram satellite off the ground and on its way to Geostationary Transfer Orbit. MUOS 5 enjoyed a flawless three-hour ride, being set free into an orbit of 3,903 by 35,654 Kilometers at an inclination of 18.97 degrees.

    By July 3 when orbit-raising was already expected to be complete, satellite trackers found the satellite stranded in an orbit around halfway between the initial transfer orbit and the planned Geostationary Orbit in terms of the velocity needed to make the transition. The U.S. Navy confirmed the satellite had to stop orbit-raising and later specified that MUOS 5 encountered a problem with its Main Propulsion System.

    By early August, the satellite’s manufacturer and its contractors concluded that the Main Propulsion System had failed for good and would not be available for any subsequent maneuvers.

    Without the use of its main engine, the satellite had to rely on its monopropellant thrusters to boost it into Geostationary Orbit - at the cost of later mission lifetime due to the consumption of propellant originally planned for use in stationkeeping once in Geostationary Orbit. Typically in such a case, the satellite would vent its oxidizer tanks to rid itself of dead weight since the oxidizer, Nitrogen Tetroxide, is no longer of any use and a reduction of vehicle mass reduces the amount of fuel needed to get to GEO.
  5. Oct 26, 2016 #80
    Some interesting excerpts from.
    While the SpaceX CEO may not like the ITS name so much, he has already settled on a name for the first ship of the line that will visit the Red Planet: Heart of Gold. A nod to the vessel of the same name from The Hitchhiker’s Guide to the Galaxy, SpaceX’s ship will precede any crewed mission and will be laden with equipment meant for constructing a propellant manufacturing plant.

    Before any ITS-class ship ever makes a journey to Mars, the company plans to send several Dragon-class missions to gather as much entry, descent, and landing data as possible to mitigate the chances of adding to the collection of craters on Mars’ surface, as well as to better understand the best process for extracting water for making the propellant.

    Ever the science fiction fan, Musk seems to take pleasure any time he can integrate something from the genre into SpaceX’s operations. ITS is no different. When asked about the number of engines in the ITS’s first stage, Musk had a quick and very Musk-esque answer:

    "It had to be 42 for important scientific and fictional reasons! The dense packing is just to max out thrust to weight, but it would be cool if there was a virtual nozzle side effect."

    The number "42" plays a notable role in The Hitchhiker’s Guide to the Galaxy as the "Answer to the Ultimate Question of Life, The Universe, and Everything".

    However, not all of Elon’s interactions were steeped in science fiction lore. Redditor TheVehicleDestroyer wanted to know some specifics on the performance of the sea-level Raptor engine when used in vacuum. Musk said the Raptors meant for atmospheric operation would still have quite a bit of power, pushing 290 metric tons of thrust and operating with a specific impulse of approximately 360 seconds.

    Although there is a preponderance of evidence that Mars may have been habitable in the past, it certainly is not welcoming to humans at present. Redditor Ulysius questioned Musk on plans for permanent human habitation on the Red Planet, to which the SpaceX founder replied:

    "Initially, glass panes with carbon fiber frames to build geodesic domes on the surface, plus a lot of miner/tunneling droids. With the latter, you can build out a huge amount of pressurized space for industrial operations and leave the glass domes for green living space."

    One of the key announcements in Musk’s address at the IAC conference was the revealing of a large composite fuel tank. Long the goal of many in the spaceflight industry with their mass savings translating into greater payload capabilities, composite propellant tanks have proven problematic at best, and catastrophic at worst.

    Elon, however, feels SpaceX has a good handle on the manufacture of large composite tanks. Responding to redditor nalyd8991, Musk fairly gushed over the composite structure:

    "Yeah, for those that know their stuff, that was really the big news. The flight tank will actually be slightly longer than the development tank shown, but the same diameter. That was built with latest and greatest carbon fiber prepreg. In theory, it should hold cryogenic propellant without leaking and without a sealing linker. Early tests are promising. Will take it up to 2/3 of burst pressure on an ocean barge in the coming weeks."

    Testing the tank at sea, away from personnel and structures, will help to ensure the maximum level of safety should a failure occur.

    SpaceX, however, has some challenges relating to not only the propellant tanks but also to the alloys used in the Raptor’s turbopumps.

    Operating at pressures much higher than any other engine, the turbopumps will be subjected to oxygen-rich conditions which may lead to erosion in the pump, though early test firings didn’t indicate that would be a likely problem.

    However, according to Musk, "there is still room for optimization."
  6. Oct 27, 2016 #81
    The Hi-res images are released.


    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.

  7. Oct 27, 2016 #82


    User Avatar
    Science Advisor
    Gold Member
    2017 Award

    cool :)
  8. Oct 27, 2016 #83
    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.

    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
  9. 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
  10. Oct 28, 2016 #85

    Jonathan Scott

    User Avatar
    Gold Member

    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.
  11. Oct 29, 2016 #86

    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.
  12. Oct 29, 2016 #87
    was that Elon Musk? 00:05. had no idea he had/has anything to do with space angencies
  13. Oct 29, 2016 #88
    Several good examples in this thread. :thumbup:
  14. Oct 30, 2016 #89
    Good point.
  15. Oct 30, 2016 #90

    Jonathan Scott

    User Avatar
    Gold Member

    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.
  16. Oct 30, 2016 #91
    "Timeout" hmm
  17. Oct 30, 2016 #92
    Does anyone think the Soyuz design is a bit un -dynamic is it just me?
  18. 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
  19. Oct 30, 2016 #94
    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.
  20. 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.
  21. Oct 31, 2016 #96
  22. Nov 1, 2016 #97


    User Avatar
    Gold Member

    I can't remember seeing this posted:


    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.

  23. Nov 1, 2016 #98
    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
    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.

    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.

    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
  24. Nov 2, 2016 #99
    Regarding post #83.
    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.
  25. Nov 2, 2016 #100


    User Avatar
    2017 Award

    Staff: Mentor

    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.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted