[ti:NASA Identifies Cause of Mars Helicopter’s Final Crash]
[by:www.21voa.com]
[00:00.00]更多听力请访问21VOA.COM
[00:00.04]The American space agency NASA
[00:03.88]says it has found the likely cause of a crash
[00:08.84]that grounded its Mars helicopter Ingenuity.
[00:13.96]The finding comes after NASA said it had carried out
[00:19.24]the "first aircraft accident investigation on another world."
[00:25.84]Ingenuity arrived on Mars along with NASA's
[00:31.00]Perseverance explorer, or rover, in February 2021.
[00:37.76]The experimental helicopter took its last flight,
[00:42.68]number 72, in January.
[00:46.32]That flight ended in a hard landing on the Martian surface.
[00:52.12]In April 2021, Ingenuity became the first aircraft
[00:58.80]to complete a powered, controlled flight on another planet.
[01:04.80]The aircraft was built to test take-off,
[01:09.12]short flight and landing operations.
[01:13.16]The flights on Mars aimed to support NASA's efforts
[01:18.48]to build new aircraft
[01:20.72]that can fly in the atmospheres of other planets.
[01:25.96]Engineers from NASA's
[01:28.64]Jet Propulsion Laboratory in California
[01:32.48]fully investigated Ingenuity's last flight on Mars.
[01:38.44]They found the cause of the crash was linked
[01:42.28]to the helicopter's navigation system.
[01:46.16]That camera-based system was not able
[01:50.24]to collect dependable data
[01:52.56]on elements of the Martian surface
[01:55.88]to support a safe landing.
[01:59.20]A detailed, final report on the accident
[02:02.92]is to be issued in the coming weeks.
[02:05.92]But the engineers have already
[02:08.88]described their main findings
[02:11.52]in a statement published online.
[02:15.24]They said the helicopter's last flight
[02:19.28]saw the aircraft climb to about 12 meters,
[02:23.36]where it stayed, or hovered,
[02:26.08]while capturing images of the Martian surface.
[02:30.24]Data records show Ingenuity
[02:33.72]began its planned descent
[02:36.32]after about 19 seconds.
[02:39.24]By 32 seconds, the helicopter was back on the surface
[02:44.80]and was no longer sending communication signals.
[02:50.00]The next day, Ingenuity team members
[02:53.52]reestablished communications
[02:56.36]and received images from its last flight.
[03:00.76]The images showed the aircraft
[03:04.04]suffered severe damage to its rotor blades.
[03:08.44]NASA explained that Ingenuity's navigation system
[03:14.12]plays an important part in collecting data
[03:18.08]about the surface to ensure the aircraft
[03:21.76]can complete a smooth landing.
[03:25.04]The helicopter uses a camera that points downward,
[03:29.68]capturing information about what is below the craft.
[03:34.44]In past flights, the engineers said the camera
[03:39.24]was able to find smooth, suitable landing possibilities.
[03:44.44]But NASA said during the final flight,
[03:48.20]the helicopter was traveling in an area
[03:51.88]with very few surface features for the camera to capture.
[03:57.00]This meant the aircraft's navigation system
[04:01.80]could not find enough of these features
[04:05.00]to choose a good landing spot.
[04:08.08]At the time, Ingenuity was operating together
[04:12.80]with NASA's Perseverance rover
[04:15.96]in an area of Mars known as Jezero Crater.
[04:20.68]The images recovered from Ingenuity
[04:24.56]suggested the navigation system's inability
[04:28.76]to pick up surface features
[04:31.36]made the helicopter descend too fast.
[04:35.76]The hard landing on a sand hill
[04:39.08]is believed to have caused the helicopter
[04:42.64]to turn over and roll.
[04:45.20]The engineers said images showed
[04:49.08]that all four of Ingenuity's rotor blades
[04:53.04]broke at their weakest point.
[04:55.96]The damaged blades also caused the aircraft to shake.
[05:01.40]Events related to the crash
[05:04.12]led to increased power demand,
[05:07.12]which resulted in the loss of communications.
[05:11.44]Although the crash ended Ingenuity's flight operations,
[05:16.84]NASA said it is still able to provide
[05:20.84]and send back weather information
[05:23.80]and other kinds of data.
[05:26.36]The space agency says this information
[05:30.36]could be helpful in designing future aircraft
[05:34.24]or other explorers to be sent to Mars.
[05:38.72]Teddy Tzanetos is Ingenuity's project manager.
[05:43.88]He said in a statement
[05:46.64]one major thing the team learned
[05:49.28]was that future aircraft designed for space travel
[05:54.04]do not necessarily need to be large flying machines.
[05:58.68]Tzanetos added that Ingenuity's longevity
[06:03.48]suggests that "not everything needs to be bigger,
[06:07.96]heavier, and radiation-hardened"
[06:11.32]to work in the Martian environment.
[06:14.60]With this in mind, NASA engineers
[06:18.32]have been testing smaller, lighter flying vehicles,
[06:22.88]with limited electronics,
[06:25.12]in order to produce future helicopters
[06:28.68]that can make a large number of smaller exploration trips.
[06:34.32]Tzanetos shared details about
[06:37.52]one aircraft NASA is currently developing.
[06:41.64]It is called the Mars Chopper rotorcraft.
[06:46.00]Tzanetos said Chopper is about
[06:48.96]20 times heavier than Ingenuity.
[06:52.56]Developers say it would be built to carry
[06:56.44]several kilograms of science equipment,
[07:00.00]while self-exploring distant areas of Mars.
[07:04.60]Chopper would also have a much longer travel ability,
[07:09.68]flying up to 3 kilometers in a day.
[07:13.16]Ingenuity's longest flight was 704 meters.
[07:18.84]Tzanetos said that overall,
[07:22.40]"Ingenuity has given us the confidence
[07:26.04]and data to envision the future of flight at Mars."
[07:32.40]I'm Bryan Lynn. 更多听力请访问21VOA.COM
END OF TRACK. "END OF TRACK." The two men bowed. "Whoever was that person you were talking to?" she enquired, as soon as they stood together. The took of triumph faded from her eyes, she had grown worn and weary. The roses were wilting on the walls, the lights were mostly down now. Hetty, looking in to see if anything was wanted, found herself driven away almost fiercely. I only saw Master Jervie once when he called at tea time, The year 1747 was opened by measures of restriction. The House of Lords, offended at the publication of the proceedings of the trial of Lord Lovat, summoned the parties to their bar, committed them to prison, and refused to liberate them till they had pledged themselves not to repeat the offence, and had paid very heavy fees. The consequence of this was that the transactions of the Peers were almost entirely suppressed for nearly thirty years from this time, and we draw our knowledge of them chiefly from notes taken by Horace Walpole and Lord Chancellor Hardwicke. What is still more remarkable, the reports of the House of Commons, being taken by stealth, and on the merest sufferance, are of the most meagre kind, sometimes altogether wanting, and the speeches are given uniformly under fictitious names; for to have attributed to Pitt or Pelham their[112] speeches by name would have brought down on the printers the summary vengeance of the House. Many of the members complained bitterly of this breach of the privileges of Parliament, and of "being put into print by low fellows"; but Pelham had the sense to tolerate them, saying, "Let them alone; they make better speeches for us than we can make for ourselves." Altogether, the House of Commons exhibited the most deplorable aspect that can be conceived. The Ministry had pursued Walpole's system of buying up opponents by place, or pension, or secret service money, till there was no life left in the House. Ministers passed their measures without troubling themselves to say much in their behalf; and the opposition dwindled to Sir John Hinde Cotton, now dismissed from office, and a feeble remnant of Jacobites raised but miserable resistance. In vain the Prince of Wales and the secret instigations of Bolingbroke and Doddington stimulated the spirit of discontent; both Houses had degenerated into most silent and insignificant arenas of very commonplace business. "It certainly will be. Miss Widgeon," answered Maria, with strictly "company manners." "One who has never had a brother exposed to the constant dangers of army life can hardly understand how glad we all feel to have Si snatched from the very jaws of death and brung back to us." "Just plug at 'em as you would at a crow, and then go on your way whistlin'?" persisted Harry. "Hurroo!" echoed Hennessey; "that's the ticket." "Come forward, keeper," continued the baron, "and state how these arrows came into your hands!" "Yes." HoMEJULIA京香2018下载
ENTER NUMBET 0015www.goodtron.com.cn
www.genbenla.com.cn
www.yrzseb.com.cn
www.wingnim.com.cn
zx88.org.cn
yixinlu.net.cn
xlnb668.com.cn
www.qltm.net.cn
www.bjbgcl.com.cn
flyayu.net.cn