[ti:NASA’s Helicopter and Rover Make New Progress on Mars]
[by:www.21voa.com]
[00:00.00]更多听力请访问21VOA.COM
[00:00.04]The U.S. space agency NASA is reporting new progress on Mars
[00:07.76]for its experimental helicopter and Perseverance explorer.
[00:15.48]The helicopter, called Ingenuity,
[00:18.92]completed its ninth flight on the Red Planet on July 5.
[00:26.12]NASA described the flight as the most successful so far.
[00:33.16]This is because Ingenuity broke several new records:
[00:38.56]for length of flight, speed and distance.
[00:44.48]The helicopter's movements are controlled by a team operating
[00:50.00]from NASA's Jet Propulsion Laboratory (JPL) in California.
[00:56.36]The team said in the ninth flight, Ingenuity traveled for the first time
[01:03.68]across what it described as "unfriendly terrain."
[01:10.04]The previous flights involved shorter trips over mostly flat terrain.
[01:17.96]The helicopter is working together
[01:21.12]with NASA's Perseverance explorer, or rover.
[01:27.12]Currently, both are in an area of Mars known as "Séítah."
[01:33.96]The area contains rocks, sandy hills and craters.
[01:40.68]This kind of terrain can present challenges for Ingenuity,
[01:46.32]raising the possibility the aircraft could crash during flight or upon landing.
[01:55.08]The team says one reason for this is that Ingenuity was built
[02:01.24]to guide itself with an algorithm
[02:04.60]designed to fly it across mainly flat ground.
[02:10.12]The main goal of the Ingenuity experiment
[02:14.08]was to demonstrate that a helicopter could successfully take off,
[02:19.96]fly and land on Mars.
[02:23.36]The aircraft was not built to perform detailed searches
[02:29.28]and other complex operations.
[02:33.32]But since Ingenuity has progressed so well in previous tests,
[02:39.52]NASA controllers decided to push its limits even further.
[02:46.32]The team described the latest flight as a "nail-biter."
[02:52.40]But in the end, it reported Ingenuity was "alive and well"
[02:58.68]after completing a trip of 625 meters through "challenging terrain."
[03:07.96]The flight lasted 2 minutes and 46 seconds.
[03:13.80]The aircraft reached a speed of 5 meters per second.
[03:20.28]As it flies, Ingenuity captures detailed images of the surface of Mars.
[03:28.24]NASA says the helicopter's ninth flight was designed
[03:33.68]to provide "the first close view of major science targets
[03:39.44]that Perseverance will not reach for quite some time."
[03:45.04]The latest images will be studied by the Perseverance team,
[03:50.28]which will then decide which areas
[03:53.12]may be most valuable for the rover to visit.
[03:58.64]Ingenuity is supporting Perseverance's goal
[04:02.92]to collect Martian soil and rocks to help scientists search
[04:09.00]for signs of ancient life on the planet.
[04:13.92]NASA also recently announced that Perseverance
[04:18.48]has started using an improved self-navigation system
[04:23.64]as it expands its exploration activities across Mars.
[04:30.40]So far, the rover's team at JPL has been planning the navigation paths
[04:37.40]and sending the travel instructions to Perseverance.
[04:42.44]But now, NASA says the rover will increasingly
[04:48.08]"take charge of the drive by itself
[04:51.80]-- using a powerful auto-navigation system."
[04:57.28]The system, called AutoNav, first creates a three-dimensional,
[05:03.48]or 3D, map of the terrain ahead.
[05:08.60]It then identifies any objects in the path
[05:12.96]and maps the best way to avoid them.
[05:16.76]JPL controllers say AutoNav can complete this process
[05:23.56]without any additional direction from them.
[05:28.32]Vandi Verma is a senior engineer,
[05:31.68]rover planner and driver at JPL.
[05:36.60]She said in a statement the system gives
[05:41.20]the rover the ability to "think while driving."
[05:45.40]She added: "The rover is thinking about the autonomous drive
[05:50.76]while its wheels are turning."
[05:54.40]NASA says that ability, combined with other improvements,
[06:00.36]might enable Perseverance to hit a top speed of 120 meters per hour.
[06:08.68]Another NASA rover on Mars, Curiosity,
[06:13.44]is equipped with an earlier version of AutoNav.
[06:17.92]On average, it moves about 30 meters per hour.
[06:23.56]I'm Bryan Lynn.
[06:25.88]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
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