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[专题专项] 美国星际探测器的最新进展、规划:New Frontiers 4开始选型

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 楼主| jingyan66 发表于 2009-1-29 16:19 | 显示全部楼层

“勇气”号异常行为困扰着NASA

本帖最后由 jingyan66 于 2009-4-14 18:41 编辑

Mars Rover's Unexpected Behavior Puzzles NASA



By Tariq Malik
Senior Editor
posted: 28 January 2009
5:49 pm ET


NASA engineers are scratching their heads over some unexpected behavior from the long-lived Spirit rover, which began its sixth year exploring Mars this month.

Spirit failed to report in to engineers at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif., last weekend, prompting a series of diagnostic tests this week to hunt the glitch's source. The aging Mars rover did not beam home a record of its weekend activities and, more puzzlingly, apparently failed to even record any of its actions on Sunday, mission managers said.

"We don't have a good explanation yet for the way Spirit has been acting for the past few days," said NASA's Sharon Laubach, who leads the JPL team that that writes and checks commands for the rover and its robotic twin Opportunity. "Our next steps will be diagnostic activities."

Sunday marked Spirit's 1,800th Martian day, or sol, exploring a region known as "Home Plate" in the planet's expansive Gusev Crater.

Spirit and its twin Opportunity were initially expected to spend just 90 days exploring the Martian surface when they landed in succession more than five years ago this month. Opportunity is currently headed for the monster crater Endeavour on the other side of Mars.

On Sunday, Spirit apparently received commands to drive to its next waypoint, but failed to move an inch, mission managers said.

While that glitch can have any number of causes, such as Spirit not properly perceiving it was ready to drive, the rover's failure to record its daily work in its non-volatile computer memory is perplexing, they added.

By Monday, Spirit's mission controllers decided to tell the rover to find the sun with its camera on Tuesday to determine its location on Mars. Early yesterday, the rover beamed back that it had tried to follow the instructions of its human handlers, but couldn't find the sun.

NASA engineers believe Spirit's woes may be due to a transitory cause, such as a high-energy cosmic ray hitting the rover's electronics. On Tuesday, the rover's non-volatile memory appeared to be working fine, mission managers said.

The rovers Spirit and Opportunity have lasted more than 20 times their initial three-month mission plan, with each suffering from aches and pains associated with their longevity.

Spirit initially bounced back from a worrying computer glitch early in its mission and has since survived frigid winters on Mars and scaled a nearby hill. Both rovers have expanded scientists' knowledge of the history of liquid water on Mars during their respective missions.

While puzzling, Spirit's new glitches don't appear to be a serious concern at present, according to NASA's rover mission chief John Callas.

"Right now, Spirit is under normal sequence control, reporting good health and responsive to commands from the ground," he added.
 楼主| jingyan66 发表于 2009-1-29 16:20 | 显示全部楼层

火星探测器团队诊断“机遇”号的异常行为

Mars Rover Team Diagnosing Unexpected Behavior


January 28, 2009


CORRECTION: In paragraph 3--Early Tuesday, Spirit reported that it had followed the commands, and in fact had located the sun, but not in its expected location.

Mars Exploration Rover Mission Status Report

PASADENA, Calif. - The team operating NASA's Mars Exploration Rover Spirit plans diagnostic tests this week after Spirit did not report some of its weekend activities, including a request to determine its orientation after an incomplete drive.

On Sunday, during the 1,800th Martian day, or sol, of what was initially planned as a 90-sol mission on Mars, information radioed from Spirit indicated the rover had received its driving commands for the day but had not moved. That can happen for many reasons, including the rover properly sensing that it is not ready to drive. However, other behavior on Sol 1800 was even more unusual: Spirit apparently did not record the day's main activities into the non-volatile memory, the part of its memory that persists even when power is off.

On Monday, Spirit's controllers at NASA's Jet Propulsion Laboratory in Pasadena, Calif., chose to command the rover on Tuesday, Sol 1802, to find the sun with its camera in order to precisely determine its orientation. Not knowing its orientation could have been one possible explanation for Spirit not doing its weekend drive. Early Tuesday, Spirit reported that it had followed the commands, and in fact had located the sun, but not in its expected location.

"We don't have a good explanation yet for the way Spirit has been acting for the past few days," said JPL's Sharon Laubach, chief of the team that writes and checks commands for the rovers. "Our next steps will be diagnostic activities."

Among other possible causes, the team is considering a hypothesis of transitory effects from cosmic rays hitting electronics. On Tuesday, Spirit apparently used its non-volatile memory properly.

Despite the rover's unexplained behavior, Mars Exploration Rovers' Project Manager John Callas of JPL said Wednesday, “Right now, Spirit is under normal sequence control, reporting good health and responsive to commands from the ground."

JPL, a division of the California Institute of Technology, Pasadena, manages the Mars Exploration Rover project for the NASA Science Mission Directorate, Washington. Spirit and its twin, Opportunity, landed on Mars in January 2004 and have operated 20 times longer than their original prime missions.
 楼主| jingyan66 发表于 2009-2-11 19:31 | 显示全部楼层
NASA设计滚筒状机器人有望出征火星

2009年02月11日


新研制的“Axel”机器人


  北京时间2月11日消息,据英国《新科学家》杂志报道,在将来的某一天,一种类似线轴的滚筒状机器人将可通过绕绳下降方式进入其它行星或卫星陡峭而险峻的陨坑,同时也可利用绳索拴住另一艘飞船。这项从空中气球或者更大型漫游者腹部启程而后潜入目标区域的技术被称之为“绳索袋”。

  目前,美国宇航局和加州理工学院的工程师正在设计这一系统——名为“Axel”的机器人。该系统看上去非常简单,仅由一个两侧装有轮子的圆柱体组成。轮子能够滚过0.5米高的岩石。Axel的机械臂可以绕轮轴进行360度旋转。机械臂的用途是收集土壤样本,并在遭遇复杂地形时为轮子提供推动力。

  连接漫游者及其“总部”的绳索可以卷绕,允许漫游者探索对未系绳机器人——例如宇航局的“机遇”号和“勇气”号火星车——来说太过陡峭而无法穿过的区域。宇航局位于加州帕萨迪纳喷气推进实验室的工程师伊萨·内斯纳斯(Issa Nesnas)说:“我们的目标是探测月球和火星上深度较大且陡峭的陨坑。”除此之外,Axel也可利用漂浮在土星卫星——土卫六“泰坦”大气层中的气球下降到目标区域。

  1月14日,Axel模拟了从陡峭陨坑收集土壤样本的任务。展示过程中,Axel从宇航局“凤凰”号登陆器实体模型的顶部甲板启程,利用绳索向下“攀爬”一个露出地面的岩层,途中遭遇多岩地形。通过机械臂尾端在地面上摆动,Axel将土壤样本收集到两个管子中。内斯纳斯说,由于仅靠电池提供能量,Axel的寿命大约只有一个小时左右。但在将来的某一天,绳索经改进后便可充当导线,允许Axel的“母舰”为其电池充电。

  此时此刻,Axel项目并没有获得额外的研发资金,但一些计划之内的变化将让这款机器人成为未来探测任务的更理想之选。这些变化包括安装更多高能效马达、在程序编写时使其更具自治性以及将重量从22公斤降至10公斤以下。

  明尼阿波利斯明尼苏达州大学机械工程师尼克斯·帕帕尼克洛普罗斯(Nikos Papanikolopoulos)表示:“人们正在寻找更小并且能够征服众多复杂恶劣地形的系统。”帕帕尼克洛普罗斯领导的研究小组正在研发一种类似的线轴形机器人,名为“Scout”。与Axel有所不同的是,Scout没有系绳,致使倾斜角度被限制在45度以下,具体倾斜角度取决于地形。帕帕尼克洛普罗斯指出,Scout也拥有自身优势,它的重量不到半公斤,长度也只有11厘米,这就允许未来执行任务时进行大规模部署。目前,他的小组正在研制一种最多可容纳10个Scout并为其提供能量的围栏。除了执行地外任务外,军队和应急反应部门也可在地球上使用这种机器人。

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 楼主| jingyan66 发表于 2009-2-12 08:48 | 显示全部楼层
Mars Mission Has Some Seeing Red


NASA's Ambitious New Rover Is Too Costly, Critics Say

By Joel Achenbach
Washington Post Staff Writer
Wednesday, February 11, 2009; Page A01

PASADENA, Calif. -- In a "clean room" in Building 150 of NASA's Jet Propulsion Laboratory is something that looks very much like a flying saucer. It's a capsule containing a huge, brawny Mars rover, a Hummer compared with the Mini Coopers that have previously rolled across the Red Planet.

This is the Mars Science Laboratory, the space agency's next big mission to the most Earth-like planet in the solar system. But it's been a magnet for controversy, and a reminder that the robotic exploration of other worlds is never a snap, especially when engineers decide to get ambitious.

The launch has been delayed for two years because of technical glitches. Approved at $1.63 billion, the mission's price tag will be at least $2.2 billion, NASA now estimates. Critics say the cost has really quadrupled since the project was first dreamed up. What no one can doubt is that ambitious missions tend to become costly ones, which jangles the nerves of officials who know how easy it is for a Mars mission to go bust.

Alan Stern, a planetary scientist and former NASA associate administrator for science missions, charged in a New York Times op-ed column last year that the cost overruns of the Mars Science Laboratory are a sign of a "cancer" of spending profligacy that is overtaking the space agency. Stern, now a private consultant, argues that the new rover is too ambitious, with too many new technologies in play, making a cost overrun all but inevitable.

"It's not just that it's a bigger rover. It's also an entirely new kind of landing system. It's also that it's nuclear-powered. It's also that it's carrying multiple instruments far beyond what's ever been done," Stern said in an interview. "We need to go to a strategy where we can access Mars frequently and take advantage of what we've already invented."

NASA officials acknowledge that they are pushing the boundaries of what's possible in Mars exploration. But they say it makes no sense to do the same things over and over again with modest changes.

The new rover, weighing 1,875 pounds, is more than twice as heavy as either Spirit or Opportunity, the remarkably durable rovers that have been sniffing around Mars for the past five years on a mission originally designed to last just 90 days. Those rovers have six instruments each; the new rover has 10, including detectors for organic compounds. The old rovers could reach out, scratch the Martian surface and try to get a sense of things, but the new rover can retrieve a sample and put it in various analytic chambers. Earlier rovers were solar powered, but this one has a nuclear power source that will allow it to operate day and night.

The new rover is more rugged, capable of navigating much trickier terrain. It can operate at higher latitudes with harsher climates. It has its own meteorology station. It has a color camera that shoots video. It can do almost everything but make espresso.

"We need a larger support structure. We need a more capable arm. We need to be able to look at not just the geology but much more the chemistry, much more the organic elements. We have to have a more capable rover," said Jim Green, director of NASA's planetary science division.

He acknowledged that the cost overruns will put a crimp in the planetary science budget, which is running at about $1.3 billion a year. The Mars program specifically will feel the effects, and there will have to be cuts or delays in the next rover mission, scheduled for 2016, he said. But he added that the Mars Science Laboratory will be worth it.

Because it's such a large rover, engineers had to invent a new landing technique, called a sky crane. The rover also needed dozens of motors and gearboxes to accomplish the many tasks outlined by scientific investigators. It was the iffy performance of those motors and gearboxes in tests that forced NASA to pull the plug on the mission's scheduled 2009 launch.

Richard Cook, the project manager, said that in calculating the cost and the amount of time necessary for designing the mission, "we didn't extrapolate how much more complex it was" than the Spirit and Opportunity mission.
 楼主| jingyan66 发表于 2009-2-13 08:00 | 显示全部楼层
Mars Mission Has Some Seeing Red

NASA's Ambitious New Rover Is Too Costly, Critics Say

By Joel Achenbach
Washington Post Staff Writer
Wednesday, February 11, 2009; Page A01

PASADENA, Cali ...
jingyan66 发表于 2009-2-12 08:48



太空探索:无法控制的成本飙升

2009年02月12日


  撰文/乔治·马瑟(George Musser)

  环球科学报道 2008 年10月, 美国航空航天局(NASA) 宣布, 计划于今年秋天发射升空的汽车大小的火星漫游车——火星科学实验室(Mars Science Laboratory,缩写为MSL),已经从价值15 亿美元变成了价值20 亿美元。而在这一计划最初构想时,预计任务花费仅有6.5 亿美元。更令人瞠目结舌的是,号称造价10 亿美元的哈勃空间望远镜继任者——詹姆斯·韦布空间望远镜(James Webb Space Telescope,缩写为JWST)已经花掉了45 亿美元。这种现象并非只发生在空间探索项目中,任何复杂项目的投资都会大大超过预算。不过专家说,在节约研究经费的问题上,研究机构应该、也必须做得更好。

登上火星并非难事,控制成本才难上加难

  美国密歇根大学的苏希尔·K·阿特雷亚(Sushil K. Atreya) 说:“ 我们必须接受科研会存在一些成本超支的事实,但我相信如果换一种管理方式,许多成本超支是可以避免的。”他是火星科学实验室研究小组成员,也是美国国家研究委员会(National Research Council,缩写为NRC)去年评估NASA 行星探测项目的评审小组的成员之一。

  评审小组的评估结果十分悲观。受制于持续增长的花费以及不断缩水的预算,NASA 已经不得不推迟甚至取消许多研究项目。一些人担心美国国会今后不会再批准一些耗资巨大的项目,比如将火星岩石带回地球进行分析——这是科学家认为能够确定火星是否曾有生命的唯一办法。艾伦·斯特恩(Alan Stern)说:“由于无视成本控制问题,我现在对火星采样返回能否实现持悲观态度。”斯特恩曾经担任NASA 科学事务副局长,2008年3 月因不满NASA 对火星科学实验室超支问题的处理而愤然辞职。

  看起来NASA 的管理层并非没有意识到超支问题。每个项目都要经过严格公正的评估,并且划拨预算的1/3 左右作为储备金,以供计划外支出。但这些措施根本不足以控制超支。航天飞机及空间站前高级主管、美国得克萨斯大学奥斯汀分校的洪堡·曼德尔(Humbolt Mandell) 说:“ 在一个几乎完全由工程师和科学家掌管的机构里,技术永远比财政更重要。”项目提案之间的竞争也加剧了这种倾向:为了得到资金投入,这些项目不得不做出不可能实现的承诺。

  许多专家坚持NASA 应该在技术开发方面投入更多资金。NASA 曾有一个独立的计划来研制火箭、供电和通讯系统,方便今后的科学任务直接使用这些系统——也能更容易地给这些科学任务“标价”。现在该计划已经取消,一些科学家争辩说,火星科学实验室成了取消该计划的受害者。“我认为所有的花费都被大大低估了,因为他们缺少足够的有用信息,过去在技术方面的投入也远远不够,”NRC评审小组联席主席、华盛顿卡内基研究所的韦斯利·亨特里斯(Wesley Huntress)总结说。

  推迟交货时间也能够减少超支。目前,设计一艘飞船需要大约一年半的时间,所耗资金占任务总预算的15%~20%。阿特雷亚评价说:“这个时间太短了。”如果把设计时间延长至少一年,工程师就有更多时间把问题消灭在图纸上,而不用在建造过程中发现问题,再花更多的资金来改正错误。

  美国密歇根大学的伦纳德·菲斯克(Lennard Fisk) 刚刚卸任NRC 空间研究委员会主席,他认为,为了填补财政缺口,NASA 总部还应该储备一些资金,数额或许应该达到科学预算总额的5%。否则一旦项目遇到资金短缺,NASA 只有两种选择:一是取消该项目,二是挪用其他项目的资金。

  两种选择都不明智:如果要恢复被取消的项目,一切就必须从头再来,可能会更加昂贵;资金被挪用的项目则会打乱计划,最终也可能要超出预算。不过斯特恩认为,就算当初采用了上述措施,火星科学实验室也难逃超支的命运。他说,最初对项目总花费的评估根本不切实际;当管理层意识到项目即将耗尽资金时,再想缩减计划规模已经不可能了。他坚持认为:“根本没有人为了让项目不至于超支而作过任何让步。”曼德尔主张,在必要的情况下,NASA 应该终止计划,“提前给一个项目设置一条严格的‘生死线’,并坚决执行这一标准,将迫使人们产生危机意识,储存足够的备用金。”

  然而, 有些资金并不在NASA的掌控之中。5 年前,布什总统下令NASA 替换航天飞机,但并未提供相应资金。这迫使NASA“拆东墙补西墙”,暂停了新技术开发,并推迟一些已经万事俱备的项目,这些措施最终都会导致开支增加。如果希望NASA能够最好地利用资金,别对NASA 抱有超过他们财力的、不切实际的预期,会很有帮助。
 楼主| jingyan66 发表于 2009-2-19 19:54 | 显示全部楼层
美欧将联手探测木星和土星


2009年02月19日   新华网

  新华网华盛顿2月18日电(记者任海军)美国宇航局18日说,该机构将和欧洲航天局一道,合作探测太阳系中的木星、土星以及它们的卫星。

  美宇航局当天发表声明说,两家机构将于2020年各自发射一个轨道航天器,按计划这两个轨道航天器将于2026年进入绕木星运行的轨道,开始对木星及其4颗卫星进行为期3年的探测。向土星发射探测器则需要在一些技术问题得到解决之后才能进行。

  目前,“卡西尼”号探测器正在环土星轨道上对土星进行探测,其土星探测使命由美宇航局、欧洲航天局以及意大利航天局共同承担。任务专家们计划将其探测使命延长至2017年。
darklighter 发表于 2009-2-21 23:45 | 显示全部楼层

美国“黎明(Dawn)”灶神星、谷神星探测器

“黎明”北京时间2月17日20:28以约549 km的最近距离飞越火星。
探测器借助火星引力改变轨道,将按计划于2011年8月首先飞抵灶神星。

NASA在之前(2月12日)发布的新闻:http://www.nasa.gov/mission_pages/dawn/news/dawnf-20090212.html

任务网站:
http://dawn.jpl.nasa.gov/
http://www.nasa.gov/mission_pages/dawn/main/index.html

探测器实时状态演示:
http://dawn.jpl.nasa.gov/mission/live_shots.asp

探测器在火星最近点附近拍摄的红外图像:

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HaleBoppComet 发表于 2009-2-23 14:41 | 显示全部楼层

美欧将联合探测木星和土星

航空航天局(NASA)和欧空局2月18日宣布,双方官员在最近的一次会议上决定首先寻求联合开展一项任务,对木星及其4颗最大的卫星进研究,并对探测土星最大的卫星土卫六和土卫二的另一项任务进行规划。这两个宏大的项目将为未来的行星科学研究搭建舞台。作为旗舰级的外行星探测任务,它们将最终回答太阳系是如何形成的以及太阳系其它地方是否存在适居条件等问题。

  这两项探测任务分别称为“木卫二木星系统任务”(EJSM)和“土卫六土星系统任务”(TSSM),是将NASA和欧空局各自原有的任务方案合并到一起后形成的。NASA最初曾在2007年研究论证了4项任务方案,2008年缩减至2项,其中一项入围方案是用轨道器来探测木卫二这颗多冰卫星及其亚表面海洋,另一项是再次发射一颗轨道器对土卫六进行探测。与此同时,欧空局也在2007年启动了竞标程序,以为其“2015~2025年宇宙愿景”空间探测项目选取一项旗舰级任务。入围开展进一步论证的两项方案分别称为“拉普拉斯”和“土卫六与土卫二任务”(TANDEM)。“拉普拉斯”任务拟由一组探测器绕木星飞行,并最终绕木卫二做轨道探测,甚至有可能降落到木卫二上。“土卫六与土卫二任务”拟使用一组探测器绕土卫六做轨道飞行,并先后探测土卫二和土卫六的表面。

  双方的论证和评审表明,“木卫二木星系统任务”(欧洲称“拉普拉斯”)的技术可行性更高,所以将会首先实施。这项任务将使用两个无人轨道探测器对木星这颗巨大的气体行星及木卫一、木卫二、木卫三和木卫四进行前所未有的详细研究。NASA将建造最初称为“木星木卫二轨道器”的探测器,而欧空局将建造起初称“木星木卫三轨道器”的另一个探测器。两个探测器拟于2020年由不同的火箭从不同的发射场发射,将在2026年到达木星系统,然后用至少3年的时间开展研究。它们将花将近1年的时间分别绕木卫二和木卫三做轨道飞行,协同地对木星系统进行研究,以更好地认识木星系统的形成和演化。

  合并后的“土卫六土星系统任务”将由一个美国轨道器和一个欧洲轨道器及科研气球组成。这项复杂的任务存在几项技术挑战,需要开展重大的研究和技术开发。
hkhtg090201 发表于 2009-2-25 09:16 | 显示全部楼层
美国家航空航天局开发火星探测气球
    [美国《军事与航空航天电子学》网站2009年2月18日报道]    美国国家航空航天局(NASA)授予极光飞机科学公司及其合作伙伴Vertigo公司一份小企业创新研究(SBIR)第一阶段合同,开发一种自动气球发射器,用于火星表面的工作。激光公司设想了一种紧凑的、轻重量的系统,该系统将可以被装载在未来的火星登陆车上,通过小型天线车辆扩大任务范围。这种系统可以实现当前火星任务难以完成的大气采样和视频数据获取工作。
    基于气球的火星探测相比火星漫游者具有更大的探测范围,相比卫星可以提供更高的精度。这种气球可以用来在火星上不同的高度和位置对大气数据进行测量。在火星地表部署这种气球所面临的一个重要挑战就是,气球的外表可能会被火星风、周边的石头或者登陆车破坏。极光公司提出的防护型火星气球发射器(SMBL)概念可以解决这个问题,SMBL概念通过使用可充气构造提供一个安全的环境用于气球的膨胀和部署。
    SMBL概念基于极光公司先前与NASA合作开发的火星飞机计划,在该计划中,极光公司已经对在火星大气中工作的飞行器所面临的挑战有了充分的认识。
cmj9808 发表于 2009-2-25 20:19 | 显示全部楼层
帮楼上补个图:)
Shielded Mars Balloon Launcher

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hkhtg090201 发表于 2009-2-25 21:42 | 显示全部楼层
本帖最后由 hkhtg090201 于 2009-2-25 21:44 编辑

谢谢楼上多次帮忙,这乡有礼了.
cmj9808 发表于 2009-2-26 12:40 | 显示全部楼层
谢谢楼上多次帮忙,这乡有礼了.
hkhtg090201 发表于 2009-2-25 21:42

举手之劳,不必客气:)
 楼主| jingyan66 发表于 2009-3-6 09:01 | 显示全部楼层

下周美奥德赛火星探测器将进行充满风险的星上计算机重启

本帖最后由 jingyan66 于 2009-3-6 10:52 编辑

Mars Orbiter Needs Risky Computer Reboot


By SPACE.com staff
posted: 05 March 2009
09:05 am ET


NASA's Mars Odyssey orbiter, which has been circling the red planet for nearly eight years, needs a risky reboot to address a long-known, potential vulnerability in its memory system.

The Odyssey team plans to perform the operation next week.

The chief concern about the potential memory vulnerability stems from the length of time that the spacecraft has been exposed to the accumulated effects of the space radiation environment since the last reboot, which occurred on Oct. 31, 2003.

As an additional benefit, the cold-reboot procedure will demonstrate whether Odyssey's onboard backup systems will be available should they ever be required.

"We have lost no functionality, but there would be advantages to knowing whether the B side [backup system] is available," said Odyssey Mission Manager Gaylon McSmith of NASA's Jet Propulsion Laboratory in Pasadena, Calif. "We have developed a careful plan for attempting to determine that."

NASA also recently revived its Mars Reconnaissance Orbiter after a glitch sent it into its protective safe mode last week.

In all the years since its April 7, 2001, launch, Odyssey has not needed to use its set of spare components. The spares are called the spacecraft's "B side," which includes an identical set of a computer processor, navigation sensors, relay radio and other subsystems. To use any of them, Odyssey would have to shift to all of them at once from its primary set of components, called the "A side."

On March 21, 2007, the B side spare of an electronic component for managing the distribution of power, called the high-efficiency power supply, became inoperable. If it is permanently disabled, then none of the B side is available for use. Engineers have investigated the inoperability of the power supply and that the component can probably be made to work properly again by rebooting the orbiter's computer, although the memory-vulnerability issue that is the current concern is not directly related to the March 2007 event that affected the power supply.

Odyssey is in the third two-year extension of its mission at Mars.

Some A side components, such as the UHF radio used for communications with spacecraft on the surface of Mars, have worked as long as they were designed to last.

In addition to its own major scientific discoveries and continuing studies of the planet, the Odyssey mission has played important roles in supporting the missions of the Mars rovers Spirit and Opportunity and the Phoenix Mars Lander.
hkhtg090201 发表于 2009-3-6 10:26 | 显示全部楼层
上面应该是‘火星探测器’吧?
calendfans 发表于 2009-3-8 16:08 | 显示全部楼层
美拟探测火星甲烷验证是否存在生命
2009年03月08日 08:10  新浪科技
  新浪科技讯 北京时间3月8日消息,据英国《新科学家》杂志网站报道,美国宇航局(NASA)目前正在制定一项新的计划,拟于2016年向火星发射一枚新的探测器。该探测器的主要任务是在火星上寻找甲烷。科学家们认为,如果最终能证实火星上的确存在甲烷,那么这颗星体就很可能存在生命。

  新探测器将在火星上寻找甲烷

  美国宇航局在华盛顿举行的火星探测研讨会上宣布,他们计划于2016年向火星发射一个登陆器或者探测器,以便在火星上寻找并绘制甲烷分布的详细地图。但是由于发射“火星科学实验室”的原因,该计划将被迫推迟2年进行。由于一个关键技术问题未能解决,核动力“火星科学实验室”的发射也由2009年推迟到2011年。随着火星周围现有轨道器的老化,美国宇航局因此决定于2016年发射一个新探测轨道器以促进火星与地球之间的通信。到2018年,他们也许还会再接着发射另一个探测器或登陆器,进一步加强对火星的探测,希望有朝一日能够取回火星表面的岩石或土壤标本。2016年发射的轨道探测器的准确载荷和预算目前尚未公布。

  该轨道器将能够帮助科学家检测火星上是否存在甲烷热区。目前,有一种想法就是当太阳转到火星背面时,利用分光计穿过火星大气层进行检测,即所谓的“掩日法”。通过测量火星大气层究竟吸收了多少太阳光线,分光计则可以检测出大气中甲烷气体的浓度,灵敏度可达万亿分之一。2016年轨道探测器项目科学精度小组成员、地球化学家吉姆-卡斯汀表示,“这可以提供足够精确的数据,来验证地面观测站的观测数据。我们还可以得到火星表面的甲烷更为精确的空间和时间分布图。”现在环绕火星运行的所有轨道器中,没有一个能够完成如此精确的测量。

  但是,美国密歇根大学科学家苏希尔-阿特雷亚表示,“仅仅只有火星表面的甲烷地图并不能够回答火星甲烷的来源问题。”阿特雷亚是第一位在火星大气中发现甲烷迹象的科学家。如果火星表面确实存在过量的甲烷气体,则有必要加强对这种气体生物源头的探测和研究。但是,如果火星大气中还在存在乙烷的话,则还必须要转向甲烷和乙烷的地质源头探测。因此,2016年轨道探测器的主要科研目标包括:测量多种碳同位素以及碳氢化合物的浓度,并试图发现甲烷气体的来源。

  甲烷或能证明火星存在生命

  据美国科学家估计,甲烷也可能由火山活动形成。但迄今为止,科学家尚未发现火星上存在任何已知的活火山。更值得关注的是,宇航局在水蒸汽形成的云层所在区域发现了甲烷,水蒸汽是支持生命产生和存在的至关重要的因素。专家们推测,生活在地下冰层下方水域的产烷生物以废物的形式将甲烷排出体外。由于甲烷仍存在于火星大气层之中,这些有机生物也应该还生活在火星之上。欧洲“火星快车”探测器项目组成员约翰-默里认为,迷你型火星生物可能以“假死”状态存在,并且能够从这种睡梦中苏醒过来。他发现的压倒性证据显示,火星赤道附近尘埃下方存在一个巨大的冰冻海洋,在这一区域,简单生命体能够以细菌形式“复活”。

  英国火星专家科林-皮林格教授认为,从发现甲烷得出的唯一结论是火星上存在生命。如果走霉运的“小猎犬2”号没有在2003年圣诞节坠毁,这个携带实验室的探测器将直接寻找类似生命存在迹象。皮林格在接受记者采访时说:“甲烷是生物群落的一个产物。既然在火星大气层中发现甲烷,那就说明一定存在一个补充源。”其中最明显的补充源自然非有机生物莫属。也就是说,如果在大气层中发现甲烷,你就可能得出存在生命的假设。这虽然不是一个铁证,但却值得我们进行更深层次的研究。美国宇航局的发现证明了欧洲“火星快车”探测器的研究,5年来,“火星快车”一直绕这颗红色星球轨道运行,并于2004年报告发现甲烷存在迹象。

  早在2003年,科学家就曾利用地球上的望远镜发现火星上疑似存在甲烷。虽然观测显示火星甲烷的数量非常稀少,与地球上每十亿份空气就有1800份甲烷相比,火星上每十亿份空气中仅有10份甲烷,但是火星上的甲烷显然都集中在赤道附近。火星上的什么东西会产生这么多甲烷呢?虽然产生甲烷的途径多种多样,但是最后的答案是生物体或者非生物来源。非生物甲烷是在地下的高温高压环境下产生的。虽然地质过程可以产生甲烷,但是氢气和二氧化碳等一些带碳分子的物质发生反应,也会形成甲烷。有一种方法可以不通过从土壤中寻找生命迹象,来确定火星甲烷的来源。这种方法涉及到所有甲烷并不是通过一种方法产生的事实。甲烷的构成成分以不同的形式存在,这种形式被称作同位素,不同同位素的质量是不一样的。(刘妍)
cmj9808 发表于 2009-3-9 01:33 | 显示全部楼层
NASA下一个20年的火星探索计划图,2016年发射的应该是MSO(Mars Science Orbiter)

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 楼主| jingyan66 发表于 2009-3-10 09:11 | 显示全部楼层

“勇气”号火星探索遇到障碍 土堆挡住去路

2009年03月09日

    据美国宇航局太空网报道,为了度过即将到来的夏天和随之而来的冬天,“勇气”号火星走捷径,前往南侧的目的地,可是在前进的过程中被一座海拔较低的高原前面堆积的松土挡住了去路。

    “勇气”号只好绕过这块名为“本垒板”的高地,而不是直接从它上面穿过。2008年“勇气”号是在“本垒板”北侧度过的,这块高地由坚硬的泥土堆积而成,顶部平坦,面积跟棒球场差不多,这座高地大约比周围地面高5英尺(约1.52米)。尽管它的行进路线发生了变化,“勇气”号已经按照它的夏季计划,开始检查一块二氧化硅丰富的岩石,收集更多与以前火星上是否有热水或蒸汽有关的信息。

    然而,即使“勇气”号选择绕行路线前往南侧的目标,也比位于火星另一侧的姊妹火星车“机遇”号的陆上远征行程要短一些。“勇气”号和“机遇”号都于2004年在火星表面降落,按照最初计划,它们将在这颗红色行星上执行为期3个月的任务,但是现在它们的运行时间已经超过5年。负责操控这两个火星车的科学家和工程师,为它们选择的2009年的目的地分别是陡峭的“冯·布劳恩”土丘和直径是150英尺的不规则盆地“戈达德(Goddard)”。当火星夏季到来,能量变得充足的时候,这种并肩作战的方式,可以为它们提供一个能获得重大发现的研究地点,而且在2009年年终火星北极冬天来临时,为两个火星车提供一个避风港。现在火星南半球正值春天。

    科学家对“冯·布劳恩”土丘和“戈达德”盆地很感兴趣,他认为“勇气”号或许能在这里发现更多火星的这个地方在过去是否存在大量水和频繁的火山活动的证据。现在“勇气”号大约已经向南行进了200米。负责这个火星车的科研组原本希望它爬上“本垒板”,然后向南方的“冯·布劳恩”土丘和“戈达德”盆地进发。要达到南侧的目的地,他们首先要让“勇气”号穿过呆了一冬的“本垒板”。但是“勇气”号右前方的一个轮子在2006年坏掉,现在它只有5个轮子可以正常旋转,它利用5个轮子根本无法攀爬斜坡。

    1月和2月,“勇气”号从“本垒板”下来,向距此大约50英尺的东边坡度较小的一个斜坡前进。松软的泥土促使该科研组选择另一条路线。加利福尼亚州帕萨迪纳美国宇航局喷气推进实验室负责这两个火星车的项目经理约翰·卡拉斯说:“‘勇气’号最近两次尝试爬上‘本垒板’的努力并没取得新进展。为此,我们命令‘勇气’号沿着‘本垒板’的一边向东前进。这个火星车必须穿过一直向东北延伸的几个小山脊,然后看一看经过‘本垒板’东部的哪条路线更容易穿过这座高原。如果最终证实那条路无法通过,他们将选择‘本垒板’西边的一条路。”

    “勇气”号1月份在向“本垒板”北部的东侧行进过程中,它中途停下来,用机械臂上的工具研究风蚀严重的岩块“斯蒂伯顿(Stapledon)”。利桑那州立大学主校区负责“勇气”号的科学家史帝夫·拉夫在看“勇气”号在冬季栖息地拍摄的图像和红外光谱时,这个岩块引起他的注意。

    拉夫说:“我们发现,‘本垒板’东侧的物质可能含有丰富的二氧化硅。在‘本垒板’附近发现二氧化硅是‘勇气’号开始研究火星的可居性以来,获得的最为重要的发现。硅石是温泉或蒸汽出口处的化学物质浓缩形成的,地球上的这两种环境都适合生命生存。”除此以外,“勇气”号的α粒子X射线分光计也发现“斯蒂伯顿”含有丰富的二氧化硅。

    拉夫说:“现在我们已经在‘本垒板’旁边的第二个地点发现二氧化硅,这进一步扩大了该地受温泉或蒸汽喷口影响的区域面积。这个系统越大,就会牵涉到越多水,因此这个体系曾经拥有的可居性也就越高。”这些研究人员计划在“勇气”号前往“冯·布劳恩”土丘和“戈达德(Goddard)”盆地的途中,利用它的热辐射光谱仪和全景照相机核实更多二氧化硅丰富的岩块。然而该科研组最先考虑的问题是,“勇气”号火星车如何才能成功到达这些目的地。

    2月6日和2月14日,风吹掉落在“勇气”号太阳板上的一些尘土,使它可利用的能量比原来增加了大约20%。与此同时,有迹象表明“机遇”号的右前轮在旋转时,摩擦越来越厉害。科研组正在设法让该火星车的计时器向后倒退几个火星日,让它重新给各个轮子分配润滑剂,这一技术在过去出现的类似情况下曾产生不错的效果。

    “机遇”号的主要目的地是直径约为14英里的“奋进”坑,现在该坑位于“机遇”号东南大约7英里处。该火星车一直在向南运行,而不是直接前往“忍耐”陨石坑。现在它活动区内的土壤非常松软,很有可能会陷下去。
 楼主| jingyan66 发表于 2009-3-11 08:56 | 显示全部楼层
Mars Orbiter Needs Risky Computer Reboot

By SPACE.com staff
posted: 05 March 2009
09:05 am ET


NASA's Mars Odyssey orbiter, which has been circling the red planet for nearly eight years, nee ...
jingyan66 发表于 2009-3-6 09:01


NASA推迟了“奥德赛”探测器星上计算机的重启工作


NASA postpones Mars Odyssey reboot

2009/3/10

PASADENA, Calif. – NASA has postponed a risky move to restart the computer on the Mars Odyssey spacecraft.

Scientists wanted to reboot the computer because they're worried that its memory may have been corrupted from years of exposure to space radiation. The spacecraft has been orbiting Mars since 2001.

They planned to restart the computer Tuesday until engineers noticed a spike in temperature on the craft's navigation camera.

Mission managers at NASA's Jet Propulsion Laboratory in California delayed the reboot until they figure out why the temperature went up. A new date has not been set.
hkhtg090201 发表于 2009-3-12 10:45 | 显示全部楼层
Odyssey重启成功
Odyssey Spacecraft Reboots Successfully
March 12th, 2009

PASADENA, Calif., (NASA) — NASA’s Mars Odyssey orbiter properly followed commands today to shut down and restart, a strategy by its engineers to clear any memory flaws accumulated in more than five years since Odyssey’s last reboot.

The procedure also restored Odyssey’s onboard set of backup systems, called the spacecraft’s “B side,” allowing its use in the future when necessary.

“For nearly two years, we have not known for certain whether the backup systems would be usable, so this successful reboot has allowed us to ascertain their health and availability for future use,” said Odyssey Project Manager Philip Varghese of NASA’s Jet Propulsion Laboratory, Pasadena, Calif.

Odyssey has been orbiting Mars since 2001 and has never switched from its primary set of components, the “A side,” to the backup set, which includes an identical computer processor, navigation sensors, relay radio and other components. In March 2006, the B-side spare of a component for managing the distribution of power became inoperable. Analysis by engineers identified a possibility that rebooting Odyssey might restore that component, which proved to be a side benefit of today’s procedure to refresh onboard memory.

The Odyssey team began a series of steps after the reboot to carefully return the spacecraft to full functioning over the next few days. Following that path, the science instruments will be back to studying Mars by next week.

An unexpected rise in temperature of the star camera in Odyssey’s navigation system on March 9 had prompted a postponement of the rebooting originally scheduled for the next day. Engineers identified the cause as a heater circuit that was temporarily stuck “on.” The circuit was turned off before today’s reboot.

JPL, a division of the California Institute of Technology, Pasadena, manages Mars Odyssey for the NASA Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, is the prime contractor for the project and built the spacecraft.

http://spacefellowship.com/News/?p=8408#more-8408
 楼主| jingyan66 发表于 2009-3-14 11:17 | 显示全部楼层

“奥德赛”火星探测器成功重启

2009年03月14日   新华网  



    法新社13日报道,美国国家航空航天局工程师已成功重启“奥德赛”火星探测器,以清除上次重启后5年多来探测器数据存储系统积累的漏洞。

    位于美国加利福尼亚州帕萨迪纳的航天局喷气推进实验室宣布,“奥德赛”地球时间11日准确执行了“关闭”和“重启”指令。

    这次重启带来一个额外好处,使工程师确认探测器备用操作系统可以发挥作用。

    “奥德赛”项目经理菲利普·瓦尔吉斯说:“将近两年来,我们一直不确定备用系统是否可用,这次成功重启使我们确认备用系统情况正常,今后可以发挥作用。”

    自2001年至今,“奥德赛”一直沿火星轨道运行,从未由名为“A面”的主操作系统切换到名为“B面”的备用操作系统。两套系统包含相同的计算机处理器、导航传感器及其他一些组件。

    2006年3月,“B面”一个配电组件操控失灵。工程师当时认为重启“奥德赛”也许可以排除故障。本次成功重启证明这一解决方法正确。

    按照“奥德赛”项目团队计划,“奥德赛”预计于下周全面恢复探测任务。
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