화성 비행접시(LDSD), 오늘 대기권 재돌입 시험 NASA set for LDSD test of Mars landing technology(VIDEO)

미 해군 태평양미사일사격장(PMRF)에서 

사진=NASA

*저밀도 초음속 감속기(LDSD)

미래에 화성에 유인 비행선을 착륙시키는 우주선 계획

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케이콘텐츠 편집

미국항공우주국(NASA)의 ‘비행접시’로 알려진 저밀도 초음속 감속기(LDSD)가 마침내 우리 시간으로 내일 낮 비행 시험에 들어간다. NASA는 오는 3일 오전 5시 30분(GMT·한국시간 오후 1시 30분) 미국 하와이 카우아이 섬에 있는 미 해군 태평양미사일사격장(PMRF)에서 LDSD의 대기권 재돌입 시험을 2시간 15분가량에 걸쳐 진행한다고 밝혔다. 이날 무게 약 3.2톤, 폭 4.6m에 달하는 LDSD의 시험 기체는 관측용 풍선에 실려 고도 37km 상공까지 올라가게 된다. 풍선 분리 이후 LDSD는 보조 로켓의 추진력을 사용해 음속 4배인 마하 4의 속도로 다시 고도 54.86km까지 도달하게 된다. 이때부터 LDSD는 본격적인 시험을 하는 것인데 기체 주위에는 일종의 에어백인 ‘초음속 팽창식 공기 역학적 감속기’(SIAD-R)가 작동, 감속을 시작해 마하 2.35가 됐을 때 새롭게 개발한 초음속 디스크세일 낙하산이 작동된다. 이 낙하산은 지난해 6월 똑같은 시험에서 속도를 이기지 못해 파손한 낙하산을 대체하기 위해 NASA가 야심차게 개발한 것으로, 지금까지 만들어진 초음속 낙하산 가운데 가장 크며 뛰어난 성능을 갖고 있다고 한다. 이후 LDSD는 하와이 근처 태평양에 안전하게 착수하는 것으로 이 시험은 종료될 예정이다. 인류의 화성 진출을 위한 첫걸음이 될 이 시험은 이날 NASA 제트추진연구소(JPL) 유스트림 인터넷 생방송으로 공개된다. NASA는 이번 시험을 LDSD에 카메라 4대를 장착해 관측한다. LDSD 프로젝트의 관리자인 JPL의 마크 아들러에 따르면, 영상으로 공개되는 모든 장면은 과학자들이 모니터링하는 것과 같은 것이다. NASA는 LDSD의 시험을 통해 미래에 화성에 유인 비행선을 착륙시키는 계획을 목표로 하고 있다.  NASA는 빠르면 오는 2020년 안에 본격적인 LDSD 운영을 시작할 예정이다. NASA의 비행접시가 우주를 비행하는 모습을 볼 날도 머지 않은 듯하다. 윤태희 기자th20022@seoul.co.kr [서울신문 나우뉴스]

NASA set for LDSD test of Mars landing technology

June 2, 2015 by Chris Bergin  NASA’s Low-Density Supersonic Decelerator (LDSD) project will conduct a second test on Wednesday, a major demonstration of technology that is being baselined into NASA’s ambitions for landing payloads on Mars. The test will be carried out at the US Navy’s Pacific Missile Range Facility (PMRF) on Kauai, Hawaii – beginning with a balloon ride to 120,000 feet. LDSD Test: NASA’s plans for landing human missions on Mars are under a major review, led by the Human Architecture Team (HAT). Working through a number of decision points, the team has begun inserting preferred technology into Concept Of Operations (CONOPS) documentation, ahead of NASA’s goal of landing humans and support hardware on the surface of the Red Planet. One major change relates to the refinement of the utilization of an aeroshell, parachute and propulsive techniques to allow huge landers to safely touchdown and deploy on the surface. The new plans show the use of a Supersonic Parachute system during part of the descent phase is now being removed as an option for the larger payloads. “The HAT held a supersonic parachute workshop in which the consensus was that supersonic parachutes are not applicable to landing human scale payloads (>10 metric tons) on Mars,” noted L2 information. “As a result, further entry, descent, and landing studies will only consider concepts for supersonic retro propulsion in combination with deployable, inflatable, and rigid aeroshells.” The amazing Entry, Descent and Landing (EDL) approach of Mars Curiosity involved many new technologies, including the SkyCrane decent, but that was for a one ton rover. The huge Mars habitats will require more ambitious landing techniques. These larger modules require “bigger brakes” to slow them down ahead of landing. LDSD will help evaluate these new options. Testing this technology is taking place in various NASA centers. However, it’s the Low-Density Supersonic Decelerator (LDSD) project that is conducting real-life testing and gathering the required data about landing payloads on Mars and other planetary surfaces, utilizing a Supersonic Inflatable Aerodynamic Decelerator (SIAD). The concept involves increasing the size of the aeroshell, creating a much larger surface area, generating more drag in the very thin Martian atmosphere. The first test of the LDSD technology occurred in June 2014. The test was a success, despite a failure of the Supersonic Disk Sail Parachute during deployment. Wednesday’s test will begin around 1:30 pm Eastern with the launch of the LDSD from the launch tower, slowly pulled uphill for more than two hours below the huge helium-filled high altitude balloon. The goal is to reach an altitude of 120,000 feet. At that point, the balloon will release from the vehicle and the test milestones will be quickly initiated. Four small rocket motors will fire to spin up and gyroscopically stabilize the saucer. A half second later, a Star 48B long-nozzle, solid-fueled rocket engine will kick in with 17,500 pounds of thrust, sending the test vehicle to the edge of the stratosphere at an altitude of 180,000 feet. With a velocity of around Mach 3.8, the doughnut-shaped SIAD will be tested. The SIAD will decelerate the test vehicle to approximately Mach 2.5 – with this objective successful completed during last year’s test. These drag devices are attached to the outer rim of a capsule-like atmospheric entry vehicle. SIAD will be available in two sizes, one at 20 feet in diameter, sized for future robotic missions and called SIAD-R – and inflated with pressurized hot gas. The other will be 26 feet in diameter, sized for payloads related for human missions and called SIAD-E – and inflated with ram air pressure. Should all go to plan, the vehicle will then deploy a mammoth parachute (the Supersonic Disk Sail Parachute), which will be used to ease the test vehicle to a water impact about 40 minutes after being dropped from the balloon. The test was delayed from Tuesday due the prediction of high waves in the splashdown zone. The parachute system failed during the first test, as much as it was not part of the mission objectives. This time, however – via improvements to the parachute – it’s now a major part of the test. Despite the Mars planning team’s recent comments about moving away from supersonic parachutes for the larger payloads, there is still likely to be a role for supersonic parachutes for smaller payloads. “These new drag devices can increase payload delivery to the surface of Mars from our current capability of 3,300 pounds (1.5 metric tons) to between 4,400 and 6,600 pounds (2 to 3 metric tons), depending on which inflatable decelerator is used in combination with the parachute,” NASA noted. “They will increase available landing altitudes by 1 to 2 miles, increasing the accessible surface area we can explore. They also will improve landing accuracy from a margin of 6 miles to just 2 miles. All these factors will increase the capabilities and robustness of robotic and human explorers on Mars.” Achieving a success with the LDSD during Wednesday’s test will help prove those projected improvements. “This year’s test is centered on how our newly-designed supersonic parachute will perform. We think we have a great design ready for the challenge, but the proof is in the pudding and the pudding will be made live for everyone to see,” project manager Mark Adler added. A third test flight is currently scheduled for the summer of 2016. (Images via NASA). http://www.nasaspaceflight.com/2015/06/nasa-ldsd-test-mars-landing-tech/

 

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