قالب وردپرس درنا توس
Home https://server7.kproxy.com/servlet/redirect.srv/sruj/smyrwpoii/p2/ Science https://server7.kproxy.com/servlet/redirect.srv/sruj/smyrwpoii/p2/ If it works, this will be the first rocket to be launched by Mars airspacemag.com

If it works, this will be the first rocket to be launched by Mars airspacemag.com

After about a decade, the Martians may finally arrive on Earth. If they do, it will be because we brought them here.

NASA and the European Space Agency are planning a bold mission to collect rock and soil samples from the surface of the red planet and transport them into space for 34 million miles – providing scientists with an unprecedented opportunity to explore what Mars is made of and look for evidence that the planet was once in life. As past missions have uncovered signs of Martian lakes and river deltas, scientists believe they can find fossils of microscopic organisms that flourished in those lakes and rivers before the planet becomes the frigid desert it is today.

Next July, a three-part Mars sampling mission will begin with the launch of the Mars 2020 rover. As the rover surveys and gathers soil, NASA engineers will continue to develop technology for the other two phases of the mission ̵

1; launching a rocket that raises samples to the Martian orbit, where it will face a waiting return vehicle that will transport the precious cargo to Earth . For each step in the process, engineers at NASA's Jet Propulsion Laboratory are facing a series of daunting challenges.

For one, no one has ever fired a rocket from the surface of another planet. This is a very different scenario from the one that brought the Apollo astronauts home from the moon, just 238,900 miles away. Unlike the ascent stage of the Apollo Lunar Module, the planned Mars Ascension Vehicle (MAV) will have to be released from planet gravity, even if the pull is only 38 percent of Earth's gravity on Earth. Even before the vehicle takes off for home, it will have to endure a physical gauntlet.

First, as a payload to a Mars lander, the MAV will be roughly launched from Earth, followed by a six- to nine-month flight through deep space, ending in a fiery entry into the atmosphere around Mars, a supersonic descent and not a particularly soft landing. The ship will then sit on the surface for half a Martian year (equal to a full year on Earth), exposed to dust storms, ultraviolet radiation and temperatures down to minus 40 degrees Fahrenheit.

Another crucial difference from Apollo's missions: There will be no people on the spacecraft. And since it can take a few minutes for a transmission to reach Mars, even remote piloting is not possible.

"We can't do it with a joystick," says Paulo Yuns, an engineer at NASA's Jet Propulsion Laboratory. "We can't communicate with him, and we don't have a person on board, so he has to be automatic."

  RV20 right-hand drive wheels
Engineers at the Jet Propulsion Laboratory install the right-hand wheels on a Mars 2020 rover , which weighs over 2,300 pounds. If everything goes according to plan, a second production rover will be sent to load the samples collected during the 2020 mission on a Mars climbing vehicle.

(NASA / JPL-Caltech)

On Feb. 18, 2021, the Mars 2020 Mars will touch the 30-mile Jezero Crater (pronounced "YEH-zuh-roh"), where it will gather samples and cache them in hermetically sealed tubes for later retrieval. NASA spent five years discussing the landing site before settling on Jezero. Scientists estimate that between 4.1 and 3.5 billion years, the crater was filled with a lake, 820 feet deep. Perhaps more exciting are the signs of the Delta River. And the delta is "extremely good at storing biosignatures, evidence of life that could exist in lake water, or at the boundary between sediment and lake water, or probably things living in the coastal waters that have been dumped from the river and deposited in the delta, "says Mars 2020 scientist Ken Farley at the announcement of the landing site last November.

The Rover will collect samples from at least five different types of rocks, including clays and carbonates, which have a high potential for preserving the indices of ancient life, whether in the form of complex organic molecules or microbial fossils. Sampling will be aided by a range of tools, including SHERLOC (Raman and Luminescence for Organic and Chemical Substances), which uses spectrometers, a UV laser, and an organic compound detection camera. But, scientists say, this equipment will not be a substitute for Earth's more sophisticated instruments – especially when faced with the challenging task of distinguishing life signs from chemical activity that can mimic organic processes.

"To really make the next big leap in understanding Mars as a system, we want to have a breakthrough here," says Charles Edwards, JPL's manager at the Mars Exploration Directorate. "By bringing these samples back to Earth, you can really release the power of all terrestrial laboratories and answer some of the questions we want to answer about Mars life – whether we're talking about a missing life or even an existing life." [19659011] NASA and the European Space Agency have joined forces to plan later missions – not yet planned – that will ultimately end Mars' return. After Mars 2020, the next step is to send another lander to the Jeterro Crater carrying the "rover rover" and the Mars Ascent vehicle. The rover will remove pipes containing rock and soil samples cached by Mars 2020, and then load them into the MAV payload container, a 17-pound volleyball cylinder. The MAV will then be raised, probably autonomously, from a horizontal to upright firing position and raised to a rendezvous with the third part of the mission: Earth Return Orbiter.

The requirements placed on the MAV project make it the most risky part of the mission. Ashley Carp, a propulsion engineer and deputy manager of the JPL ascension vehicle, says developing the rocket propulsion system is the most difficult engineering challenge she has worked on in her seven years at NASA's facility. "We have to fit into the entry, descent and landing system to get us to Mars, and then be able to launch and deliver the samples to another system," Carp says. "So there are many interfaces in play."

The propulsion system will require fuel that can withstand the temperature extremes of Mars, while meeting the volume and weight requirements that will allow the MAV to fit into the Mars landing : Can be no heavier than about 880 pounds and no higher than about 10 feet. Over the past two decades, NASA engineers have been playing with MAV's numerous propulsion structures and are already taking advantage of two options: a single-stage hybrid rocket engine and a two-stage solid-fuel rocket engine.

The key advantage of a solid engine – Rocket propellants are that the technology is well understood, says Carp. In fact, they have already been used in previous missions – such as Pathfinder, Spirit and Opportunity – to land Mars. Solid fuel motors are less sophisticated than liquid fuel engines that require a supply system as well as a pressure system or pumps. And because solid fuel is less corrosive and more stable than liquid fuel, it can easily be stored for long periods.

Hybrid rockets – which store the oxidant as liquid or gas and the fuel as a solid – are a more difficult problem. I allow. Engineers have been working on designs since 1933, when the Soviet Union launched a rocket that combines liquid oxygen and a solid form of gasoline. But unlike solid rockets, where the oxidant and the fuel are already combined into one fuel, it is difficult to safely achieve high thrust with hybrid rockets because the solid fuel component does not burn fast enough when the liquid oxidizer is sprayed separately during flight. And yet, although less sophisticated, NASA believes the potential benefits of a hybrid rocket for a Mars mission are too numerous to ignore. After a solid rocket launches, it must remain on fire. The hybrid offers more room for maneuver as it can be muted, switched off and redirected during flight.

NASA is optimistic about the hybrid due to new fuel with a higher burn rate. It's a paraffin called SP7, a waxy solid made from a mixture of saturated hydrocarbons. The oxidizer is called MON25, a liquid oxidizer that contains 25 percent mixed nitrogen oxides.

The problem with conventional solid fuels is that Mars' extreme temperatures can crack it and eventually explode when ignited. As such, if NASA chooses a solid propellant rocket engine, the lander will have to allocate decisive power to keep the MAV warm. In contrast, the wax SP7 used in a hybrid rocket engine can remain structurally sound when exposed to large fluctuations in temperature, and the MON25 oxidizer has a freezing point of minus 67 degrees Fahrenheit, which also offers an abundance of the range of temperatures expected at Crater Jezero between the time when the MAV landed on Mars and lifted a full Earth a year later.

At the end of April, the hybrid rocket crosses a crucial threshold: successful ignition at minus four degrees Fahrenheit. "It was the first demonstration that it actually works," Carp says. Two more tests were conducted at the end of July. The first tests the rapid-ignition system of the second-burning rocket as well as a new rocket nozzle, and the second tests the formulated formula SP7.

  Earth Return Orbiter
This will be a high-catch game when the Earth Return Orbiter (artist's impression) catches a 17-pound volleyball container with alien soil blowing in the space between 185 and 250 miles above Mars .

(ESA / ATG Medialab)

Whatever MAV project is selected, it will require autonomous guidance, navigation and control technologies to achieve the proper orbit of Mars for the Earth's orbiter to return to Earth. find it. For Evan Anzalone, a Navigation and Navigation Engineer at the Marshall Space Flight Center, the most difficult challenge would be to establish initial conditions prior to launch – exactly where the surface of the MAV is in terms of its target orbit and exactly ( his attitude). The ratio of the rocket is determined not only by the direction of its nose cone, but also by the speed of rotation of the planet and the local gravitational environment.

"The better we can measure these things, the better we can understand what our original attitude is," says Anzalon. "The problem can be solved and we did it with big vehicles. But when you get to this smaller size, you have to do all this autonomously, with great delay for all kinds of commands and checks … ”

Anzalon and his colleagues are studying two approaches for orientation, control and navigation. One is called open-loop guidance, in which the rocket is essentially pre-programmed to fly a particular trajectory. "You just give commands to your drives and go," Anzalon says. It's a relatively simple way to launch a rocket, but it has risks. For example, if the MAV carrier carrying the MAV lands in the Jezero crater so that the rocket ratio is only one degree, the open guidance system will start with this initial error and the MAV will not reach its target orbit. [19659011] In contrast, the other option is a "closed loop" guidance, a much more complex system. With this approach, the rocket monitors its position, thrust and speed during flight and adjusts where it points its nozzle to tweak its trajectory.

Once the MAV has reached its designated orbit, it must release the capsule containing the samples. Earth A reverse orb, aligned in the same orbit, would crawl on it at a shutter speed of about two inches per second. The sample container is likely to be light in color, probably with QR code-like characters, says Paulo Yuns, a JPL engineer developing the capture and retention system. These features would allow cameras on orbit to find their target more easily. Until about 328 feet apart, flight dispatchers will be able to monitor the approach and possibly make course adjustments before the meeting. But then "everything is aboard the [and] spacecraft will fly alone," says Jeffrey Umland, chief engineer for NASA's current Mars InSight mission to Mars, and a capture and containment system contributor.

"We have this very valuable thing, and it has some inertia to it," says Youns. "It moves and rotates at low speed, and the challenge now is to capture this robot in orbit and bring it into our system, pack it in a container so we can seal it and bring it back to Earth, we never we did something so complicated. "

As the European Space Agency orbits the Earth's orbit, JPL engineers design a capture and containment system for this spacecraft.

At the front of that system would be a capture cone with a set of sensors. that they would find when the container was completely inside – at this point the lid would quickly (within two seconds) close over the top of the cone before the container could hit the back of the cone and bounce back into space. for that more or less cat oh mouse trap, but we fly to the mouse, "says Umland.

Inside the cone, a mechanical arm attached to a paddle will then swing over the container and push it down to the back of the capture cone and into an airtight container Another device, possibly a type of wiper mechanism, will pass over the container to orient it so that the test tubes are stored to the right upward against the spacecraft's heat shield. a good chance to survive if they face e an escape route from the time of re-departure and arrival on Earth – probably in the Utah landing area.

Not so science fiction writers have traditionally imagined that Martians arrive on Earth. But if it succeeds, we can finally get proof of the life of another world.

Source link