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Are Chemical Rockets or Solar Sails Better to Return Resources from Asteroids?

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If and when we ever get an asteroid mining industry off the ground, one of the most important decisions to be made in the structure of any asteroid mining mission would be how to get the resources back to where all of our other infrastructure is – somewhere around the Earth. That decision typically will focus on one of two propulsion methodologies – chemical rockets, such as those we already use to get us into space in the first place, or solar sails, which, while slower and unable to get us into orbit, don’t require any fuel. So, which propulsion methodology is better for these future missions? A study by researchers at the University of Glasgow looked at those two scenarios and came out with a clear-cut answer – solar sails.

 

When answering these types of theoretical questions, it is essential to impose limits on the answers. For example, billions of asteroids exist in the solar system, so it’s more realistic to only look at those known as Near Earth Asteroids (NEAs). But even so, there are over 30,000 known NEAs. It would have been impossible for lead author Merel Vergaaij, then a Ph.D. student at the University, and her colleagues to calculate optimized trajectories for each of them.

So they broke the area around Earth down into generalized orbital parameters – semi-major axis distance, eccentricity, and inclination. With those three parameters, it is easier to get a handle on what a general transfer orbit would look like to a given asteroid in that region of space, some of which would be quite close to Earth on its orbital path.

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Other constraints were also necessary – such as calculating only the cost and benefit of transferring material back from the asteroid, not the mining of the asteroid itself. Getting the mining equipment there and set up was considered beyond the scope of this paper. Moreover, there needed to be a wait time at the asteroid itself so the return mission could have time to stock up on the material it would be carrying.

That material, in this calculation, was volatiles. Volatiles, such as water, have been a focal point of asteroid mining discussions, as they form the basis of rocket fuel that would be needed to explore farther into the solar system and cost a lot of money to bring up from Earth itself. Moreover, chemical rockets can then use some of those volatiles as their own fuel to make their way back to the Earth system.

A few more constraints fell into place, including sending the volatiles back to geostationary orbit (GEO), some assumptions about launch costs based on the projected costs of Starship, and determining that all-important metric of economic studies – the net present value (NPV). NPV is the outcome that the solutions would be judged on and based on various calculated factors. These would include a variety of costs, such as launch cost, development cost, manufacturing cost, and operational cost. The revenue would be calculated based on the expected value of the volatiles delivered to orbit. When the revenue exceeds the cost of the mission, the NPV turns positive, which, in this case, indicates whether a mission to an asteroid in that area would be worth it.

To make that determination, the authors used a technique called a genetic algorithm to solve an optimization problem. Essentially, they gave the algorithm a bunch of parameters, such as the orbital mechanics, masses of the spacecraft, and the amount of volatiles returned and told the algorithm to optimize the all-important NPV value. The algorithm’s outcome was very clear – solar sails have positive NPVs for a wider variety of areas located in near-Earth space.

Primarily this was due to some weaknesses in chemical rockets. They had to use some of their delivered material to get back to GEO. And, while the time for their transfer orbit was shorter, another factor of the NPV, the discount rate, which lowers the amount of expected value of a resource the farther in the future it is sold, doesn’t take enough out of the value of that which the solar sail can bring back that would make it on par with the chemical rocket.

There were still some areas of near-Earth space that even solar sails were not profitable in, so the authors suggest that future asteroid miners look at asteroids in the specific regions they call out as potentially profitable if they are looking for their first major mining site. In addition, the researchers made some modifications to their original baseline missions structure, such as stopping at a Lunar Gateway, adding a second trip, and running a series of variable simulations, known as Monte Carlo simulations, that would test the extent to which these different schemes were profitable.

The volatiles returned from the asteroid would be used for orbital refueling, as described in this UT video.

Both adding a second trip and stopping off at the Lunar Gateway rather than GEO added significant value to each type of mission architecture. The Monte Carlo simulations also showed that their profitability was consistent with slight input costs and output revenue variations. Overall, while there are potentially profitable targets for each type of propulsion system, it seems that solar sails are clearly the winner between the two. Now it’s up to those who hope to build the first asteroid mining empire to listen.

 

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Marine plankton could act as alert in mass extinction event: UVic researcher – Langley Advance Times

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A University of Victoria micropaleontologist found that marine plankton may act as an early alert system before a mass extinction occurs.

With help from collaborators at the University of Bristol and Harvard, Andy Fraass’ newest paper in the Nature journal shows that after an analysis of fossil records showed that plankton community structures change before a mass extinction event.

“One of the major findings of the paper was how communities respond to climate events in the past depends on the previous climate,” Fraass said in a news release. “That means that we need to spend a lot more effort understanding recent communities, prior to industrialization. We need to work out what community structure looked like before human-caused climate change, and what has happened since, to do a better job at predicting what will happen in the future.”

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According to the release, the fossil record is the most complete and extensive archive of biological changes available to science and by applying advanced computational analyses to the archive, researchers were able to detail the global community structure of the oceans dating back millions of years.

A key finding of the study was that during the “early eocene climatic optimum,” a geological era with sustained high global temperatures equivalent to today’s worst case global warming scenarios, marine plankton communities moved to higher latitudes and only the most specialized plankton remained near the equator, suggesting that the tropical temperatures prevented higher amounts of biodiversity.

“Considering that three billion people live in the tropics, the lack of biodiversity at higher temperatures is not great news,” paper co-leader Adam Woodhouse said in the release.

Next, the team plans to apply similar research methods to other marine plankton groups.

Read More: Global study, UVic researcher analyze how mammals responded during pandemic

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Scientists Say They Have Found New Evidence Of An Unknown Planet… – 2oceansvibe News

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In the new work, scientists looked at a set of trans-Neptunian objects, or TNOs, which is the technical term for those objects that sit out at the edge of the solar system, beyond Neptune

The new work looked at those objects that have their movement made unstable because they interact with the orbit of Neptune. That instability meant they were harder to understand, so typically astronomers looking at a possible Planet Nine have avoided using them in their analysis.

Researchers instead looked towards those objects and tried to understand their movements. And, Dr Bogytin claimed, the best explanation is that they result from another, undiscovered planet.

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The team carried out a host of simulations to understand how those objects’ orbits were affected by a variety of things, including the giant planets around them such as Neptune, the “Galactic tide” that comes from the Milky Way, and passing stars.

The best explanation was from the model that included Planet 9, however, Dr Bogytin said. They noted that there were other explanations for the behaviour of those objects – including the suggestion that other planets once influenced their orbit, but have since been removed – but claim that the theory of Planet 9 remains the best explanation.

A better understanding of the existence or not of Planet 9 will come when the Vera C Rubin Observatory is turned on, the authors note. The observatory is currently being built in Chile, and when it is turned on it will be able to scan the sky to understand the behaviour of those distant objects.

Planet Nine is theorised to have a mass about 10 times that of Earth and orbit about 20 times farther from the Sun on average than Neptune. It may take between 10,000 and 20,000 Earth years to make one full orbit around the Sun.

You may be tempted to ask how an entire planet could ‘hide’ in our solar system when we have zooming capabilities such as the new iPhone 15 has, but consider this: If Earth was the size of a marble, the edge of our solar system would be 11 kilometres away. That’s a lot of space to hide a planet.

[source:independent]

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Dragonfly: NASA Just Confirmed The Most Exciting Space Mission Of Your Lifetime – Forbes

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NASA has confirmed that its exciting Dragonfly mission, which will fly a drone-like craft around Saturn’s largest moon, Titan, will cost $3.35 billion and launch in July 2028.

Titan is the only other world in the solar system other than Earth that has weather and liquid on the surface. It has an atmosphere, rain, lakes, oceans, shorelines, valleys, mountain ridges, mesas and dunes—and possibly the building blocks of life itself. It’s been described as both a utopia and as deranged because of its weird chemistry.

Set to reach Titan in 2034, the Dragonfly mission will last for two years once its lander arrives on the surface. During the mission, a rotorcraft will fly to a new location every Titan day (16 Earth days) to take samples of the giant moon’s prebiotic chemistry. Here’s what else it will do:

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  • Search for chemical biosignatures, past or present, from water-based life to that which might use liquid hydrocarbons.
  • Investigate the moon’s active methane cycle.
  • Explore the prebiotic chemistry in the atmosphere and on the surface.

Spectacular Mission

“Dragonfly is a spectacular science mission with broad community interest, and we are excited to take the next steps on this mission,” said Nicky Fox, associate administrator of the Science Mission Directorate at NASA Headquarters in Washington. “Exploring Titan will push the boundaries of what we can do with rotorcraft outside of Earth.”

It comes in the wake of the Mars Helicopter, nicknamed Ingenuity, which flew 72 times between April 2021 and its final flight in January 2023 despite only being expected to make up to five experimental test flights over 30 days. It just made its final downlink of data this week.

Dense Atmosphere

However, Titan is a completely different environment to Mars. Titan has a dense atmosphere on Titan, which will make buoyancy simple. Gravity on Titan is just 14% of the Earth’s. It sees just 1% of the sunlight received by Earth.

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The atmosphere is 98% nitrogen and 2% methane. Its seas and lakes are not water but liquid ethane and methane. The latter is gas in Titan’s atmosphere, but on its surface, it exists as a liquid in rain, snow, lakes, and ice on its surface.

COVID-Affected

Dragonfly was a victim of the pandemic. Slated to cost $1 billion when it was selected in 2019, it was meant to launch in 2026 and arrive in 2034 after an eight-year cruise phase. However, after delays due to COVID, NASA decided to compensate for the inevitable delayed launch by funding a heavy-lift launch vehicle to massively shorten the mission’s cruise phase.

The end result is that Dragonfly will take off two years later but arrive on schedule.

Previous Visit

Dragonfly won’t be the first time a robotic probe has visited Titan. As part of NASA’s landmark Cassini mission to Saturn between 2004 and 2017, a small probe called Huygens was despatched into Titan’s clouds on January 14, 2005. The resulting timelapse movie of its 2.5 hours descent—which heralded humanity’s first-ever (and only) views of Titan’s surface—is a must-see for space fans. It landed in an area of rounded blocks of ice, but on the way down, it saw ancient dry shorelines reminiscent of Earth as well as rivers of methane.

The announcement by NASA makes July 2028 a month worth circling for space fans, with a long-duration total solar eclipse set for July 22, 2028, in Australia and New Zealand.

Wishing you clear skies and wide eyes.

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