Our understanding of the Universe is profound. Only a century ago, astronomers held a Great Debate to argue over whether our galaxy was an island universe, or whether nebulae such as Andromeda were galaxies in a much larger cosmos. Now we know that the Universe is billions of years old, ever expanding to billions of light-years across, and filled with not just stars and galaxies but with dark energy and cold dark matter. Astronomers summarize this understanding as the LCDM model, which is the standard model of cosmology. While the observational data we have strongly supports this model, it is not without its challenges.
The most striking challenge is known as the Hubble tension. When we measure the rate of cosmic expansion in various ways, we can calculate what is known as the Hubble constant or Hubble parameter, which defines the rate of cosmic expansion. This rate also tells us things such as the age of the Universe and the average density of dark energy and matter. While the various observations generally cluster around 68-69 km/s/Mpc, several of the methods give results outside that range. There is some evidence to support the idea that the current rate of cosmic expansion is greater than that during the early Universe, which is known as cosmic shear tension. All of this means either some of our methods are in error somehow or there is a fundamental aspect of cosmic expansion we don’t yet understand.
Related to this are the mysteries surrounding dark energy. Within the standard model, dark energy is a property of space and time and is universal throughout the cosmos. But there is an alternative view that holds dark energy is an independent scalar field within spacetime, sometimes referred to as quintessence. Observations such as the clustering scale of galaxies generally support the former model, but there are a few studies here and there that suggest the latter. We don’t yet have enough data to rule out either completely.
Observations of the Hubble parameter. Credit: N. Palanque-DelabrouilleThen, of course, there is the great bugbear of dark matter. Observations strongly support its existence, and that dark matter makes up most of the matter in the Universe. But within the standard model of particle physics, there is nothing that could comprise dark matter, and countless experiments trying to detect dark matter directly have so far yielded nothing. Alternative models such as modified gravity can account for some of our observations, but models must be tweaked just so to fit data, and no alternative approach agrees with all our observations. Dark matter remains central to the standard cosmological model, but its true nature remains in shadow.
In short, we are tantalizingly close to a complete and unifying model of the Universe, but there are deep and subtle mysteries we have yet to solve. We need more theoretical ideas, and we desperately need more observational data. Fortunately, there are exciting projects in the pipeline that could solve these mysteries in the near future.
One of these is the Dark Energy Spectroscopic Instrument (DESI) survey, which is currently underway. Over the course of the five-year project, DESI will observe the spectra of more than 35 million distant galaxies, giving us a detailed 3D map of the Universe. In comparison, the Sloan Digital Sky Survey (SDSS) gathered data on 4 million galaxies and gave us the most detailed view of galactic clustering at the time. With DESI, we will be able to see the interaction between dark matter and dark energy across billions of years and hopefully determine whether dark energy is constant or changes over time.
Comparison of SDSS (left) with DESI (right). Credit: David J. SchlegelAnother useful tool will be the Vera Rubin observatory, which should come online in a few months. By giving us a high-resolution map of the sky every few days, Rubin will allow us to study transient phenomena such as supernovae used to measure cosmic expansion. It will also give us a rich view of matter within our galaxy and could reveal aspects of how that matter interacts with dark matter.
Further into the future, there are planned projects such as the Wide-field Spectroscopic Telescope (WST), which will expand on the abilities of Rubin observatory, and the Spec-S5, which will complement the DESI surveys. Both of these are still in the planning stage, but could become the DESI surveys. Both of these are still in the planning stage but could become operational within a decade or so.
In the 1920s, the Great Debate of Astronomy was solved thanks to a wealth of data. The rise of photographic astronomy allowed us to see the Universe in transformative new ways and made modern cosmology possible. We are now entering an era of large data astronomy, where wide-field telescopes and large surveys will provide more data in an evening than could be gathered in a year just decades ago. Brace yourselves for another revolutionary era of astronomy.
Reference: Palanque-Delabrouille, N. “Future directions in cosmology.” arXiv preprint arXiv:2411.03597 (2024).
The post Cosmology is at a Crossroads, But New Instruments are Coming to Help appeared first on Universe Today.
One of the great things about CubeSat designs is that they constrain the engineers who design them. Constraints are a great way to develop novel solutions to problems that might otherwise be ignored without them. As CubeSats become increasingly popular, more and more researchers are looking at how to get them to do more with less. A paper from 2020 contributes to that by designing a 3U CubeSat mission that weighs less than 4 kilograms to perform a fly-by of a Near Earth Asteroid (NEA) using entirely off-the-shelf parts.
The research, carried out by a team based at the Delft University of Technology, had several mission requirements they were trying to meet. Some were standard like it had to have a propulsion system and a way to get data back to Earth. However, some were more challenging – it had to weigh less than 4 kg, it had to fit into a 3U CubeSat body (which measures (100mm x 100mm x 340.5mm), it had to perform its mission in less than 650 days, and, perhaps the most technically challenging goal – it has to “exploit a fully-autonomous navigation strategy.”
First, let’s look at the mission design. Since there are around 35,000 known NEAs, mission designers would be spoiled for choice. However, getting to one with a relatively limited propulsion budget (since propellant increases the weight – one of the design constraint limits) and finding the right one would require extensive searching of the JPL Small-Body Database.
Fraser discusses how we find NEAsOnce an NEA has been selected, the mission designers could plan the optimal trajectory. However, to meet the requirement of an autonomous navigation strategy, the CubeSat itself will have to find its way to the asteroid and enact any course corrections along the way. This could be extremely difficult, given the low brightness of many of the target asteroids and how that brightness might change based on what side of it is facing the Sun and what angle the CubeSat is approaching it from. The scientific payload, including a visible light and IR camera, would have to work in tandem with a micro star tracker to ensure the trajectory is optimal for scientific data collection.
That data collection might only last a few minutes, as the limited propellant for the mission would require it to be a fly-by rather than an orbit. The resulting image might be as small as a 6 x 6 pixel image for a 300m diameter asteroid. This would provide orders of magnitude with more resolution than ground-based observations for most. Still, it would not be enough to get into the details of mass and composition that planetary protectors and asteroid mining enthusiasts alike would most desire.
Any new information is better than no information, though, and the simplicity of the design for this mission’s hardware makes it relatively inexpensive and, therefore, mass-producible. It consists of six major sub-systems – the “payload,” which is essentially a visible light and infrared camera; the propulsion system, which is a microjet ion propulsion engine; the attitude determination and control system (ADCS), which helps navigate; a communication system that uses an X-band antenna to communicate back to the Deep Space Network infrastructure, and a power system that would involve deployable solar panels.
Some of the engineering that goes into CubeSats is pretty impressive, as this JPL video shows.Overall, the mission met the goal of fitting entirely into a 3U package and came in at 3.8kg using off-the-shelf components. However, thermal management systems and radiation shielding were not considered in the design. Other challenges, like getting time on the already overstretched Deep Space Network ground antennas, are left for another paper.
But if nothing else, this paper proves that it is possible, on paper at least, to design an inexpensive mission to collect data on an asteroid and that that mission can be replicated hundreds or even thousands of times at relatively low cost. As CubeSats gain more and more capabilities and more and more traction, and as launch costs get lower and lower, it’s becoming increasingly plausible that someday, a system like this might very well make its way past an asteroid and send data back that we otherwise wouldn’t have gotten.
Learn More:
Casini et al – Novel 3U Stand-Alone CubeSat Architecture for Autonomous Near Earth Asteroid Fly-By
UT – A Pair of CubeSats Using Ground Penetrating Radar Could Map The Interior of Near Earth Asteroids
UT – A Mission To Find 10 Million Near Earth Asteroids Every Year
UT – Swarms of Orbiting Sensors Could Map An Asteroid’s Surface
Lead Image:
ESA’s Hera Mission is joined by two triple-unit CubeSats to observe the impact of the NASA-led Demonstration of Autonomous Rendezvous Technology (DART) probe with the secondary Didymos asteroid, planned for late 2022.
Credit: ESA
The post A 3U CubeSat Could Collect Data During an Asteroid Flyby appeared first on Universe Today.
As I reported on November 22, I was shocked to find that, on a list of 18 U.S. Senators who voted to move forward with Bernie Sanders’s bill to block a $20 billion sale of weapons to Israel, was one of my own Senators, Democrat Dick Durbin. Here’s the whole list:
The measure failed miserably on the Senate floor, with none of its three provisions garnering more than 19 votes. But of course I wrote to Senator Durbin, expressing my dissatisfaction as a constituent, and chastising him for giving succor to Israel’s enemies and impeding the self-defense of Jewish state in its attempt to root out Hamas.
Yesterday I got this weaselly response from Durbin:
December 4, 2024
MY ADDRESS REDACTED
Dear Dr. Coyne:
Thank you for contacting me about measures to block weapons shipments to Israel. I appreciate hearing from you.
On September 25, 2024, Senator Bernie Sanders of Vermont introduced six measures that would block a proposed $20 billion in arms sales to Israel. These sales include joint direct attack munitions and launchers, mortar and tank cartridges, F-15s, and other defense articles. Under the Foreign Assistance Act of 1961 (P.L. 87-195) and the Arms Export Control Act of 1976 (P.L. 94-329), the president must notify Congress of a pending arms sale. These statutes also give Congress the authority to suspend such a sale by passing a joint resolution of disapproval through both the House of Representatives and the Senate. All six of these measures were referred to the Senate Committee on Foreign Relations.
On November 20, 2024, the Senate considered whether to discharge three of Senator Sanders’ joint resolutions of disapproval, S.J. Res. 111, S.J. Res. 113, and S.J. Res. 115, from the Senate Committee on Foreign Relations. While I voted in favor of discharging these three measures from the Senate Foreign Relations Committee, all three of these measures were rejected by the Senate. S.J. Res. 111 was rejected by a vote of 18-79, S.J. Res. 113 was rejected by a vote of 19-78, and S.J. Res. 115 was rejected by a vote of 17-80.
My reason for supporting these measures is straightforward. More than 43,000 Palestinians have died in the conflict in Gaza since October 7, 2023, and 60 percent of them have been women, children, and elderly. The denial of humanitarian aid to Gaza threatens the lives of so many more.
I believe that Israel has not only the right to exist, but the right to defend itself in the face of threats such as from Hamas, Hezbollah, and Iran. I consistently have voted for security assistance to Israel throughout my career to protect it from these threats. But this war must end. I will stand by Israel, but I will not support the devastation of Gaza and the deaths of thousands of innocent Palestinians.
For too long, this protracted conflict has inflicted untold suffering on innocent Israelis and Palestinians alike. I hope out of the ashes and pain of this current crisis that there can be a renewed focus on a two-state solution.
Thank you again for contacting me. Please feel free to keep in touch.
Sincerely,
Richard J. Durbin
United States Senator
I sent this response to Malgorzata, and when I woke up this morning she had written a response, one that I reproduce here with permission. Durbin is apparently as dumb and uninformed about the Gaza conflict as many Americans.
Malgorzata’s response is indented.
Durbin’s figures are taken directly from Hamas, figures that have been debunked many times.
Hamas doesn’t count combatants and civilians separately. In this fictitious number of dead are the non-existent 500 people allegedly killed in a strike on the hospital Al-Ahli. As was discovered and confirmed by independent authorities (and admitted by the real perpetrator: Palestinian Islamic Jihad), it was a misfired PIJ rocket that fell short, creating the strike. Instead of killing Israeli civilians, the rocket fell on the hospital’s parking lot (NOT THE HOSPITAL). It killed several people, but far less than 100—not to mention 500.
How many other Palestinian civilians killed by rockets from PIJ and Hamas rockets have been counted by Hamas’s Ministry of Health as having been killed by Israel? After previous wars between Gaza and Israel, when there was really time to count the dead and ascertain their identities, it always turned out that Hamas had counted everybody (including combatants killed in war as well as people who died in Gaza of natural causes) in their earlier communicates about people “killed by Israel”.
The percentages of women, children, and elderly given by Durbin (and Hamas) are also false. According to the IDF, up to 19,000 Hamas combatants were killed. Moreover, both Hamas and PIJ use teenagers as fighters. Everybody killed when he/she is under 18 is counted as a child. A 17-year-old fighter killed when shooting a rocket at Israelis is counted as a child. Even if you accept the false numbers given by Hamas, the ratio of civilian to combatant deaths is the lowest ever achieved in urban warfare by any army.
Further, not one person in Gaza would have been killed by the IDF if Hamas and PIJ didn’t invade Israel on October 7, 2023, didn’t kill, rape, torture, and burn 1200 Israeli women, men, children and the elderly, and didn’t take 252 hostages, including women, children and the elderly. There are still 101 hostages somewhere in the dungeons of Hamas, among them baby Kfir (9 months old at the moment of kidnapping) and his older brother Ariel (4 years at the moment of kidnapping).
From Jerry. I would add this. Besides credulously adopting Hamas’s misleading figures that count dead combatants as “innocent Palestinians”, Durbin implicitly calls for a cease-fire and explicitly for a “two-state solution,” something that, if implemented now, would be a disaster for Israel.
We already know that the ratio of civilians killed to combatants killed is far lower than seen in other conflicts in which the U.S. has engaged, including World War II and the more recent battles in the Middle East. Durbin of course ignores that, just as he ignores what happened on October 7 of last year. In his attempt to look evenhanded, Durbin has proven himself a useful asset for Hamas. And I will communicate this to the misguided Senator.
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The post Pycnogenol – Does maritime pine bark extract live up to the hype? first appeared on Science-Based Medicine.What is Power-to-X (PtX)? It’s just a fancy marketing term for green hydrogen – using green energy, like wind, solar, nuclear, or hydroelectric, to make hydrogen from water. This process does not release any CO2, just oxygen, and when the hydrogen is burned back with that oxygen it creates only water as a byproduct. Essentially hydrogen is being used as an energy storage medium. This whole process does not create energy, it uses energy. The wind and solar etc. are what create the energy. The “X” refers to all the potential applications of hydrogen, from fuel to fertilizer. Part of the idea is that intermittent energy production can be tied to hydrogen production, so when there is excess energy available it can be used to make hydrogen.
A recent paper explores the question of why, despite all the hype surrounding PtX, there is little industry investment. Right now only 0.1% of the world’s hydrogen production is green. Most of the rest comes from fossil fuel (gray and brown hydrogen) and in many cases is actually worse than just burning the fossil fuel. Before I get into the paper, let’s review what hydrogen is currently used for. Hydrogen is essentially a high energy molecule and it can be used to drive a lot of reactions. It is mostly used in industry – making fertilizer, reducing the sulfur content of gas, producing industrial chemicals, and making biofuel. It can also be used for hydrogen fuel cells cars, which I think is a wasted application as BEVs are a better technology and any green hydrogen we do make has better uses. There are also emerging applications, like using hydrogen to refine iron ore, displacing the use of fossil fuels.
A cheap abundant source of green hydrogen would be a massive boost to multiple industries and would also be a key component to achieving net zero carbon emissions. So where is all the investment? This is the question the paper explores.
The short answer has to do with investment risk. Investors, especially when we are talking about billions of dollars, like predictability. Uncertainty increases their risk and is a huge disincentive to invest large sums of money. The paper concludes that there are two main sources of uncertainty that make PtX investments seem like they are high risk – regulatory uncertainty and lack of infrastructure.
Regulations in many countries are still in flux. This, fortunately, is an entirely solvable problem. Governments can put resources and priority into hammering out comprehensive regulations for the hydrogen and related industries, lock in those regulations for years, and provide the stability that investors want. Essentially the lack of proper regulations is a hurdle for green hydrogen investment, and governments simply need to do their job.
The second issue is lack of infrastructure, with further uncertainty about the completion of planned hydrogen projects –
“For instance, in October, the Danish government announced that a planned hydrogen pipeline to Germany would not be established until 2031 at the earliest, whereas the previous target was scheduled for 2028.”
The fossil fuel industry has the advantage of a mature infrastructure. Imagine if we had to develop all the oil rigs, oil wells, pipelines, trucking infrastructure, and gas stations from scratch. That would be a massive investment on an uncertain timeline. Hydrogen is facing the same issue. Again, this is a solvable issue – invest in hydrogen infrastructure. Make sure projects are sufficiently funded to keep on the originally promised timeline. Governments are supposed to craft regulation and invest in common infrastructure in order to facilitate private industry investing in new technologies. This may be all that is necessary to accelerate the green transition. At least we shouldn’t be holding it back because governments are doing their job.
The authors of the paper also explore another aspect of this issue – incentives for industry to specifically invest in green technology. This is essentially what the IRA did in the US. Here incentives fall into two broad categories, carrots and sticks. One type of carrot is to reduce risk for private investment. Beyond what I already mentioned, government can, for example, guarantee loans to reduce financial risk. They can also provide direct subsidies, such as tax breaks for investments in green technology. For context, the fossil fuel industry received $1.4 trillion in 2022 in direct subsidies worldwide. It is also estimated that the fossil fuel industry was allowed to externalize $5.6 trillion in health and environmental costs (whether or not you consider this a “subsidy”). This is for a mature industry with massive profits sitting on top of a massive infrastructure partly paid for with public dollars. The bottom line is that some targeted subsidies for green energy technology is perfectly reasonable, and in fact is a good investment.
But the authors argue that this might not be enough. They also recommend we add some sticks to the equation. This usually takes the form of some type of carbon tax, which would make fossil fuels less profitable. This seems perfectly reasonable. They also recommend mandated phase out of fossil fuel investments. This is trickier, and I think this type of approach should be a last resort if anything. You won’t have to mandate a phase out if you make green technologies more attractive through subsidies and infrastructure, and fossil fuels less attractive by eliminating subsidies and perhaps taxing carbon.
At the very least governments should be not slowing down the green transition because they are neglecting to do their basic job.
The post Power-To-X and Climate Change Policy first appeared on NeuroLogica Blog.