The widespread explanations of the greenhouse effect taught to millions of schoolchildren are misleading. The objective of this work is to clarify how increasing CO2 produces warming in current times. It is found that there are two contexts for the greenhouse gas effect. In one context, the fundamental greenhouse gas effect, one imagines a dry Earth starting with no water or CO2 and adding water and CO2. This leads to the familiar “thermal blanket” that strongly inhibits IR transmission from the Earth to the atmosphere. The Earth is... much warmer with H2O and CO2. In the other context, the current greenhouse gas effect, CO2 is added to the current atmosphere. The thermal blanket on IR radiation hardly changes. But the surface loses energy primarily by evaporation and thermals. Increased CO2 in the upper atmosphere carries IR radiation to higher altitudes. The Earth radiates to space at higher altitudes where it is cooler, and the Earth is less able to shed energy. The Earth warms to restore the energy balance. The “thermal blanket” is mainly irrelevant to the current greenhouse gas effect. It is concluded that almost all discussions of the greenhouse effect are based on the fundamental greenhouse gas effect, which is a hypothetical construct, while the current greenhouse gas effect is what is happening now in the real world. Adding CO2 does not add much to a “thermal blanket” but instead, drives emission from the Earth to higher, cooler altitudes.Read more

The conventional method to send payloads to Mars is by direct trans-Mars injection (TMI) from LEO. NASA is considering an alternative of fueling large Mars-bound cargo transfer vehicles in cis-lunar space with propellants derived from the Moon by in situ propellant production (ISPP) prior to trans-Mars injection from cis-lunar space. A large team of investigators developed an Evolvable Lunar Campaign (ELC) that defined its strategic objective as follows:"The ELC strategic objective is commercial mining of propellant from lunar poles where ...it will be transported to lunar orbit to be used by NASA to send humans to Mars."Unfortunately, sending Mars-bound vehicles to cis-lunar space prior to trans-Mars injection saves little mass in LEO, unnecessarily includes lunar ISPP, which is costly, complex, and risky, and at the bottom line, has no benefits. The problem is that the amount of propellant needed to go from LEO to cis-lunar space is roughly comparable to the amount of propellant used for direct TMI from LEO, so the lunar-derived propellants only offset a small amount of propellant used to augment Mars Orbit Insertion and Entry, Descent, and Landing, and the amount of propellant required in LEO is almost the same in both cases. The initial mass in low Earth orbit (IMLEO) is not reduced much by utilizing lunar ISPP.At the bottom line, sending Mars-bound MCTV to cis-lunar space adds complexity, cost, and risk and provides essentially no benefits.Read more

The astronomical theory of ice ages is widely accepted. Yet, it is not abundantly clear just exactly what the astronomical theory of ice ages is, other than the vague statement that variations in the Earth's orbit produce changes in solar irradiance at northern latitudes which is somehow related to the formation and termination of ice ages. Periodic variations in the Earth’s orbit produce variations in the insolation at high latitudes and ice ages begin on down lobes of insolation and terminate on up lobes of insolation. However, not all ...down lobes create ice ages and not all up lobes produce terminations. The ice ages changed character at the so-called mid-Pleistocene transition, about a million years ago. There is no current physical explanation for these difficulties with the astronomical theory. A reasonable explanation has been developed, that solidifies the astronomical theory by explaining the rise and fall of ice ages in both eras. The solar power absorbed at high northern latitudes depends on the insolation and absorptivity of the surface. The absorptivity is particularly affected by the obliquity in the pre-MPT era, and by dust deposits late in the post-MPT era. When these are included, it can be explained why some down lobes produce ice ages, and some up lobes produce terminations in both eras. In the pre-MPT era, ice ages originate when the insolation enters a down lobe and the obliquity is minimal (higher reflectivity) and ice ages terminate at a coincidence of high insolation and high obliquity (lower reflectivity). These links between SIHL and obliquity tend to be repetitive with approximately 41,000-year spacing. In the post-MPT era, ice ages also originate at a down lobe of SIHL. However, once an ice age is started, each successive up lobe in SIHL might cause a slight decrease in ice volume but doesn’t bring about a termination. After several precession cycles, high dust levels increase absorptivity, and the next-up lobe produces a termination.Read more

The International Panel on Climate Change (IPCC) published a lengthy report on climate change in early 2023. This report hypothesizes five potential scenarios of greenhouse gas emissions from 2015 to the end of the century (2100) and estimates the global average temperature gain in the year 2100 from the mid-1800s for each scenario. The method of calculation in the IPCC report is obscure. The results are merely stated.The present paper provides a clear method for estimating the temperature gain each year from 2015 until 2100, along with yearly ...estimates of ppm of CO2. To facilitate the calculations, a set of scenarios of future emissions was chosen that is analogous to the scenarios used by the IPCC but is more amenable to computation.The basic assumption in this paper is that most of the temperature gain from the mid-1800s to 2015 (1.15 C – as reported by the IPCC) was due to rising CO2 concentration in the atmosphere and a relationship is thereby derived between warming and gigatons of CO2 emitted for the period: 1800s to 2015. If it is assumed that the amount of warming per gigaton CO2 from the past persists into the 21st century, then future warming in the 21st century can be estimated for any assumed future scenario of CO2 emissions.This paper provides a simple and clear estimate of yearly CO2 ppm and temperature rise from 2015 to 2100 since the 1800s for a set of scenarios that cover the likely range of future emissions.Read more

Studies of Mars missions over the past thirty years lacked credible cost estimates, so the total mass of materiel delivered to Low-Earth Orbit (LEO) was typically used as a rough measure of relative mission cost because the complexity of the mission was thought to be roughly proportional to the initial mass in LEO (IMLEO). Historically, high launch costs led to large investments in space hardware development which led to high space mission costs. Reducing mass became the central theme of space mission engineering. We are now entering a new era ...where launch costs no longer have the impact that they would have two decades ago. Launch costs are coming down to the point where we must ask ourselves whether it now makes sense to bring ascent propellants and life support resources from Earth (with higher reliability as a bonus), as opposed to using in situ propellant production and cycling of life support resources.This paper compares various options for bringing ascent propellants and life support resources from Earth vs. developing in situ. In short, it examines the “take it or make it” options for both technologies. For ISPP, the answer is clear: Mars ISPP is not worth the investment when launch costs are low. For life support, the most robust option is to bring life survival resources from Earth, and only use cycling to upgrade the quality of life for the crew.Read more

In recent years, SpaceX posted several glossy websites claiming they would implement a very ambitious human mission to Mars as early as 2028. This is an innovative mission concept using several 100 MT “Starships” to transport multiple 100 MT payloads to the Mars surface and return the crew directly to Earth without a rendezvous. Although many details are not available, it has been revealed that it would utilize 1,200 MT of CH4 and O2 propellants in LEO, and an additional 1,200 MT of ISRU-generated CH4 + O2 propellants on Mars for th...e return flight. The landed crew would number 12. It would land about six Starships on Mars, requiring about 72 heavy lift launches to fuel the vehicles in LEO. The challenges include landing a 200 MT loaded Starship on Mars, a massive water-based ISRU system to provide propellants on Mars, and launching many vehicles within a launch window. While reducing mass was a central theme years ago, launch costs have decreased sharply, and reducing mass is no longer a priority. The SpaceX mission maximizes mass to reduce risk and maximize accomplishments. In this study, an attempt was made to determine whether mass allocations for such a mission are feasible. The results suggest that it might be theoretically possible for SpaceX to carry out a variety of such missions. However, the SpaceX mission faces herculean challenges and probably is at least three decades away. Nevertheless, the general approach is probably more relevant today than the NASA architectures generated so far. The claim of landing humans on Mars in 2028 seems overly ambitious.Read more

The NASA approach for technology development for missions is to (1) wait for a mission need, and (2) upgrade the technology available at that time, however inadequate. This is illustrated with two important NASA technologies: in situ resource utilization (ISRU) and recycling wastewater. It also serves as a review with 49 references provided. NASA funding for ISRU has been sporadic and minimal, probably because no mission was being implemented that used ISRU. The state of the technology remains underdeveloped. For example, CO2 in the M...ars atmosphere supplies carbon and oxygen. However, we still do not have a viable system to acquire CO2 and compress it with acceptable power requirements and adequate lifetime.NASA technology for recycling wastewater was developed for the International Space Station. It requires frequent attention with replenishment and replacement of subsystems. This system appears to be inadequate for Mars missions and there is no evidence that NASA has a viable plan to fix that.Read more