Interplanetary contamination refers to biological contamination of a planetary body by a space probe or spacecraft, either deliberate or unintentional.
There are two types of interplanetary contamination:
- Forward contamination is the transfer of life and other forms of contamination from Earth to another celestial body.
- Back contamination is the introduction of extraterrestrial organisms and other forms of contamination into Earth's biosphere. It also covers infection of humans and human habitats in space and on other celestial bodies by extraterrestrial organisms, if such habitats exist.
The main focus is on microbial life and on potentially invasive species. Non-biological forms of contamination have also been considered, including contamination of sensitive deposits (such as lunar polar ice deposits) of scientific interest.[1] In the case of back contamination, multicellular life is thought unlikely but has not been ruled out. In the case of forward contamination, contamination by multicellular life (e.g. lichens) is unlikely to occur for robotic missions, but it becomes a consideration in crewed missions to Mars.[2]
Current space missions are governed by the Outer Space Treaty and the COSPAR guidelines for planetary protection. Forward contamination is prevented primarily by sterilizing the spacecraft. In the case of sample-return missions, the aim of the mission is to return extraterrestrial samples to Earth, and sterilization of the samples would make them of much less interest. So, back contamination would be prevented mainly by containment, and breaking the chain of contact between the planet of origin and Earth. It would also require quarantine procedures for the materials and for anyone who comes into contact with them.
https://en.wikipedia.org/wiki/Interplanetary_contamination
Dysgenics (also known as cacogenics)[1] is the study of factors producing the accumulation and perpetuation of defective or disadvantageous genes and traits in offspring of a particular population or species.[2][3]
The adjective "dysgenic" is the antonym of "eugenic". It was first used c. 1915 by David Starr Jordan, describing the supposed dysgenic effects of World War I.[4] Jordan believed that healthy men were as likely to die in modern warfare as anyone else and that war killed only the physically healthy men of the populace whilst preserving the disabled at home.[5]
In the context of human genetics, a dysgenic effect is the projected or observed tendency of a reduction in selection pressures and decreased infant mortality since the Industrial Revolution resulting in the increased propagation of deleterious traits and genetic disorders. Richard Lynn in his Dysgenics: Genetic Deterioration in Modern Populations (1996) identified three main concerns: deterioration in health, in intelligence, and in conscientiousness.
https://en.wikipedia.org/wiki/Dysgenics
Biotechnology risk is a form of existential risk that could come from biological sources, such as genetically engineered biological agents.[1][2] The origin of such a high-consequence pathogen could be a deliberate release (in the form of bioterrorism or biological weapons), an accidental release, or a naturally occurring event.
A chapter on biotechnology and biosecurity was published in Nick Bostrom's 2008 anthology Global Catastrophic Risks, which covered risks including as viral agents.[3] Since then, new technologies like CRISPR and gene drives have been introduced.
While the ability to deliberately engineer pathogens has been constrained to high-end labs run by top researchers, the technology to achieve this (and other astonishing feats of bioengineering) is rapidly becoming cheaper and more widespread. Such examples include the diminishing cost of sequencing the human genome (from $10 million to $1,000), the accumulation of large datasets of genetic information, the discovery of gene drives, and the discovery of CRISPR.[4] Biotechnology risk is therefore a credible explanation for the Fermi paradox.[5]
https://en.wikipedia.org/wiki/Biotechnology_risk
Biodiversity loss includes the extinction of species worldwide, as well as the local reduction or loss of species in a certain habitat, resulting in a loss of biological diversity. The latter phenomenon can be temporary or permanent, depending on whether the environmental degradation that leads to the loss is reversible through ecological restoration/ecological resilience or effectively permanent (e.g. through land loss). Global extinction is being driven by human activities which overreach beyond the planetary boundaries as part of the Anthropocene and has so far been proven to be irreversible.
Even though permanent global species loss is a more dramatic and tragic phenomenon than regional changes in species composition, even minor changes from a healthy stable state can have dramatic influence on the food weband the food chain insofar as reductions in only one species can adversely affect the entire chain (coextinction), leading to an overall reduction in biodiversity, possible alternative stable states of an ecosystem notwithstanding. Ecological effects of biodiversity are usually counteracted by its loss. Reduced biodiversity in particular leads to reduced ecosystem services and eventually poses an immediate danger for food security, but also can have more lasting public health consequences for humans.[1]
International environmental organizations have been campaigning to prevent biodiversity loss for decades, public health officials have integrated it into the One Health approach to public health practice, and increasingly preservation of biodiversity is part of international policy. For example, the UN Convention on Biological Diversity is focused on preventing biodiversity loss and proactive conservation of wild areas. The international commitment and goals for this work is currently embodied by Sustainable Development Goal 15 "Life on Land" and Sustainable Development Goal 14 "Life Below Water". However, the United Nations Environment Programme report on "Making Peace with Nature" released in 2020 found that most of these efforts had failed to meet their international goals.[2]
https://en.wikipedia.org/wiki/Biodiversity_loss
The Year 2038 problem (also called Y2038, Epochalypse,[1][2] Y2k38, Y2038 erroror Unix Y2K) relates to representing time in many digital systems as the number of seconds passed since 00:00:00 UTC on 1 January 1970 and storing it as a signed 32-bit integer. Such implementations cannot encode times after 03:14:07 UTC on 19 January 2038. Similar to the Y2K problem, the Year 2038 problem is caused by insufficient capacity used to represent time
Cause[edit]
The latest time since 1 January 1970 that can be stored using a signed 32-bit integer is 03:14:07 on Tuesday, 19 January 2038 (231−1 = 2,147,483,647 seconds after 1 January 1970).[3]
Programs that attempt to increment the time beyond this date will cause the value to be stored internally as a negative number, which these systems will interpret as having occurred at 20:45:52 on Friday, 13 December 1901 (2,147,483,648 seconds before 1 January 1970) rather than 19 January 2038. This is caused by integer overflow, during which the counter runs out of usable binary digits or bits, and flips the sign bit instead. This reports a maximally negative number, and continues to count up, towards zero, and then up through the positive integers again. Resulting erroneous calculations on such systems are likely to cause problems for users and other reliant parties.
Early problems[edit]
In May 2006, reports surfaced of an early manifestation of the Y2038 problem in the AOLserver software. The software was designed with a kludge to handle a database request that should "never" time out. Rather than specifically handling this special case, the initial design simply specified an arbitrary time-out date in the future. The default configuration for the server specified that the request should time out after one billion seconds. One billion seconds (approximately 32 years) after 01:27:28 UTC on 13 May 2006 is beyond the 2038 cutoff date. Thus, after this time, the time-out calculation overflowed and returned a date that was actually in the past, causing the software to crash. When the problem was discovered, AOLServer operators had to edit the configuration file and set the time-out to a lower value.[4][5]
Players of games or apps which are programmed to impose waiting periods[6] are running into this problem when the players try to bypass the waiting period by setting the date on their devices to a date past 19 January 2038, but are unable to do so, since a 32-bit Unix time format is being used.
Vulnerable systems[edit]
Embedded systems that use dates for either computation or diagnostic logging are most likely to be affected by the 2038 problem.[7]
Many transportation systems from flight to automobiles use embedded systems extensively. In automotive systems, this may include anti-lock braking system (ABS), electronic stability control (ESC/ESP), traction control (TCS) and automatic four-wheel drive; aircraft may use inertial guidance systems and GPS receivers.[note 1] However, this does not imply that all these systems will suffer from the Y2038 problem, since many such systems do not require access to dates. For those that do, those systems which only track the difference between times/dates and not absolute times/dates will, by the nature of the calculation, not experience a major problem. This is the case for automotive diagnostics based on legislated standards such as CARB (California Air Resources Board).[8]
Another major use of embedded systems is in communications devices, including cell phones and Internet appliances (routers, wireless access points, IP cameras, etc.) which rely on storing an accurate time and date and are increasingly based on UNIX-like operating systems. For example, the Y2038 problem makes some devices running 32-bit Android crash and not restart when the time is changed to that date.[9]
Despite the modern 18–24 month generational update in computer systems technology, embedded systems are designed to last the lifetime of the machine in which they are a component. It is conceivable that some of these systems may still be in use in 2038. It may be impractical or, in some cases, impossible to upgrade the software running these systems, ultimately requiring replacement if the 32-bit limitations are to be corrected.
MySQL database's built-in functions like UNIX_TIMESTAMP() will return 0 after 03:14:07 UTC on 19 January 2038.[10]
Early Mac OS X versions[11] are susceptible to the Year 2038 problem.
Data structures with time problems[edit]
Many data structures in use today have 32-bit time representations embedded into their structure. A full list of these data structures is virtually impossible to derive but there are well-known data structures that have the Unix time problem:
- file systems (many file systems use only 32 bits to represent times in inodes)
- binary file formats (that use 32-bit time fields)
- databases (that have 32-bit time fields)
- database query languages, like SQL that have
UNIX_TIMESTAMP()-like commands
Examples of systems using data structures that may contain 32-bit time representations include:
- embedded factory, refinery control and monitoring subsystems
- assorted medical devices
- assorted military devices
Any system making use of data structures containing 32-bit time representations will present risk. The degree of risk is dependent on the mode of failure.
Possible solutions [edit]
There is no universal solution for the Year 2038 problem. For example, in the C language, any change to the definition of the time_t data type would result in code-compatibility problems in any application in which date and time representations are dependent on the nature of the signed 32-bit time_tinteger. For example, changing time_t to an unsigned 32-bit integer, which would extend the range to 2106 (specifically, 06:28:15 UTC on Sunday, 7 February 2106), would adversely affect programs that store, retrieve, or manipulate dates prior to 1970, as such dates are represented by negative numbers. Increasing the size of the time_t type to 64 bits in an existing system would cause incompatible changes to the layout of structures and the binary interface of functions.
Most operating systems designed to run on 64-bit hardware already use signed 64-bit time_t integers. Using a signed 64-bit value introduces a new wraparound date that is over twenty times greater than the estimated age of the universe: approximately 292 billion years from now. The ability to make computations on dates is limited by the fact that tm_year uses a signed 32-bit integer value starting at 1900 for the year. This limits the year to a maximum of 2,147,485,547 (2,147,483,647 + 1900).[12]
FreeBSD uses 64-bit time_t for all 32-bit and 64-bit architectures except 32-bit i386, which uses signed 32-bit time_t instead.[13]
Starting with NetBSD version 6.0 (released in October 2012), the NetBSD operating system uses a 64-bit time_t for both 32-bit and 64-bit architectures. Applications that were compiled for an older NetBSD release with 32-bit time_t are supported via a binary compatibility layer, but such older applications will still suffer from the Year 2038 problem.[14]
OpenBSD since version 5.5, released in May 2014, also uses a 64-bit time_t for both 32-bit and 64-bit architectures. In contrast to NetBSD, there is no binary compatibility layer. Therefore, applications expecting a 32-bit time_t and applications using anything different from time_t to store time values may break.[15]
Linux originally used a 64-bit time_t for 64-bit architectures only; the pure 32-bit ABI was not changed due to backward compatibility.[16] Starting with version 5.6, 64-bit time_t is supported on 32-bit architectures, too. This was done primarily for the sake of embedded Linux systems.[17]
The x32 ABI for Linux (which defines an environment for programs with 32-bit addresses but running the processor in 64-bit mode) uses a 64-bit time_t. Since it was a new environment, there was no need for special compatibility precautions.[16]
While the native APIs of OpenVMS can support timestamps up to the 31st of July 31086,[18] the C runtime library (CRTL) uses 32-bit integers for time_t.[19] As part of Y2K compliance work that was carried out in 1998, the CRTL was modified to use unsigned 32-bit integers to represent time; extending the range of time_t up to the 7th of February 2106.[20]
Network File System version 4 has defined its time fields as struct nfstime4 {int64_t seconds; uint32_t nseconds;} since December 2000.[21] Values greater than zero for the seconds field denote dates after the 0-hour, January 1, 1970. Values less than zero for the seconds field denote dates before the 0-hour, January 1, 1970. In both cases, the nseconds (nanoseconds) field is to be added to the seconds field for the final time representation.
Alternative proposals have been made (some of which are already in use), such as storing either milliseconds or microseconds since an epoch (typically either 1 January 1970 or 1 January 2000) in a signed 64-bit integer, providing a minimum range of 300,000 years at microsecond resolution.[22][23] In particular, Java's use of 64-bit long integers everywhere to represent time as "milliseconds since 1 January 1970" will work correctly for the next 292 million years. Other proposals for new time representations provide different precisions, ranges, and sizes (almost always wider than 32 bits), as well as solving other related problems, such as the handling of leap seconds. In particular, TAI64[24] is an implementation of the International Atomic Time (TAI) standard, the current international real-time standard for defining a second and frame of reference.
See also[edit]
- GPS week number rollover that happens in November 2038
- Deep Impact is believed to have been lost at the time its internal clock reached 232 100-millisecond intervals (one-tenth second) since 2000, on 11 August 2013, 00:38:49 UTC.
- Time formatting and storage bugs
Notes[edit]
- ^ GPS suffers its own time counter overflow problem known as GPS Week Number Rollover.
https://en.wikipedia.org/wiki/Year_2038_problem
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