As part of NASA’s Mars Sample Return (MSR ) programme, the Perseverance rover has been collecting samples since it landed on the Red Planet in 2021, and the return was scheduled to happen in 2031. However, a NASA statement on April 15 suggests that the mission will have to be reworked with a simpler, less costly, and less risky alternative because of challenges to the original budget of $11 billion. This is also in response to the MSR Independent Review Board report of September 2023.
The objective of the mission is to understand the formation and evolution of our solar system and to prepare for future human explorations to Mars.
While sample collection after safe landing of the rover has been achieved, launching a rocket off another planet, which is unprecedented, and safely transporting the samples over 21 million km back to the earth is no small task. “We need to look outside the box to find a way ahead that is both affordable and returns samples in a reasonable time frame,” Bill Nelson, NASA Administrator, said in the statement.
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“This includes: an updated mission design with reduced complexity, improved resiliency, risk posture, stronger accountability and coordination, and an overall budget likely in the $8 billion to $11 billion range. Given the FY 2025 budget and anticipated budget constraints, as well as the need to maintain a balanced science portfolio, the current mission design will return samples in 2040,” the statement said.
CERN measures width of decaying W boson
A view of an ATLAS collision event in which a candidate W boson decays into a muon and a neutrino. The reconstructed tracks of the charged particles in the inner part of the ATLAS detector are shown as orange lines. The energy deposits in the detector’s calorimeters are shown as yellow boxes. The identified muon is shown as a red line. | Photo Credit: ATLAS/CERN
THE discovery of the Higgs boson in 2012, named after Peter Higgs, who had theorised it and who passed away recently, plugged the final missing piece in the Standard Model (SM), the most successful physical theory of fundamental forces and particles in the universe. Yet, the model fails to explain/accommodate several things such as gravity, the nature of dark matter, dark energy and the origin of matter-antimatter asymmetry at the cosmic scale to the anomalous magnetic moment of the muon, B meson decays, and the anomalous mass of the W boson.
Is there physics beyond this framework that would solve the universe’s remaining mysteries? One parameter that may hold clues about new physics phenomena is the “width” of the W boson, the electrically charged carrier of the weak force (the subatomic force that causes radioactive decay). A particle’s width is directly related to its lifetime and is a measure of how it decays into other particles. If the W boson decays in unexpected ways, such as into yet-to-be-discovered new particles, these will influence the measured width. Its value is precisely predicted by the SM on the basis of the strength of the charged weak force and the mass of the W boson. Any deviation from the prediction would imply new physics.
In a new study, the ATLAS collaboration measured the width of the W boson at CERN’s Large Hadron Collider (LHC) for the first time. The width had previously been measured at CERN’s Large Electron-Positron collider and Fermilab’s Tevatron collider, yielding an average value of 2,085±42 million electronvolts (MeV), consistent with the SM prediction of 2,088±1 MeV. Using proton- proton collision data at an energy of 7 tera electronvolts collected with the LHC in 2010, ATLAS measured the W boson’s width as 2,202±47 MeV. This is the most precise measurement to date made by a single experiment. Although larger, it is still statistically consistent with the SM prediction. Although the departure of the measured width from the prediction is not yet statistically significant, future measurements may alter the scenario.
Spectroscopy to tell asteroid from space junk
The upper stage of a Centaur rocket similar to one that may have been masquerading as an asteroid in the form of the object 2020 SO. | Photo Credit: NASA Glenn Research Center
WITH many upcoming surveys looking for near-earth objects (NEOs) such as asteroids, dozens of them are likely to be detected every night. But some of those objects may well be space junk. How to distinguish natural NEOs from space junk? The number of rocket launches and space missions has multiplied many folds worldwide since the first rocket was sent into space over six decades ago. It is therefore not unusual to find cast-off rocket parts in unexpected places, even in regions of space where scientists expect to find NEOs.
Adam Battle of the University of Arizona and collaborators have found a new use for an often used astronomical tool: spectroscopy. They revisited the space junk from a rocket body discarded in 1966, initially mistaken for an NEO, to devise ways to distinguish NEOs from space debris. This work was recently published in The Planetary Science Journal.
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In 2020, a survey named PAN-STARRS discovered an asteroid candidate that was named 2020 SO. Later, dynamical studies showed that it was the discarded upper stage of the Centaur-D rocket from NASA’s Surveyor 2 moon mission. Its low velocity relative to the earth and, later on, the noticeable effects of solar radiation pressure on its orbit gave rise to the suspicion that it could be an artificial object. The confirmation came when spectroscopic studies in December 2020 found that the object’s spectrum was similar to stainless steel (SS). On February 19, 2021, the object was removed from the Minor Planet Centre’s database.
Battle’s team searched for spectral signatures from 2020 SO and showed that 2020 SO’s colour is redder than is typical for most asteroids and is closer to three known Centaur-D rocket bodies now in the earth’s orbit. Further, the body of a Centaur-D rocket is largely covered in SS and a polymer called polyvinyl fluoride. The researchers compared the spectrum of 2020 SO to the spectrum of a known Centaur-D rocket and to laboratory spectra of SS and polyvinyl fluoride.
The spectrum of 2020 SO was found to be similar to that of SS, and it had the distinct absorption feature at 2.3 micrometres (2.3 ×10–6 m), characteristic of the polyvinyl fluoride spectrum. 2020 SO’s area-to-mass ratio, colour, and spectrum taken together pointed to the object being a rocket body rather than an asteroid. The authors have suggested the creation of a database of artificial-object spectra and laboratory studies of common spacecraft materials to take the spectroscopy technique to differentiate between artificial objects and NEOs a step further.
