ISRO preps for re-entry experiment of decommissioned satellite on March 7
Bengaluru ( PTI): The Indian Space Research Organisation (ISRO) is preparing for a challenging experiment of controlled re-entry of a decommissioned low earth orbit satellite, Megha-Tropiques-1 (MT1), into the earth's atmosphere on March 7.
MT1 was launched on October 12, 2011, as a joint satellite venture of ISRO and French space agency CNES for tropical weather and climate studies.
Although the mission life of the satellite was originally three years, the satellite continued to provide valuable data services for more than a decade supporting regional and global climate models till 2021, the Bengaluru-headquartered space agency noted in a statement on Sunday.
UN/IADC (Inter-Agency Space Debris Coordination Committee) space debris mitigation guidelines recommend deorbiting a LEO (Low Earth Orbit) object at its end-of-life (EOL), preferably through controlled re-entry to a safe impact zone, or by bringing it to an orbit where the orbital lifetime is less than 25 years, according to ISRO.
It is also recommended to carry out "passivation" of on-board energy sources to minimise the risk of any post-mission accidental break-up.
The orbital lifetime of MT1, weighing about 1,000 kilograms, would have been more than 100 years in its 20 degree inclined operational orbit of 867 km altitude. About 125 kg on-board fuel remained unutilised at its end-of-mission that could pose risks for accidental break-up.
This leftover fuel was estimated to be sufficient to achieve a fully-controlled atmospheric re-entry to impact an uninhabited location in the Pacific Ocean.
Controlled re-entries involve deorbiting to very low altitudes to ensure impact occurs within a targeted safe zone.
Usually, large satellites/rocket bodies which are likely to survive aero-thermal fragmentation upon re-entry are made to undergo controlled re-entry to limit ground casualty risk. However, all such satellites are specifically designed to undergo controlled re-entry at EOL.
MT1 was not designed for EOL operations through controlled re-entry which made the entire exercise extremely challenging.
Furthermore, the on-board constraints of the aged satellite, where several systems had lost redundancy and showed degraded performance, and maintaining subsystems under harsher environmental conditions at much lower than originally designed orbital altitude added to the operational complexities.
Innovative workarounds were implemented by the operations team based on the study, deliberations, and exchanges among the mission, operations, flight dynamics, aerodynamics, propulsion, controls, navigation, thermal, and other subsystem design teams across the ISRO centres, which worked in synergy to surmount these challenges.
An uninhabited area in the Pacific Ocean between 5 degrees south to 14 degrees south latitude and 119 degrees west to 100 degrees west longitude was identified as the targeted re-entry zone for MT1.
Since August 2022, 18 orbit manoeuvres were performed to progressively lower the orbit. In between the de-orbiting, aero-braking studies at different solar panel orientations were also carried out to gain better insights into the physical process of atmospheric drag affecting the orbital decay of the satellite.
The final de-boost strategy has been designed after taking into consideration several constraints, including visibility of the re-entry trace over ground stations, ground impact within the targeted zone, and allowable operating conditions of subsystems, especially the maximum deliverable thrust and the maximum firing duration of the thrusters.
The final two de-boost burns followed by the ground impact are expected to take place between 16.30 hours to 19.30 hours on March 7.
Simulations show that no large fragments of the satellites are likely to survive the aerothermal heating during the re-entry.
"As a responsible space agency committed to safe and sustainable operations in outer space, ISRO proactively takes efforts for better compliance with the UN/IADC space debris mitigation guidelines on post-mission disposal of LEO objects," the statement said.
The re-entry experiment of MT1 has been undertaken as a part of the ongoing efforts as this satellite with sufficient leftover fuel presented a unique opportunity to test the relevant methodologies and understand the associated operational nuances of post mission disposal by direct re-entry into the Earth's atmosphere, it was stated.
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MP HC sets up judicial commission to probe water contamination in Indore
Indore (PTI): The Indore bench of Madhya Pradesh High Court on Tuesday set up a commission of inquiry comprising a former HC judge to probe the issue of water contamination in city's Bhagirathpura, saying the matter requires probe by an independent, credible authority and "urgent judicial scrutiny".
It also directed the commission to submit an interim report after four weeks from the date of commencement of proceedings.
A division bench of Justices Vijay Kumar Shukla and Alok Awasthi constituted the commission while hearing several public interest litigations (PILs) filed simultaneously regarding the deaths of several people in Bhagirathpura due to the consumption of contaminated water.
The HC reserved the order after hearing all the parties during the day, and released it late at night.
The state government on Tuesday told the HC that the deaths of 16 people in Indore's Bhagirathpura area was possibly linked to a month-long outbreak of vomiting and diarrhoea caused by contaminated drinking water.
The government presented an audit report of 23 deaths from the current gastroenteritis epidemic in Bhagirathpura before the bench, suggesting that 16 of these fatalities may have been linked to the outbreak of vomiting and diarrhoea caused by contaminated drinking water.
The report, prepared by a committee of five experts from the city's Government Mahatma Gandhi Memorial Medical College, stated that the deaths of four people in Bhagirathpura were unrelated to the outbreak, while no conclusion could be reached regarding the cause of death of three other people in the area.
During the hearing, the high court sought to know from the state government the scientific basis behind its report.
The division bench also expressed surprise at the state government's use of the term "verbal autopsy" in relation to the report, sarcastically stating that it had heard the term for the first time.
The HC expressed concern over the Bhagirathpura case, stating that the situation was "alarming," and noted that cases of people falling ill due to contaminated drinking water have also been reported in Mhow, near Indore.
In its order, the HC said the serious issue concerning contamination of the drinking water supply in Bhagirathpura area allegedly resulted in widespread health hazards to residents, including children and elderly persons.
According to the petitioners and media reports, death toll is about 30 till today, but the report depicts only 16 without any basis or record, it said.
It is averred that sewage mixing, leakage in the pipeline, and failure of civic authorities to maintain potable water standards have led to the outbreak of water-borne diseases. Photographs, medical reports, and complaints submitted to the authorities prima facie indicate a matter requiring urgent judicial scrutiny, the HC said.
"Considering the gravity of the allegation and affecting the right to life under Article 21 of the Constitution of India and the need for an independent fact-finding exercise, the Court is of the opinion that the matter requires investigation by an independent, credible authority," it said.
"Accordingly, we appoint Justice Sushil Kumar Gupta, former judge of the Madhya Pradesh High Court, a one-man commission of inquiry into the issues relating to water contamination in Bhagirathpura, Indore, and its impact on other areas of the city," the HC added.
As per the order, the commission shall inquire into and submit a report on the cause of contamination -- whether the drinking water supplied to Bhagirathpura was contaminated; and the source and nature of contamination (sewage ingress, industrial discharge, pipeline damage etc).
The panel will also probe the number of actual deaths of affected residents on account of contaminated water; find out the nature of disease reported and adequacy of medical response and preventive measures; suggest immediate steps required to ensure safe drinking water as well as long-term infrastructural and monitoring reforms.
It will also identify and fix responsibility upon the officers and officials found prima facie responsible for the Bhagirathpura water contamination incident, and suggest guidelines for compensation to affected residents, particularly vulnerable sections.
The commission shall have powers of a civil court for the purpose of summoning officials and witnesses; calling up records from the government department, hospitals, laboratories and civic bodies; ordering water quality testing through accredited laboratories; conducting spot inspections.
All state authorities involving district administration, Indore Municipal Corporation, public health engineering department and Madhya Pradesh Pollution Control Board shall extend full co-operation and provide records as sought by the commission, it said.
The state government shall provide office space, staff, and logistical support to the commission, it said.
During the hearing in the day, the state government also presented a status report to the court in this matter.
According to reports, a total of 454 patients were admitted to local hospitals during the vomiting and diarrhea outbreak, of whom 441 have been discharged after treatment, and 11 are currently hospitalised.
According to officials, due to a leak in the municipal drinking water pipeline in Bhagirathpura, sewage from a toilet was also mixed in the water.
