Freitag, 10. Februar 2023 - 20:00

Raumfahrt - Start von ISRO’s SSLV-D2 is intended to inject EOS-07, Janus-1 and AzaadiSAT-2 satellites

5.01.2023

ISRO Chairman S Somnath said India is also planning to send scientific missions to Mars and Venus this year apart from attempting to send a Land Rover to the Moon.

ISRO’s Small Satellite Launch Vehicle (SSLV) may make its second flight next month. ISRO Chairman S Somnath told media at the 108th Indian Science Congress that he cannot tell any exact date yet but they are planning a test flight next month.

SSLV was intended to launch satellites up to 500 kg in planar orbit. But it had failed in its maiden development flight on August 7 last year. Both the satellites Earth Observation Satellite (EOS)-2 and Azadisat sent with the rocket could not be placed in the correct orbit and failed.

It did turnout to be a big disappointment not only for ISRO but also fore the whole country as the world was eyeing at India’s trail. Just like Mangalyaan (Mission Mars), Chandrayaan Mission would have also added another feather in India’s science technology. But however, after first failed attempt, ISRO is back in action.

ISRO Chairman S Somnath said India is also planning to send scientific missions to Mars and Venus this year apart from attempting to send a Land Rover to the Moon. He further said that Chandrayaan-3 spacecraft is almost ready with orbiter, lander and rover. But they are waiting for the right time to launch the mission, which is in June. “We will try our best to be successful this time,” said ISRO chairman.

A senior ISRO official said the space agency will also test the satellite-based Automatic Dependent Surveillance-Broadcast (ADS-B) receiver system on SSLV next month. He said the space-based ADS-B system will be tested in the SSLV test flight next month.

If India’s second attempt to reach moon is successful then India would become the fourth country after the US, the USSR and China to land on the moon. Also India became the first country to reach Mars in it’s first attempt on November 5, 2013.

Quelle: APN

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Update: 9.02.2023

SSLV-D2. ISRO set to launch second developmental flight of SSLV on Friday from Sriharikota

It is intended to inject EOS-07, Janus-1 and AzaadiSAT-2 satellites into 450 km circular orbit

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SSLV-D2, the second developmental flight of the Small Satellite Launch Vehicle (SSLV), is scheduled for launch at 9.18 am on February 10, 2023 from the first launch pad at SDSC SHAR, Sriharikota.

In it its 15-minute flight, SSLV-D2 is intended to inject EOS-07, Janus-1 and AzaadiSAT-2 satellites into 450 km circular orbit.

One of the major objectives of the mission is to demonstrate the designed payload capability of SSLV in Low Earth Orbit (LEO).

SSLV is capable of launching 500 kg satellites into LEOs on ‘launch-on-demand’ basis.

It provides low-cost access to space, offers low turn-around time and flexibility in accommodating multiple satellites, and demands minimal launch infrastructure. It is configured with three solid propulsion stages and a velocity terminal module. It is a 34 metre tall, 2 metre diameter vehicle having a lift-off mass of 120 ton, says a release from ISRO.

The EOS-07 is a 156.3 kg satellite designed, developed and realised by ISRO. New experiments include mm-Wave Humidity Sounder and Spectrum Monitoring Payload. Janus-1, a 10.2 kg satellite, belongs to ANTARIS, US. Janus-1 is a technology demonstrator, smart satellite mission, based on Antaris software platform.

The 8.7 kg satellite AzaadiSAT-2 is a combined effort of about 750 girl students across India guided by Space Kidz India, Chennai. It aims to demonstrate LoRa and Amateur Radio communication satellites, measure radiation levels in space and demonstrate expanding satellite structure, the release said.

The first developmental flight of SSLV lifted off from SDSC on August 7, 2022. The objective of the mission (SSLV-D1/EOS-02) was to inject EOS-02 satellite of ISRO into a circular orbit of 356.2 km with an inclination of 37.21 degrees.

Quelle: The Hindu

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Update: 10.02.2023

ISRO’s second SSLV mission successfully launches trio of satellites

India’s new SSLV rocket has successfully reached orbit on its second attempt Friday, six months after its maiden flight ended in failure. Friday’s launch carried a trio of satellites, lifting off at 9:18 AM local time (03:48 UTC) from the Satish Dhawan Space Centre.

The Small Satellite Launch Vehicle, or SSLV, has been developed by India to enable lower-cost and more rapidly responsive access to space for small satellite missions. It flew for the first time last August, however, an issue during stage separation meant that it could not achieve a stable orbit. As a result of that failure, changes were made to the rocket to give Friday’s launch a better chance of success.

As a demonstration flight, the principal objective of Friday’s launch were to prove SSLV’s ability to reach orbit, although the rocket also took three satellites along for the ride. The largest of these was Earth Observing Satellite-07 (EOS-07) for the Indian Space Research Organisation (ISRO). It was joined within SSLV’s payload fairing by the smaller AzaadiSAT-2 and Janus-1 spacecraft.

EOS-07 is the latest mission in ISRO’s Earth Observing Satellite (EOS) series, a loose collection of missions dedicated to collecting scientific data about our planet. EOS includes satellites that were formerly part of multiple programs — including Cartosat, Oceansat, and RISAT — as well as technology demonstrators like EOS-07. When the series began, satellites already in orbit were not renamed, so the first EOS satellite was EOS-01 — formerly RISAT-2BR2 — which was deployed by a PSLV rocket in November 2020.

The EOS-07 satellite will serve to demonstrate new technologies for future Earth-observing missions. While ISRO has not published many details about the satellite, it appears to be based on an Indian Mini Satellite 1 (IMS-1) derived bus, and it has a mass of 156.3 kilograms with an expected on-orbit lifetime of about a year. EOS-07 carries two instruments: the Millimetre-wave Humidity Sounder (MHS) and Spectrum Monitoring Payload (SMP).

AzaadiSAT-2 is the second satellite ISRO has launched for Space Kidz India, an organization aimed at giving students at schools and colleges in India the experience of building and operating space hardware. AzaadiSAT-2 replaces the organization’s first satellite, which was aboard SSLV’s unsuccessful maiden flight. In orbit, it will broadcast telemetry to amateur radio users and provide a store-and-forward communication capability. The satellite is also equipped with a number of student-built experiments including a low-resolution camera and radiation detector whose output will also be made available to amateur radio enthusiasts.

With a mass of about 8.7 kilograms, AzaadiSAT-2 is a rare example of an eight-unit (8U) CubeSat. The CubeSat standard, which has become ubiquitous for small satellite missions, consists of a series of form factors based around a cube with sides of 10 centimeters — which is defined as one unit. The size of a CubeSat is typically given in terms of the number of units of which it is comprised, so an 8U satellite would take up eight units — in the case of AzaadiSAT-2, arranged two by two by two — to give the overall satellite a cube shape with sides of 20 centimeters.

Janus-1 is also a CubeSat, although built to the more common 6U configuration, with sides measuring 10, 20, and 30 centimeters and a mass of 11.5 kilograms. Operated by US company Antaris Inc, it is intended to serve as a proof-of-concept for the company’s software platform. The satellite was developed in ten months and carries a suite of five experiments, including radio and optical communication, internet of things (IoT) data relay, and on-orbit machine learning. In another aspect of the mission, a virtual clone of the satellite’s software is being operated in a simulated mission, which Antaris will be able to compare with the operation of the real satellite to help refine its simulation technology.

Friday’s mission, which is designated SSLV D2, injected the three satellites into a circular low Earth orbit at an altitude of 450 kilometers at an inclination of 37.2 degrees. The mission lasted about fifteen minutes from liftoff to the final spacecraft separation.

SSLV is a four-stage vehicle, consisting of three solid-propellant stages designated SS1, SS2, and SS3, topped with a liquid-propellant fourth stage — called the Velocity Trimming Module (VTM) — which is responsible for ensuring an accurate insertion into the planned target orbit.

All three solid-fueled stages use a propellant formula based on hydroxyl-terminated polybutadiene (HTPB), with the motors designated S-85 for SS1, S-7 for SS2, and S-4 for SS3. The VTM burns monomethylhydrazine (MMH) and mixed oxides of nitrogen (MON3) — a mixture of 97% dinitrogen tetroxide and 3% nitric oxide.

The August 2022 launch of SSLV D1 — SSLV’s maiden flight. (Credit: ISRO)

After SSLV failed to reach orbit on its maiden flight last August, ISRO conducted a review of the mission to determine the cause of the failure and what lessons could be learned from it. This determined that although all three of the solid-propellant stages had operated as expected, a vibration during second stage separation disrupted the operation of the inertial navigation system (INS).

The vibration temporarily overloaded the six accelerometers that feed data to the INS to determine the rocket’s trajectory and orientation, causing them to provide differing and incorrect data. Although the problem was transient, it continued for long enough for the INS to determine that the sensors were faulty and that their input should be disregarded, and for the vehicle to enter its contingency “salvage mode.” Without input from the accelerometers, the rocket attempted to continue the mission using the expected mission parameters and timings.

Because data from the accelerometers was being ignored, the vehicle had no way to determine its acceleration or to ensure accurate orientation, which resulted in a shortfall of about 56 meters per second in its final velocity. This corresponded to an orbital perigee of 75.66 kilometers — within the atmosphere — instead of the planned 356 kilometers.

The report on SSLV D1’s failure made five recommendations that were implemented for Friday’s SSLV D2 mission. The separation system between the second and third stages has been changed from an expanding bellow type to a marman band with springs to push the stages apart. Changes have also been made to the equipment bay and satellite deck to adjust their resonant frequencies.

The INS has been modified to be more resilient in the face of transient events and to implement a longer delay before implementing salvage mode when sensor failures are detected. A new contingency mode will allow the rocket to be guided using position data from the Navigation with Indian Constellation (NavIC – formerly IRNSS) satellite navigation system before resorting to open-loop control. Finally, if the rocket is forced to fall back to salvage mode, it will include the capabilities of the VTM stage when calculating available performance.

ISRO plans to build dedicated launch facilities for SSLV, including a pad at a new spaceport near the town of Kulasekharapatnam that will allow direct access to polar orbits without the need to fly complex dog-leg trajectories that can limit a rocket’s payload capacity. For its initial test launches, however, SSLV is flying from the First Launch Pad (FLP) at the Satish Dhawan Space Centre. The FLP was built in the early 1990s for ISRO’s Polar Satellite Launch Vehicle (PSLV), with which SSLV shares the launch pad.

Integration of SSLV D1 at the First Launch Pad ahead of its August 2022 launch (Credit: ISRO)

The FLP is one of two active launch pads at the Satish Dhawan Space Centre, along with the Second Launch Pad (SLP), which is used by PSLV and Geosynchronous Satellite Launch Vehicle (GSLV) rockets. The center — formerly known as the Sriharikota High Altitude Range — has been the site of all of India’s orbital launches to date.

As Friday’s countdown reached zero, SSLV’s first stage ignited and the vehicle lifted off. Burning for about 114.6 seconds, SS1 provides the thrust that powers the vehicle through Earth’s atmosphere. Just over nine seconds after burnout, with the rocket at an altitude of 94 kilometers, the stage separation sequence began. This saw the SS2 stage ignite, followed three-tenths of a second later by the jettison of the spent first stage. Finally, five seconds after first stage separation, the second stage discarded its interstage.

The second stage burn lasted 124 seconds. SSLV’s payload fairing separated about 34 seconds into the burn, exposing the satellites to space for the first time. After the end of the burn, Friday’s mission entered a brief coast phase as the rocket climbed, before second stage separation took place at six minutes, 24.2 seconds mission elapsed time. The third stage ignited 9.8 seconds later for its 103.9-second burn.

After the third stage burned out, there was another 177-second coast phase before the third stage separated from the fourth. The fourth stage — the VTM — ignited eight and a half seconds later to complete orbital insertion. ISRO did not published the planned burn time for the VTM prior to Friday’s launch, however, it was a fairly short firing, with EOS-07 separating from the upper stage at the 13-minute, five-second mark in the mission — 102 seconds after the burn started.

Mission timeline for the SSLV D2 flight (Credit: ISRO)

Janus-1 was the next satellite to be deployed, separating 95 seconds after EOS-07. AzaadiSAT-2 followed 20 seconds later at fifteen minutes mission elapsed time.

Friday’s launch marked India’s first of 2023 and the country’s first orbital mission since November’s successful launch of a PSLV rocket with the EOS-06 satellite. Success for the SSLV D2 mission is a big step forwards for ISRO, proving the rocket that the organization hopes will help it to capture a larger proportion of the commercial launch industry. SSLV is expected to fly at least one more demonstration mission this year before it can be declared operational.

ISRO’s next launch is currently expected to take place in March. This could be the second OneWeb mission to launch aboard a GSLV Mk.III rocket, which was expected to occur early this year. A GSLV Mk.II mission is also scheduled, carrying NVS-01 — a replacement satellite for the NavIC navigation system. These missions require the same launch pad, so it is unclear if both will be able to take place in the same month; one of them will likely take place at a later date.

Quelle: NS

Raumfahrt - ISRO’s SSLV to make second flight next month, Chandrayaan-3 spacecraft almost ready Raumfahrt - Start von ISRO’s SSLV-D2 is intended to inject EOS-07, Janus-1 and AzaadiSAT-2 satellites

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